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第一个servlet小例子

2016-07-10 17:59 302 查看

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 {
}

}

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