多次读取请求request里数据

如果请求是GET方法,可以直接通过getParameter(String param)方法读取指定参数,可读取多次;

而POST方法的参数是存储在输入流中,只能读一次,不能多次读取。

有时需要在filter里打印请求参数,因而在filter里读取post请求里的输入流后,会导致具体的controller里拿不到请求参数。

解决方法:

  • 采用ThreadLocal,在filter里把读取到的post参数存入ThreadLocal里,而controller就可以再从ThreadLocal里把请求参数读取出来
  • 使用servlet提供的HttpServletRequestWrapper类,重写相关ServletRequest方法,实现多次读取的能力

 

1.ThreadLocal方法

ThreadLocal实现:

public class ThreadCache {
  // ThreadLocal里只存储了简单的String对象,也可以自己定义对象,存储更加复杂的参数
private static ThreadLocal<String> threadLocal = new ThreadLocal<String>(); public static String getPostRequestParams{ return threadLocal.get(); } public static void setPostRequestParams(String postRequestParams){ threadLocal.set(postRequestParams); } public static void removePostRequestParams(){ threadLocal.remove(); } }

一个简单的filter:

import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Created by EndStart on 16/12/19.
 */
@WebFilter(value = {"/test/threadLocal/*"})
public class SimpleFilter implements Filter {
    private static Logger log = LoggerFactory.getLogger(SimpleFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        try {
            if ("POST".equals(req.getMethod().toUpperCase())) {
          // 获取请求参数
byte[] bytes = IOUtils.toByteArray(request.getInputStream()); String params = new String(bytes, req.getCharacterEncoding()); ThreadCache.setPostRequestParams(params); log.info("filer-post请求参数:[params={}]", params); } else { log.info("非post请求"); } chain.doFilter(request, response); } catch (Exception e) { log.error(e.getMessage(), e); } } @Override public void destroy() { } }

简单的测试controller:

import com.sankuai.xm.ems.auth.filter.ThreadCache;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * Created by Endstart on 16/12/19.
 */
@Controller
@RequestMapping("/test")
public class TestController {
    private static Logger log = LoggerFactory.getLogger(TestController.class);

    @RequestMapping(value = "/threadLocal/getPostRequestParams",method = RequestMethod.POST)
    @ResponseBody
    public void getPostRequestParams() {
        String params = ThreadCache.getPostRequestParams();

        log.info("controller-post请求参数:[params={}]", params);
    }

}

 

这里我们只保存了post参数,从ThreadLocal中反复读取,而get方法的还需要从request里获取;

 

2.HttpServletRequestWrapper方法

  实现一个HttpServletRequestWrapper子类:

import org.apache.commons.io.IOUtils;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;

/**
 * Created by Endstart on 16/11/30.
 */
public class WrappedHttpServletRequest extends HttpServletRequestWrapper {

    private byte[] bytes;
    private WrappedServletInputStream wrappedServletInputStream;

    public WrappedHttpServletRequest(HttpServletRequest request) throws IOException {
        super(request);
        // 读取输入流里的请求参数,并保存到bytes里
        bytes = IOUtils.toByteArray(request.getInputStream());
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes);
        this.wrappedServletInputStream = new WrappedServletInputStream(byteArrayInputStream);

     // 很重要,把post参数重新写入请求流      
reWriteInputStream(); } /** * 把参数重新写进请求里 */ public void reWriteInputStream() { wrappedServletInputStream.setStream(new ByteArrayInputStream(bytes != null ? bytes : new byte[0])); } @Override public ServletInputStream getInputStream() throws IOException { return wrappedServletInputStream; } @Override public BufferedReader getReader() throws IOException { return new BufferedReader(new InputStreamReader(wrappedServletInputStream)); } /** * 获取post参数,可以自己再转为相应格式 */ public String getRequestParams() throws IOException { return new String(bytes, this.getCharacterEncoding()); } private class WrappedServletInputStream extends ServletInputStream { public void setStream(InputStream stream) { this.stream = stream; } private InputStream stream; public WrappedServletInputStream(InputStream stream) { this.stream = stream; } @Override public int read() throws IOException { return stream.read(); } @Override public boolean isFinished() { return true; } @Override public boolean isReady() { return true; } @Override public void setReadListener(ReadListener readListener) { } } }

 实现另一个filter:

import com.sankuai.xm.ems.utils.wrap.WrappedHttpServletRequest;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/**
 * Created by EndStart on 16/12/19.
 */
@WebFilter(value = {"/test/wrapped/*"})
public class SimpleWrappedFilter implements Filter {
    private static Logger log = LoggerFactory.getLogger(SimpleWrappedFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        try {
            WrappedHttpServletRequest requestWrapper = new WrappedHttpServletRequest((HttpServletRequest) request);

            if ("POST".equals(requestWrapper.getMethod().toUpperCase())) {
          // 获取请求参数 String params
= requestWrapper.getRequestParams(); log.info("filer-post请求参数:[params={}]", params); } else { log.info("非post请求"); } // 这里doFilter传入我们实现的子类 chain.doFilter(requestWrapper, response); } catch (Exception e) { log.error(e.getMessage(), e); } } @Override public void destroy() { } }

我们在上面的TestController里加入一个新的处理方法:

    @RequestMapping(value = "/wrapped/getPostRequestParams",method = RequestMethod.POST)
    @ResponseBody
//    public void getPostRequestParams(@RequestBody String params) {
    public void getPostRequestParams(HttpServletRequest request) throws Exception{
        byte[] bytes = IOUtils.toByteArray(request.getInputStream());
        String params = new String(bytes, request.getCharacterEncoding());
        
        log.info("controller-post请求参数:[params={}]", params);
    }

这种方法里,我们在SimpleWrappedFilter里一个实现了WrappedHttpServletRequest类,其构造器自动读取了servletRequest里的输入流,并把数据保存了下来,最后又把数据重新写入servletRequest里,使得cotroller可以再次从request里读取到输入参数。

posted @ 2016-12-19 12:42  tianyanfl  阅读(10385)  评论(2编辑  收藏  举报