Spring事务传播机制详解和 @Transactional 失效情况原因及解决方法（IT枫斗者）

分手后的思念是犯贱 2024-03-16 09:54 36阅读 0赞

## Spring事务传播机制详解和 @Transactional 失效情况原因及解决方法 ##

### 什么是事务传播机制 ###

*  事务的传播，是A方法调用B方法并将事务传递给它。事务的转播机制主要针对**被调用者**而言，控制它是否被传播或者被怎样传播。[spring事务][spring]的传播机制有七种：
 *  <table> 
     <thead> 
      <tr> 
       <th><strong>传播行为</strong></th> 
       <th><strong>描述</strong></th> 
      </tr> 
     </thead> 
     <tbody> 
      <tr> 
       <td>PROPAGATION_REQUIRED</td> 
       <td>默认的Spring事物传播级别，若当前存在事务，则加入该事务，若不存在事务，则新建一个事务</td> 
      </tr> 
      <tr> 
       <td>PROPAGATION_REQUIRE_NEW</td> 
       <td>若当前没有事务，则新建一个事务。若当前存在事务，则新建一个事务，<strong>新老事务相互独立</strong>。外部事务抛出异常回滚不会影响内部事务的正常提交</td> 
      </tr> 
      <tr> 
       <td>PROPAGATION_NESTED</td> 
       <td>如果当前存在事务，则嵌套在当前事务中执行。如果当前没有事务， 则新建一个事务，类似于REQUIRE_NEW</td> 
      </tr> 
      <tr> 
       <td>PROPAGATION_SUPPORTS</td> 
       <td>支持当前事务，若当前不存在事务，以非事务的方式执行</td> 
      </tr> 
      <tr> 
       <td>PROPAGATION_NOT_SUPPORTED</td> 
       <td>以非事务的方式执行，若当前存在事务，则把当前事务挂起</td> 
      </tr> 
      <tr> 
       <td>PROPAGATION_MANDATORY</td> 
       <td>强制事务执行，若当前不存在事务，则抛出异常</td> 
      </tr> 
      <tr> 
       <td>PROPAGATION_NEVER</td> 
       <td>以非事务的方式执行，如果当前存在事务，则抛出异常</td> 
      </tr> 
     </tbody> 
    </table>
 *  传播级别一般不需要定义，默认就是PROPAGATION\_REQUIRED，除非在嵌套事务的情况。上述描述表格的描述还是比较抽象，下面我们使用一个例子来说明这个传播机制。假定方法A调用方法B：
 *  <table> 
     <thead> 
      <tr> 
       <th><strong>方法B定义的事务类型</strong></th> 
       <th><strong>A方法有事务时</strong></th> 
       <th><strong>A方法无事务</strong></th> 
      </tr> 
     </thead> 
     <tbody> 
      <tr> 
       <td>@Transactional(propagation = Propagation.REQUIRED)</td> 
       <td>B和A事务合并成一个事务</td> 
       <td>B新建一个事务</td> 
      </tr> 
      <tr> 
       <td>@Transactional(propagation = Propagation.REQUIRES_NEW)</td> 
       <td>B新建一个事务，和A事务无关，互不影响（A回滚不会影响到B的提交）</td> 
       <td>B新建一个事务</td> 
      </tr> 
      <tr> 
       <td>@Transactional(propagation = Propagation.NESTED)</td> 
       <td>B新建一个A的子事务，A回滚会导致B已经提交的事务一起回滚；B回滚不会影响到A</td> 
       <td>B新建一个事务</td> 
      </tr> 
      <tr> 
       <td>@Transactional(propagation = Propagation.SUPPORTS)</td> 
       <td>B加入到A事务中</td> 
       <td>B无事务</td> 
      </tr> 
      <tr> 
       <td>@Transactional(propagation = Propagation.NOT_SUPPORTED)</td> 
       <td>挂起A事务，B以无事务方式执行</td> 
       <td>B无事务</td> 
      </tr> 
      <tr> 
       <td>@Transactional(propagation = Propagation.MANDATORY)</td> 
       <td>B加入到A事务中</td> 
       <td>B抛异常</td> 
      </tr> 
      <tr> 
       <td>@Transactional(propagation = Propagation.NEVER)</td> 
       <td>B抛异常</td> 
       <td>B无事务</td> 
      </tr> 
     </tbody> 
    </table>

### 七种事务传播机制 ###

*  现在在这里，我们假定`方法A` 是 `StudentService`类中的方法，`方法B`是`CourseService`类中的方法

#### @[Transactional][](propagation = Propagation.REQUIRED) ####

*  A中没有事务，B中有事务
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //这里没有开启事务，courseService.insertCourse会自己开启一个事务运行
            //而且两个添加操作都会成功，因为studentMapper.insert(student);是自动提交的
            public void insert0(){
        
                courseService.insertCourse();
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
        
                int i = 1/0;//这里抛出异常，两个添加操作都不会回滚
            }
        
        }
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.REQUIRED)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }
 *  A和B两个方法都有事务
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //两个方法都使用了@Transactional(propagation = Propagation.REQUIRED)
            //courseService.insertCourse()会加入到insert0方法开启的事务中，所以两个方法在同一事务中
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                courseService.insertCourse();
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
        
                int i = 1/0;//这里抛出异常，两个添加操作都被回滚
            }
            
        }
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.REQUIRED)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }

#### @Transactional(propagation = Propagation.REQUIRES\_NEW) ####

**在A方法的事务中抛出异常，B方法正确执行，正常提交**

*      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //courseService.insertCourse()方法用了@Transactional(propagation = Propagation.REQUIRES_NEW)
            //开启了一个独立的新的事务，在独立的事务中运行，
            // 并且insert0()开启的事务被挂起
            //等courseService.insertCourse()运行完毕，再恢复insert0()的事务
            //两个事务的提交和回滚都在各自事务中完成
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                courseService.insertCourse();
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
        
                //这里抛出异常，courseService.insertCourse()不会回滚
                //但是studentMapper.insert会被回滚
                int i = 1/0;
            }
        
        }
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.REQUIRES_NEW)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }
 *  **在B方法中抛出异常，A和B都被回滚**
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //courseService.insertCourse()方法用了@Transactional(propagation = Propagation.REQUIRES_NEW)
            //courseService.insertCourse()会抛出异常给insert0()方法，导致两个方法都被回滚
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
                //这里调用的insertCourse会抛出异常
                courseService.insertCourse();
        
        
            }
        
        }
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.REQUIRES_NEW)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
                //这里抛出异常，异常会被抛给调用这个方法的调用者
                int i = 1/0;
            }
        }

#### @Transactional(propagation = Propagation.SUPPORTS) ####

**A方法有事务，B加入到事务中**

*      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.SUPPORTS)
            //所以会加入到insert0()开启的事务中，被一起回滚
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                courseService.insertCourse();
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
                //这里抛出异常，courseService.insertCourse()也会被回滚
                int i=1/0;
        
        
            }
        
        }
        
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.SUPPORTS)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }
 *  A没有事务，B以无事务方式运行
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.SUPPORTS)
            //由于insert0没有开启事务，所以两个方法都以无事务方式运行，都会自动提交
            public void insert0(){
        
                courseService.insertCourse();
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
                //这里抛出异常，courseService.insertCourse()不会被回滚
                //studentMapper.insert(student);也不会被回滚
                int i=1/0;
        
        
            }
        
        }
        
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.SUPPORTS)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }

#### @Transactional(propagation = Propagation.NOT\_SUPPORTED) ####

*  A有事务，B以无事务方式运行（自动提交）
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.NOT_SUPPORTED)
            //所以courseService.insertCourse会以无事务方式运行，自动提交
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                courseService.insertCourse();
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
                //这里抛出异常，courseService.insertCourse()不会被回滚
                //studentMapper.insert(student);会被回滚
                int i=1/0;
        
        
            }
        
        }
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.NOT_SUPPORTED)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }

#### @Transactional(propagation = Propagation.MANDATORY) ####

*  A有事务，B加入事务中
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.MANDATORY)
            //所以courseService.insertCourse会加入到insert0()的事务中，一起回滚
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                courseService.insertCourse();
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
                //这里抛出异常，courseService.insertCourse()会被回滚
                //studentMapper.insert(student);会被回滚
                int i=1/0;
        
            }
            
           
        }
        
        
        @Service
        public class CourseService {
        
        
            @Autowired
            private CourseMapper courseMapper;
        
            @Transactional(propagation = Propagation.MANDATORY)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }
 *  A没有事务，B会抛出异常
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.MANDATORY)
            //courseService.insertCourse();会抛出异常
            public void insert0(){
        
                courseService.insertCourse();
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
            }
        
        }
        
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.MANDATORY)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }

#### @Transactional(propagation = Propagation.NEVER) ####

*  A方法无事务，A和B都以无事务方式运行
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.NEVER)
            //courseService.insertCourse();以无事务方式运行，两个添加都不会被回滚
            public void insert0(){
        
                courseService.insertCourse();
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
                //这里抛出异常，但是两个添加操作都是自动提交的，都不会被回滚
                int i = 1/0;
        
            }
        
        }
        
        @Service
        public class CourseService {
        
        
            @Autowired
            private CourseMapper courseMapper;
        
            @Transactional(propagation = Propagation.NEVER)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }
 *  A方法有事务，B抛出异常
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.NEVER)
            //由于insert0()开启了一个事务，所以courseService.insertCourse();会抛出异常
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
        
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
                //这里会抛出异常，因为courseService.insertCourse不支持事务
                courseService.insertCourse();
        
            }
        
        }
        
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.NEVER)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }

#### @Transactional(propagation = Propagation.NESTED) ####

*  A方法抛出异常，B方法成功的提交也被回滚
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.NESTED)
            //由于insert0()开启了一个事务，所以courseService.insertCourse();在嵌套事务内层运行
            //当courseService.insertCourse()成功提交后，insert0()最后抛出异常，会导致courseService.insertCourse()也会被回滚
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                try {
                    courseService.insertCourse();
                } catch (Exception e) {
                    e.printStackTrace();
                }
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
                //这里抛出异常会导致courseService.insertCourse()成功的提交也被回滚
                //studentMapper.insert(student)提交的也会被回滚
                int i = 1/0;
            }
        
        }
        
        
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.NESTED)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
        
            }
        }
 *  A方法执行成功，B方法抛出异常，只有B的提交被回滚，A的提交成功执行
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.NESTED)
            //由于insert0()开启了一个事务，所以courseService.insertCourse();在嵌套事务内层运行
            //当courseService.insertCourse()抛出异常会被catch，insert0会成功执行
            //最后，insert0成功提交，courseService.insertCourse()被回滚了
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                try {
                    courseService.insertCourse();
                } catch (Exception e) {
                    e.printStackTrace();
                }
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
        
            }
        
        }
        
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.NESTED)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
                //这个方法抛出异常，只会回滚当前这个方法
                int i = 1/0;
            }
        }
 *  A方法提交成功，B方法也提交成功
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
            //由于courseService.insertCourse使用@Transactional(propagation = Propagation.NESTED)
            //由于insert0()开启了一个事务，所以courseService.insertCourse();在嵌套事务内层运行
            //当courseService.insertCourse()抛出异常会被catch，insert0会成功执行
            //最后，insert0成功提交，courseService.insertCourse()被回滚了
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                try {
                    courseService.insertCourse();
                } catch (Exception e) {
                    e.printStackTrace();
                }
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
        
            }
        
        }
        
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.NESTED)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
            }
        }
 *  B方法都用@Transactional(propagation = Propagation.REQUIRES\_NEW)来修饰，是否也能达到这个效果呢？
 *      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
            @Autowired
            private CourseService courseService;
        
        
        
        
            @Transactional(propagation = Propagation.REQUIRED)
            public void insert0(){
        
                try {
                    //由于这个方法使用了@Transactional(propagation = Propagation.REQUIRES_NEW)
                    //尽管内部抛出异常，但是，insert0()方法的事务不会被影响
                    courseService.insertCourse();
                } catch (Exception e) {
                    e.printStackTrace();
                }
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
        
            }
        
        }
        
        
        
        @Service
        public class CourseService {
        
            @Autowired
            private CourseMapper courseMapper;
        
        
            @Transactional(propagation = Propagation.REQUIRES_NEW)
            public void insertCourse(){
                Course course = new Course();
                course.setId(1);
                course.setName("course_"+  System.currentTimeMillis());
                courseMapper.insert(course);
        
                int i = 1/0;
            }
        }

#### 无事务运行 ####

*      @Service
        public class StudentService {
        
        
            @Autowired
            private StudentMapper studentMapper;
        
        
        
            //没有使用@Transactional注解，以无事务方式运行
            //studentMapper.insert(student);自动提交，不会被回滚
            public void insert0(){
        
                Student student = new Student();
                student.setId(1);
                student.setName("student_"+ System.currentTimeMillis());
                studentMapper.insert(student);
        
                int i = 1/0;//这里抛出异常，但是studentMapper.insert会自动提交，不会被回滚
        
        
            }
        
        }

### 事务失效情况 ###

#### 使用了@Transactional的方法，被同一个类里面的无@Transactional方法调用，@Transactional的方法无效。 ####

*  下面的这种情况，student表 和 source表 都能成功添加数据，回滚失败。**注意：这是在同一个类中的方法相互调用，上述的是不同类的方法调用，上下文不违背！**
 *      @Service
        public class StudentImpl implements IStudent {
        
            @Autowired
            public StudentMapper studentMapper;
        
            @Autowired
            public SourceMapper sourceMapper;
        
            @Autowired
            public ISource source;
        
        	@Override
            public void insert0() {
                Student student = new Student();
                student.setId(1);
                student.setName("student:123-sad");
                studentMapper.insert(student);
                
                insertProxy();
            }
        
            @Transactional
            public void insertProxy(){
                Source source = new Source();
                source.setId(210);
                source.setName("source:210=qqwe");
                sourceMapper.insert(source);
                
                int i = 1/0;
            }
 *  但是下面这种情况B方法是可以回滚成功的，但A方法不能回滚，与第二章说明的情况一致
 *      @Service
        public class StudentImpl implements IStudent {
        
            @Autowired
            public StudentMapper studentMapper;
        
            @Autowired
            public SourceMapper sourceMapper;
        
            @Autowired
            public ISource source;
        
        	@Override
            public void insert0() {
                Student student = new Student();
                student.setId(1);
                student.setName("student:123-sad");
                studentMapper.insert(student);
                
                insertProxy();
            }
        
        	//无论这里有没有@Transactional注解，source.insert0()一样能回滚成功
            @Transactional	
            public void insertProxy(){
        		source.insert0();
            }
            
        
            
        @Service
        public class SourceImpl implements ISource {
        
            @Autowired
            public SourceMapper sourceMapper;
        
            @Override
            @Transactional
            public void insert0() {
                Source source = new Source();
                source.setId(210);
                source.setName("source:210=qqwe");
                sourceMapper.insert(source);
        
                int i = 1/0;
        
            }
        }
 *  原因：Spring的事务管理是基于**动态代理对象的代理逻辑实现的**，那么如果在类内部的非事务方法调用类内部的事务方法，这个调用事务方法的过程并不是通过**代理对象来调用的**，而是直接通过**this对象**来调用方法，绕过的代理对象，肯定就是没有代理逻辑了。
 *  解决方法：使用在类中注入自己的bean，加上@Lazy是为了防止bean的循环依赖注入。但是在实际开发中很少这样写，但这样确实能解决@Transactional失效的问题
 *      @Service
        public class StudentImpl implements IStudent {
        
            @Autowired
            public StudentMapper studentMapper;
        
            @Autowired
            public SourceMapper sourceMapper;
        
            @Autowired
            public ISource source;
        
            @Autowired
            @Lazy
            public StudentImpl studentImpl;
        
            @Override
            public void insert0() {
        
                Student student = new Student();
                student.setId(1);
                student.setName("student:123-sad");
                studentMapper.insert(student);
        
                studentImpl.insertProxy();
            }
        
        	//insertProxy()方法能成功回滚，Source表没有数据，但insert0()还是会添加成功，Student表有数据
            @Transactional
            public void insertProxy(){
                Source source1 = new Source();
                source1.setId(999);
                source1.setName("source:999=qqwe");
                sourceMapper.insert(source1);
        
                int i = 1/0;
            }
        }

### 奇特的回滚方式 ###

*  我们都知道，在Service层打上@Transactional后，若在该层操作出错了，不捕获异常，交由Controller层去捕获，则会回滚；但是如果异常在Service层就被捕获了，则不会回滚。但有以下方式，即使在Service层捕获了异常，仍然可以回滚成功。
 *      @RestController
        public class InsertController {
        
            @Autowired
            public IStudent studentService;
        
            @GetMapping("/insert")
            public String insert(){
                String result = "error";
                try {
                    result = studentService.insert0();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                return result;
            }
        }
        
        @Service
        public class StudentImpl implements IStudent {
            @Autowired
            public ISource sourceService;
        
            @Override
            @Transactional(rollbackFor = Exception.class, propagation = Propagation.REQUIRED)
            public String insert0() throws Exception {
                String result = sourceService.insert0();
                if ("fail".equals(result)) {
                    throw new Exception();
                }
                return "OK";
            }
        }
        
        
        @Service
        public class SourceImpl implements ISource {
        
            @Autowired
            public SourceMapper sourceMapper;
        
            @Override
            @Transactional(rollbackFor = Exception.class, propagation = Propagation.REQUIRED)
            public String insert0() throws Exception{
                String result = "success";
                try {
                    Source source = new Source();
                    source.setName("source:210=qqwe");
                    sourceMapper.insert(source);
        
                    int i = 1/0;
                }catch (Exception e){
                    result = "fail";
                }
                return result;
            }
        }
 *  这是因为A方法调用了B方法，A方法和B方法组成了一个事务，虽然B方法异常确实是被捕获到了，但是抛出异常的是A方法，由于A方法和B方法已经组成了一个事务了，所以这两个方法会一起回滚！

[spring]: https://so.csdn.net/so/search?q=spring%E4%BA%8B%E5%8A%A1&spm=1001.2101.3001.7020
[Transactional]: https://so.csdn.net/so/search?q=Transactional&spm=1001.2101.3001.7020