所用的思想是在mvc模式下进行开发，主要涉及到的内容有：jsP、javaBean、Servlet、JDBC、以及前端 CSS、js，从具体实施来看主要涉及到的知识有：对jsp主要内置对象的熟练使用。例如，request请求、response响应、session会话、以及利用cookie来进行免登录，EL表达式，JSTL标签,Filter过滤器，Listener监视器，前端的灵活使用等。

2.系统主要用到的数据库表

admins(管理员)表 管理员相关信息

Books(图书)表 记录图书相关信息

Students（学生）表 记录学生相关信息

Borrows(借书)表 记录借阅相关信息

3.主要功能

此次系统分为两个板块，管理员和用户。管理员主要进行用户和图书的增删改查，用户则进行借还操作。

下面简述两者主要功能及实现方法，具体可见后文详解。

管理员：

增加学生、删除学生、查看学生、添加图书、修改图书、删除图书、查看图书

对学生的增删查，主要是在ManageStudent.Servlet里面进行。另外有专门处理学生的数据库类Student.Dao,首先增加和查看功能，直接利用前端提交的post请求，通过method字段在servlet里执行相对应的方法，将结果最终呈现在jsp页面中。至于删除的功能则是利用前端提交的get请求，将学生信息绑定在服务器前台,在后端通过request获取到相应数据，执行删除的方法。

对图书的增删改查类似以上机制，主要是在ManageBook.Servlet里面进行。同理也有Book.Dao,增删基本同添加学生一致。查看这里涉及到分页查看的机制，分页查看利用limit限制条件，对每次浏览的记录分条处理。通过后端每次传输的页值，将结果存储到session会话中，在jsp页面里，通过获取存储的对象输出到浏览器中。至于修改同查看一样，只不过这里，要将原先数据存到文本框内，需要通过get请求，将绑定的数据存储到会话中，然后重定向要修改的页面，中间借用EL表达式比较简洁。

用户：

查看图书、借书、借阅信息查看、还书、查看个人信息

当用户登录成功后，在左边功能框可查看所有图书信息，也可以查看具体类别的图书，这里主要是在userchoise.Servlet里面执行，当用户点击具体某类图书时，会将图书类别传输到服务器端，在servlet里面通过request获取类别，然后调用Book.Dao里面的方法将结果进行封装，在show.jsp页面里通过获取图书对象进行显示。每条图书信息后面附有借书操作功能，主要在Borrow.servlet里面进行，通过get机制将用户信息和图书信息上传到服务器，在servlet里面获取，然后利用Bean来声名对象，对借阅书籍进行更改，同时通过调用borrow.Dao，对图书信息数量进一步修改。

借阅信息的查看可直接在相应jsp里面，根据用户信息调用相应的Dao方法，来获取借阅书籍信息显示当浏览器上。在借阅信息里面可对图书进行归还操作，主要使用return.Servlet，在前端通过get机制，将学生信息和书籍信息上传到服务器端。在后端通过request获取，然后借用borrow.Dao，里面的方法对书籍数量进一步修改。查看个人信息比较见到，直接通过session会话，将事先绑定好的用户信息，直接读取，显示在相应页面中。

3.1管理员功能

管理员主要管理学生和图书，在其项目里面有managestudent.servlet和managebook.servlet两个主要的servlet类。通过前端提供不同的请求来响应对应servlet里面的方法。

3.11登录

首先是管理员需要登录验证，判断数据库中是否有管理员账号相关信息。此次开发中，管理员账号为事先在数据库中录入，不支持注册和记住密码。管理员登录，需要请求adminlogin.servlet处理登录信息，如下（账号：admin 密码：admin）：

图1- 1 管理员登录页面

若输入错误密码，则会提示密码错误重新登录（账号：admin 密码：123456）：

图1- 2 管理员登录错误页面

3.12添加学生

添加学生功能，主要涉及到 student.dao（主要对学生进行数据库操纵，jdbc代码），student.bean(封装保存学生的基本信息)，managestudent.servlet(用来后端操作控制添加学生信息的功能)以及addstusent.jsp（添加学生信息的前端页面）。添加信息的时候注意每项信息不能为空、以及添加的学生信息原数据库中是否有信息等需要在servlet里面做出判断。核心就是student.dao里面的连接数据库操纵语言，以及managestudent.servlet里面的对信息进行控制封装。如下：

图1-3 addstudent.jsp

3.13查看学生

查看学生功能是将数据库中的所有学生信息，展现在前端页面。这里主要涉及到studentDao、managestudent.servlet、student.javabean、showstudent.jsp等，在这里另外增加了一个分页查看的功能，主要思想就是在数据库里查询的时候将其分割，limit（beginpage，pagesize），然后通过查询的所有记录count/pagesize，得出总共的页数,然后在pageservlet里面，整理，最后输出到前端页面。

3.14删除学生

管理员可以删除选中的学生，主要是利用前端绑定的机制，在get模式下，绑定用户的信息，通过前端传入的值，在后端进行相应的处理，在数据库中进行删除学生。所涉及到的类和前面几乎一致，不再重述。

3.15添加书籍

添加书籍类似添加学生，book.javabean（存有图书信息），managebook.Servlet(图书管理的servlet)，以及对应的jsp页面.

3.16查看书籍

管理员可查看所有图书信息。

在show_book.jsp里面同时包含修改和删除图书的功能。两个方法对应不同的链接，跳转到相应的servlet中，在处理更改的时候需要用到重定向方法，将原先存到session中的数据，重定向到一个页面进行修改，同时该页面，要保留原有的信息，可以使用EL表达式来进行处理。

3.2用户端功能

3.2.1登录

用户登录页面同管理员登录页面一致，且在同一个jsp里，分两个fORM表单完成。在用户登录界面增加了注册、和记住密码的功能。首先看登录功能，用户输入账号和密码，前端将数据提交到后端的userloginServlet来进行处理，通过后端的处理与数据库中的结果作比较。验证登录是否成功，下图为登录成功界面。

在用户进行登录的时候有一个复选框，为记住密码的操作。当用户点击记住密码的时候，下次登录不用在输入账号密码，直接点击登录即可。这是利用cookie的机制，通过创建cookie，将账号信息保存到硬盘中。此次系统设计的cookie时间为三天。具体效果如下:

3.2.2注册

注册功能同管理员添加学生一致，只不过这个注册会跳转到userloginsrvlet里面进行处理。结合数据库往里边添加数据，同时也会对，信息是否填写完整，以及原有数据库里面是否有数据做出判断。

3.2.3查询图书

等用户登录成功后，即可看到左面功能栏里面的功能，最上面的就是查看所有图书功能，接下来的一系列则是根据图书类别进行查看图书，方便用户浏览，快速查找结果。里面的一些显示功能主要是，利用超链接的target，来将查询的结果输出到，showBook.jsp页面上。

3.2.4借阅书籍

每个书籍后面附有借书操作的功能，借阅实现的方法主要是，利用前端绑定机制，将用户的信息，和图书信息整合到一块，后端来进行获取。

当borrowservlet，接收到用户信息和图书信息后，通过studentBean,bookBean以及borrowBean，来对借阅功能进行封装处理，这时需要borrowdao来进行数据库的读写操作。

在这里设置每位用户最大借阅量为10本，所以在servlet里面，做出判断借阅量是否大于最大借阅书籍量。来响应用户是否还能继续借阅。若能借阅的话，则通过后台，处理Bean数据，用户借阅量发生变化，图书量也发生变化。

3.2.5借阅信息查询

借阅信息查询这个页面中，可以显示所有借的图书信息，并且在这个页面附有还书的功能，借阅信息主要是利用BorrowServlet和BorrowDAO里面根据用户信息，来获取当前用户下共计的借阅量。

3.2.6还书

还书对应的则是returnservlet,根据用户信息，以及图书信息，来做出合理的判断，在通过BorrowDao,里面的数据库操作对借书量，图书量数据上做出相应的改变。

3.2.7我的基本信息

在我的基本信息里面可以查看除密码以外的所有信息，包括当前借阅量，可借图书量等。具体实施为通过后台数据库将个人信息展现到页面上。

4.代码部分

4.1 dao类

adminDao

package com.demo.dao;import com.demo.javabean.*;import java.sql.SQLException;public class AdminDAO {DBAccess db ;public boolean valid(String username, String passWord) {boolean isValid = false;db=new DBAccess();if(db.createConn()) {try {String sql="select * from admins where admin=? and password=?";db.pre=db.getConn().prepareStatement(sql);db.pre.setString(1, username);db.pre.setString(2, password);db.setRs(db.pre.executeQuery());if(db.getRs().next()){isValid=true;}}catch (Exception e) {// TODO: handle exception}finally {db.closeRs();try {db.pre.close();} catch (SQLException e) {// TODO 自动生成的 catch 块e.printStackTrace();}db.closeConn();}}return isValid ;}public boolean isExist(String username) {boolean isExist = false;db = new DBAccess();if(db.createConn()) {try {String sql="select * from admins where admin=?";db.pre=db.getConn().prepareStatement(sql);db.pre.setString(1,username );db.setRs(db.pre.executeQuery());if(db.getRs().next()){isExist=true;}} catch (Exception e) {// TODO: handle exception}finally {db.closeRs();if(db.pre!=null){try {db.pre.close();} catch (Exception e2) {// TODO: handle exception}}db.closeConn();}}return isExist;}}

BookDao

package com.demo.dao;import com.demo.javabean.*;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;public class BookDAO  {DBAccess db;private Books book;public ArrayList getAllBooks() throws Exception{db=new DBAccess();//db.setSql("SELECT * FROM books");ArrayList books = new ArrayList();if(db.createConn()){//db.query(sql);String sql= "SELECT * FROM books";db.query(sql);while(db.getRs().next()){book = this.assemble(db.getRs());books.add(book);}}db.closeRs();db.closeStm();db.closeConn();return books;}public ArrayList getBooksByCateGory(String category) throws Exception{//在这里进行分页判断ArrayList books = new ArrayList();DBAccess db=new DBAccess();java.sql.PreparedStatement pre = null;if(db.createConn()){//db.query(sql);String sql = "select * from books where category = ? ";pre=db.getConn().prepareStatement(sql);pre.setString(1, category);//pre.setInt(2, (page-1)*Students.PAGE_SIZE);//pre.setInt(3, Students.PAGE_SIZE);db.setRs(pre.executeQuery());while(db.getRs().next()){book = this.assemble(db.getRs());books.add(book);}}db.closeRs();db.closeStm();pre.close();db.closeConn();int a=books.size();System.out.println(a);return books;}public void addBook(String name,String author,String intro,String amount,String category) throws Exception{// boolean flag = false;DBAccess db = new DBAccess();if(db.createConn()){String sql = "insert into books(name,author,intro,amount,category) values('"+name+"','"+author+"','"+intro+"','"+amount+"','"+category+"')";db.update(sql);db.closeStm();db.closeConn();}}public boolean delbook(String name)throws Exception{//删除书籍DBAccess db = new DBAccess();boolean flag=false;if(db.createConn()){//db.setSql("delete from books where name = ?");String sql="delete from books where name = ?";db.pre=db.getConn().prepareStatement(sql);db.pre.setString(1, name);if(db.pre.executeUpdate()>0)flag=true;//String sql = "delete from books where name = '"+name+"'";//db.update(sql);//db.closeStm();//db.closeConn();}db.closeRs();db.closeStm();db.pre.close();db.closeConn();return flag;}public boolean isExist(String name) {boolean isExist = false;DBAccess db = new DBAccess();if(db.createConn()) {String sql = "select * from books where name='"+name+"'";db.query(sql);if(db.next()) {isExist = true;}db.closeRs();db.closeStm();db.closeConn();}return isExist;}public boolean updateBook(Books book) throws Exception{//借还更新 主要书籍数量boolean flag = false;DBAccess db=new DBAccess();String sql = "UPDATE books SET amount=? WHERE id=?";java.sql.PreparedStatement pre=null;if(db.createConn()){pre=db.getConn().prepareStatement(sql);//conn = OpenConnection.getConnection();// ps = conn.prepareStatement(sql_str);pre.setInt(1,book.getAmount());pre.setInt(2,book.getId());if(pre.executeUpdate() > 0) flag = true;}db.closeRs();db.closeStm();pre.close();db.closeConn();// this.release();// OpenConnection.closeConnection(conn);return flag;}public boolean updateBook2(Books book) throws Exception{//修改更新 修改图书信息boolean flag = false;DBAccess db=new DBAccess();//db.setSql("UPDATE books SET name=?,author=?,amount=?,category=? where id=?");if(db.createConn()){String sql="UPDATE books SET name=?,author=?,amount=?,category=? where id=?";db.pre=db.getConn().prepareStatement(sql);db.pre.setString(1, book.getName());db.pre.setString(2, book.getAuthor());db.pre.setInt(3, book.getAmount());db.pre.setString(4, book.getCategory());db.pre.setInt(5, book.getId());if(db.pre.executeUpdate() > 0) flag = true;}db.closeRs();db.closeStm();db.pre.close();db.closeConn();return flag;}public Books getBookById(int id) throws Exception{DBAccess db=new DBAccess();String sql = "SELECT * FROM books WHERE id = ?";java.sql.PreparedStatement pre=null;if(db.createConn()){pre=db.getConn().prepareStatement(sql);// conn = OpenConnection.getConnection();// ps = conn.prepareStatement(sql_str);pre.setInt(1,id);db.setRs(pre.executeQuery());if (db.getRs().next()) book = this.assemble(db.getRs());}db.closeRs();db.closeStm();pre.close();db.closeConn();//this.release();// OpenConnection.closeConnection(conn);return book;}public Books assemble(ResultSet rs) throws Exception{book = new Books();book.setId(rs.getInt("id"));book.setName(rs.getString("name"));book.setAuthor(rs.getString("author"));book.setIntro(rs.getString("intro"));book.setAmount(rs.getInt("amount"));book.setCategory(rs.getString("category"));return book;}public ArrayList findAll(Integer page){//分页查询信息DBAccess  db=new DBAccess();ArrayList list=new ArrayList();try {if(db.createConn()){String sql="select  * from books limit ?,? ";db.pre=db.getConn().prepareStatement(sql);db.pre.setInt(1, (page-1)*Students.PAGE_SIZE);db.pre.setInt(2, Students.PAGE_SIZE);db.setRs(db.pre.executeQuery());while(db.getRs().next()){Books book=new Books();book.setId(db.getRs().getInt("id"));book.setName(db.getRs().getString("name"));book.setAuthor(db.getRs().getString("author"));book.setCategory(db.getRs().getString("category"));book.setAmount(db.getRs().getInt("amount"));list.add(book);}db.closeRs();db.pre.close();db.closeConn();}} catch( SQLException e) {e.printStackTrace();}return list;}public ArrayList getBooksByCategory(String category,Integer page) throws Exception{//在这里进行分页判断(学生端)ArrayList books = new ArrayList();DBAccess db=new DBAccess();java.sql.PreparedStatement pre = null;if(db.createConn()){//db.query(sql);String sql = "select * from books where category = ? limit ?,?";pre=db.getConn().prepareStatement(sql);pre.setString(1, category);pre.setInt(2, (page-1)*Students.PAGE_SIZE);pre.setInt(3, Students.PAGE_SIZE);db.setRs(pre.executeQuery());while(db.getRs().next()){book = this.assemble(db.getRs());books.add(book);}}db.closeRs();db.closeStm();pre.close();db.closeConn();int a=books.size();System.out.println(a);return books;}public int countPage(String singal){//查询记录总数DBAccess  db=new DBAccess();int count=0;try {if(db.createConn()){String sql;if(!"1".equals(singal)){sql="select count(*) from books where category=?";db.pre=db.getConn().prepareStatement(sql);db.pre.setString(1, singal);db.setRs(db.pre.executeQuery());}else {sql="select count(*) from books";db.pre=db.getConn().prepareStatement(sql);db.setRs(db.pre.executeQuery());}if(db.getRs().next()){count=db.getRs().getInt(1);}}} catch( SQLException e) {e.printStackTrace();}finally {db.closeRs();try {if(db.pre!=null){db.pre.close();}} catch (Exception e2) {// TODO: handle exception}db.closeConn();}return count;}}

BorrowDao

package com.demo.dao;import com.demo.javabean.*;import java.sql.ResultSet;import java.util.ArrayList;import com.demo.javabean.DBAccess;public class BorrowDAO  {    private Borrows borrow = null;    public ArrayList getAllBorrows() throws Exception{    DBAccess db=new DBAccess();    java.sql.PreparedStatement pre=null;       String sql = "SELECT * FROM borrows";        ArrayList borrows = new ArrayList();        //conn = OpenConnection.getConnection();       // ps = conn.prepareStatement(sql_str);        //rs = ps.executeQuery();if(db.createConn()){pre=db.getConn().prepareStatement(sql);db.setRs(pre.executeQuery());//db.query(sql);        while(db.getRs().next()) {            borrow = this.assemble(db.getRs());            borrows.add(borrow);        }}        //this.release();db.closeRs();db.closeStm();db.closeConn();       // OpenConnection.closeConnection(conn);        return borrows;    }    public ArrayList getBorrowsBySId(int s_id) throws Exception{        ArrayList borrows = new ArrayList();        DBAccess db=new DBAccess();        java.sql.PreparedStatement pre=null;       String sql = "SELECT * FROM borrows WHERE s_id = ?";       if(db.createConn()){       pre=db.getConn().prepareStatement(sql);       pre.setInt(1, s_id);       db.setRs(pre.executeQuery());        while (db.getRs().next()){            borrow = this.assemble(db.getRs());            borrows.add(borrow);        }       }       db.closeRs();       db.closeStm();       pre.close();       db.closeConn();        return borrows;    }    public boolean addBorrows(Borrows borrow) throws Exception{        boolean flag = false;        DBAccess db=new DBAccess();        java.sql.PreparedStatement pre=null;        String sql = "INSERT INTO borrows VALUES(?,?,?)";        if(db.createConn()){        pre=db.getConn().prepareStatement(sql);               // conn = OpenConnection.getConnection();       // ps = conn.prepareStatement(sql_str);        pre.setInt(1,borrow.getS_id());        pre.setInt(2,borrow.getB_id());        pre.setInt(3,borrow.getAmount());        if(pre.executeUpdate() > 0)  flag = true;        }        //this.release();        db.closeRs();        pre.close();        db.closeConn();        //OpenConnection.closeConnection(conn);        return flag;    }    public boolean deleteBorrow(Borrows borrow) throws Exception{        boolean flag = false;        DBAccess db=new DBAccess();        java.sql.PreparedStatement pre=null;        String sql = "DELETE FROM borrows WHERE s_id = ? AND b_id = ? AND amount = ?";        if(db.createConn()){        pre=db.getConn().prepareStatement(sql);                        //conn = OpenConnection.getConnection();        //ps =conn.prepareStatement(sql_str);        pre.setInt(1,borrow.getS_id());        pre.setInt(2,borrow.getB_id());        pre.setInt(3,borrow.getAmount());        if(pre.executeUpdate() > 0) flag = true;        }        return flag;    }    public Borrows getBorrowById(int s_id, int b_id) throws Exception{    DBAccess db=new DBAccess();        String sql = "SELECT * FROM borrows WHERE s_id = ? AND b_id = ?";        java.sql.PreparedStatement pre=null;        if(db.createConn()){        pre=db.getConn().prepareStatement(sql);                //conn = OpenConnection.getConnection();        //ps = conn.prepareStatement(sql_str);        pre.setInt(1,s_id);        pre.setInt(2,b_id);        //rs = ps.executeQuery();        db.setRs(pre.executeQuery());        if(db.getRs().next()) borrow = this.assemble(db.getRs());        }        db.closeRs();        db.closeStm();        pre.close();        db.closeConn();       // this.release();       // OpenConnection.closeConnection(conn);        return borrow;    }   public boolean updateBorrow(Borrows borrow) throws  Exception{        boolean flag = false;        DBAccess db=new DBAccess();        String sql = "UPDATE borrows SET amount = ? WHERE s_id = ? AND b_id = ?";        java.sql.PreparedStatement pre=null;        if(db.createConn()){        pre=db.getConn().prepareStatement(sql);                //conn = OpenConnection.getConnection();       // ps = conn.prepareStatement(sql_str);        pre.setInt(1,borrow.getAmount());        pre.setInt(2,borrow.getS_id());        pre.setInt(3,borrow.getB_id());        if(pre.executeUpdate() > 0) flag = true;        }        db.closeRs();        db.closeStm();        pre.close();        db.closeConn();        //this.release();        //OpenConnection.closeConnection(conn);        return flag;    }    public Borrows assemble(ResultSet rs) throws Exception{        borrow = new Borrows();        borrow.setS_id(rs.getInt("s_id"));        borrow.setB_id(rs.getInt("b_id"));        borrow.setAmount(rs.getInt("amount"));        return borrow;    }}

studentDao

package com.demo.dao;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import com.demo.javabean.*;public class StudentDAO {DBAccess db;public boolean valid(String username, String password) {boolean isValid = false;//DBAccess db = new DBAccess();db = new DBAccess();if(db.createConn()) {//String sql = "select * from students where user='"+username+"' and password='"+password+"'";//db.setSql("select * from students where user='"+username+"' and password='"+password+"'");String sql="select * from students where user= ? and password= ?";try {//这里引用prepareStatement是为了防止SQL注入db.pre=db.getConn().prepareStatement(sql);db.pre.setString(1, username);db.pre.setString(2, password);db.setRs(db.pre.executeQuery());if(db.getRs().next()){isValid=true;}} catch (SQLException e) {// TODO 自动生成的 catch 块e.printStackTrace();}finally {db.closeRs();if(db.pre!=null)try {db.pre.close();} catch (SQLException e) {// TODO 自动生成的 catch 块e.printStackTrace();}db.closeConn();}//db.query(sql);//db.query(db.getSql());//if(db.next()) {//isValid = true;//}//db.closeRs();//db.closeStm();//db.closeConn();}return isValid ;}public boolean isExist(String username) {boolean isExist = false;db = new DBAccess();if(db.createConn()) {//String sql = "select * from students where user='"+username+"'";//db.setSql("select * from students where user='"+username+"'");String sql="select * from students where user=?";try {db.pre=db.getConn().prepareStatement(sql);db.pre.setString(1, username);db.setRs(db.pre.executeQuery());if(db.getRs().next()){isExist=true;}} catch (SQLException e) {// TODO 自动生成的 catch 块e.printStackTrace();}finally {db.closeRs();if(db.pre!=null){try {db.pre.close();} catch (Exception e2) {// TODO: handle exception}db.closeConn();}}//db.query(sql);//db.query(db.getSql());//if(db.next()) {//isExist = true;//}//db.closeRs();//db.closeStm();//db.closeConn();}return isExist;}public boolean add(Students student) throws Exception{//添加boolean flag = false;db=new DBAccess();String sql = "INSERT INTO students(user,password,department,grade,classes,email,amount) VALUES(?,?,?,?,?,?,?)";if(db.createConn()){db.pre=db.getConn().prepareStatement(sql);db.pre.setString(1,student.getUser());db. pre.setString(2,student.getPassword());db.pre.setString(3,student.getDepartment());db.pre.setString(4,student.getGrade());db. pre.setString(5,student.getClasses());db.pre.setString(6,student.getEmail());db.pre.setInt(7,student.getAmount());if(db.pre.executeUpdate() > 0) flag = true;}db.closeRs();db.closeStm();db.pre.close();db.closeConn();return flag;}public void del(String usename){//删除DBAccess db = new DBAccess();if(db.createConn()) {String sql = "delete from students where user = '"+usename+"'";db.update(sql);db.closeStm();db.closeConn();}}private Students student = null;public ArrayListgetAllStudents() throws Exception{DBAccess db = new DBAccess();ArrayList students = new ArrayList();String sql = "SELECT * FROM students";if(db.createConn()){db.query(sql);while(db.getRs().next()){student = this.assemble(db.getRs());students.add(student);}db.closeStm();db.closeRs();db.closeConn();}return students;}public Students assemble(ResultSet rs) throws Exception{student = new Students();student.setId(rs.getInt("id"));student.setUser(rs.getString("user"));student.setPassword(rs.getString("password"));student.setDepartment(rs.getString("department"));student.setGrade(rs.getString("grade"));student.setClasses(rs.getString("classes"));student.setEmail(rs.getString("email"));student.setAmount(rs.getInt("amount"));return student;}public boolean delStudentByName(String user) throws Exception{//删除DBAccess db=new DBAccess();boolean flag = false;String sql="DELETE FROM students WHERE user = ?";if(db.createConn()){db.pre=db.getConn().prepareStatement(sql);db.pre.setString(1, user);if(db.pre.executeUpdate()>0)flag=true;}db.closeConn();db.closeStm();db.pre.close();db.closeRs();return flag;}public Students getStudentById(int id) throws Exception{DBAccess db=new DBAccess();String sql = "SELECT * FROM students WHERE id = ?";java.sql.PreparedStatement pre=null;if(db.createConn()){pre=db.getConn().prepareStatement(sql);pre.setInt(1, id);db.setRs(pre.executeQuery());//conn = OpenConnection.getConnection();//ps = conn.prepareStatement(sql_str);//ps.setInt(1,id);// rs = ps.executeQuery();if (db.getRs().next()) student = this.assemble(db.getRs());}db.closeRs();db.closeStm();pre.close();db.closeConn();//this.release();//OpenConnection.closeConnection(conn);return student;}public boolean updateStudent(Students student) throws Exception{boolean flag = false;DBAccess db=new DBAccess();String sql = "update students set amount = ? where id = ?";java.sql.PreparedStatement pre=null;if(db.createConn()){pre=db.getConn().prepareStatement(sql);//conn = OpenConnection.getConnection();// ps = conn.prepareStatement(sql_str);pre.setInt(1,student.getAmount());pre.setInt(2,student.getId());if(pre.executeUpdate() > 0) flag = true;}//this.release();//OpenConnection.closeConnection(conn);db.closeRs();pre.close();db.closeStm();db.closeConn();return flag;}public Students getStudentByName(String name) throws Exception{DBAccess  db=new DBAccess();String sql = "SELECT * FROM students WHERE user = ?";java.sql.PreparedStatement pre=null;if(db.createConn()){pre=db.getConn().prepareStatement(sql);pre.setString(1, name);db.setRs(pre.executeQuery());// conn = OpenConnection.getConnection();//ps = conn.prepareStatement(sql_str);//ps.setString(1,name);// rs = ps.executeQuery();if(db.getRs().next()) student = this.assemble(db.getRs());}db.closeRs();db.closeStm();pre.close();db.closeConn();//this.release();// OpenConnection.closeConnection(conn);return student;}public ArrayList findAll(Integer page){//分页查询信息DBAccess  db=new DBAccess();ArrayList list=new ArrayList();try {if(db.createConn()){String sql="select  * from students limit ?,? ";db.pre=db.getConn().prepareStatement(sql);db.pre.setInt(1, (page-1)*Students.PAGE_SIZE);db.pre.setInt(2, Students.PAGE_SIZE);db.setRs(db.pre.executeQuery());while(db.getRs().next()){Students stu=new Students();stu.setUser(db.getRs().getString("user"));stu.setPassword(db.getRs().getString("password"));stu.setDepartment(db.getRs().getString("department"));stu.setGrade(db.getRs().getString("grade"));stu.setClasses(db.getRs().getString("classes"));stu.setEmail(db.getRs().getString("email"));stu.setAmount(db.getRs().getInt("amount"));list.add(stu);}db.closeRs();db.pre.close();db.closeConn();}} catch( SQLException e) {e.printStackTrace();}return list;}public int countPage(){//查询记录总数DBAccess  db=new DBAccess();int count=0;try {if(db.createConn()){String sql="select count(*) from students  ";db.pre=db.getConn().prepareStatement(sql);db.setRs(db.pre.executeQuery());if(db.getRs().next()){count=db.getRs().getInt(1);}}} catch( SQLException e) {e.printStackTrace();}finally {db.closeRs();try {if(db.pre!=null){db.pre.close();}} catch (Exception e2) {// TODO: handle exception}db.closeConn();}return count;}}

4.2 Servlet类

userlojinServlet

package com.demo.servlet;import com.demo.dao.AdminDAO;import com.demo.dao.StudentDAO;import com.demo.javabean.*;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WEBServlet;import javax.servlet.Http.*;import java.io.IOException;import java.io.PrintWriter;import java.io.UnsupportedEncodingException;import java.sql.SQLException;public class UserLoginServlet extends httpservlet {private static final long serialVersionUID = 1L;@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String method = (String)request.getParameter("method");if(method==null) {PrintWriter out = response.getWriter();out.println("invalid request!");} else if(method.equals("login")) {try {Login(request, response);} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}}else if(method.equals("reGISter")) {try {Register(request, response);} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}}else if(method.equals("logout")){Logout(request,response);}}//用户登录protected void Login(HttpServletRequest request,HttpServletResponse response) throws Exception {//request.setCharacterEncoding("utf-8");//response.setCharacterEncoding("utf-8");//response.setContentType("text/html;charset=utf-8");    PrintWriter out = response.getWriter();String a_user = request.getParameter("user");String a_password = request.getParameter("password");System.out.println(a_user);String rem=request.getParameter("remember");HttpSession session = request.getSession();StudentDAO a_dao=new StudentDAO();if ("".equals(a_user) ||"".equals(a_password)) {//System.out.println("登录失败，账号或密码不能为空！");//response.sendRedirect("login.jsp");out.println("");return;}else if(a_dao.isExist(a_user)){Students student=a_dao.getStudentByName(a_user);session.setAttribute("student", student);if(a_dao.valid(a_user, a_password)){session.setAttribute("a_user", a_user);user user=new user();session.setAttribute("user",user);if("1".equals(rem)){//创建2个CookieCookie namecookie=new Cookie("username", a_user);//设置Cookie的有效期为三天namecookie.setMaxAge(60*60*24*3);Cookie pwdcookie=new Cookie("password", a_password);pwdcookie.setMaxAge(60*60*24*3);response.addCookie(namecookie);response.addCookie(pwdcookie);}//response.sendRedirect(request.getContextPath()+"/user.jsp");//System.out.println("登录成功！");out.println("");}else {//System.out.println("登录失败2，密码错误！");//response.sendRedirect(request.getContextPath()+"/login.jsp");out.println("");}}else {//System.out.println("登录失败3，用户名不存在！");//response.sendRedirect(request.getContextPath()+"/login.jsp");out.println("");}}//用户退出protected void Logout(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {HttpSession session = request.getSession();session.removeAttribute("a_user");session.removeAttribute("user");response.sendRedirect("login.jsp");}//用户注册protected void Register(HttpServletRequest request, HttpServletResponse response) throws IOException,ServletException{//request.setCharacterEncoding("utf-8");//response.setCharacterEncoding("utf-8");//response.setContentType("text/html;charset=utf-8");    PrintWriter out = response.getWriter();String user =  request.getParameter("user");String password = request.getParameter("password");String repwd= request.getParameter("repwd");String department =  request.getParameter("department");String grade =  request.getParameter("grade");String classes = request.getParameter("classes");String email =  request.getParameter("email");if ("".equals(user) ||"".equals(password) || "".equals(repwd) || !password.equals(repwd)||"".equals(department)||"".equals(grade)||"".equals(classes)||"".equals(email)) {//response.sendRedirect("reg.jsp");out.println("");return;}else{Students student = null;StudentDAO a_dao = new StudentDAO();boolean isExist =a_dao.isExist(user);if(isExist){//System.out.println("'此学号已注册过，请重试!");//response.sendRedirect("reg.jsp");out.println("");}else{student = new Students();student.setUser(user);student.setPassword(password);student.setDepartment(department);student.setGrade(grade);student.setClasses(classes);student.setEmail(email);student.setAmount(0);try {if(a_dao.add(student)){student = a_dao.getStudentByName(student.getUser());request.getSession().setAttribute("student",student);//System.out.println("注册成功，即将跳转到主界面!");//response.sendRedirect("login.jsp");out.println("");return;}} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}}}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//req.setCharacterEncoding("utf-8");this.doGet(req, resp);}}

adminlojinServlet

package com.demo.servlet;import java.io.*;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import com.demo. dao.AdminDAO;import com.demo.javabean.*;public class AdminLoginServlet extends HttpServlet {private static final long serialVersionUID = 1L;    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {    String method = (String)req.getParameter("method");    if(method==null) {PrintWriter out = resp.getWriter();out.println("invalid request!");} else if(method.equals("login")) {Login(req, resp);}    }    //管理员登录    protected void Login(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {    //request.setCharacterEncoding("utf-8");    //response.setCharacterEncoding("utf-8");//response.setContentType("text/html;charset=utf-8");    PrintWriter out = response.getWriter();        String a_user =request.getParameter("a_user");        String a_password = request.getParameter("a_password");        //HttpSession session = request.getSession();        AdminDAO a_dao = new AdminDAO();       //String admin = null;        if ( a_user .equals("") ||a_password .equals("")) {        //System.out.println("登录失败");//response.sendRedirect("login.jsp");//重定向        out.println("");return;}        boolean isValid =  a_dao.valid(a_user, a_password);if (isValid) {HttpSession session = request.getSession();session.setAttribute("a_user", a_user);out.println("");//response.sendRedirect("admin.jsp");//重定向return;}else {//System.out.println("登录失败");//response.sendRedirect("login.jsp");//重定向out.println("");return;}}//    protected void Logout(HttpServletRequest request,//HttpServletResponse response) throws ServletException, IOException {//HttpSession session = request.getSession();//session.removeAttribute("a_user");//response.sendRedirect("login.jsp");//}//            @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        doGet(req,resp);    }}

managebookservlet

package com.demo.servlet;import com.demo.dao.BookDAO;import com.demo.javabean.*;import javax.security.auth.message.callback.PrivateKeyCallback.Request;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import java.io.IOException;import java.io.PrintWriter;import java.io.UnsupportedEncodingException;public class ManageBookServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//HttpSession session=request.getSession();//if(session!=null&&session.getAttribute("a_user1")!=null){//String action = (String)request.getParameter("action");//if(action==null) {//PrintWriter out = response.getWriter();//out.println("invalid request!");//} else if(action.equals("addbook")) {//AddBook(request, response);//}//else if(action.equals("delbook")) {//DelBook(request, response);//}//else if(action.equals("updatebook")) {//UpdateBook(request, response);//}//else if(action.equals("update")) {//Update(request, response);//}//}//else {//response.sendRedirect("login.jsp");//}String action = (String)request.getParameter("action");if(action==null) {PrintWriter out = response.getWriter();out.println("invalid request!");} else if(action.equals("addbook")) {AddBook(request, response);}else if(action.equals("delbook")) {DelBook(request, response);}else if(action.equals("updatebook")) {UpdateBook(request, response);}else if(action.equals("update")) {Update(request, response);}}//更新图书private void Update(HttpServletRequest req, HttpServletResponse resp) throws ServletException,IOException{// TODO 自动生成的方法存根//req.setCharacterEncoding("utf-8");//resp.setCharacterEncoding("utf-8");//resp.setContentType("text/html;charset=utf-8");Integer sid = Integer.parseInt(req.getParameter("sid"));BookDAO b_dao=new BookDAO();String page="";try {Books book=b_dao.getBookById(sid);req.setAttribute("book", book);req.getRequestDispatcher("admin/update_book.jsp").forward(req, resp);} catch (Exception e) {//page="error.jsp";//TODO 自动生成的 catch 块e.printStackTrace();}//        finally{//        page="admin/update_book.jsp";//        }//        req.getRequestDispatcher(page).forward(req, resp);}private void UpdateBook(HttpServletRequest req, HttpServletResponse resp)throws ServletException,IOException {//修改图书信息// TODO 自动生成的方法存根//req.setCharacterEncoding("utf-8");//resp.setCharacterEncoding("utf-8");//resp.setContentType("text/html;charset=utf-8");PrintWriter out=resp.getWriter();String sid=req.getParameter("sid");String name=req.getParameter("name");String author=req.getParameter("author");String amount = req.getParameter("amount");String category = req.getParameter("category");BookDAO b_dao=new BookDAO();Books book=new Books();if(name != "" && author != "" && amount != "" && category != ""){book.setName(name);book.setAuthor(author);book.setAmount(Integer.parseInt(amount));book.setCategory(category);book.setId(Integer.parseInt(sid));try {if(b_dao.updateBook2(book)){//System.out.println("修改书籍成功！");//resp.sendRedirect("PageServlet.do?method=showBook");out.println("");return;}else//System.out.println("修改书籍失败！内容不能为空");out.println("");} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}}else//System.out.println("修改书籍失败！");//resp.sendRedirect("");out.println("");}//删除图书private void DelBook(HttpServletRequest request, HttpServletResponse response) throws ServletException,IOException {// TODO 自动生成的方法存根//request.setCharacterEncoding("utf-8");//response.setCharacterEncoding("utf-8");//response.setContentType("text/html;charset=utf-8");PrintWriter out=response.getWriter();String name=request.getParameter("name");BookDAO b_dao = new BookDAO();if(name!=null){try {if(b_dao.delbook(name)){//System.out.println("删除书籍成功！");//response.sendRedirect("PageServlet.do?method=showBook");//return;out.println("");return;}else //System.out.println("删除书籍失败！");//response.sendRedirect("admin/del_book.jsp");out.println("");} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}}else{//System.out.println("删除图书失败！无此图书");//response.sendRedirect("admin/del_book.jsp");out.println("");}}//添加图书private void AddBook(HttpServletRequest req, HttpServletResponse resp)throws ServletException,IOException {// TODO 自动生成的方法存根//req.setCharacterEncoding("utf-8");//resp.setCharacterEncoding("utf-8");//resp.setContentType("text/html;charset=utf-8");PrintWriter out=resp.getWriter();String name = req.getParameter("name");String author = req.getParameter("author");String amount = req.getParameter("amount");String category = req.getParameter("category");String intro="暂未介绍";BookDAO b_dao = new BookDAO();Books book = null;if(name != "" && author != "" && amount != "" && category != ""){book = new Books();book.setName(name);book.setAuthor(author);book.setIntro("暂未介绍");book.setAmount(Integer.parseInt(amount));book.setCategory(category);//PrintWriter out = resp.getWriter();try {b_dao.addBook(name, author, intro, amount, category);//System.out.println("添加书籍成功！");//resp.sendRedirect("admin/reg_book.jsp");out.println("");} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}}else{//System.out.println("添加书籍失败！其他原因");//resp.sendRedirect("admin/reg_book.jsp");out.println("");}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//req.setCharacterEncoding("utf-8");doGet(req,resp);}}

managestudentservlet

package com.demo.servlet;import com.demo.dao.StudentDAO;import com.demo.javabean.*;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import java.io.IOException;import java.io.PrintWriter;public class ManageStudentServlet extends HttpServlet {private static final long serialVersionUID = 1L;    @Override    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//    HttpSession session=request.getSession();//    if(session!=null&&session.getAttribute("a_user1")!=null){//    String action = (String)request.getParameter("action");//    if(action==null) {//PrintWriter out = response.getWriter();//out.println("invalid request!");//} else if(action.equals("addstudent")) {//AddStudent(request, response);//}//else if(action.equals("delstudent")) {//DelStudent(request, response);//}//else if(action.equals("showstudent")){//ShowStudent(request,response);//}//    }//    else {//response.sendRedirect("login.jsp");//}    String action = (String)request.getParameter("action");    if(action==null) {PrintWriter out = response.getWriter();out.println("invalid request!");} else if(action.equals("addstudent")) {AddStudent(request, response);}else if(action.equals("delstudent")) {DelStudent(request, response);}else if(action.equals("showstudent")){ShowStudent(request,response);}    }        private void ShowStudent(HttpServletRequest request, HttpServletResponse response) throws ServletException,IOException{// TODO 自动生成的方法存根//request.setCharacterEncoding("utf-8");String user=request.getParameter("user");StudentDAO studao=new StudentDAO();Students student=new Students();try {student=studao.getStudentByName(user);request.setAttribute("student", student);} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}request.getRequestDispatcher("admin/show_student.jsp").forward(request, response);}private void DelStudent(HttpServletRequest req, HttpServletResponse resp)throws ServletException,IOException {        req.setCharacterEncoding("utf-8");        resp.setCharacterEncoding("utf-8");        resp.setContentType("text/html;charset=utf-8");        PrintWriter out=resp.getWriter();        String user=req.getParameter("user");        StudentDAO s_dao = new StudentDAO();        if(user!=null){         System.out.println(user);        try {if(s_dao.delStudentByName(user)){// System.out.println("删除成功！"); //resp.sendRedirect("PageServlet.do?method=showStudent");out.println(""); return;}else//System.out.println("删除失败！");//resp.sendRedirect("admin/del_student.jsp");out.println("");} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}        }             else{              //System.out.println("删除失败，无此账号！");              //resp.sendRedirect("admin/del_student.jsp");             out.println("");                }        }// TODO 自动生成的方法存根private void AddStudent(HttpServletRequest req, HttpServletResponse resp) throws ServletException,IOException {// TODO 自动生成的方法存根//req.setCharacterEncoding("utf-8");//resp.setCharacterEncoding("utf-8");//resp.setContentType("text/html;charset=utf-8");PrintWriter out=resp.getWriter();        String user=req.getParameter("user");        String password = req.getParameter("password");        String relpwd=req.getParameter("relpwd");        String department=req.getParameter("department");        String grade = req.getParameter("grade");        String classes=req.getParameter("classes");        String email = req.getParameter("email");        String admin=req.getParameter("admin");        if ("".equals(user) || "".equals(password) ||"".equals(relpwd) || !password.equals(relpwd)||"".equals(department)||"".equals(grade)||"".equals(classes)||"".equals(email)) {//resp.sendRedirect("admin/add_student.jsp");//System.out.println("信息不全");        out.println("");return;}else{        StudentDAO a_dao = new StudentDAO();        Students student=new Students();boolean isExist =a_dao.isExist(user);if(isExist){//System.out.println("此学号已注册！");//resp.sendRedirect("admin/add_student.jsp");out.println("");}else{ student = new Students();            student.setUser(user);            student.setPassword(password);            student.setDepartment(department);            student.setGrade(grade);            student.setClasses(classes);;            student.setEmail(email);            student.setAmount(0);            try {if(a_dao.add(student)){student = a_dao.getStudentByName(student.getUser());    req.getSession().setAttribute("student",student);//System.out.println("添加成功!");//resp.sendRedirect("");    out.println("");return;}} catch (Exception e) {// TODO 自动生成的 catch 块e.printStackTrace();}}}}    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {    //req.setCharacterEncoding("utf-8");        doGet(req,resp);    }}

javaBean类

admin

package com.demo.javabean;public class Admins {    private int id;                     //定义管理员的id序号    private String admin;               //登录账号    private String password;            //密码    private String realname;            //真实姓名    private String phone;               //电话号码    private String email;               //邮箱    private String address;             //地址    //获取管理员的id序号    public int getId() {        return id;    }    //设置管理员的id序号    public void setId(int id) {        this.id = id;    }    //获取管理员的账号    public String getAdmin() {        return admin;    }    //设置管理员的账号    public void setAdmin(String admin) {        this.admin = admin;    }    //获取管理员的密码    public String getPassword() {        return password;    }    //设置管理员的密码    public void setPassword(String password) {        this.password = password;    }    //获取管理员的真实姓名    public String getRealname() {        return realname;    }    //设置管理员的真实姓名    public void setRealname(String realname) {        this.realname = realname;    }    //获取管理员的电话    public String getPhone() {        return phone;    }    //设置管理员的电话号码    public void setPhone(String phone) {        this.phone = phone;    }    //获得管理员的邮箱地址    public String getEmail() {        return email;    }    //设置管理员的邮箱地址    public void setEmail(String email) {        this.email = email;    }    //获取管理员的地址    public String getAddress() {        return address;    }    //设置管理员的地址    public void setAddress(String address) {        this.address = address;    }}

student

package com.demo.javabean;public class Students {public static final int PAGE_SIZE=5;    private int id;    private String user;    private String password;   private String department;    private String grade;    private String classes;    private String email;    private int amount;    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getUser() {        return user;    }    public void setUser(String user) {        this.user = user;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    public String getDepartment() {        return department;    }    public void setDepartment(String department) {        this.department = department;    }    public String getGrade() {        return grade;    }    public void setGrade(String grade) {        this.grade = grade;    }    public String getClasses() {        return classes;    }    public void setClasses(String classes) {        this.classes = classes;    }    public String getEmail() {        return email;    }    public void setEmail(String email) {        this.email = email;    }    public int getAmount() {        return amount;    }    public void setAmount(int amount) {        this.amount = amount;    }}

book

package com.demo.javabean;public class Books {private static final long serialVersionUID = 1L;public static final int PAGE_SIZE=5;    private int id;    private String name;    private String author;    private String intro;    private int amount;    private String category;    //取得图书的id序号    public int getId() {        return id;    }    //设置图书的id序号    public void setId(int id) {        this.id = id;    }    //获取图书的名字    public String getName() {        return name;    }    //设置图书的名字    public void setName(String name) {        this.name = name;    }    //获取图书的作者    public String getAuthor() {        return author;    }    //设置图书的作者    public void setAuthor(String author) {        this.author = author;    }    //获取图书的简介    public String getIntro() {        return intro;    }    //设置图书的简介    public void setIntro(String intro) {        this.intro = intro;    }    //获取图书的数量    public int getAmount() {        return amount;    }    //设置图书的数量    public void setAmount(int amount) {        this.amount = amount;    }    //获取图书的类别    public String getCategory() {        return category;    }    //设置图书的类别    public void setCategory(String category) {        this.category = category;    }}

filter（过滤器类）

loginfilter

package com.demo.filter;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class LoginFilter implements Filter {//对登录进行验证过滤@Overridepublic void destroy() {// TODO 自动生成的方法存根}@Overridepublic void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)throws IOException, ServletException {// TODO 自动生成的方法存根HttpServletRequest request=(HttpServletRequest) req;HttpServletResponse response=(HttpServletResponse)resp;HttpSession session=request.getSession(false);if(session!=null&&session.getAttribute("a_user")!=null){//继续往下走chain.doFilter(request, response);}else {response.sendRedirect("login.jsp");}}@Overridepublic void init(FilterConfig arg0) throws ServletException {// TODO 自动生成的方法存根}}

characterfilter

package com.demo.filter;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class CharacterFilter implements Filter {//对字符乱码问题进行过滤@Overridepublic void destroy() {// TODO 自动生成的方法存根}@Overridepublic void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)throws IOException, ServletException {// TODO 自动生成的方法存根HttpServletRequest request=(HttpServletRequest)req;HttpServletResponse response=(HttpServletResponse) resp;request.setCharacterEncoding("utf-8");response.setCharacterEncoding("utf-8");response.setContentType("text/html;charset=utf-8");//继续执行chain.doFilter(request, response);}@Overridepublic void init(FilterConfig arg0) throws ServletException {// TODO 自动生成的方法存根}}

。。。因代码量较多，就不一一粘贴，有兴趣的友友可以交流。

来源地址：https://blog.csdn.net/qq_52705208/article/details/125424807

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本文标题: 基于Java Web的图书管理系统

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