章节一：Servlet的doGet、doPost方法，如何被HTML（JSP）页面调用

1.新建一个Dynamic Web Project项目，里面新建一个servlet，新建一个jsp，整体的框架结构如下所示：

2.getLengthOrAreaServlet.java文件的代码如下所示：


package servlet;
 
import java.io.IOException;
import java.io.PrintWriter;
 
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
@WebServlet("/getLengthOrAreaServlet")
public class getLengthOrAreaServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
 
    @Override
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=GBK");
        PrintWriter out = response.getWriter();
        String l = request.getParameter("length");
        String w = request.getParameter("width");
        out.println("<html><body>");
        double m = 0;
        double n = 0;
        try {
            m = Double.parseDouble(l);
            n = Double.parseDouble(w);
            out.println("矩形的周长是：" + (m + n) * 2);
        } catch (NumberFormatException e) {
            out.println("请输入数字字符！");
        }
        out.println("</html></body>");
    }
 
    @Override
    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=GBK");
        PrintWriter out = response.getWriter();
        String l = request.getParameter("length");
        String w = request.getParameter("width");
        out.println("<html><body>");
        double m = 0;
        double n = 0;
        try {
            m = Double.parseDouble(l);
            n = Double.parseDouble(w);
            out.println("矩形的面积是：" + m * n);
        } catch (NumberFormatException e) {
            out.println("请输入数字字符！");
        }
        out.println("</html></body>");
    }
 
}

3.login.jsp文件的代码如下所示，注意，这里虽然是一个JSP页面，但其实根本没有用到JSP的功能，只相当于一个HTML页面，只有一个表单。


<%@ 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>login.jsp</title>
</head>
<body>
    <h2>输入矩形的长和宽，提交给servlet（post方式）求面积：</h2>
    <form action="getLengthOrAreaServlet" method="post">
        长：<input type="text" name="length"/><br>
        宽：<input type="text" name="width"/><br>
        <input type="submit" value="提交"/>
    </form>
    <h2>输入矩形的长和宽，提交给servlet（get方式）求周长：</h2>
    <form action="getLengthOrAreaServlet" method="get">
        长：<input type="text" name="length"/><br>
        宽：<input type="text" name="width"/><br>
        <input type="submit" value="提交"/>
    </form>
</body>
</html>

4.在浏览器里面输入http://localhost:8080/Servlet/login.jsp运行之后得到的结果如下所示：

章节一 ：Servlet的doGet、doPost方法，如何被HTML（JSP）页面调用

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章节一：Servlet的doGet、doPost方法，如何被HTML（JSP）页面调用