调试：Spring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。

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() &&   //执行
                    method.getDeclaringClass().isAssignableFrom(Advised.class)) {
                // Service invocations on ProxyConfig with the proxy config...
                return AopUtils.invokeJoinpointUsingReflection(this.advised, method, args);  //调用Joinpoint
            }

            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();
            }

            // 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，穿建反射方法调用
                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：

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