目的: 改变请求参数的值,满足项目需求(如:过滤请求中 lang != zh 的请求)

方法: 1.使用 HttpServletRequestWrapper重写

1 public class ChangeRequestWrapper extends HttpServletRequestWrapper { 2     private Map
     
       parameterMap; // 所有参数的Map集合 3  4     public ChangeRequestWrapper(HttpServletRequest request) { 5         super(request); 6         parameterMap = request.getParameterMap(); 7     } 8  9     // 重写几个HttpServletRequestWrapper中的方法10 11     /**12      * 获取所有参数名13      *14      * @return 返回所有参数名15      */16     @Override17     public Enumeration
      
        getParameterNames() {18         Vector
       
         vector = new Vector
        
         (parameterMap.keySet());19         return vector.elements();20     }21 22     /**23      * 获取指定参数名的值，如果有重复的参数名，则返回第一个的值 接收一般变量 ，如text类型24      *25      * @param name 指定参数名26      * @return 指定参数名的值27      */28     @Override29     public String getParameter(String name) {30         String[] results = parameterMap.get(name);31         return results[0];32     }33 34 35     /**36      * 获取指定参数名的所有值的数组，如：checkbox的所有数据37      * 接收数组变量 ，如checkobx类型38      */39     @Override40     public String[] getParameterValues(String name) {41         return parameterMap.get(name);42     }43 44     @Override45     public Map
         
           getParameterMap() {46         return parameterMap;47     }48 49     public void setParameterMap(Map
          
            parameterMap) {50 this.parameterMap = parameterMap;51 }52 }
          
         
        
       
      
     

 

2.新增Filter

1 public class LangFilter implements Filter { 2     @Override 3     public void init(FilterConfig filterConfig) throws ServletException { 4  5     } 6  7     @Override 8     public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { 9 10         ChangeRequestWrapper changeRequestWrapper = new ChangeRequestWrapper((HttpServletRequest) servletRequest);11 12         Map
     
       parameterMap = new HashMap<>(changeRequestWrapper.getParameterMap());13 14         String[] strings = parameterMap.get("lang");            //逻辑代码给定默认的参数值,如果参数不为中文,则直接返回异常15         if (strings == null || strings.length == 0) {16             strings = new String[1];17             strings[0] = "zh";18             parameterMap.put("lang", strings);19             changeRequestWrapper.setParameterMap(parameterMap);20         }else{21             String language = strings[0];22             if (!language.equals("zh")) {23                 Map
      
        error = new HashMap<>();24                 error.put("code","500");25 26                 ServletOutputStream outputStream = null;27                 try {28                     outputStream = servletResponse.getOutputStream();29                     outputStream.write(JSONUtils.obj2Byte(error));30                 } finally {31                     if (outputStream != null) {32                         outputStream.flush();33                         outputStream.close();34                     }35                 }36 37                 return;38             }39         }40         //使用复写后的wrapper41         filterChain.doFilter(changeRequestWrapper, servletResponse);42     }43 44     @Override45     public void destroy() {46 47     }48 }
      
     

     3.web.xml增加一个过滤器处理

1 　　
     
       2         
      
       languageFilter
       3         
      
       com.intercepor.LangFilter
       4         
      
        5             
       
        encoding
        6             
       
        UTF-8
        7         
       8         
      
        9             
       
        forceEncoding
       10             
       
        true
       11         
      12     
     13 14     
     
      15         
      
       languageFilter
      16         
      
       *.do
      17     
     

所有.do的请求,都会验证此参数