调试：Spring AOP执行过程

调试项目：https://github.com/1367356/laboratoryWeb

断点位置

点击查询：http://localhost:9002/queryNews?htmlid=1531872732684

1：  controler拦截，进入调试点。

News news=foreService.queryNews(htmlid);  //查询新闻

2:  进入service层打log

logger.debug(htmlid);

3:  打log,  省略后面n步....

    public void debug(final Object message) {
        logIfEnabled(FQCN, Level.DEBUG, null, message, null);
    }

4：service层 查询新闻。这是已经生成了Mapper代理对象 MapperProxy

return foreMapper.queryNews(htmlid);

5：进入JDK动态代理，执行代理方法，proxy是Mapper代理对象 ：final class JdkDynamicAopProxy

进入代理方法之前生成了已经生成了ForeMapper代理类,代理类包含SqlSession信息，Mapper.xml中的sql信息。

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        MethodInvocation invocation;
        Object oldProxy = null;
        boolean setProxyContext = false;

        TargetSource targetSource = this.advised.targetSource;
        Class<?> targetClass = null;
        Object target = null;

        try {
            if (!this.equalsDefined && AopUtils.isEqualsMethod(method)) {
                // The target does not implement the equals(Object) method itself.
                return equals(args[0]);
            }
            else if (!this.hashCodeDefined && AopUtils.isHashCodeMethod(method)) {
                // The target does not implement the hashCode() method itself.
                return hashCode();
            }
            else if (method.getDeclaringClass() == DecoratingProxy.class) {
                // There is only getDecoratedClass() declared -> dispatch to proxy config.
                return AopProxyUtils.ultimateTargetClass(this.advised);
            }
            else if (!this.advised.opaque && method.getDeclaringClass().isInterface() &&
                    method.getDeclaringClass().isAssignableFrom(Advised.class)) {
                // Service invocations on ProxyConfig with the proxy config...
                return AopUtils.invokeJoinpointUsingReflection(this.advised, method, args);
            }

            Object retVal;

            if (this.advised.exposeProxy) {
                // Make invocation available if necessary.
                oldProxy = AopContext.setCurrentProxy(proxy);
                setProxyContext = true;
            }

            // May be null. Get as late as possible to minimize the time we "own" the target,
            // in case it comes from a pool.
            target = targetSource.getTarget();
            if (target != null) {
                targetClass = target.getClass();  //执行，获取目标类
            }

            // Get the interception chain for this method.
            List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);

            // Check whether we have any advice. If we don't, we can fallback on direct  ,检查是否有 通知advice  aop:aftere等（拦截链），也就是说该方法是否被拦截。
            // reflective invocation of the target, and avoid creating a MethodInvocation.
            if (chain.isEmpty()) {
                // We can skip creating a MethodInvocation: just invoke the target directly
                // Note that the final invoker must be an InvokerInterceptor so we know it does
                // nothing but a reflective operation on the target, and no hot swapping or fancy proxying.
                Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
                retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
            }
            else {
                // We need to create a method invocation...      //如果有通知，创建反射方法调用
                invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
                // Proceed to the joinpoint through the interceptor chain.
                retVal = invocation.proceed();       //执行切入点
            }

            // Massage return value if necessary.
            Class<?> returnType = method.getReturnType();
            if (retVal != null && retVal == target &&
                    returnType != Object.class && returnType.isInstance(proxy) &&
                    !RawTargetAccess.class.isAssignableFrom(method.getDeclaringClass())) {
                // Special case: it returned "this" and the return type of the method
                // is type-compatible. Note that we can't help if the target sets
                // a reference to itself in another returned object.
                retVal = proxy;
            }
            else if (retVal == null && returnType != Void.TYPE && returnType.isPrimitive()) {
                throw new AopInvocationException(
                        "Null return value from advice does not match primitive return type for: " + method);
            }
            return retVal;
        }
        finally {
            if (target != null && !targetSource.isStatic()) {
                // Must have come from TargetSource.
                targetSource.releaseTarget(target);
            }
            if (setProxyContext) {
                // Restore old proxy.
                AopContext.setCurrentProxy(oldProxy);
            }
        }
    }

6：使用target,生成一个代理类 targetClass.  生成的是字节码对象。

7:  获取方法的拦截链

https://blog.csdn.net/xiejx618/article/details/43820417

List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);

8：    因为拦截连不为空执行下面的。生成反射方法调用对象，是生成一个含有调用方法的对象，不是生成包含ForeMapper中所有方法的对象。

                invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);  //生成包含 反射方法 的对象，如下
                // Proceed to the joinpoint through the interceptor chain.  //执行切入点
                retVal = invocation.proceed();

生成的invocation对象，代理了ForeMapper中一个方法（queryNews）的代理对象。

9：执行代理方法

retVal = invocation.proceed();

进入：public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Cloneable

    @Override
    public Object proceed() throws Throwable {
        //    We start with an index of -1 and increment early.
        if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
            return invokeJoinpoint();
        }

        Object interceptorOrInterceptionAdvice =
                this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);   //执行
        if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {
            // Evaluate dynamic method matcher here: static part will already have
            // been evaluated and found to match.
            InterceptorAndDynamicMethodMatcher dm =
                    (InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;
            if (dm.methodMatcher.matches(this.method, this.targetClass, this.arguments)) {
                return dm.interceptor.invoke(this);
            }
            else {
                // Dynamic matching failed.
                // Skip this interceptor and invoke the next in the chain.
                return proceed();
            }
        }
        else {
            // It's an interceptor, so we just invoke it: The pointcut will have
            // been evaluated statically before this object was constructed.
            return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);   //执行
        }
    }

10：进入：public class PersistenceExceptionTranslationInterceptor

      implements MethodInterceptor, BeanFactoryAware, InitializingBean {

    @Override
    public Object invoke(MethodInvocation mi) throws Throwable {
        try {
            return mi.proceed();  //执行
        }
        catch (RuntimeException ex) {
            // Let it throw raw if the type of the exception is on the throws clause of the method.
            if (!this.alwaysTranslate && ReflectionUtils.declaresException(mi.getMethod(), ex.getClass())) {
                throw ex;
            }
            else {
                if (this.persistenceExceptionTranslator == null) {
                    this.persistenceExceptionTranslator = detectPersistenceExceptionTranslators(this.beanFactory);
                }
                throw DataAccessUtils.translateIfNecessary(ex, this.persistenceExceptionTranslator);
            }
        }
    }

11：进入 public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Cloneable

执行：

    @Override
    public Object proceed() throws Throwable {
        //    We start with an index of -1 and increment early.
        if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
            return invokeJoinpoint();   //执行
        }

        Object interceptorOrInterceptionAdvice =
                this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
        if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {
            // Evaluate dynamic method matcher here: static part will already have
            // been evaluated and found to match.
            InterceptorAndDynamicMethodMatcher dm =
                    (InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;
            if (dm.methodMatcher.matches(this.method, this.targetClass, this.arguments)) {
                return dm.interceptor.invoke(this);
            }
            else {
                // Dynamic matching failed.
                // Skip this interceptor and invoke the next in the chain.
                return proceed();
            }
        }
        else {
            // It's an interceptor, so we just invoke it: The pointcut will have
            // been evaluated statically before this object was constructed.
            return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
        }
    }

执行：

    protected Object invokeJoinpoint() throws Throwable {
        return AopUtils.invokeJoinpointUsingReflection(this.target, this.method, this.arguments);
    }

12 进入： * @see org.springframework.aop.framework.AopProxyUtils

         public abstract class AopUtils   执行下面

    public static Object invokeJoinpointUsingReflection(Object target, Method method, Object[] args)
            throws Throwable {

        // Use reflection to invoke the method.  //使用反射调用方法
        try {
            ReflectionUtils.makeAccessible(method);  //对方法进行验证13步
            return method.invoke(target, args);      //调用方法14步
        }
        catch (InvocationTargetException ex) {
            // Invoked method threw a checked exception.
            // We must rethrow it. The client won't see the interceptor.
            throw ex.getTargetException();
        }
        catch (IllegalArgumentException ex) {
            throw new AopInvocationException("AOP configuration seems to be invalid: tried calling method [" +
                    method + "] on target [" + target + "]", ex);
        }
        catch (IllegalAccessException ex) {
            throw new AopInvocationException("Could not access method [" + method + "]", ex);
        }
    }

13：进入：public abstract class ReflectionUtils   对方法进行验证

    public static void makeAccessible(Method method) {
        if ((!Modifier.isPublic(method.getModifiers()) ||
                !Modifier.isPublic(method.getDeclaringClass().getModifiers())) && !method.isAccessible()) {
            method.setAccessible(true);
        }
    }

14： 调用方法，

return method.invoke(target, args);

15：进入Mapper代理：public class MapperProxy<T> implements InvocationHandler, Serializable

 public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    try {
      if (Object.class.equals(method.getDeclaringClass())) {
        return method.invoke(this, args);
      } else if (isDefaultMethod(method)) {
        return invokeDefaultMethod(proxy, method, args);
      }
    } catch (Throwable t) {
      throw ExceptionUtil.unwrapThrowable(t);
    }
    final MapperMethod mapperMethod = cachedMapperMethod(method);  //执行
    return mapperMethod.execute(sqlSession, args);
  }

16：生成MapperMethod对象,  这是一个只包含调用方法的代理对象。当调用时，会在代理对象中执行SqlSession信息（Sql语句）。

  private MapperMethod cachedMapperMethod(Method method) {
    MapperMethod mapperMethod = methodCache.get(method);
    if (mapperMethod == null) {
      mapperMethod = new MapperMethod(mapperInterface, method, sqlSession.getConfiguration());
      methodCache.put(method, mapperMethod);
    }
    return mapperMethod;
  }

17: 进入SqlSessionTemplate ： public class SqlSessionTemplate implements SqlSession, DisposableBean ，执行

  public Configuration getConfiguration() {
    return this.sqlSessionFactory.getConfiguration();
  }

18：进入DefaultSqlSessionFactory ：public class DefaultSqlSessionFactory implements SqlSessionFactory  执行：

  public Configuration getConfiguration() {
    return configuration;
  }

configuration包含Mapper中的各个Sql信息。

19：SqlSessionTemplate 返回包含configuration的sqlSessionFactory

  @Override
  public Configuration getConfiguration() {
    return this.sqlSessionFactory.getConfiguration();
  }

20:  进入：public class MapperMethod 

用configuration配置  MapperMethod，生成MapperMethod对象。

  public MapperMethod(Class<?> mapperInterface, Method method, Configuration config) {
    this.command = new SqlCommand(config, mapperInterface, method);
    this.method = new MethodSignature(config, mapperInterface, method);
  }

21：SqlCommand  方法生成Sql命令，将configuration中的sql信息取出。Sql命令是MapperMethod对象的一部分。

    public SqlCommand(Configuration configuration, Class<?> mapperInterface, Method method) {
      final String methodName = method.getName();
      final Class<?> declaringClass = method.getDeclaringClass();
      MappedStatement ms = resolveMappedStatement(mapperInterface, methodName, declaringClass,
          configuration);     //生成的sql Statement
      if (ms == null) {
        if (method.getAnnotation(Flush.class) != null) {
          name = null;
          type = SqlCommandType.FLUSH;
        } else {
          throw new BindingException("Invalid bound statement (not found): "
              + mapperInterface.getName() + "." + methodName);
        }
      } else {
        name = ms.getId();
        type = ms.getSqlCommandType();
        if (type == SqlCommandType.UNKNOWN) {
          throw new BindingException("Unknown execution method for: " + name);
        }
      }
    }

22:执行method

23:进入MapperMethod :执行

  public Object execute(SqlSession sqlSession, Object[] args) {
    Object result;
    switch (command.getType()) {
      case INSERT: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.insert(command.getName(), param));
        break;
      }
      case UPDATE: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.update(command.getName(), param));
        break;
      }
      case DELETE: {
        Object param = method.convertArgsToSqlCommandParam(args);
        result = rowCountResult(sqlSession.delete(command.getName(), param));
        break;
      }
      case SELECT:
        if (method.returnsVoid() && method.hasResultHandler()) {
          executeWithResultHandler(sqlSession, args);
          result = null;
        } else if (method.returnsMany()) {
          result = executeForMany(sqlSession, args);
        } else if (method.returnsMap()) {
          result = executeForMap(sqlSession, args);
        } else if (method.returnsCursor()) {
          result = executeForCursor(sqlSession, args);
        } else {
          Object param = method.convertArgsToSqlCommandParam(args);   //执行
          result = sqlSession.selectOne(command.getName(), param);
        }
        break;
      case FLUSH:
        result = sqlSession.flushStatements();
        break;
      default:
        throw new BindingException("Unknown execution method for: " + command.getName());
    }
    if (result == null && method.getReturnType().isPrimitive() && !method.returnsVoid()) {
      throw new BindingException("Mapper method '" + command.getName()
          + " attempted to return null from a method with a primitive return type (" + method.getReturnType() + ").");
    }
    return result;
  }

24： 得到参数param=... ,commond.getName=queryNews()

25：  通过sqlSession执行方法，返回结果。

26：返回结果，成功。

Spring Aop简单实现：https://github.com/1367356/GradleTestUseSubModule/tree/master/SpringAOPTheory

Spring AOP的执行流程：https://blog.csdn.net/qq418517226/article/details/51284298