SpringBoot超详细讲解事务管理

package com.nowcoder.commUnity.service;
import com.nowcoder.community.dao.AlphaDao;
import com.nowcoder.community.dao.DiscussPostMapper;
import com.nowcoder.community.dao.UserMapper;
import com.nowcoder.community.entity.DiscussPost;
import com.nowcoder.community.entity.User;
import com.nowcoder.community.util.CommunityUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Service;
import org.springframework.transaction.TransactionDefinition;
import org.springframework.transaction.TransactionStatus;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.transaction.support.TransactionCallback;
import org.springframework.transaction.support.TransactionTemplate;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import java.util.Date;
@Service
//@Scope("prototype")
public class AlphaService {
    @Autowired
    private AlphaDao alphaDao;
    @Autowired
    private UserMapper userMapper;
    @Autowired
    private DiscussPostMapper discussPostMapper;
    @Autowired
    private TransactionTemplate transactionTemplate;
    public AlphaService() {
//        System.out.println("实例化AlphaService");
    }
    @PostConstruct
    public void init() {
//        System.out.println("初始化AlphaService");
    }
    @PreDestroy
    public void destroy() {
//        System.out.println("销毁AlphaService");
    }
    public String find() {
        return alphaDao.select();
    }
    // REQUIRED: 支持当前事务(外部事务),如果不存在则创建新事务.
    // REQUIRES_NEW: 创建一个新事务,并且暂停当前事务(外部事务).
    // NESTED: 如果当前存在事务(外部事务),则嵌套在该事务中执行(独立的提交和回滚),否则就会REQUIRED一样.
    @Transactional(isolation = Isolation.READ_COMMITTED, propagation = Propagation.REQUIRED)
    public Object save1() {
        // 新增用户
        User user = new User();
        user.setUsername("alpha");
        user.setSalt(CommunityUtil.generateUUID().substring(0, 5));
        user.setPassword(CommunityUtil.md5("123" + user.getSalt()));
        user.setEmail("alpha@qq.com");
        user.setHeaderUrl("/file/imgs/upload/202211/13/nk3GCecrdwq.jpg");
        user.setCreateTime(new Date());
        userMapper.insertUser(user);
        // 新增帖子
        DiscussPost post = new DiscussPost();
        post.setUserId(user.getId());
        post.setTitle("Hello");
        post.setContent("新人报道!");
        post.setCreateTime(new Date());
        discussPostMapper.insertDiscussPost(post);
        Integer.valueOf("abc");
        return "ok";
    }
    public Object save2() {
        transactionTemplate.setIsolationLevel(TransactionDefinition.ISOLATION_READ_COMMITTED);
        transactionTemplate.setPropagationBehavior(TransactionDefinition.PROPAGATION_REQUIRED);
        return transactionTemplate.execute(new TransactionCallback<Object>() {
            @Override
            public Object doInTransaction(TransactionStatus status) {
                // 新增用户
                User user = new User();
                user.setUsername("beta");
                user.setSalt(CommunityUtil.generateUUID().substring(0, 5));
                user.setPassword(CommunityUtil.md5("123" + user.getSalt()));
                user.setEmail("beta@qq.com");
                user.setHeaderUrl("/file/imgs/upload/202211/13/avkkletk3sz.jpg");
                user.setCreateTime(new Date());
                userMapper.insertUser(user);
                // 新增帖子
                DiscussPost post = new DiscussPost();
                post.setUserId(user.getId());
                post.setTitle("你好");
                post.setContent("我是新人!");
                post.setCreateTime(new Date());
                discussPostMapper.insertDiscussPost(post);
                Integer.valueOf("abc");
                return "ok";
            }
        });
    }
}