spring boot拦截器中获取request post请求中的参数

程序汪丶 2019-06-04 13:52:18

 

最近有一个需要从拦截器中获取post请求的参数的需求，这里记录一下处理过程中出现的问题。

首先想到的就是request.getParameter(String )方法，但是这个方法只能在get请求中取到参数，post是不行的，后来想到了使用流的方式，调用request.getInputStream()获取流，然后从流中读取参数，如下代码所示：

String body = "";
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
InputStream inputStream = null;
try {
 inputStream = request.getInputStream();
 if (inputStream != null) {
 bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
 char[] charBuffer = new char[128];
 int bytesRead = -1;
 while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
 stringBuilder.append(charBuffer, 0, bytesRead);
 }
 } else {
 stringBuilder.append("");
 }
} catch (IOException ex) {
 e.printStackTrace();
} finally {
 if (inputStream != null) {
 try {
 inputStream.close();
 }
 catch (IOException e) {
 e.printStackTrace();
 }
 }
 if (bufferedReader != null) {
 try {
 bufferedReader.close();
 }
 catch (IOException e) {
 e.printStackTrace();
 }
 }
}
body = stringBuilder.toString();

代码中的body就是request中的参数，我这里传的是JSON数据：{"page": 1, "pageSize": 10}，那么body就是：body = "{"page": 1, "pageSize": 10}"，一个JSON字符串。这样是可以成功获取到post请求的body，但是，经过拦截器后，参数经过@RequestBody注解赋值给controller中的方法的时候，却抛出了一个这样的异常：

org.springframework.http.converter.HttpMessageNotReadableException: Required request body is missing

request的输入流只能读取一次，那么这是为什么呢？下面是答案：

那是因为流对应的是数据，数据放在内存中，有的是部分放在内存中。read 一次标记一次当前位置（mark position），第二次read就从标记位置继续读（从内存中copy）数据。 所以这就是为什么读了一次第二次是空了。 怎么让它不为空呢？只要inputstream 中的pos 变成0就可以重写读取当前内存中的数据。javaAPI中有一个方法public void reset() 这个方法就是可以重置pos为起始位置，但是不是所有的IO读取流都可以调用该方法！ServletInputStream是不能调用reset方法，这就导致了只能调用一次getInputStream()。

那么有什么办法可以用户解决呢？上面这篇博客中提到了解决方案，就是重写HttpServletRequestWrapper把request保存下来，然后通过过滤器把保存下来的request再填充进去，这样就可以多次读取request了。步骤如下所示：

①写一个类，继承HttpServletRequestWrapper

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
public class RequestWrapper extends HttpServletRequestWrapper {

 private final String body;
 public RequestWrapper(HttpServletRequest request) {
 super(request);
 StringBuilder stringBuilder = new StringBuilder();
 BufferedReader bufferedReader = null;
 InputStream inputStream = null;
 try {
 inputStream = request.getInputStream();
 if (inputStream != null) {
 bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
 char[] charBuffer = new char[128];
 int bytesRead = -1;
 while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
 stringBuilder.append(charBuffer, 0, bytesRead);
 }
 } else {
 stringBuilder.append("");
 }
 } catch (IOException ex) {
 } finally {
 if (inputStream != null) {
 try {
 inputStream.close();
 }
 catch (IOException e) {
 e.printStackTrace();
 }
 }
 if (bufferedReader != null) {
 try {
 bufferedReader.close();
 }
 catch (IOException e) {
 e.printStackTrace();
 }
 }
 }
 body = stringBuilder.toString();
 }

 @Override
 public ServletInputStream getInputStream() throws IOException {
 final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());
 ServletInputStream servletInputStream = new ServletInputStream() {
 @Override
 public boolean isFinished() {
 return false;
 }
 @Override
 public boolean isReady() {
 return false;
 }
 @Override
 public void setReadListener(ReadListener readListener) {
 }
 @Override
 public int read() throws IOException {
 return byteArrayInputStream.read();
 }
 };
 return servletInputStream;
 }

 @Override
 public BufferedReader getReader() throws IOException {
 return new BufferedReader(new InputStreamReader(this.getInputStream()));
 }
 public String getBody() {
 return this.body;
 }
}

②拦截器层面

import com.alibaba.fastjson.JSON;
import com.miniprogram.api.douyin.user.req.DyuserReq;
import com.miniprogram.common.auth.VisitLimitCount;
import com.miniprogram.common.cache.RedisCache;
import com.miniprogram.common.config.InterceptorConfigMap;
import com.miniprogram.common.config.InterceptorUrlConfig;
import com.miniprogram.common.douyin.SearchEngineMapConstants;
import com.miniprogram.common.response.Response;
import com.miniprogram.common.session.*;
import com.miniprogram.common.utils.DateUtil;
import com.miniprogram.dao.common.UserLoginEntity.Users;
import com.miniprogram.service.douyin.users.UsersService;
import com.miniprogram.web.douyin.config.RequestWrapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Component("authSecurityInterceptor")
public class AuthSecurityInterceptor extends HandlerInterceptorAdapter {
 private Logger logger = LoggerFactory.getLogger(AuthSecurityInterceptor.class);
 @Autowired
 private RedisCache redisCache;
 @Autowired
 private VisitLimitCount visitLimitCount;
 @Override
 public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
 try {
 RequestWrapper requestWrapper = new RequestWrapper(httpServletRequest);
 String body = requestWrapper.getBody();
 System.out.println(body);
 return true;
 }catch (Exception e){
 logger.error("权限判断出错",e);
 }
 return false;
 }
 @Override
 public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
 }
 @Override
 public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
 }
}

③过滤器Filter，用来把request传递下去

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

@WebFilter(urlPatterns = "/*",filterName = "channelFilter")
public class ChannelFilter implements Filter {
 @Override
 public void init(FilterConfig filterConfig) throws ServletException {
 }
 
 @Override
 public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
 ServletRequest requestWrapper = null;
 if(servletRequest instanceof HttpServletRequest) {
 requestWrapper = new RequestWrapper((HttpServletRequest) servletRequest);
 }
 if(requestWrapper == null) {
 filterChain.doFilter(servletRequest, servletResponse);
 } else {
 filterChain.doFilter(requestWrapper, servletResponse);
 }
 }
 
 @Override
 public void destroy() {
 }
}

④在启动类中注册拦截器

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.MultipartConfigFactory;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@SpringBootApplication
// @ServletComponentScan //注册过滤器注解
@Configuration
public class WebApplication {
 public static void main(String[] args) {
 SpringApplication.run(WebApplication.class, args);
 }
}

经测试，问题解决

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