为了在后台统一设定编码，不必在每个servlet中单独设定编码，从而避免重复的劳作，又增加代码的可读性和可维护性的目的，使用Filter是一个很不错的选择。
1. EncodingFilter类
1 public class EncodingFilter implements Filter{ 2 3 //设定默认编码 4 private String charset = "UTF-8"; 5 private FilterConfig config; 6 7 @Override 8 public void destroy() { 9 charset = null; 10 config = null; 11 } 12 13 @Override 14 public void doFilter(ServletRequest request, ServletResponse response, 15 FilterChain chain) throws IOException, ServletException { 16 //设置请求响应字符编码 17 HttpServletRequest req = (HttpServletRequest)request; 18 HttpServletResponse res = (HttpServletResponse)response; 19 req.setCharacterEncoding(charset); 20 res.setContentType("text/html;charset=utf-8"); 21 //对get请求编码统一处理 22 if(req.getMethod().equalsIgnoreCase("GET")){ 23 //通过调用自己写的EncodingWrapper类，对request进行包装 24 EncodingWrapper wrapper = new EncodingWrapper(req,charset); 25 chain.doFilter(wrapper, res); 26 }else{ 27 chain.doFilter(req, res); 28 } 29 } 30 31 @Override 32 public void init(FilterConfig config) throws ServletException { 33 this.config = config; 34 //从web.xml配置中读取设定的编码方式 35 String charset = config.getServletContext().getInitParameter("charset"); 36 if(StringUtils.isNotEmpty(charset)){ 37 this.charset = charset; 38 } 39 } 40 41 }
2. EncodingWrapper类
1 public class EncodingWrapper extends HttpServletRequestWrapper{ 2 3 private String charset = "UTF-8"; 4 5 /** 6 * 创建一个新的实例 EncodingWrapper. 7 * @param request 8 */ 9 public EncodingWrapper(HttpServletRequest request) { 10 super(request); 11 } 12 13 /** 14 * 获取被装饰对象的引用和采用的字符编码 15 * @param request 16 * @param charset 17 */ 18 public EncodingWrapper(HttpServletRequest request, String charset){ 19 super(request); 20 this.charset = charset; 21 } 22 23 @Override 24 public String getParameter(String name){ 25 String value = super.getParameter(name); 26 if(StringUtils.isEmpty(value))return null; 27 try { 28 value = new String(value.getBytes("ISO-8859-1"),charset); 29 return value; 30 } catch (UnsupportedEncodingException e) { 31 e.printStackTrace(); 32 } 33 return value; 34 } 35 36 }
3. jsp页面
1 <%@page language="java" import="java.util.*" pageEncoding="UTF-8"%> 2 <!DOCTYPE HTML> 3 <html> 4 <head> 5 <title>servlet测试</title> 6 <meta http-equiv="pragma" content="no-cache"> 7 <meta http-equiv="cache-control" content="no-cache"> 8 <meta http-equiv="expires" content="0"> 9 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 10 <meta http-equiv="description" content="This is my page"> 11 <style type="text/css"> 12 *{margin:0;padding:0} 13 body{font-size:12px;font-family:"微软雅黑";color:#333;} 14 .wrap{width:640px;border:1px solid #333;} 15 input[type="text"]{width:300px;height:30px;margin:10px;outline:none;padding-left:10px;} 16 .wrap label{width:60px;display:inline-block;text-align:right} 17 </style> 18 </head> 19 <body> 20 <div class="wrap"> 21 <form action="../ServletTest" method="get" > 22 <label> 用户名：</label><input type="text" name="username" /><br /> 23 <label> 密码：</label><input type="text" name="password" /> 24 <input type="submit" /> 25 </form> 26 </div> 27 </body> 28 </html>
4. servletTest类
1 //这种注解的方式不需要再web.xml中配置 2 //@WebServlet(name = "MyFirstServlet", urlPatterns = {"/ServletTeaa"}) 3 public class ServletTest extends HttpServlet{ 4 5 private static final long serialVersionUID = 1L; 6 7 @Override 8 protected void doGet(HttpServletRequest req, HttpServletResponse resp) 9 throws ServletException, IOException { 10 doPost(req,resp); 11 } 12 13 @Override 14 protected void doPost(HttpServletRequest req, HttpServletResponse resp) 15 throws ServletException, IOException { 16 //有了统一的编码过滤器，以下两行代码可以“隐身”了 17 //req.setCharacterEncoding("utf-8"); 18 //resp.setCharacterEncoding("utf-8"); 19 System.out.println("进入了ServletTest"); 20 String username = req.getParameter("username"); 21 String password = req.getParameter("password"); 22 System.out.println("用户名："+username+",密码： "+password); 23 //resp.setContentType("text/html;charset=utf-8"); 24 PrintWriter out = resp.getWriter(); 25 out.println("<html>"); 26 out.println("<head>"); 27 out.println("<title>Servlet编码测试</title>"); 28 out.println("</head>"); 29 out.println("<body>"); 30 out.println("<h2>Servlet编码测试" + req.getContextPath() + "</h2>"); 31 out.println("</body>"); 32 out.println("</html>"); 33 System.out.println("退出了ServletTest"); 34 } 35 36 @Override 37 public void service(ServletRequest req, ServletResponse res) 38 throws ServletException, IOException { 39 super.service(req, res); 40 } 41 42 }
最后，在web.xml中作好配置
<context-param> <param-name>charset</param-name> <param-value>UTF-8</param-value> </context-param> <!-- 过滤器配置 --> <filter> <description>统一编码过滤器</description> <filter-name>encodingFilter</filter-name> <filter-class>com.ue.filter.EncodingFilter</filter-class> </filter> <filter-mapping> <filter-name>encodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <!-- servlet配置 --> <servlet> <description>servlet测试</description> <servlet-name>MyFirstServlet</servlet-name> <servlet-class>com.ue.servlet.ServletTest</servlet-class> </servlet> <servlet-mapping> <servlet-name>MyFirstServlet</servlet-name> <url-pattern>/ServletTest</url-pattern> </servlet-mapping>
当然，你也可以直接在server.xml直接设置你的编码方式。