转载:http://blog.sina.com.cn/s/blog_870cd7b90101fg58.html
最近使用spring mvc做项目,数据格式是json,有一个功能是实现记录请求的参数,而请求的参数是整个RequestBody,Controller里是用过@RequestBody获取的。实现方法是通过一个Filter读取整个RequestBody并记录。但是这时就遇到一个问题,ServletRequest的getReader()和getInputStream()两个方法只能被调用一次,而且不能两个都调用。那么如果Filter中调用了一次,在Controller里面就不能再调用了。查看了下ServletRequest的说明,如下:
- public ServletInputStream getInputStream() throws IOException;
- public BufferedReader getReader() throws IOException;
两个方法都注明方法只能被调用一次,由于RequestBody是流的形式读取,那么流读了一次就没有了,所以只能被调用一次。既然是因为流只能读一次的原因,那么只要将流的内容保存下来,就可以实现反复读取了。
实现方法:先将RequestBody保存为一个byte数组,然后通过Servlet自带的HttpServletRequestWrapper类覆盖getReader()和getInputStream()方法,使流从保存的byte数组读取。然后再Filter中将ServletRequest替换为ServletRequestWrapper。代码如下:
BodyReaderHttpServletRequestWrapper类包装ServletRequest,将流保存为byte[],然后将getReader()和getInputStream()方法的流的读取指向byte[]
- import java.io.BufferedReader;
- import java.io.ByteArrayInputStream;
- import java.io.IOException;
- import java.io.InputStreamReader;
- import javax.servlet.ServletInputStream;
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletRequestWrapper;
- import jodd.JoddDefault;
- import jodd.io.StreamUtil;
- public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {
- private final byte[] body;
- public BodyReaderHttpServletRequestWrapper(HttpServletRequest request)
- throws IOException {
- super(request);
- body = StreamUtil.readBytes(request.getReader(), JoddDefault.encoding);
- }
- @Override
- public BufferedReader getReader() throws IOException {
- return new BufferedReader(new InputStreamReader(getInputStream()));
- }
- @Override
- public ServletInputStream getInputStream() throws IOException {
- final ByteArrayInputStream bais = new ByteArrayInputStream(body);
- return new ServletInputStream() {
- @Override
- public int read() throws IOException {
- return bais.read();
- }
- };
- }
- }
在Filter中将ServletRequest替换为ServletRequestWrapper
- public class HttpServletRequestReplacedFilter implements Filter {
- @Override
- public void init(FilterConfig filterConfig) throws ServletException {
- //Do nothing
- }
- @Override
- public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)throws IOException, ServletException {
- ServletRequest requestWrapper = null;
- if(request instanceof HttpServletRequest) {
- requestWrapper = new BodyReaderHttpServletRequestWrapper((HttpServletRequest) request);
- }
- if(null == requestWrapper) {
- chain.doFilter(request, response);
- } else {
- chain.doFilter(requestWrapper, response);
- }
- }
- @Override
- public void destroy() {
- //Do nothing
- }
- }