使用HttpServletRequestWrapper重写Request请求参数
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<String, String[]> 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 @Override 17 public Enumeration<String> getParameterNames() { 18 Vector<String> vector = new Vector<String>(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 @Override 29 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 @Override 40 public String[] getParameterValues(String name) { 41 return parameterMap.get(name); 42 } 43 44 @Override 45 public Map<String, String[]> getParameterMap() { 46 return parameterMap; 47 } 48 49 public void setParameterMap(Map<String, String[]> 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<String, String[]> 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<String,String> 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wrapper 41 filterChain.doFilter(changeRequestWrapper, servletResponse); 42 } 43 44 @Override 45 public void destroy() { 46 47 } 48 }
3.web.xml增加一个过滤器处理
1 <filter> 2 <filter-name>languageFilter</filter-name> 3 <filter-class>com.intercepor.LangFilter</filter-class> 4 <init-param> 5 <param-name>encoding</param-name> 6 <param-value>UTF-8</param-value> 7 </init-param> 8 <init-param> 9 <param-name>forceEncoding</param-name> 10 <param-value>true</param-value> 11 </init-param> 12 </filter> 13 14 <filter-mapping> 15 <filter-name>languageFilter</filter-name> 16 <url-pattern>*.do</url-pattern> 17 </filter-mapping>
所有.do的请求,都会验证此参数
