java web學習日常自用

火眼猊發表於2020-09-28

請求和響應

Servlet最主要的作用是用來處理客戶機的請求，並向客戶做出響應。因此Web伺服器再呼叫Service（）方法之前都會建立HTTPServletRequest和HttpServletResponse兩個物件。

上圖為瀏覽器訪問Servlet的過程
1.SetStatus（int status）方法
用於設定HTTP響應訊息的狀態碼，生成響應狀態行。正常情況下，會產生一個預設的狀態碼200的狀態行
2.SendError（int sc）方法
用於傳送表示錯誤的狀態碼。
3.傳送相應訊息頭相關的方法
可以點開這裡看一下他的描述還是很全面的

下面的程式碼我用來自己看的
Test1

package cn.itcast.servlet;

import java.io.IOException;
import java.io.OutputStream;

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

/**
 * Servlet implementation class Test1
 */
public class Test1 extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String data="itcast";
		//獲取位元組輸出物件
		OutputStream out = response.getOutputStream();
		out.write(data.getBytes());//輸出資訊
		
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

Test2

package cn.itcast.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;

/**
 * Servlet implementation class Test3
 */
public class Test3 extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String data="fire";
		//獲取字元輸出流物件
		PrintWriter print = response.getWriter();
		 print.write(data);//輸出資訊
		 
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

Test3

package cn.itcast.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;

/**
 * Servlet implementation class Test4
 */
public class Test4 extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// 設定字元編碼
		response.setContentType("text/html;charset=utf-8");
		String data="中國";
		PrintWriter out=response.getWriter();
		out.println(data);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

Test4

package cn.itcast.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Test5
 */
public class Test5 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// 兩秒後重新整理並跳轉到傳智播客官網首頁
		response.setHeader("Refresh","2;URL=http://www.itcast.cn");
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

Test5

package cn.itcast.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Test6
 */
public class Test6 extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//每隔三秒定時重新整理當前頁面
		response.setHeader("Refresh","3");
		response.getWriter().print(new java.util.Date());//輸出當前時間
		
		
		
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

實現網頁定時重新整理並跳轉的登入頁面*
首先login.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Trasitional//EN""http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta charset="UTF-8" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="/chapter/LoginServlet" method="post">
使用者名稱:<input type="text" name="username"/><br>
密&nbsp;&nbsp;&nbsp;碼:<input type="password" name="password"/><br>
<input type="submit" value="登入"/>
	</form>
</body>
</html>

接下來是登入成功的頁面

<!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>
歡迎你，登陸成功！
</body>
</html>

最後Servlet

package cn.itcast.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class LoginServlet
 */
public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setContentType("text/html,charset=utf-8");
		//用HttpServletResquest物件的getParameter()方法獲取使用者名稱和密碼
		String username=request.getParameter("username");
		String password=request.getParameter("password");
		System.out.println("name:"+username);
		//假設使用者名稱和密碼分別為：itcast和123
		if (("itcast").equals(username)&&("123").equals(password)) {
			//如果使用者名稱和密碼正確，重定向到welcome.html
			response.sendRedirect("/chapter/welcome.html");
		}else{
			//如果使用者名稱和密碼不正確，重定向到login.html
			response.sendRedirect("/chapter/login.html");
		}
			
		
		
		
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

Java多執行緒學習筆記（自用）
2020-11-24
Java執行緒筆記
Java小白的學習日記一（自用筆記）
2020-11-09
Java筆記
JAVA學習筆記—JAVA WEB（二）JAVA WEB核心（下）
2020-12-16
Java筆記Web
Tensorflow 深度學習簡介（自用）
2018-09-20
深度學習
Java Web 學習路線
2018-10-22
JavaWeb
資料庫日常遇到的需求筆記（自用）
2018-05-22
資料庫筆記
java web視訊學習-Cookie
2019-03-24
JavaWebCookie
Java Web學習之旅開始
2017-11-22
JavaWeb
如何學習Java Web開發
2012-03-24
JavaWeb
學習Angular日常筆記
2019-07-12
Angular筆記
java web視訊學習-Tomcat
2019-02-27
JavaWebTomcat
java web、各種框架學習地址
2016-06-29
JavaWeb框架
Laravel 日常學習提升站點
2020-06-14
Laravel
學習日常：造資料 - 下
2024-08-08
【JAVA Web基礎學習】Day1
2018-03-19
JavaWeb
MyBatis-Plus日常工作學習
2021-04-14
MyBatis
【轉載】職場人士日常學習方法
2011-07-10
Java WEB學習資料,思維導圖
2017-09-17
JavaWeb
狂神說Java Web學習筆記_Cookie
2024-04-11
JavaWeb筆記Cookie
Docker容器學習梳理 - 日常操作總結
2016-07-28
Docker
狂神說Java Web學習筆記_Tomcat
2024-04-08
JavaWeb筆記Tomcat
java學習之道 --- 如何學習java？
2018-08-08
Java
日常學習儲存--陣列和指標
2020-10-31
陣列指標
Web前端如何學？Web前端學習方法分享
2022-03-07
Web前端
java-web-j2ee學習建議路線
2015-11-05
JavaWeb
新手Java學習路線乾貨教材《Java Web開發實戰》
2019-07-22
JavaWeb
CSRF&SSRF練習（自用筆記）
2024-03-13
筆記
web前端學習——零基礎web前端學習路線
2017-10-16
Web前端
web知識學習
2019-04-12
Web
web前端學習之路
2019-06-21
Web前端
web前端學習方案
2018-10-18
Web前端
Web開發學習
2020-10-21
Web
web前端學習指南
2022-05-30
Web前端
Web前端學習——JavaScript
2017-12-07
Web前端JavaScript
Web前端學習——HTML
2017-12-04
Web前端HTML
Web前端學習——CSS
2017-12-04
Web前端CSS
Web【轉載學習】
2024-04-22
Web
【Web】Web 階段學習筆記
2024-03-09
Web筆記

java web學習 日常自用

請求和響應

相關文章

java web學習日常自用