Java读取Properties的方式

项目结构：经典的Maven项目结构

配置文件1和2内容一致：

jdbc.driver=com.Mysql.cj.jdbc.Driverjdbc.url=mysql://localhost:3306/database?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghaijdbc.username=rootjdbc.passWord=123456

1. this.getClass().getResourceAsStream()

//读取配置文件1public void readProperties1() throws ioException {    //不加/会从当前包进行寻找，加上/会从src开始找    InputStream inputStream = this.getClass().getResourceAsStream("/jdbc.properties");    Properties properties=new Properties();    properties.load(inputStream);    System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));    System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));    System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));    System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));}      //读取配置文件2         public void readProperties1() throws IOException {        InputStream inputStream = this.getClass().getResourceAsStream("/config/jdbc2.properties");        Properties properties=new Properties();        properties.load(inputStream);        System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));        System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));        System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));        System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));}

2.当前类的加载器进行读取this.getClass().getClassLoader().getResourceAsStream()

//读取配置文件1public void readProperties2() throws IOException {    //不加/，若加了会为null    InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("jdbc.properties");    Properties properties=new Properties();    properties.load(inputStream);    System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));    System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));    System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));    System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));}//读取配置文件2public void readProperties2() throws IOException {        InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("config/jdbc2.properties");        Properties properties=new Properties();        properties.load(inputStream);        System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));        System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));        System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));        System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));}

• 方法1和2区别： （classpath即为target/classes 这个目录）

• Class.getResourceAsStream() 从当前类所在的位置开始查找配置文件位置。要找到jdbc.properties和jdbc2.properties必须加/从classpath下开始查找

• Class.getClassLoader().getResourceAsStream() 默认就从classpath路径下开始查找，加上/会报空指针

• 十分有必要知道java中类的加载过程！！！

3. ClassLoader类的static方法 getSystemResourceAsStream()

public void readProperties3() throws IOException {        //InputStream inputStream = ClassLoader.getSystemResourceAsStream("config/jdbc2.properties");        InputStream inputStream = ClassLoader.getSystemResourceAsStream("jdbc.properties");        Properties properties=new Properties();        properties.load(inputStream);        System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));        System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));        System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));        System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));    }

4. spring中的 ClassPathResource读取

public void readProperties4() throws IOException {        //ClassPathResource resource = new ClassPathResource("jdbc.properties");        ClassPathResource resource = new ClassPathResource("config/jdbc2.properties");        Properties properties= PropertiesLoaderUtils.loadProperties(resource);        System.out.println("jdbc.driver="+properties.getProperty("jdbc.driver"));        System.out.println("jdbc.url="+properties.getProperty("jdbc.url"));        System.out.println("jdbc.username="+properties.getProperty("jdbc.username"));        System.out.println("jdbc.password="+properties.getProperty("jdbc.password"));}

5. PropertyResourceBundle读取InputStream流

public void readProperties5() throws IOException {        //InputStream inputStream = ClassLoader.getSystemResourceAsStream("jdbc.properties");    InputStream inputStream = ClassLoader.getSystemResourceAsStream("config/jdbc2.properties");        PropertyResourceBundle bundle = new PropertyResourceBundle(inputStream);        System.out.println(bundle.getString("jdbc.driver"));        System.out.println(bundle.getString("jdbc.url"));        System.out.println(bundle.getString("jdbc.username"));        System.out.println(bundle.getString("jdbc.password"));    }

6.ResourceBundle.getBundle()

//不用输入后缀public void readProperties6()  {        //ResourceBundle bundle=ResourceBundle.getBundle("jdbc");        ResourceBundle bundle=ResourceBundle.getBundle("config/jdbc2");        System.out.println(bundle.getString("jdbc.driver"));        System.out.println(bundle.getString("jdbc.url"));        System.out.println(bundle.getString("jdbc.username"));        System.out.println(bundle.getString("jdbc.password"));    }

来源地址：https://blog.csdn.net/yirenDM/article/details/130488107