JavaWeb入门之Servlet小练习

原创

黄桂期

发布于 2018-05-16 17:27:55

1.1K50

代码可运行

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代码可运行

写给还是小白的我们，一起加油！

今天来一个巨简单的Servlet小练习，顺带温习下前两天的内容~

练习：

在web.xml文件中设置两个WEB应用的初始化参数，username,password，创建一个html页面，定义两个请求字段并发送到一个Servlet中，对应web.xml中的参数是否一样；若一致，响应hello:username；若失败则Sorry:username

html:

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
    <form action="PracticeServlet" method="post">
    username:<input type="text" name="username"/>
    password:<input type="password" name="password"/>
    <input type="submit" value="Submit"/>
    </form>
</body>
</html>

PracticeServlet：

package per.huang.pra;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class PracticeServlet implements Servlet {

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        
    }

    @Override
    public ServletConfig getServletConfig() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public String getServletInfo() {
        // TODO Auto-generated method stub
        return null;
    }
    private ServletConfig servletConfig;
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        // TODO Auto-generated method stub
        this.servletConfig=servletConfig;
    }

    @Override
    public void service(ServletRequest request, ServletResponse response)
            throws ServletException, IOException {
        //1,获取请求参数：username,password
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        //2,获取当前WEB应用的初始化参数：user,password
        //需要使用ServletContext对象
        ServletContext servletContext=servletConfig.getServletContext();
        String initUser=servletContext.getInitParameter("user");
        String initPassword=servletContext.getInitParameter("password");
        PrintWriter out=response.getWriter();
        //3,比对
        //4,打印响应字符串
        if(initUser.equals(username)&&initPassword.equals(password)){
            out.print("Hello:"+username);
        }else{
            out.print("Sorry"+username);;
        }
        
        
    }

}

web.xml：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
         xmlns="http://java.sun.com/xml/ns/javaee" 
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" 
         id="WebApp_ID" version="3.0">
  <display-name>Day0516</display-name>
  <!-- 配置当前WEB应用的初始化参数 -->
  <context-param>
      <param-name>user</param-name>
      <param-value>huang</param-value>
  </context-param>
  <context-param>
      <param-name>password</param-name>
      <param-value>123456</param-value>
  </context-param>
  <!-- 配置Servlet -->
  <servlet>
      <servlet-name>PracticeServlet</servlet-name>
      <servlet-class>per.huang.pra.PracticeServlet</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>PracticeServlet</servlet-name>
      <url-pattern>/PracticeServlet</url-pattern><!-- 和跳转的action后面的内容一样 -->
  </servlet-mapping>
</web-app>

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