java - 已为此响应调用 HandlerInterceptor getOutputStream()

Question

我正在使用 Spring @RestController 并以 Json 格式发送响应。这工作正常，但我需要向记录器发送响应，所以我已经实现了 Spring 的 HandlerInterceptor 和

@Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
            Object handler, Exception ex) throws Exception {

    System.out.println("--afterCompletion method executed--"+ request.getRequestURL());
    System.out.println("--afterCompletion method executed--"+ response.getWriter());
}    

获取异常

--afterCompletion方法执行-- http://localhost:8080/login2015-11-29 05:48:29.184错误9116 --- [nio-8080-exec-1] o.s.web.servlet.HandlerExecutionChain:HandlerInterceptor.afterCompletion抛出异常

java.lang.IllegalStateException: getOutputStream() has already been called for this response at org.apache.catalina.connector.Response.getWriter(Response.java:578) at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:212) at to.lookup.api.logger.LoggingInterceptor.afterCompletion(LoggingInterceptor.java:32)

Answer 1

您不能在 Spring 拦截器中执行此操作，因为在处理响应的 OutputStream 时，一旦您读取了一部分或一个流，它就会被“消耗”，并且无法返回并再次读取它。

要启用对请求或响应的重新读取，您必须将它们包装起来并在 servlet 过滤器中执行此操作，然后将包装的实现沿着过滤器链传播。

您可以找到一个已经实现的包装器，您可以从中学习，例如spring-mvc-logger 。实现基于TeeInputStream将从 OutputStream 读取的所有字节复制到允许重新读取的辅助 OutputStream。

发布所使用的ResponseWrapper类的代码

   public class ResponseWrapper extends HttpServletResponseWrapper {

    private final ByteArrayOutputStream bos = new ByteArrayOutputStream();
    private PrintWriter writer = new PrintWriter(bos);
    private long id;

    public ResponseWrapper(Long requestId, HttpServletResponse response) {
        super(response);
        this.id = requestId;
    }

    @Override
    public ServletResponse getResponse() {
        return this;
    }

    @Override
    public ServletOutputStream getOutputStream() throws IOException {
        return new ServletOutputStream() {
            private TeeOutputStream tee = new TeeOutputStream(ResponseWrapper.super.getOutputStream(), bos);

            @Override
            public void write(int b) throws IOException {
                tee.write(b);
            }
        };
    }

    @Override
    public PrintWriter getWriter() throws IOException {
        return new TeePrintWriter(super.getWriter(), writer);
    }

    public byte[] toByteArray(){
        return bos.toByteArray();
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }
}