Analysis of Hello2 source code

時間 2019-12-08

標籤 analysis hello2 hello source code 简体版

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GreetingServlet.java

package javaeetutorial.hello2; //導入包

//import 導入類和接口

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.RequestDispatcher;

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("/greeting") //指定上下文根的相對URL模式

public class GreetingServlet extends HttpServlet { //定義一個GreetingServlet類繼承HttpServlet

@Override //覆蓋方法

public void doGet(HttpServletRequest request, //定義一個doGet方法，有兩個參數

HttpServletResponse response)

throws ServletException, IOException { //拋出異常

response.setContentType("text/html"); //獲取上下文類型的響應

response.setBufferSize(8192); //設置BufferSize爲8192

try (PrintWriter out = response.getWriter()) { //定義一個PrintWriter類型的變量out 寫入

out.println("<html lang=\"en\">" //html代碼

+ "<head><title>Servlet Hello</title></head>");

// then write the data of the response

out.println("<body bgcolor=\"#ffffff\">"

+ "<img src=\"resources/images/duke.waving.gif\" "

+ "alt=\"Duke waving his hand\">"

+ "<form method=\"get\">"

+ "<h2>Hello, my name is Duke. What's yours?</h2>"

+ "<input title=\"My name is: \" type=\"text\" "

+ "name=\"username\" size=\"25\"/>"

+ "<p></p>"

+ "<input type=\"submit\" value=\"Submit\"/>"

+ "<input type=\"reset\" value=\"Reset\"/>"

+ "</form>");

String username = request.getParameter("username"); //定義string類型變量name 將響應獲得的username賦給它

if (username != null && username.length() > 0) { //判斷username不存在而且長度大於0

RequestDispatcher dispatcher =

getServletContext().getRequestDispatcher("/response"); //將內容跳轉到服務器的/response地址上

if (dispatcher != null) {

dispatcher.include(request, response); //包含響應中的資源

}

out.println("</body></html>");

}

@Override //覆蓋，方法重寫

public String getServletInfo() { //重寫getServletInfo方法並返回字符串

return "The Hello servlet says hello.";

}

ResponseServlet.java

package javaeetutorial.hello2; //引入包

//導入須要使用的類和接口

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("/response") //指定上下文的相對URL

public class ResponseServlet extends HttpServlet { //定義一個ResponseServlet類繼承HttpServlet

@Override//覆蓋

public void doGet(HttpServletRequest request, //定義doGet方法，有兩個參數

HttpServletResponse response)

throws ServletException, IOException { //拋出異常

try (PrintWriter out = response.getWriter()) { //定義PrintWrite類型變量out 將getWriter輸出的數據賦給它

String username = request.getParameter("username"); //將響應獲得的username賦值給String類型的變量username

if (username != null && username.length() > 0) { //若是username不爲空而且長度大於0

out.println("<h2>Hello, " + username + "!</h2>");//輸出hello+username

}

@Override//覆蓋方法

public String getServletInfo() { //返回字符串

return "The Response servlet says hello.";

}

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