Servlet学习A——实现servlet

最新推荐文章于 2024-03-22 20:52:09 发布

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最新推荐文章于 2024-03-22 20:52:09 发布

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分类专栏： JAVA-WEB开发文章标签： servlet

本文链接：https://blog.youkuaiyun.com/chenpx1224/article/details/44491669

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本文介绍如何创建并部署一个简单的Servlet，包括使用MyEclipse集成Tomcat应用服务器进行开发、配置web.xml文件、实现doGet和doPost方法，并展示了如何在浏览器中访问Servlet。

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1.新建一个web Project

2.利用servlet向导新建一个servlet类，类名是FIrstServlet

web.xml文件中

  <servlet-mapping>
    <servlet-name>FirstServlet</servlet-name>
    <url-pattern>/servlet/FirstServlet</url-pattern>
  </servlet-mapping>

FirstServlet类

package net.xiang168.test1;

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;

public class FirstServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.log("执行doGet方法的输出");  //servlet自带的日志 输出信息到控制台
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out
				.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
		out.println("<HTML>");
		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
		out.println("  <BODY>");
		out.print("    This is ");
		out.print(this.getClass());
		out.println(", using the GET method");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html");

	//	this.execute(request, response);
		PrintWriter out = response.getWriter();
		out
				.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
		out.println("<HTML>");
		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
		out.println("  <BODY>");
		out.print("    This is ");
		out.print(this.getClass());
		out.println(", using the POST method");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}
	//初始化方法
	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
		
	}
	//执行方法
   private void execute( HttpServletRequest request ,HttpServletResponse response )throws ServletException, IOException{
	   
	   
   }
}

3. RUN as Server Application

使用的是MyEclipse集成Tomcat应用服务器

4.浏览器上访问

http://localhost:8080/test20/servlet/FirstServlet

// 输出的是doGet方法的处理结果

控制台输出

this.log() 方法中的内容

<span style="color:#ff9966;">2015-3-20 14:36:31 org.apache.catalina.core.ApplicationContext log
信息: FirstServlet: 执行doGet方法的输出</span>

5. 对FirstServlet进行重构

package net.xiang168.test1;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

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

public class FirstServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.log("执行doGet方法的输出");  //servlet自带的日志 输出信息到控制台
		this.execute(request , response);
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String msg ="执行doPost方法的输出结果" ;
	this.log(msg);
	this.execute(request, response);
	}
	//初始化方法
	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
		
	}
	//执行方法
   private void execute( HttpServletRequest request ,HttpServletResponse response )throws ServletException, IOException{
	   response.setCharacterEncoding("UTF-8"); //设置response的编码方式
	   request.setCharacterEncoding("UTF-8");  //设置request的编码方式
	   
	   String requestURL =request.getRequestURI(); //访问该Servlet的URI
	   
	   String method = request.getMethod(); //获取访问servlet的方式
	   String  param = request.getParameter("param" );
	   
	   response.setContentType("text/html");
	   PrintWriter out = response.getWriter();
	   out.println("<!DOCUTYPE HTML PUBLIC \" -//W3C//DTD HTML 4.01 Transitional //EN \">");
	   out.println("<HTML>") ;
	   out.println("<HEADER><TITLE>A servlet</TITLE></HEADER>");
	   out.println("<BODY>");
	   out.println("以 " + method + "方式访问该页面。取得的param参数是"  + param +"" );
	   
	   //out.println("<form action ='"+requestURL+"'	method ='get'>");  //get方法提交表单
	   out.println("<form action ='"+requestURL+"'	method ='post'>");
	   out.println(" <input  type='text' name ='param' value='Hello World!'> <input type='submit' value='以get方法查询查询页面"+requestURL+ "' >");
	   out.println("</form>");
	   
	   // 由客户端浏览器读取该文档的更新时间
	   out.println("  <script> document.write('本页的最后更新时间是" +(new Date()).toString() + "'); </script>");
	   
	   out.println("</BODY>");

	   out.println("</HTML>") ;
	   
	   out.flush();
	   out.close();
	   
	   
	   
   }
}