hello2代码分析

Responseservlet.java:
package javaeetutorial.hello2;  #软件包名为javaeetutorial.hello2


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;

  #导入io 和 serverlet相关的各类包
@WebServlet("/response")

  #注解WebServerlet 为response
public class ResponseServlet extends HttpServlet {

  #定义类ReponseServerlet从HttpServerlet拓展而来

@Override

  #注解Override
public void doGet(HttpServletRequest request,

  #定义对象doGet ,定义HttpServerletRequest 为request

HttpServletResponse response)

  #定义HttpServerResponse 为response
throws ServletException, IOException {

  #抛出异常
try (PrintWriter out = response.getWriter()) {

  #将response的getWeite方法赋值给PrintWrite的out,response的getWrite方法来自于HttpServletResponse接口方法
String username = request.getParameter("username");

  #将request的getParameter方法获得的username赋值给字符串username,requset来自于HttpServerletRequest接口方法
if (username != null && username.length() > 0) {

  #当username字符串不为空且username的长度大于0时
out.println("<h2>Hello, " + username + "!</h2>");

  #调用out的println打印Hello,和字符串
}
}
}

@Override
public String getServletInfo() {
return "The Response servlet says hello.";

  #定义字符串getServerletinfo,返回内容

}
}

GreetingServlet.java:

package javaeetutorial.hello2;  

  #包名hello2

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;

  #导入各类需要的资源包

@WebServlet("/greeting")  

  #注解名greeting
public class GreetingServlet extends HttpServlet {

  #拓展类GreetingServlet从HttpServlet接口

@Override

  #注解Override
public void doGet(HttpServletRequest request,
HttpServletResponse response)

  #同上定义对象 HttpServletRequest名为request,HttpServletResponse名为response
throws ServletException, IOException {

  #抛出异常

response.setContentType("text/html");

  #定义文本类型为text,html
response.setBufferSize(8192);

  #定义缓冲池大小8192
try (PrintWriter out = response.getWriter()) {
out.println("<html lang="en">"
+ "<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>");

  #以上是打印网页页面相关内容

String username = request.getParameter("username");
if (username != null && username.length() > 0) {
RequestDispatcher dispatcher =
getServletContext().getRequestDispatcher("/response");
  #将response响应赋给dispatcher分发调度
if (dispatcher != null) {
dispatcher.include(request, response);
}

  #当匹配到处理请求响应的处理服务时,就返回请求和response.java的响应内容结果
}
out.println("</body></html>");
}
}

@Override
public String getServletInfo() {
return "The Hello servlet says hello.";

  #在页面返回响应的文字

}
}

原文地址:https://www.cnblogs.com/lijianxuan/p/10606299.html