Servlet登陸功能的實現
來源：程序員人生 發布時間：2014-09-19 18:54:49 閱讀次數：3086次
（1）創建動態的Login頁面
//登陸界面
package com.lc;
import javax.servlet.http.*;
import java.io.*;
public class Login extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
//業務邏輯
try{
//解決中文亂碼
res.setContentType("text/html;charset=gbk");
PrintWriter pw = res.getWriter();
//返回登陸界面
pw.println("<html>");
pw.println("<body>");
pw.println("<h1>用戶登錄</h1>");
pw.println("<form action=logincl method=post>"); //action的是servlet的url
pw.println("用戶名：<input type=text name=username><br/>");
pw.println("密碼：<input type=password name=passwd><br/>");
pw.println("<input type=submit value=loing><br/>");
pw.println("</form>");
pw.println("</body>");
pw.println("</html>");
}
catch(Exception ex){
ex.printStackTrace();
}
}
public void doPost(HttpServletRequest req,HttpServletResponse res){
this.doGet(req,res);
}
}
（2）創建接受Login的servlet
//登陸界面
package com.lc;
import javax.servlet.http.*;
import java.io.*;
public class Logincl extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
//業務邏輯
try{
//解決中文亂碼
//接受用戶名和密碼
String u = req.getParameter("username");
String p = req.getParameter("passwd");
//驗證
if(u.equals("lc") && p.equals("123"))
{
//合法的情況 跳轉到Welcome
res.sendRedirect("welcome");//這里跳轉的仍是servlet的url
}
else
{
//不合法的情況
//跳轉
res.sendRedirect("login");//跳轉的是要到servlet的url
}
}
catch(Exception ex){
ex.printStackTrace();
}
}
public void doPost(HttpServletRequest req,HttpServletResponse res){
this.doGet(req,res);
}
}
（3）登陸成功要跳轉的welcome頁面
//登陸界面
package com.tsinghua;
import javax.servlet.http.*;
import java.io.*;
public class Welcome extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
//業務邏輯
try{
//解決中文亂碼
res.setContentType("text/html;charset=gbk");
PrintWriter pw = res.getWriter();
pw.println("hello welcome！");
}
catch(Exception ex){
ex.printStackTrace();
}
}
public void doPost(HttpServletRequest req,HttpServletResponse res){
this.doGet(req,res);
}
}
（4）配置文件web.xml的編寫
<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0"
metadata-complete="true">
<display-name>Welcome to Tomcat</display-name>
<description>
Welcome to Tomcat
</description>
<!--JSP servlet mappings starts-->
<servlet>
<servlet-name>Login</servlet-name>
<servlet-class>com.lc.Login</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>Logincl</servlet-name>
<servlet-class>com.<span style="font-family:Arial, Helvetica, sans-serif;">lc</span>.Logincl</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Logincl</servlet-name>
<url-pattern>/logincl</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>Welcome</servlet-name>
<servlet-class>com.lc.Welcome</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Welcome</servlet-name>
<url-pattern>/welcome</url-pattern>
</servlet-mapping>
<!--JSP servlet mappings end-->
</web-app>
（5）運行結果：
生活不易，碼農辛苦
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