JAVA@Transactional常用失效场景

    @Transactional(rollbackFor = {RuntimeException.class, Error.class})
    @Override
    public boolean create() {
        create1();
        create2();
        return true;
    }

public void create1() {
   Student student = new Student();
   student.setName("事务1");
   //不能为空
   student.setGender(1);
   int result = studentMapper.insert(student);
   if (result != 1) {
      throw new RuntimeException("新增失败");
   }
}

public void create2() {
   Student student = new Student();
   student.setName("事务2");
   student.setGender(1);
   studentMapper.insert(student);
   Student student2 = new Student();
   student2.setName("事务3");
   int result = studentMapper.insert(student2);
   if (result != 1) {
      throw new RuntimeException("新增失败");
   }
}

以上事务生效。在create()方法上添加事务，create2()因为gender为空产生报错，促使整个create()方法回滚，整体可以理解为是长事务；

@Override
public boolean create() {
   create1();
   create2();
   return true;
}

@Transactional(rollbackFor = {RuntimeException.class, Error.class})
public void create1() {
   Student student = new Student();
   student.setName("事务1");
   //不能为空
   student.setGender(1);
   int result = studentMapper.insert(student);
   if (result != 1) {
      throw new RuntimeException("新增失败");
   }
}
@Transactional(rollbackFor = {RuntimeException.class, Error.class})
public void create2() {
   Student student = new Student();
   student.setName("事务2");
   student.setGender(1);
   studentMapper.insert(student);
   Student student2 = new Student();
   student2.setName("事务3");
   int result = studentMapper.insert(student2);
   if (result != 1) {
      throw new RuntimeException("新增失败");
   }
}

以上事务触发不生效规则——同一个类中里层方法（create1(),create2()）添加@Transactional注解不生效，需要在外层方法(create())添加@Transactional注解才会生效。以上两个方法create1和create2均加有 @Transactional注解,但是这种方式不会生效，create1会执行成功并提交到数据库，create2的事务2会成功插入数据库，但是事务3不会插入数据库，从而引发了数据的不一致性。

    @Override
    public boolean create() {
        studentService2.create1();
        studentService2.create2();
        return true;
    }

StudentService:

@Transactional(rollbackFor = {RuntimeException.class, Error.class})
    public void create1() {
        Student student = new Student();
        student.setName("事务1");
        //不能为空
        student.setGender(1);
        int result = studentMapper.insert(student);
        if (result != 1) {
            throw new RuntimeException("新增失败");
        }
    }
    @Transactional(rollbackFor = {RuntimeException.class, Error.class})
    public void create2() {
        Student student = new Student();
        student.setName("事务2");
        student.setGender(1);
        studentMapper.insert(student);
        Student student2 = new Student();
        student2.setName("事务3");
        int result = studentMapper.insert(student2);
        if (result != 1) {
            throw new RuntimeException("新增失败");
        }
    }

此种方式事务生效，事务1能够成功保存到数据库，事务2和事务3因为异常无法保存到数据库。