1、sendForward.jsp
<%@ 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>Insert title here</title> </head> <body> <form action="Verify" method="post"> 请输入一个实数：<input type="text" name="number"> <input type="submit" value="确定"> </form> </body> </html>
如图所示：
2、servlet类：Verify.java
package servlet; import java.io.IOException; import java.io.PrintWriter; 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 Verify extends HttpServlet { public Verify() { super(); } public void destroy() { super.destroy(); // Just puts "destroy" string in log } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); doPost(request,response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); String number=request.getParameter("number"); double n=Double.parseDouble(number); //上面是String，把String类型转为double类型 if(n>6000||n<-6000){ response.sendRedirect("sendForward.jsp"); }else{ //转发到另一个servlet文件 request.getRequestDispatcher("ShowMessage").forward(request, response); } } public void init() throws ServletException { } }
两种重定向方式：
（1）重定向： response.sendRedirect("sendForward.jsp");
（2）请求转发：request.getRequestDispatcher("ShowMessage").forward(request, response);
3、servlet类：ShowMessage.java
package servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ShowMessage extends HttpServlet { public ShowMessage() { super(); } public void destroy() { super.destroy(); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); doPost(request,response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); PrintWriter out=response.getWriter(); String number=request.getParameter("number"); double n=Double.parseDouble(number); out.println(number+"的平方："+(n*n)); } public void init() throws ServletException { } }
