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"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>动态代理解决get方式乱码问题</title>
</head>
<body>
<form action="/proxy/DataServlet" method="get">
用户名：<input type="text" name="username" value="胡根得" /><br/>
密码：<input type="password" name=password value="就不告诉你"><br/>
<input type="submit" value="提交get请求">
</form>
</body>
</html>
写一个Servlet：
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);
}
}
对请求进行拦截的过滤器：
<span style="font-size:18px;">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 {
}
}
</span>
动态代理解决这个问题，将增强放到了过滤器中，不同之处他没有专门的增强类，而是通过动态代理技术在运行期间动态生成的，对于InvocationHandler接口采用了匿名内部类的方式。
时间： 2025-01-31 02:13:44