场景：
服务编排框架支持编排webservice服务。call webservice的client是基于cxf做的。为了使用服务编排的开发者调试与定位问题方便，需要将webservice的请求与响应报文打出来。
这个诉求不是很复杂加上LoggingInInterceptor(打印响应报文)与LoggingOutInterceptor(打印请求报文)两个拦截器即可。
好，开始考虑异常场景，当提供webservice的服务后台不通时，理论上也是应该可以打出请求报文的，但是在对cxf的client的httpClientPolicy的chunk设置成false之后，请求的报文就不会被打出了。
分析：
分析源码后发现cxf依赖大量的拦截器，可以说对拦截器这个pattern用的还是比较深入的：
1. 拦截的phase有很多
2.触发拦截后还可以注册回调
3.拦截器形成自己的chain
4.触发拦截器执行过程中还可以动态增加拦截器
触发拦截器调用逻辑的代码在
org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(Message)
的255行： currentInterceptor.handleMessage(message);
通过调用堆栈不难发现，触发输出日志动作是在执行org.apache.cxf.inte[email protected]17d602ac这个拦截器时。
可以猜测在chunk设置成false是没有成功执行到这个拦截器的。
好，对比两种场景下执行的拦截器的情况
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在chunk未关闭的时候：
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===========================
在chunk设置成false关闭时：
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果然很清晰的发现在org.apache.cxf.binding.soap.interceptor.SoapOutInterceptor执行时出现了异常，使得拦截器执行不下去了，日志如下，显而易见，服务不通：
exception, unwinding now
org.apache.cxf.binding.soap.SoapFault: Error writing to XMLStreamWriter.
at org.apache.cxf.binding.soap.interceptor.SoapOutInterceptor.writeSoapEnvelopeStart(SoapOutInterceptor.java:175)
at org.apache.cxf.binding.soap.interceptor.SoapOutInterceptor.handleMessage(SoapOutInterceptor.java:81)
at org.apache.cxf.binding.soap.interceptor.SoapOutInterceptor.handleMessage(SoapOutInterceptor.java:61)
at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:255)
at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:544)
at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:341)
at org.apache.cxf.endpoint.ClientImpl.invoke(ClientImpl.java:294)
at org.apache.cxf.frontend.ClientProxy.invokeSync(ClientProxy.java:73)
at org.apache.cxf.jaxws.JaxWsClientProxy.invoke(JaxWsClientProxy.java:124)
at com.sun.proxy.$Proxy26.queryUser(Unknown Source)
at org.simonme.demo.cxf.client.user.UserService_UserServicePort_Client.main(UserService_UserServicePort_Client.java:77)
Caused by: javax.xml.stream.XMLStreamException: java.net.ConnectException: Connection refused: connect
at com.sun.xml.internal.stream.writers.XMLStreamWriterImpl.writeStartElement(XMLStreamWriterImpl.java:1344)
at org.apache.cxf.binding.soap.interceptor.SoapOutInterceptor.writeSoapEnvelopeStart(SoapOutInterceptor.java:122)
... 10 more
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:579)
org.apache.cxf.io.AbstractThresholdOutputStream.write(int)
@Override
public void write(int b) throws IOException {
if (buffer != null) {
buffer.write(b);
if (buffer.size() >= threshold) {
thresholdReached();
unBuffer();
}
return;
}
super.write(b);
}
threshold 在chunk设置成false时 为0 ，不设置时(默认true) 为4096
当设置成0时，一定会触发unBuffer逻辑，这个逻辑会去请求后台，此时后台又不通 那么就出现了异常。具体可以看上面日志的异常栈。
如何设置的4096
看org.apache.cxf.transports.http.configuration.HTTPClientPolicy.getChunkingThreshold()
threshold 如何设置的0
if (csPolicy.isAllowChunking()
&& isChunkingSupported(message, connection.getRequestMethod())) {
//TODO: The chunking mode be configured or at least some
// documented client constant.
//use -1 and allow the URL connection to pick a default value
isChunking = true;
chunkThreshold = csPolicy.getChunkingThreshold();
if (chunkThreshold <= 0) {
chunkThreshold = 0;
connection.setChunkedStreamingMode(-1);
}
}
org.apache.cxf.transport.http.HTTPConduit.prepare(Message)
方法中chunkThreshold初始值为0 因为isAllowChunking为false 所以上面逻辑不会进入，所以chunkThreshold依然为0
为什么设置启用chunk，就要设置成4096？
you’ll be receiving in some arbitrary chunk size, (4096 or 8192 is frequently a good match for network buffer sizes)
还有些类库 默认是2048的
The default chunk size in Apache HttpClient 4.3 is set to 2048 bytes.
如何解决这个问题，可以考虑修改(重写)这个拦截器的触发时机等。