拦截器（Interceptor）是CXF功能最基本的扩展点，能够在不正确核心模块进行改动的情况下。动态加入非常多功能。拦截器和JAX-WS Handler、Filter的功能相似，当服务被调用时。就会创建一个拦截器链（Interceptor Chain），拦截器链在服务输入（IN）或输出（OUT）阶段实现附加功能。
拦截器能够在client，也能够在服务端加入。当client发起一个WebService请求时。在client会创建输出拦截器链，服务端接收到client的后。会创建输入拦截器链。当服务端返回响应消息时，响应消息会经过服务端的输出拦截链。client接收到服务端的响应时。会创建输入拦截器链，响应消息先经过输入拦截器链处理。拦截器在服务端和client的作用如图所看到的。
拦截器链阶段
拦截器链有多个阶段，每一个阶段都有多个拦截器。拦截器在拦截器链的哪个阶段起作用。能够在拦截器的构造函数中声明。
输入拦截器链有例如以下几个阶段，这些阶段依照在拦截器链中的先后顺序排列。
| 阶段名称 | 阶段功能描写叙述 |
|---|---|
| RECEIVE | Transport level processing(接收阶段，传输层处理) |
| (PRE/USER/POST)_STREAM | Stream level processing/transformations(流处理/转换阶段) |
| READ | This is where header reading typically occurs(SOAPHeader读取) |
| (PRE/USER/POST)_PROTOCOL | Protocol processing, such as JAX-WS SOAP handlers(协议处理阶段，比如JAX-WS的Handler处理) |
| UNMARSHAL | Unmarshalling of the request(SOAP请求解码阶段) |
| (PRE/USER/POST)_LOGICAL | Processing of the umarshalled request(SOAP请求解码处理阶段) |
| PRE_INVOKE | Pre invocation actions(调用业务处理之前进入该阶段) |
| INVOKE | Invocation of the service(调用业务阶段) |
| POST_INVOKE | Invocation of the outgoing chain if there is one(提交业务处理结果，并触发输入连接器) |
输出拦截器链有例如以下几个阶段，这些阶段依照在拦截器链中的先后顺序排列。
| 阶段名称 | 阶段功能描写叙述 |
|---|---|
| SETUP | Any set up for the following phases(设置阶段) |
| (PRE/USER/POST)_LOGICAL | Processing of objects about to marshalled |
| PREPARE_SEND | Opening of the connection(消息发送准备阶段。在该阶段创建Connection) |
| PRE_STREAM | 流准备阶段 |
| PRE_PROTOCOL | Misc protocol actions(协议准备阶段) |
| WRITE | Writing of the protocol message, such as the SOAP Envelope.(写消息阶段) |
| MARSHAL | Marshalling of the objects |
| (USER/POST)_PROTOCOL | Processing of the protocol message |
| (USER/POST)_STREAM | Processing of the byte level message(字节处理阶段，在该阶段把消息转为字节) |
| SEND | 消息发送 |
在输出拦截器链的SEND阶段后，还会触发以_ENDING结尾阶段，这些ENDING阶段与以上阶段相应，主要用于清理或者关闭资源。ENDING阶段触发的顺序例如以下：
- SEND_ENDING
- POST_STREAM_ENDING
- USER_STREAM_ENDING
- POST_PROTOCOL_ENDING
- USER_PROTOCOL_ENDING
- MARSHAL_ENDING
- WRITE_ENDING
- PRE_PROTOCOL_ENDING
- PRE_STREAM_ENDING
- PREPARE_SEND_ENDING
- POST_LOGICAL_ENDING
- USER_LOGICAL_ENDING
- PRE_LOGICAL_ENDING
- SETUP_ENDING
CXF默认拦截器链
在CXF中，全部对消息的处理都是通过各种拦截器实现。CXF已经实现了多种拦截器，如操纵消息头、运行认证检查、验证消息数据、日志记录、消息压缩等。有些拦截器在公布服务、訪问服务时已经默认加入到拦截器链。
CXF默认输入拦截器链，假设没有加入额外的拦截器。CXF输入会顺序经过下面拦截器：
| 拦截器名称 | 拦截器功能 |
|---|---|
| AttachmentInInterceptor | Parse the mime headers for mime boundaries, finds the “root” part and resets the input stream to it, and stores the other parts in a collection of Attachments |
| StaxInInterceptor | Creates an XMLStreamReader from the transport InputStream on the Message |
| ReadHeadersInterceptor | Parses the SOAP headers and stores them on the Message |
| SoapActionInInterceptor | Parses “soapaction” header and looks up the operation if a unique operation can be found for that action. |
| MustUnderstandInterceptor | Checks the MustUnderstand headers, its applicability and process it, if required |
| SOAPHandlerInterceptor | SOAP Handler as per JAX-WS |
| LogicalHandlerInInterceptor | Logical Handler as per JAX-WS |
| CheckFaultInterceptor | Checks for fault, if present aborts interceptor chain and invokes fault handler chain |
| URIMappingInterceptor | Can handle HTTP GET, extracts operation info and sets the same in the Message |
| DocLiteralnInterceptor | Examines the first element in the SOAP body to determine the appropriate Operation (if soapAction did not find one) and calls the Databinding to read in the data. |
| SoapHeaderInterceptor | Perform databinding of the SOAP headers for headers that are mapped to parameters |
| WrapperClassInInterceptor | For wrapped doc/lit, the DocLiteralInInterceptor probably read in a single JAXB bean. This interceptor pulls the individual parts out of that bean to construct the Object[] needed to invoke the service. |
| SwAInInterceptor | For Soap w/ Attachments, finds the appropriate attachments and assigns them to the correct spot in the parameter list. |
| HolderInInterceptor | For OUT and IN/OUT parameters, JAX-WS needs to create Holder objects. This interceptor creates the Holders and puts them in the parameter list. |
| ServiceInvokerInInterceptor | Actually invokes the service. |
CXF默认输出拦截器链，假设没有加入额外的拦截器，CXF输入会顺序经过下面拦截器：
| 拦截器名称 | 拦截器功能 |
|---|---|
| HolderOutInterceptor | For OUT and IN/OUT params, pulls the values out of the JAX-WS Holder objects (created in HolderInInterceptor) and adds them to the param list for the out message. |
| SwAOutInterceptor | For OUT parts that are Soap attachments, pulls them from the list and holds them for later. |
| WrapperClassOutInterceptor | For doc/lit wrapped, takes the remaining parts and creates a wrapper JAXB bean to represent the whole message. |
| SoapHeaderOutFilterInterceptor | Removes inbound marked headers |
| SoapActionOutInterceptor | Sets the SOAP Action |
| MessageSenderInterceptor | Calls back to the Destination object to have it setup the output streams, headers, etc… to prepare the outgoing transport. |
| SoapPreProtocolOutInterceptor | This interceptor is responsible for setting up the SOAP version and header, so that this is available to any pre-protocol interceptors that require these to be available. |
| AttachmentOutInterceptor | If this service uses attachments (either SwA or if MTOM is enabled), it sets up the Attachment marshallers and the mime stuff that is needed. |
| StaxOutInterceptor | Creates an XMLStreamWriter from the OutputStream on the Message. |
| SoapHandlerInterceptor | JAX-WS SOAPHandler |
| SoapOutInterceptor | Writes start element for soap:envelope and complete elements for other header blocks in the message. Adds start element for soap:body too. |
| LogicalHandlerOutInterceptor | JAX-WS Logical handler stuff |
| WrapperOutInterceptor | If wrapped doc/lit and not using a wrapper bean or if RPC lit, outputs the wrapper element to the stream. |
| BareOutInterceptor | Uses the databinding to write the params out. |
| SoapOutInterceptor$SoapOutEndingInterceptor | Closes the soap:body and soap:envelope |
| StaxOutInterceptor$StaxOutEndingInterceptor | Flushes the stax stream. |
| MessageSenderInt$MessageSenderEnding | Closes the exchange, lets the transport know everything is done and should be flushed to the client. |
