1）htmlcode：
<html>
<head>
<title>$Title$</title>
</head>
<body>
<form action="/login" method="post" >
姓名：<input type="text" name="username"><br>
备注：<textarea></textarea>
<input type="submit"><br>
</form>
</body>
</html>
2）servlet code
1 package jd.com.coding; 2 3 import javax.servlet.ServletException; 4 import javax.servlet.annotation.WebServlet; 5 import javax.servlet.http.HttpServlet; 6 import javax.servlet.http.HttpServletRequest; 7 import javax.servlet.http.HttpServletResponse; 8 import java.io.IOException; 9 10 @WebServlet(name = "Servletlogin" ,urlPatterns ="/login") 11 public class Servletlogin extends HttpServlet { 12 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 13 String username=request.getParameter("username"); 14 System.out.println(username); 15 16 17 18 } 19 20 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 21 22 } 23 }
3）filter代码：
1 package jd.com.coding; 2 3 import javax.servlet.*; 4 import javax.servlet.annotation.WebFilter; 5 import javax.servlet.http.HttpServletRequest; 6 import javax.servlet.http.HttpServletResponse; 7 import java.io.IOException; 8 import java.lang.reflect.InvocationHandler; 9 import java.lang.reflect.Method; 10 import java.lang.reflect.Proxy; 11 12 @WebFilter(filterName = "FilterCoding",urlPatterns = "/login") 13 public class FilterCoding implements Filter { 14 public void destroy() { 15 } 16 17 public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException { 18 //增强 19 HttpServletResponse response= (HttpServletResponse) resp; 20 HttpServletRequest request= (HttpServletRequest) req; 21 22 HttpServletRequest reqproxy =(HttpServletRequest) Proxy.newProxyInstance(HttpServletRequest.class.getClassLoader(), (Class<?>[]) request.getClass().getGenericInterfaces(), new InvocationHandler() { 23 @Override 24 public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { 25 if(method.getName().equalsIgnoreCase("getParameter")){ 26 if(request.getMethod().equalsIgnoreCase("get")){ 27 // String[get] ar=(String[]) args; 28 // String str=request.getParameter(ar[0]); 29 String str= (String) method.invoke(request,args); 30 return new String(str.getBytes("iso8859-1"),"utf-8"); 31 }else if(request.getMethod().equalsIgnoreCase("post")){ 32 request.setCharacterEncoding("utf-8"); 33 return method.invoke(request,args); 34 } 35 } 36 37 return method.invoke(request,args); 38 } 39 }); 40 chain.doFilter(reqproxy, resp); 41 } 42 43 public void init(FilterConfig config) throws ServletException { 44 45 } 46 47 }
其中获取类的接口集合使用Class类的方法：getClassLoader()
public Type[] getGenericInterfaces()
然后强转即可。