《慕课网java架构师直通车》课程笔记

1. 事务的传播

REQUIRED（必须的）(TransactionDefinition.PROPAGATION_REQUIRED) 使用当前的事务，如果当前没有事务，则自己新建一个事务，子方法是必须运行在一个事务中的，如果当前存在事务，则加入这个事务，成为一个整体。
例如：领导没有钱，但是我有钱，我就会自己买了吃（不存在事务）； 如果领导有钱，就会分一些给我（事务）；

SUPPORTS（支持）(TransactionDefinition.PROPAGATION_SUPPORTS) 如果当前有事务，则使用事务，如果没有，则不使用。
例如：领导没饭吃，我也没饭吃，领导有饭吃，我也有饭吃，也就是说如下面的代码，我在savechild（）方法上加了事务，但是在父级方法中没有加，则不会有事务，如果我在父级方法中也加了事务，才会实现事务。

    @Transactional(propagation = Propagation.REQUIRED)
    @Test
    public void saveParent(){
        stuService.saveParent();
        stuService.saveChild();
    }
    //当propagation =  Propagation.SUPPORTS时，单独加这个事务，在调用过程中是不起作用的
    @Transactional(propagation = Propagation.SUPPORTS)
    @Override
    public void saveChild() {
        saveChild1();
        int s = 1/0;
        saveChild2();

    }
    public void saveChild1(){
        Stu stu = new Stu();
        stu.setAge(23);
        stu.setName("child1");
    }

    public void saveChild2(){
        Stu stu = new Stu();
        stu.setAge(23);
        stu.setName("child2");
    }

MANDATORY（强制的）(TransactionDefinition.PROPAGATION_MANDATORY) 这个则会强制要求父级调用者添加事务，否则会报如下错误；
例如 ：领导必须管饭，不管饭我就不干了

org.springframework.transaction.IllegalTransactionStateException: No existing transaction found for transaction marked with propagation 'mandatory'

	at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:364)
	at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:475)
	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:289)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
	at com.imooc.service.impl.StuServiceImpl$$EnhancerBySpringCGLIB$$ab72f9f8.saveChild(<generated>)
	at com.imooc.TranTest.saveParent(TranTest.java:33)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
	at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)

REQUIRES_NEW（必须创建新的）(TransactionDefinition.PROPAGATION_REQUIRES_NEW) 如果当前有事务，则挂起该事务，并且创建一个新的事务给自己用。如果当前没有事务，则同REQUIRED。

NOT_SUPPORTED(TransactionDefinition.PROPAGATION_NOT_SUPPORTED) 如果当前有事务，则把该事务挂起，自己不执行。

NOT_SUPPORTED(TransactionDefinition.PROPAGATION_NOT_SUPPORTED) 调用方不允许有任何的事务。
NESTED(TransactionDefinition.PROPAGATION_NESTED) 调用方发生异常，子事务也会受影响回滚。子事务 发生异常，则也会回滚，但是，如果我们给被调用方加上trycatch的话，则就算被调用方发生了异常，也不会影响调用方的执行。