HttpServletRequestWrapper拦截body并解决编码问题

本是古典何须时尚 2022-12-26 11:24 326阅读 0赞

# HttpServletRequestWrapper拦截body并解决编码问题 #

> 这个话题来自于做互联网接口时对数据签名引发的问题。数据签名主要是为了验证数据的完整性，同时起到身份验证的作用。  
> post请求body体里的内容，是以流的形式存在的，流不能多次读取，做签名验证时拦截器要先取读取数据做校验，导致后面controller无法再次读取到数据。

#### 1、自定义一个HttpServletRequestWrapper的子类，用于对request进行包装 ####

package com.mrx.common.wrapper;
    import lombok.extern.slf4j.Slf4j;
    import javax.servlet.ReadListener;
    import javax.servlet.ServletInputStream;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletRequestWrapper;
    import java.io.*;
    @Slf4j
    public class CustomRequestWrapper extends HttpServletRequestWrapper { 
        private final String body;
        public CustomRequestWrapper(HttpServletRequest request) throws IOException { 
            super(request);
            StringBuilder sb = new StringBuilder(128);
            BufferedReader br = null;
            try { 
                InputStream is = request.getInputStream();
                if (is != null) { 
                    //br = new BufferedReader(new InputStreamReader(is));
                    /** * 当中文乱码时 * tomcat配置中加 * -Dfile.encoding=UTF-8 */
                    br = new BufferedReader(new InputStreamReader(is,"UTF-8"));
                    char[] charBuffer = new char[128];
                    int byteRead = -1;
                    while ((byteRead = br.read(charBuffer)) > 0) { 
                        sb.append(charBuffer, 0, byteRead);
                    }
                }
            } catch (IOException e) { 
                log.error(e.getMessage());
                throw e;
            } finally { 
                if (br != null) { 
                    br.close();
                }
            }
            body = sb.toString();
            if (log.isDebugEnabled()){ 
                log.debug("body:{}",body);
            }
        }
    
        @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 body;
        }
    }

#### 2、定义一个过滤器，对需要进行签名校验的请求提前进行拦截 ####

package com.mrx.filter;
    
    import com.mrx.common.wrapper.CustomRequestWrapper;
    import com.mrx.constants.Constants;
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
    import org.springframework.core.annotation.Order;
    import org.springframework.stereotype.Component;
    import org.springframework.util.AntPathMatcher;
    import org.springframework.web.filter.OncePerRequestFilter;
    
    import javax.servlet.FilterChain;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @Slf4j
    @Order(3)
    @Component
    public class HttpServletFilter extends OncePerRequestFilter { 
        @Override
        protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { 
            AntPathMatcher matcher = new AntPathMatcher();
            String uri = request.getRequestURI();
            if (matcher.match(Constants.API_URI_PREFIX, uri)) { 
                CustomRequestWrapper requestWrapper;
                requestWrapper = new CustomRequestWrapper(request);
                if (requestWrapper == null){ 
                    filterChain.doFilter(request, response);
                }else { 
                    filterChain.doFilter(requestWrapper, response);
                }
            } else { 
                filterChain.doFilter(request, response);
            }
        }
    }

### 3、后续读取 ###

> 因为在CustomRequestWrapper提前读取流并把信息保存到了变量body中，后续再次从流中读取信息时，其实都是从body转化来的。body里面永远有值，可以不限次数的读取。

#### 4、中文乱码问题 ####

> 在实际应用中，部署到服务器后，签名验证失败。后续排查发现解析出来的数据中文是乱码。  
> br = new BufferedReader(new InputStreamReader(is,“UTF-8”)); 读取流的时候统一使用UTF8编码，在IDE调试时都可以顺利进行，到了服务器上的tomcat还是乱码，疑惑…

#### 5、tomcat设置编码 ####

> 在tomcat服务器上配置编码  
> \-Dfile.encoding=UTF-8  
> ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjgzMTQ3Nw_size_16_color_FFFFFF_t_70_pic_center]

#### 6、总结 ####

> 程序中设置UTF8编码  
> tomcat服务器设置UTF8编码，  
> 通过两个地方的设置，中文字符不再乱码

> 小尾巴~~  
> 只要有积累，就会有进步

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjgzMTQ3Nw_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/7b91023667eb4d41a8b0fb0acc2d7f88.png