java web实现请求转发和重定向

编写处理用户登录请求的LoginServlet类，如果在登录页面输入的用户名和密码正确就重定向到欢迎页面（welcome.html），否则重定向到登录页面（login.html）
LoginServle.java

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 LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String name="admin";
		String pw="123456";
		String username=request.getParameter("name");
		String password=request.getParameter("password");
		if(!name.equals(username)) {
			response.sendRedirect("/WEB_TASK/login.html");
		}else if(!pw.equals(password)) {
			response.sendRedirect("/WEB_TASK/login.html");
		}else {
			response.sendRedirect("/WEB_TASK/welcome.html");
		}
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {		
		doGet(request, response);
	}

}

welcome.html

WELCOME To Login!!!!

login.html

登录页面

用户名:

密   码:

	

输入正确的用户名admin和密码123456

此时跳转到welcome.html页面

输入错误的用户名和密码，会再次登陆

跳转到login.html页面

编写接收用户请求的RequestForwardServlet，保存字符串数据到请求对象中，然后将请求转发给ResultServlet，ResultServlet取出保存在请求对象中的字符串数据并输出到客户端。

代码1：RequestForwardServlet.java

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class RequestForwardServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//		获取转发对象 转发到ResultServlet
		RequestDispatcher dispatcher=request.getRequestDispatcher("/ResultServlet");
//		调用转发方法 实现转发效果
		request.setAttribute("name", "aynu");
		dispatcher.forward(request, response);
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}

}

代码2：ResultServlet.java

package lxq;

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 ResultServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
//		解决中文乱码问题
		response.setContentType("text/html;charset=utf-8");
		Object attribute=request.getAttribute("name");
		response.getWriter().write("RequestForwardServlet中保存的字符串是 ： "+attribute);
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}

}

在RequestForwardServlet转发到ResultServlet，并输出