1、首先看一个装饰模式解决字符集编码问题

　　我们使用装饰者对request进行增强，从而使得get和post使用request.getParameter()获得的数据没有乱码：

　　首先来一个Servlet，用于处理客户端请求：

package 装饰者模式解决乱码;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class DataServlet extends HttpServlet {	private static final long serialVersionUID = 1L;           public DataServlet() {        super();    }	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {		//获得数据		String username = request.getParameter("username");		String password = request.getParameter("password");		System.out.println("前：" +username+"@"+password);	}	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {		//获得数据		String username = request.getParameter("username");		String password = request.getParameter("password");		System.out.println("前：" +username+"@"+password);	}	}

　　创建HttpServletRequest的增强类，借助HttpServletRequestWrapper：

package 装饰者模式解决乱码;import java.io.UnsupportedEncodingException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;/** * *  sun 提供 HttpServletRequest 接口使用装饰者编写默认类，及所有的方法都没有增强的。 *  * 之后我们只需要继承即可 *   *  增强response对象，提供使用装饰者设计模式编写默认类：HttpServletResponseWrapper */public class MyRequest extends HttpServletRequestWrapper {	//保持对接口的引用	private HttpServletRequest request;	//构造方法	public MyRequest(HttpServletRequest request) {		super(request);		//赋值		this.request = request;	}	//重写某个方法	@Override	public String getParameter(String name) {		//首先获得参数,这是没有改变编码的值		String value =  request.getParameter(name);		//首先判断请求方式		String method = request.getMethod();		if ("GET".equals(method)) {			try {				value = new String(value.getBytes("ISO-8859-1"), "utf-8");			} catch (UnsupportedEncodingException e) {				e.printStackTrace();			}		}else {			try {				request.setCharacterEncoding("utf-8");			} catch (UnsupportedEncodingException e) {				e.printStackTrace();			}		}		return value;	}}

　　在客户端向服务器发送请求时，我们需要对其进行拦截：

package 装饰者模式解决乱码;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class EncodingFilter implements Filter {    public EncodingFilter() {    }	public void destroy() {	}	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {		//强转		HttpServletRequest request = (HttpServletRequest) req;		HttpServletResponse response = (HttpServletResponse) res;		//post编码		response.setCharacterEncoding("UTF-8");		//使用装饰者模式增强		MyRequest myRequest = new MyRequest(request);		//放行		chain.doFilter(myRequest, response);		System.out.println("我是中国人！");					/*//0 强转			HttpServletRequest request = (HttpServletRequest) req;			HttpServletResponse response = (HttpServletResponse) resp;						//1 post乱码			request.setCharacterEncoding("UTF-8");					//2 使用装饰者增强request			MyRequest myRequest = new MyRequest(request);					chain.doFilter(myRequest, response);*/				}	public void init(FilterConfig fConfig) throws ServletException {	}}

2、动态代理解决

　　客户端页面：

<%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%>
    	
    
     		用户名：
     
     
		密码：
     
     
		
     	
    

package solveresponseencoding;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/DataServlet")public class DataServlet extends HttpServlet {	private static final long serialVersionUID = 1L;           public DataServlet() {        super();    }	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {		//获得请求参数		String username = request.getParameter("username");		String password = request.getParameter("password");		//打印值		System.out.println(request.getMethod() + " ： " + username + " @ " + password);	}	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {		doGet(request, response);	}}

package solveresponseencoding;import java.io.IOException;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.annotation.WebFilter;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebFilter("/*")public class EncodingFilter implements Filter {    public EncodingFilter() {    }	public void destroy() {	}	/*	 * 本方法会拦截所有请求，在本方法中对request进行增强	 */	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {		//强转		final HttpServletRequest request = (HttpServletRequest) req;		HttpServletResponse response = (HttpServletResponse) res;		//解决post乱码		request.setCharacterEncoding("utf-8");		//创建动态代理对象		HttpServletRequest myRequest = (HttpServletRequest) Proxy.newProxyInstance(				EncodingFilter.class.getClassLoader(), 				new Class[]{HttpServletRequest.class},				new InvocationHandler() {										@Override					public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {						//如果是getParameter方法，获取参数						if ("getParameter".equals(method.getName())) {							String value = request.getParameter((String)args[0]);							//System.out.println("value值为："+value);							//如果是get请求，就增强							if ("GET".equalsIgnoreCase(request.getMethod())) {								value = new String(value.getBytes("ISO-8859-1"), "utf-8");								System.out.println("我是get方法：");							}							return value;						}						return method.invoke(request, args);					}				});		chain.doFilter(myRequest, response);	}	public void init(FilterConfig fConfig) throws ServletException {	}}