Filter处理HttpServletRequest & HttpServletResponse 笔记

HttpServletRequest 及HttpServletResponse 的复制 通过BufferedServletRequestWrapper和ContentCachingResponseWrapper进行处理

import javax.servlet.ServletInputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;/** * Created by ylzhou on 2017/6/22. */public class BufferedServletRequestWrapper extends HttpServletRequestWrapper {    private byte[] buffer;    public BufferedServletRequestWrapper(HttpServletRequest request) throws IOException {        super(request);        InputStream is = request.getInputStream();        ByteArrayOutputStream baos = new ByteArrayOutputStream();        byte buff[] = new byte[1024];        int read;        while ((read = is.read(buff)) > 0) {            baos.write(buff, 0, read);        }        this.buffer = baos.toByteArray();    }    @Override    public ServletInputStream getInputStream() throws IOException {        return new BufferedServletInputStream(this.buffer);    }}

import javax.servlet.ReadListener;import javax.servlet.ServletInputStream;import java.io.ByteArrayInputStream;import java.io.IOException;/** * Created by ylzhou on 2017/6/22. */public class BufferedServletInputStream extends ServletInputStream {    private ByteArrayInputStream inputStream;    public BufferedServletInputStream(byte[] buffer) {        this.inputStream = new ByteArrayInputStream(buffer);    }    @Override    public int read(byte[] b, int off, int len) throws IOException {        return inputStream.read(b, off, len);    }    @Override    public int available() throws IOException {        return inputStream.available();    }    @Override    public int read() throws IOException {        return inputStream.read();    }    @Override    public boolean isFinished() {        return false;    }    @Override    public boolean isReady() {        return false;    }    @Override    public void setReadListener(ReadListener listener) {    }}

需要注意的是复制出的HttpServletRequest 需要关闭，而复制出的HttpServletResponse 需要回写结果

 @Override    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {        if (!(servletRequest instanceof HttpServletRequest) || !(servletResponse instanceof HttpServletResponse)) {            throw new ServletException("Filter just supports HTTP requests");        }        // 复制request        HttpServletRequest bufferedWrapper = new BufferedServletRequestWrapper((HttpServletRequest) servletRequest);        // 切入        ContentCachingRequestWrapper requestWrapper = new ContentCachingRequestWrapper(bufferedWrapper);        ContentCachingResponseWrapper responseWrapper = new ContentCachingResponseWrapper((HttpServletResponse) servletResponse);        // 截取request值        HttpHeaders requestHeaders = new HttpHeaders();        Enumeration headerNames = requestWrapper.getHeaderNames();        while (headerNames.hasMoreElements()) {            String headerName = (String) headerNames.nextElement();            requestHeaders.add(headerName, requestWrapper.getHeader(headerName));        }        Map<String, String[]> requestParams = requestWrapper.getParameterMap();        String requestBody = "";        InputStream inputStream = null;        try {            inputStream = requestWrapper.getInputStream();            requestBody = IOUtils.toString(requestWrapper.getInputStream(), StandardCharsets.UTF_8);        } catch (IOException e) {            logger.error("获取请求body失败{}", e);        } finally {            // 由于inputStream是复制出来的，所以需要关闭            IOUtils.closeQuietly(inputStream);        }        try {            new SpanExtraInfo                    .SpanExtraInfoBuild()                    .requestHeaders(JSONUtils.toJson(requestHeaders))                    .requestParams(JSONUtils.toJson(requestParams))                    .requestBody(requestBody)                    .build();        } catch (JsonProcessingException exc) {            log.warn("request info analyze error! {}", exc);        }        // 调用父，这里的需传入bufferedWrapper        super.doFilter(bufferedWrapper, responseWrapper, filterChain);    }

        SpanExtraInfo spanExtraInfo = SpanExtraInfo.getInstance();        tracer.addTag("requestHeaders", spanExtraInfo.getRequestHeaders());        tracer.addTag("requestParams", spanExtraInfo.getRequestParams());        tracer.addTag("requestBody", spanExtraInfo.getRequestBody());        if (response instanceof ContentCachingResponseWrapper) {            ContentCachingResponseWrapper responseWrapper = (ContentCachingResponseWrapper) response;            HttpHeaders responseHeaders = new HttpHeaders();            for (String headerName : responseWrapper.getHeaderNames()) {                responseHeaders.add(headerName, responseWrapper.getHeader(headerName));            }            try {                tracer.addTag("responseHeaders", JSONUtils.toJson(responseHeaders));            } catch (JsonProcessingException exc) {                log.warn("responseHeaders analyze error! {}", exc);            }            try {                String responseBody = IOUtils.toString(responseWrapper.getContentInputStream(), StandardCharsets.UTF_8);                tracer.addTag("responseBody", responseBody);                // 最后需要回写下servletResponse，否则会返回一个空的servletResponse                responseWrapper.copyBodyToResponse();            } catch (IOException exc) {                log.warn("responseBody analyze error! {}", exc);            }        }