CXF客户端请求服务流程

CXF(使用版本2.7.6)对Web服务封装度已经非常高了,你只需要像正常写代码一样,附加几个额外的注解直接发布,服务端差不多就完成了;对于客户端更简单,只需要知道Web服务的URL地址和接口,就能如调用本地代码一样,几乎感觉不到与本地代码有什么区别。这就是封装的威力,虽然高度封装简化了我们对Web服务的使用,但也间接地阻挡了我们对其深入了解。本文就将源码层面来分析CXF其内部是如何完成客户端对Web服务的调用封装的,但并不包含服务端对服务请求的处理过程,如有需要可参看上篇,CXF中Web服务请求处理流程。

以SOAP协议服务为例,当我们使用代码调用Web服务时,一般情况如下:

JaxWsProxyFactoryBean factoryBean = new JaxWsProxyFactoryBean();
String address = "...";//Web服务发布地址
factoryBean.setAddress(address);
factoryBean.setServiceClass(HelloService.class);//Web服务接口
HelloService helloService = factoryBean.create(HelloService.class);
helloService.sayHello("xtayfjpk");

最重要的当然是factoryBean.create()方法了,从代码表面上看,只知道其返回了一个实现了HelloService接口类实例,但它具体到底是什么呢?这当然就得去看看源码了:


public  ProxyServiceType create(Class serviceClass) {
	setServiceClass(serviceClass);
	//看上去很简单啊,别急,操作都是create()方法中呢
	return serviceClass.cast(create());
}

public synchronized Object create() {
	ClassLoaderHolder orig = null;
	try {
		if (getBus() != null) {
			ClassLoader loader = getBus().getExtension(ClassLoader.class);
			if (loader != null) {
				orig = ClassLoaderUtils.setThreadContextClassloader(loader);
			}
		}
		//配置this,即JaxWsProxyFactoryBean对象
		configureObject();
		
		if (properties == null) {
			properties = new HashMap();
		}

		if (username != null) {
			AuthorizationPolicy authPolicy = new AuthorizationPolicy();
			authPolicy.setUserName(username);
			authPolicy.setPassword(password);
			properties.put(AuthorizationPolicy.class.getName(), authPolicy);
		}
		
		//为clientFactoryBean与ServiceFactory设置features
		initFeatures();
		clientFactoryBean.setProperties(properties);

		if (bus != null) {
			clientFactoryBean.setBus(bus);
		}

		if (dataBinding != null) {
			clientFactoryBean.setDataBinding(dataBinding);
		}

		//由工厂类创建出Client对象,实现类为ClientImpl,并且创建出了Endpoint、Service对象
		Client c = clientFactoryBean.create();
		//将各种拦截器设置进Client中
		if (getInInterceptors() != null) {
			c.getInInterceptors().addAll(getInInterceptors());
		}
		if (getOutInterceptors() != null) {
			c.getOutInterceptors().addAll(getOutInterceptors());
		}
		if (getInFaultInterceptors() != null) {
			c.getInFaultInterceptors().addAll(getInFaultInterceptors());
		}
		if (getOutFaultInterceptors() != null) {
			c.getOutFaultInterceptors().addAll(getOutFaultInterceptors());
		}
		
		//创建客户端代理对象
		ClientProxy handler = clientClientProxy(c);
		//获取代理需要实现的接口,包含Web服务接口与java.io.Closeable
		Class classes[] = getImplementingClasses();
		
		//这里是最关键代码,使用JDK提供的Proxy类创建出一个代理对象,该代理对象实现了Web服务接口与java.io.Closeable接口
		//而调用处理器(InvocationHandler)对象就是刚创建的ClientProxy对象
		Object obj = Proxy.newProxyInstance(clientFactoryBean.getServiceClass().getClassLoader(),
											classes,
											handler);

		this.getServiceFactory().sendEvent(FactoryBeanListener.Event.PROXY_CREATED,
										   classes, handler, obj);
		return obj;
	} finally {
		if (orig != null) {
			orig.reset();
		}
	}
}

因为调用处理器为ClientProxy,则客户端所有的Web服务调用都是调用ClientProxy的invoke方法,Web服务返回值就是invoke方法返回值,如下:

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
	//省略...
	MethodDispatcher dispatcher = (MethodDispatcher)endpoint.getService().get(MethodDispatcher.class
																				  .getName());
	BindingOperationInfo oi = dispatcher.getBindingOperation(method, endpoint);
	//省略...

	Object[] params = args;
	if (null == params) {
		params = new Object[0];
	}
	
	//进行同步调用
	Object o = invokeSync(method, oi, params);
	//call a virtual method passing the object.  This causes the IBM JDK
	//to keep the "this" pointer references and thus "this" doesn't get 
	//finalized in the midst of an invoke operation
	return adjustObject(o); 
}

通过create()方法,可以知道在创建ClientProxy时传入了Client对象,而在invokeSync(method, oi, params);中主要就是调用了Client的invoke方法,其invoke方法经过多个重的invoke方法调用,最后调用的是doInvoke()方法:


private Object[] doInvoke(ClientCallback callback,
                              BindingOperationInfo oi,
                              Object[] params,
                              Map context,
                              Exchange exchange) throws Exception {
	Bus origBus = BusFactory.getAndSetThreadDefaultBus(bus);
	ClassLoaderHolder origLoader = null;
	try {
		ClassLoader loader = bus.getExtension(ClassLoader.class);
		if (loader != null) {
			origLoader = ClassLoaderUtils.setThreadContextClassloader(loader);
		}
		if (exchange == null) {
			//创建Exchange对象
			exchange = new ExchangeImpl();
		}
		exchange.setSynchronous(callback == null);
		Endpoint endpoint = getEndpoint();
		if (LOG.isLoggable(Level.FINE)) {
			LOG.fine("Invoke, operation info: " + oi + ", params: " + Arrays.toString(params));
		}
		//创建Out消息
		Message message = endpoint.getBinding().createMessage();
		
		// Make sure INVOCATION CONTEXT, REQUEST_CONTEXT and RESPONSE_CONTEXT are present
		// on message
		//将调用上下文、请求上下文、响应上下文三个Map放置在Message与Exchange相应位置
		Map reqContext = null;
		Map resContext = null;
		if (context == null) {
			context = new HashMap();
		}
		reqContext = CastUtils.cast((Map)context.get(REQUEST_CONTEXT));
		resContext = CastUtils.cast((Map)context.get(RESPONSE_CONTEXT));
		if (reqContext == null) { 
			reqContext = new HashMap(getRequestContext());
			context.put(REQUEST_CONTEXT, reqContext);
		}
		if (resContext == null) {
			resContext = new HashMap();
			context.put(RESPONSE_CONTEXT, resContext);
		}
		
		message.put(Message.INVOCATION_CONTEXT, context);
		setContext(reqContext, message);
		exchange.putAll(reqContext);
		
		//设置参数,将参数包装成一个MessageContentsList对象
		//CXF中,Web服务的参数与返回结果都会包装成这种数据类型
		setParameters(params, message);

		if (null != oi) {
			//设置Exchange是否为单向的
			exchange.setOneWay(oi.getOutput() == null);
		}
		//将Message作为Exchange的输出消息
		exchange.setOutMessage(message);
		//设置回调接口,一般情况为null
		exchange.put(ClientCallback.class, callback);
		
		//设置消息属性
		setOutMessageProperties(message, oi);
		//设置Exchange属性,设置的属性有很多,具体的要看源码,其中一个最重要的属性是MessageObserver对象
		//exchange.put(MessageObserver.class, this);即把ClientImpl作为Message观察者,也就是当Web服务响应
		//结果返回后将调用ClientImpl的onMessage方法
		setExchangeProperties(exchange, endpoint, oi);

		//收集Bus、Client、Endpoint、Binding、DataBinding的输出拦截器至拦截器链中
		PhaseInterceptorChain chain = setupInterceptorChain(endpoint);
		//将拦截器链设置进Message中
		message.setInterceptorChain(chain);
		//为拦截器链设置错误观察者,即处理器
		chain.setFaultObserver(outFaultObserver);
		//准备ConduitSelector对象,其内部维护了一个Conduit列表,如果你在JaxWsProxyFactoryBean没有设置ConduitSelector
		//则默认会使用org.apache.cxf.endpoint.UpfrontConduitSelector,ConduitSelector会根据Message的设置情况选取或创建一个Conduit
		//Conduit对象是CXF中传输层用作客户端与服务端之间传输数据的管道,封装也客户端与服务端之间数据通信协议
		//对于JaxWsProxyFactoryBean调用Web服务,使用的是org.apache.cxf.transport.http.URLConnectionHTTPConduit,是一种基于
		//java.net.URLConnection的管道,客户端与服务端之间的数据通信最终都是通过URLConnection对象来完成的。
		prepareConduitSelector(message);

		//添加一些额外的拦截器,根据消息中是否含有拦截器提供者
		modifyChain(chain, message, false);
		try {
			//调用拦截器链doIntercept()方法,依赖调用链中各个拦截器中的handleMessage()方法 
			chain.doIntercept(message);
		} catch (Fault fault) {
			enrichFault(fault);
			throw fault;
		}
		
		if (callback != null) {
			return null;
		} else {
			//处理执行结果
			return processResult(message, exchange, oi, resContext);
		}
	} finally {
		if (origLoader != null) {
			origLoader.reset();
		}
		if (origBus != bus) {
			BusFactory.setThreadDefaultBus(origBus);
		}
	}
}

在客户端的输出拦截器链中默认含有的拦截器如下:
1. org.apache.cxf.ws.policy.PolicyOutInterceptor
2. org.apache.cxf.jaxws.interceptors.HolderOutInterceptor
3. org.apache.cxf.jaxws.interceptors.SwAOutInterceptor
4. org.apache.cxf.jaxws.interceptors.WrapperClassOutInterceptor
5. org.apache.cxf.binding.soap.interceptor.SoapHeaderOutFilterInterceptor
6. org.apache.cxf.binding.soap.interceptor.SoapPreProtocolOutInterceptor
7. org.apache.cxf.interceptor.MessageSenderInterceptor
8. org.apache.cxf.interceptor.AttachmentOutInterceptor
9. org.apache.cxf.interceptor.StaxOutInterceptor
10. org.apache.cxf.binding.soap.interceptor.SoapOutInterceptor
11. org.apache.cxf.interceptor.WrappedOutInterceptor
12. org.apache.cxf.interceptor.BareOutInterceptor
13. org.apache.cxf.management.interceptor.ResponseTimeMessageOutInterceptor
14. org.apache.cxf.binding.soap.interceptor.SoapOutInterceptor$SoapOutEndingInterceptor
15. org.apache.cxf.interceptor.StaxOutEndingInterceptor
16. org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndingInterceptor

上面的序号也是拦截器被执行的顺序,其中第7、9、12、16号拦截器非常重要,这里将作详细解释,由于拦截器太多,其它的就得自己看了。
org.apache.cxf.interceptor.MessageSenderInterceptor:

public void handleMessage(Message message) {
	try {
		getConduit(message).prepare(message);
	} catch (IOException ex) {
		throw new Fault(new org.apache.cxf.common.i18n.Message("COULD_NOT_SEND", BUNDLE), ex);
	}    
	
	//添加org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndingInterceptor到链中
	message.getInterceptorChain().add(ending);
}

看上去是不是特别简单呢?这么想可就错了,现在我们就去看一看prepare()方法,从doInvoke方法的注释中可以知道Conduit的实现类为URLConnectionHTTPConduit,prepare()方法就定义在其父类HTTPConduit中:

public void prepare(Message message) throws IOException {
	// This call can possibly change the conduit endpoint address and 
	// protocol from the default set in EndpointInfo that is associated
	// with the Conduit.
	URI currentURI;
	try {
		//获取要访问的URI
		currentURI = setupURI(message);
	} catch (URISyntaxException e) {
		throw new IOException(e);
	}       

	// The need to cache the request is off by default
	boolean needToCacheRequest = false;
	
	HTTPClientPolicy csPolicy = getClient(message);
	//获取并配置Connection,该方法为抽象方法,实现在URLConnectionHTTPConduit中
	setupConnection(message, currentURI, csPolicy);
	
	//获取请求方法,GET或POST,默认使用POST
	String httpRequestMethod = 
		(String)message.get(Message.HTTP_REQUEST_METHOD);
	if (httpRequestMethod == null) {
		httpRequestMethod = "POST";
		message.put(Message.HTTP_REQUEST_METHOD, "POST");
	}
	
	//省略...
	
	//创建OutputStream对象,用于向服务端发送请求,并将其放置在Message中
	//createOutputStream也是一抽象方法,实现在URLConnectionHTTPConduit中
	message.setContent(OutputStream.class, 
					   createOutputStream(message,
										  needToCacheRequest, 
										  isChunking,
										  chunkThreshold));
	//至此,所有准备工作都已经OK,可以发送消息了
}

现在去看看那两个抽象方法,即setupConnection与createOutputStream:

protected void setupConnection(Message message, URI currentURL, HTTPClientPolicy csPolicy) throws IOException {
	//创建出HttpURLConnection
	HttpURLConnection connection = createConnection(message, currentURL, csPolicy);
	//设置输出标志
	connection.setDoOutput(true);       
	//计算连接超时时间
	int ctimeout = determineConnectionTimeout(message, csPolicy);
	connection.setConnectTimeout(ctimeout);
	//计算读取超时时间
	int rtimeout = determineReceiveTimeout(message, csPolicy);
	connection.setReadTimeout(rtimeout);
	//不使用缓存
	connection.setUseCaches(false);
	//因为URLConnectionHTTPConduit自己实现了重定向功能,所以不再使用HttpURLConnection的重定向
	connection.setInstanceFollowRedirects(false);

	// 如果HTTP_REQUEST_METHOD没有设置,则默认为POST
	String httpRequestMethod = 
		(String)message.get(Message.HTTP_REQUEST_METHOD);
	if (httpRequestMethod == null) {
		httpRequestMethod = "POST";
		message.put(Message.HTTP_REQUEST_METHOD, "POST");
	}
	//设置请求方法
	connection.setRequestMethod(httpRequestMethod);
	
	//将HttpURLConnection放置在Message中,给创建输出流的时候使用
	message.put(KEY_HTTP_CONNECTION, connection);
}

protected OutputStream createOutputStream(Message message, 
                                              boolean needToCacheRequest, 
                                              boolean isChunking,
                                              int chunkThreshold) throws IOException {
	//取出在setupConnection方法中放置在Message中的HttpURLConnection对象
	HttpURLConnection connection = (HttpURLConnection)message.get(KEY_HTTP_CONNECTION);
	
	if (isChunking && chunkThreshold <= 0) {
		chunkThreshold = 0;
		connection.setChunkedStreamingMode(-1);                    
	}
	try {
		//返回一个包装好的输出流
		return new URLConnectionWrappedOutputStream(message, connection,
									   needToCacheRequest, 
									   isChunking,
									   chunkThreshold,
									   getConduitName());
	} catch (URISyntaxException e) {
		throw new IOException(e);
	}
}


org.apache.cxf.interceptor.StaxOutInterceptor:

public void handleMessage(Message message) {
	OutputStream os = message.getContent(OutputStream.class);
	XMLStreamWriter xwriter = message.getContent(XMLStreamWriter.class);
	Writer writer = null;
	if (os == null) {
		writer = message.getContent(Writer.class);
	}
	if ((os == null && writer == null) || xwriter != null) {
		return;
	}

	String encoding = getEncoding(message);
	
	try {
		XMLOutputFactory factory = getXMLOutputFactory(message);
		if (factory == null) {
			if (writer == null) {
				os = setupOutputStream(message, os);
				xwriter = StaxUtils.createXMLStreamWriter(os, encoding);
			} else {
				xwriter = StaxUtils.createXMLStreamWriter(writer);
			}
		} else {
			synchronized (factory) {
				if (writer == null) {
					os = setupOutputStream(message, os);
					xwriter = factory.createXMLStreamWriter(os, encoding);
				} else {
					xwriter = factory.createXMLStreamWriter(writer);
				}
			}
		}
		if (MessageUtils.getContextualBoolean(message, FORCE_START_DOCUMENT, false)) {
			xwriter.writeStartDocument(encoding, "1.0");
			message.removeContent(OutputStream.class);
			message.put(OUTPUT_STREAM_HOLDER, os);
			message.removeContent(Writer.class);
			message.put(WRITER_HOLDER, writer);
		}
	} catch (XMLStreamException e) {
		throw new Fault(new org.apache.cxf.common.i18n.Message("STREAM_CREATE_EXC", BUNDLE), e);
	}
	//将XMLStreamWriter设置进Message中
	message.setContent(XMLStreamWriter.class, xwriter);

	// Add a final interceptor to write end elements
	message.getInterceptorChain().add(ENDING);
}

该拦截器所做的工作就是取得Message中的OutputStream将其封装成一个XMLStreamWriter对象,方便对XML内容的操作,因为客户端与服务端通信的媒介就是XML格式。


org.apache.cxf.interceptor.BareOutInterceptor:

public void handleMessage(Message message) {
	Exchange exchange = message.getExchange();
	BindingOperationInfo operation = (BindingOperationInfo)exchange.get(BindingOperationInfo.class.getName());
	
	if (operation == null) {
		return;
	}
	
	//获取参数列表
	MessageContentsList objs = MessageContentsList.getContentsList(message);
	if (objs == null || objs.size() == 0) {
		return;
	}
	
	List parts = null;
	BindingMessageInfo bmsg = null;
	//现在是客户端,则为true
	boolean client = isRequestor(message);

	if (!client) {
		if (operation.getOutput() != null) {
			bmsg = operation.getOutput();
			parts = bmsg.getMessageParts();
		} else {
			// partial response to oneway
			return;
		}
	} else {
		bmsg = operation.getInput();
		//获取消息内容
		parts = bmsg.getMessageParts();
	}
	//将消息内容通过XMLStreamWriter以XML格式写入输出流,最终通过URLConnection写给服务端
	writeParts(message, exchange, operation, objs, parts);
}

org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndingInterceptor,该拦截器是在执行MessageSenderInterceptor时添加到拦截器链中的。

public void handleMessage(Message message) throws Fault {
	try {
		getConduit(message).close(message);
	} catch (IOException e) {
		throw new Fault(new org.apache.cxf.common.i18n.Message("COULD_NOT_SEND", BUNDLE), e);
	}
}

Conduit的实现类为URLConnectionHTTPConduit,调用其close(message)方法,该方法定义在URLConnectionHTTPConduit基类AbstractConduit中,从Message中取出OutputStream,也就是被包装过的URLConnectionWrappedOutputStream对象,再调用其close()方法其定义在org.apache.cxf.transport.http.HTTPConduit.WrappedOutputStream中,最终调用了handleResponseInternal()用于处理响应请求:


protected void handleResponseInternal() throws IOException {
	//获取Exchage对象
	Exchange exchange = outMessage.getExchange();
	//获取响应状态码
	int responseCode = getResponseCode();
	if (responseCode == -1) {
		LOG.warning("HTTP Response code appears to be corrupted");
	}
	if (exchange != null) {
		exchange.put(Message.RESPONSE_CODE, responseCode);
	}
			   
	//处理异常
	boolean noExceptions = MessageUtils.isTrue(outMessage.getContextualProperty(
		"org.apache.cxf.http.no_io_exceptions"));
	if (responseCode >= 400 && responseCode != 500 && !noExceptions) {
		throw new HTTPException(responseCode, getResponseMessage(), url.toURL());
	}

	InputStream in = null;
	
	//创建in message,即响应消息,因为请求已经提交,接下来就是要接收服务端的响应消息
	Message inMessage = new MessageImpl();
	inMessage.setExchange(exchange);
	//更新响应头
	updateResponseHeaders(inMessage);
	inMessage.put(Message.RESPONSE_CODE, responseCode);

	if (isOneway(exchange) || HttpURLConnection.HTTP_ACCEPTED == responseCode) {
		//省略...	因为Exchange不是单向的
	} else {
		//not going to be resending or anything, clear out the stuff in the out message
		//to free memory
		//将输出流移出outMessage,释放输出消息,输出消息的工作到此完成
		outMessage.removeContent(OutputStream.class);
		if (cachingForRetransmission && cachedStream != null) {
			cachedStream.close();
		}
		cachedStream = null;
	}
	
	//获取编码
	String charset = HttpHeaderHelper.findCharset((String)inMessage.get(Message.CONTENT_TYPE));
	String normalizedEncoding = HttpHeaderHelper.mapCharset(charset);
	if (normalizedEncoding == null) {
		String m = new org.apache.cxf.common.i18n.Message("INVALID_ENCODING_MSG",
														   LOG, charset).toString();
		LOG.log(Level.WARNING, m);
		throw new IOException(m);   
	} 
	inMessage.put(Message.ENCODING, normalizedEncoding);
	if (in == null) {
		//获取输入流,实现在URLConnectionWrappedOutputStream中,由URLConnection返回一个InputStream对象
		in = getInputStream();
	}
	if (in == null) {
		// Create an empty stream to avoid NullPointerExceptions
		in = new ByteArrayInputStream(new byte[] {});
	}
	//将输出流放置在输出消息中,以供后用
	inMessage.setContent(InputStream.class, in);
	
	//调用输入消息观察者的onMessage方法(观察者模式的使用)
	incomingObserver.onMessage(inMessage);
}

在上面的doInvoke方法解释中说到,输出消息的观察者就是ClientImpl对象,所以调用的就是ClientImpl的onMessage方法:

public void onMessage(Message message) {

	Endpoint endpoint = message.getExchange().getEndpoint();
	//省略...

	//将MessageImpl包装成SOAPMessage
	message = endpoint.getBinding().createMessage(message);
	message.getExchange().setInMessage(message);
	message.put(Message.REQUESTOR_ROLE, Boolean.TRUE);
	message.put(Message.INBOUND_MESSAGE, Boolean.TRUE);
	
	//省略...

	InterceptorChain chain;
	//与输出拦截器链类似,收集Bus、Client、Endpoint、Binding、DataBinding的输入拦截器
	message.setInterceptorChain(chain);

	chain.setFaultObserver(outFaultObserver);
	modifyChain(chain, message, true);
	modifyChain(chain, message.getExchange().getOutMessage(), true);
	
	Bus origBus = BusFactory.getAndSetThreadDefaultBus(bus);
	// execute chain
	ClientCallback callback = message.getExchange().get(ClientCallback.class);

	
	try {
		//省略很多代码...

		if(callback!=null) {
			//do something with callback
		}
		//调用输入拦截器链的doIntercept,依次调用链中的各个拦截器的handleMessage方法
		chain.doIntercept(message);
	} finally {
		//省略...
	}
}

在输入拦截器链中最主要的工作就是完成了从InputStream中获取服务端的响应,然后将XML格式的内容反序列化为java对象,即得到Web服务实现的返回值。在上面的doInvoke方法中,当输入拦截器链也执行完成后,接下来执行的就是processResult方法:

protected Object[] processResult(Message message,
                                   Exchange exchange,
                                   BindingOperationInfo oi,
                                   Map resContext) throws Exception {
	//异常处理...
	
	//处理202响应
	Integer responseCode = (Integer)exchange.get(Message.RESPONSE_CODE);
	if (null != responseCode && 202 == responseCode) {
		Endpoint ep = exchange.getEndpoint();
		if (null != ep && null != ep.getEndpointInfo() && null == ep.getEndpointInfo().
			getProperty("org.apache.cxf.ws.addressing.MAPAggregator.decoupledDestination")) {
			return null;
		}
	}

	// Wait for a response if we need to
	if (oi != null && !oi.getOperationInfo().isOneWay()) {
		synchronized (exchange) {
			//等待服务端响应
			waitResponse(exchange);
		}
	}

	//是否保存输出入为打开状态,默认为否
	Boolean keepConduitAlive = (Boolean)exchange.get(Client.KEEP_CONDUIT_ALIVE);
	if (keepConduitAlive == null || !keepConduitAlive) {
		//关闭输入流
		getConduitSelector().complete(exchange);
	}

	// Grab the response objects if there are any
	List resList = null;
	Message inMsg = exchange.getInMessage();
	if (inMsg != null) {
		if (null != resContext) {
			resContext.putAll(inMsg);
			// remove the recursive reference if present
			resContext.remove(Message.INVOCATION_CONTEXT);
			responseContext.put(Thread.currentThread(), resContext);
		}
		//获取消息中的List类型对象,也就是MessageConentList
		resList = CastUtils.cast(inMsg.getContent(List.class));
	}

	//处理异常...

	if (resList != null) {
		//返回Object[]
		return resList.toArray();
	}

	return null;
} 
  
现在回到ClientProxy的invokeSync方法,该方法的返回值就是服务端返回的结果,ClientProxy的invoke方法的返回值,而ClientProxy又是调用Proxy.newInstance时的InvocationHandler,所以该返回值也就是调用客户端服务方法的返回结果;下面是invokeSync方法源码:

public Object invokeSync(Method method, BindingOperationInfo oi, Object[] params)
	throws Exception {
	if (client == null) {
		throw new IllegalStateException("The client has been closed.");
	}
	//client实现类就是ClientImpl
	Object rawRet[] = client.invoke(oi, params);

	if (rawRet != null && rawRet.length > 0) {
		//取返回结果Object[]中的第一个元素,得到最终的返回结果
		return rawRet[0];
	} else {
		return null;
	}
}

至此,CXF客户端调用流程也就完成了,这其中重要的是涉及了两个拦截器链的执行,输出链执行完成后,在其关闭时又触发了输入链的执行。输出链完成服务请求(部分而非所有),输出链完成对服务端响应处理(部分而非所有),得到返回结果。那么,剩下的就是你对返回结果的处理了,如有错误之处,尽请指正。

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