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总要造一下轮子才知道别人的轮子有多厉害
最近笔者遇到一个问题：在SpringMVC框架下，没有直接的方式可以打印完整的AccessLog，因为request body 和response body是通过inputstream和outputstream来封装的，在使用过很多人提供的方式后，发现效果总是不尽人意，所以自己摸索了一下，完成了这个功能
请慎重在生产环境使用这个功能，因为打印完整的AccessLog是一个很大的消耗
项目工程目录结构和代码获取地址
https://github.com/laiyijie/spring-access-log-filter
详解核心类AccessLogFilter
完整代码如下：
public class AccessLogFilter extends OncePerRequestFilter {
private static final Logger logger = LogManager.getLogger(AccessLogFilter.class);
private String usernameKey = "username";
private Integer payloadMaxLength = 1024;
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
FilterChain filterChain) throws ServletException, IOException {
Long startTime = System.currentTimeMillis();
ContentCachingRequestWrapper requestWrapper = new ContentCachingRequestWrapper(request);
ContentCachingResponseWrapper responseWrapper = new ContentCachingResponseWrapper(response);
filterChain.doFilter(requestWrapper, responseWrapper);
String requestPayload = getPayLoad(requestWrapper.getContentAsByteArray(),
request.getCharacterEncoding());
String responsePayload = getPayLoad(responseWrapper.getContentAsByteArray(),
response.getCharacterEncoding());
responseWrapper.copyBodyToResponse();
BLog.accessJsonLogBuilder()
.addRequestPayLoad(requestPayload)
.addResponsePayLoad(responsePayload)
.put(request, usernameKey)
.put(response)
.put("_COST_", System.currentTimeMillis() - startTime)
.log();
}
private String getPayLoad(byte[] buf, String characterEncoding) {
String payload = "";
if (buf == null) return payload;
if (buf.length > 0) {
int length = Math.min(buf.length, getPayloadMaxLength());
try {
payload = new String(buf, 0, length, characterEncoding);
} catch (UnsupportedEncodingException ex) {
payload = "[unknown]";
}
}
return payload;
}
public String getUsernameKey() {
return usernameKey;
}
public void setUsernameKey(String usernameKey) {
this.usernameKey = usernameKey;
}
public Integer getPayloadMaxLength() {
return payloadMaxLength;
}
public void setPayloadMaxLength(Integer payloadMaxLength) {
this.payloadMaxLength = payloadMaxLength;
}
}
其核心思想是实现了OncePerRequestFilter这个虚基类，而这个虚基类是实现了Filter接口，并且要基于SpringMVC框架的，因此这个方法只能适用于SpringMVC工程
核心方法是doFilterInternal
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
FilterChain filterChain) throws ServletException, IOException {
Long startTime = System.currentTimeMillis();
ContentCachingRequestWrapper requestWrapper = new ContentCachingRequestWrapper(request);
ContentCachingResponseWrapper responseWrapper = new ContentCachingResponseWrapper(response);
filterChain.doFilter(requestWrapper, responseWrapper);
String requestPayload = getPayLoad(requestWrapper.getContentAsByteArray(),
request.getCharacterEncoding());
String responsePayload = getPayLoad(responseWrapper.getContentAsByteArray(),
response.getCharacterEncoding());
responseWrapper.copyBodyToResponse();
BLog.accessJsonLogBuilder()
.addRequestPayLoad(requestPayload)
.addResponsePayLoad(responsePayload)
.put(request, usernameKey)
.put(response)
.put("_COST_", System.currentTimeMillis() - startTime)
.log();
}
首先通过
ContentCachingRequestWrapper requestWrapper = new ContentCachingRequestWrapper(request);
ContentCachingResponseWrapper responseWrapper = new ContentCachingResponseWrapper(response);
这两个方式对请求和返回进行包装（让body可以被缓存），这样来解决inputstream不能多次读取的问题
调用
filterChain.doFilter(requestWrapper, responseWrapper);
来执行其他的filter之后
可以通过
String requestPayload = getPayLoad(requestWrapper.getContentAsByteArray(),
request.getCharacterEncoding());
String responsePayload = getPayLoad(responseWrapper.getContentAsByteArray(),
response.getCharacterEncoding());
这种方式取出request和response的payload，不要忘记
responseWrapper.copyBodyToResponse();
重新写入response
最后打印出整个log
