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1、编写form.jsp页面
在web-chapter08的WebContent目录中,编写一个form.jsp页面,该页面用于提交用户登陆的表单信息,代码如下:
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8" import="java.util.*"%>
<!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">
</head>
<center>
<h3>用户登录</h3>
</center>
<body style="text-align: center;">
<a href="<%=request.getContextPath()%>/CharacterServlet?name=传智播客&password=123456">单击超链接登录</a>
<form action="<%=request.getContextPath()%>/CharacterServlet"
method="post">
<table border="1" width="600px" cellpadding="0" cellspacing="0"
align="center">
<tr>
<td height="30" align="center">用户名:</td>
<td> <input type="text" name="name" />
</td>
</tr>
<tr>
<td height="30" align="center">密 码:</td>
<td> <input type="password" name="password" />
</td>
</tr>
<tr>
<td height="30" colspan="2" align="center">
<input type="submit" value="登录" />
<input type="reset" value="重置" />
</td>
</tr>
</table>
</form>
</body>
2、创建servlet
创建一个名为CharacterServlet类,该类用于获取用户输入的请求参数,并将参数发送到控制台
代码如下:
package cn.itcast.chapter08.filter;
import java.io.IOException;
import javax.servlet.*;
import javax.servlet.http.*;
public class CharacterServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println(request.getParameter("name"));
System.out.println(request.getParameter("password"));
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
3、创建过滤器
创建一个名为CharacterFilter类,该类用于拦截用户的请求访问,实现统一全站编码,只是针对请求的方式不同,解决乱码的方式也不相同,代码如下:
package cn.itcast.chapter08.filter;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class CharacterFilter implements Filter {
public void init(FilterConfig filterConfig) throws ServletException {
}
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) resp;
// 拦截所有的请求 解决全站中文乱码
// 指定 request 和 response 的编码
request.setCharacterEncoding("utf-8"); // 只对消息体有效
response.setContentType("text/html;charset=utf-8");
// 对request进行包装
CharacterRequest characterRequest = new CharacterRequest(request);
chain.doFilter(characterRequest, response);
}
public void destroy() {
}
}
// 继承 默认包装类HttpServletRequestWrapper
class CharacterRequest extends HttpServletRequestWrapper {
private HttpServletRequest request;
public CharacterRequest(HttpServletRequest request) {
super(request);
this.request = request;
}
// 子类继承父类一定会覆写一些方法,此处用于重写getParamter()方法
public String getParameter(String name) {
// 调用被包装对象的getParameter()方法,获得请求参数
String value = super.getParameter(name);
if (value == null)
return null;
// 判断请求方式
String method = super.getMethod();
if ("get".equalsIgnoreCase(method)) {
try {
value = new String(value.getBytes("iso-8859-1"), "utf-8");
} catch (UnsupportedEncodingException e) {
throw new RuntimeException(e);
}
}
// 解决乱码后返回结果
return value;
}
}
4、配置映射信息
在web.xml中配置CharacterFilter以及CharacterServlet的映射信息
代码如下:
<servlet>
<description></description>
<display-name>CharacterServlet</display-name>
<servlet-name>CharacterServlet</servlet-name>
<servlet-class>cn.itcast.chapter08.filter.CharacterServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CharacterServlet</servlet-name>
<url-pattern>/CharacterServlet</url-pattern>
</servlet-mapping>
<filter>
<filter-name>CharacterFilter</filter-name>
<filter-class>cn.itcast.chapter08.filter.CharacterFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>CharacterFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
5、启动tomcat,进行测试
在网址栏输入http://localhost:8080/web-chapter08/form.jsp,结果如下:
点击登录后,控制台输出了用户名以及密码,将form.jsp的表单提交方式改为get之后再次点击登录,观察就会发现控制台输出的用户名和密码与刚刚使用post方式提交的表单是一致的,说明过滤器Filter起作用了