Spring中事务理解

这里save方法统一叫A方法 saveTest叫B方法

两个方法是再同类中！！

一、@Transactional(propagation = Propagation.REQUIRED)

如果存在一个事务，则支持当前事务。如果没有事务则开启一个新的事务。

1、A方法加上注解调用B方法，此时事务生效

    @Override
    @Transactional(propagation = Propagation.REQUIRED)
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        return 0;
    }

    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);
        System.out.println(1/0);
    }

2、A方法上加事务，调用B方法，此时事务生效

    @Override
    @Transactional(propagation = Propagation.REQUIRED)
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        System.out.println(1/0);
        return 0;
    }

    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);

    }

3、A方法上没有事务，B方法上有事务，此时事务不生效，两条数据都能插入

    @Override
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        System.out.println(1/0);
        return 0;
    }
    @Transactional(propagation = Propagation.REQUIRED)
    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);

    }

   @Override
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        return 0;
    }
    @Transactional(propagation = Propagation.REQUIRED)
    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);
        System.out.println(1/0);
    }

4、A方法和B方法同时加上事务，A方法调用B方法，此时事务生效

    @Override
    @Transactional(propagation = Propagation.REQUIRED)
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        return 0;
    }
    @Transactional(propagation = Propagation.REQUIRED)
    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);
        System.out.println(1/0);
    }

    @Override
    @Transactional(propagation = Propagation.REQUIRED)
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        System.out.println(1/0);
        return 0;
    }
    @Transactional(propagation = Propagation.REQUIRED)
    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);

    }

二、@Transactional(propagation = Propagation.SUPPORTS)

如果存在一个事务，支持当前事务。如果没有事务，则非事务的执行。但是对于事务同步的事务管理器，PROPAGATION_SUPPORTS与不使用事务有少许不同

1、如果事务设置为propagation = Propagation.SUPPORTS则A方法和B方法上的事务都不生效

    @Override
    @Transactional(propagation = Propagation.SUPPORTS)
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        System.out.println(1/0);
        return 0;
    }
    @Transactional(propagation = Propagation.SUPPORTS)
    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);


    }

2、A方法上没有事务B方法有事务，此时事务不生效

    @Override
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        return 0;
    }
    @Transactional(propagation = Propagation.SUPPORTS)
    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);
        System.out.println(1/0);
    }

3、A方法上有事务B方法没有事务，此时事务不生效

    @Override
    @Transactional(propagation = Propagation.SUPPORTS)
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        return 0;
    }
    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);
        System.out.println(1/0);
    }

4、A方法上加@Transactional(propagation = Propagation.REQUIRED) B方法加上@Transactional(propagation = Propagation.SUPPORTS)此时事务生效

 @Override
    @Transactional(propagation = Propagation.REQUIRED)
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        return 0;
    }
    @Transactional(propagation = Propagation.SUPPORTS)
    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);
        System.out.println(1/0);
    }

5、A方法上加@Transactional(propagation = Propagation.SUPPORTS)B方法加@Transactional(propagation = Propagation.REQUIRED)此时事务不生效

 @Override
    @Transactional(propagation = Propagation.SUPPORTS)
    public int save(Testtran testtran) {
        testtran.setName("张三");
        testtran.setAge("18");
        testtranMapper.insertSelective(testtran);
        saveTest();
        return 0;
    }
    @Transactional(propagation = Propagation.REQUIRED)
    public void saveTest(){
        Testtran testtran =new Testtran();
        testtran.setName("李四");
        testtran.setAge("19");
        testtranMapper.insertSelective(testtran);
        System.out.println(1/0);
    }

后面再验证另外5种。。。。。