观看慕课老师milanlover视频Tomcat装在Servlet的三种情况+Servlet获取表单数据+Servlet相对路径

原创 于 2019-05-05 12:27:56 发布 · 367 阅读 · 0 ·
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本文介绍了在Tomcat中Servlet的三种加载情况，强调了优先级与执行顺序。通过示例展示了Servlet如何在服务器启动时被加载到内存。讲解了如何使用Servlet获取表单数据，并讨论了日期类型的转换。同时，文章还涵盖了Servlet中相对路径和绝对路径的使用，以及请求重定向和服务器内部跳转的方法。最后，演示了如何从网页获取资源文件。

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在src新建TestServlet1：

package servlet;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class TestServlet1
 */
@WebServlet("/TestServlet1")
public class TestServlet1 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestServlet1() {
        System.out.println("TestServlet1构造方法被执行....");
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see Servlet#init(ServletConfig)
	 */
	public void init(ServletConfig config) throws ServletException {
		// TODO Auto-generated method stub
		System.out.println("TestServlet1初始化方法被执行....");
	}

	/**
	 * @see Servlet#destroy()
	 */
	public void destroy() {
		// TODO Auto-generated method stub
		System.out.println("TestServlet1销毁方法被执行....");
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("TestServlet1的doGet()方法被执行...");
		response.setContentType("text/html;charset=utf-8");
		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.println("<h1>你好，我是TestServlet1！</h1>");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("TestServlet1的doPost()方法被执行...");
		doGet(request,response);//让doPost()执行与doGet()相同的操作。
	}

}

 新建index.jsp：

<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<!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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
	<h1>Servlet生命周期</h1>
	<hr>
	<a href="servlet/TestServlet1">以Get方式请求TestServlet1</a>
</body>
</html>

web.xml：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	xmlns="http://java.sun.com/xml/ns/javaee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name></display-name>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>TestServlet1</servlet-name>
    <servlet-class>servlet.TestServlet1</servlet-class>
    <!-- 
    <load-on-startup>2</load-on-startup>
    -->
  </servlet>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>TestServlet2</servlet-name>
    <servlet-class>servlet.TestServlet2</servlet-class>
    <!-- 
    <load-on-startup>1</load-on-startup>
    -->
  </servlet>


  <servlet-mapping>
    <servlet-name>TestServlet1</servlet-name>
    <url-pattern>/servlet/TestServlet1</url-pattern>
  </servlet-mapping>
  
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

 

执行结果：

 Stop Server：

 以上说明Servlet的执行顺序。

 

 

数字越小表示装在的优先级别越高。 

修改web.xml：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	xmlns="http://java.sun.com/xml/ns/javaee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name></display-name>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>TestServlet1</servlet-name>
    <servlet-class>servlet.TestServlet1</servlet-class>
    
    <load-on-startup>2</load-on-startup>
   
  </servlet>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>TestServlet2</servlet-name>
    <servlet-class>servlet.TestServlet2</servlet-class>
    
    <load-on-startup>1</load-on-startup>
   
  </servlet>


  <servlet-mapping>
    <servlet-name>TestServlet1</servlet-name>
    <url-pattern>/servlet/TestServlet1</url-pattern>
  </servlet-mapping>
  
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

修改TestServlet2.java：

package servlet;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class TestServlet2
 */
@WebServlet("/TestServlet2")
public class TestServlet2 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestServlet2() {
    	 System.out.println("TestServlet2构造方法被执行....");
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see Servlet#init(ServletConfig)
	 */
	public void init(ServletConfig config) throws ServletException {
		// TODO Auto-generated method stub
		System.out.println("TestServlet2初始化方法被执行....");
	}

	/**
	 * @see Servlet#destroy()
	 */
	public void destroy() {
		// TODO Auto-generated method stub
		System.out.println("TestServlet2销毁方法被执行....");
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("TestServlet2的doGet()方法被执行...");
		response.setContentType("text/html;charset=utf-8");
		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.println("<h1>你好，我是TestServlet2！</h1>");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("TestServlet2的doPost()方法被执行...");
		doGet(request,response);//让doPost()执行与doGet()相同的操作。
	}

}

注意：这两个servlet实例已经驻留在服务器的内存当中，其实客户端并没有请求这两个servlet，但在服务器启动的时候已被事先装在。

 

 

D:\技术\爬虫\java\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\ServletLifeCycleDemo\WEB-INF\classes\servlet 

 修改TestServlet1.java源文件后：

package servlet;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class TestServlet1
 */
@WebServlet("/TestServlet1")
public class TestServlet1 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestServlet1() {
        System.out.println("TestServlet1构造方法被执行....");
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see Servlet#init(ServletConfig)
	 */
	public void init(ServletConfig config) throws ServletException {
		// TODO Auto-generated method stub
		System.out.println("TestServlet1初始化方法被执行....");
	}

	/**
	 * @see Servlet#destroy()
	 */
	public void destroy() {
		// TODO Auto-generated method stub
		System.out.println("TestServlet1销毁方法被执行....");
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("TestServlet1的doGet()方法被执行...");
		response.setContentType("text/html;charset=utf-8");
		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.println("<h1>大家好，我是TestServlet1！</h1>");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("TestServlet1的doPost()方法被执行...");
		doGet(request,response);//让doPost()执行与doGet()相同的操作。
	}

}

 此时servlet实例被重新装载。

SimpleDateFormat转换接收到的字符串类型为日期型（也可以将日期型转换为某种格式的字符串）。

parse方法：将指定类型的字符串转换为日期型。

 

Servlet获取表单数据

reg.jsp：用户注册的静态页面

<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'reg.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
    <style type="text/css">
	 .label{
		  width: 20%	
	 }
	 .controler{
		  width: 80%	
	 }
   </style>  
   <script type="text/javascript" src="js/Calendar3.js"></script>
  </head>
  
  <body>
    <h1>用户注册</h1>
    <hr>
    <form name="regForm" action="servlet/RegServlet" method="post" >
			  <table border="0" width="800" cellspacing="0" cellpadding="0">
			    <tr>
			    	<td class="lalel">用户名：</td>
			    	<td class="controler"><input type="text" name="username" /></td>
			    </tr>
			    <tr>
			    	<td class="label">密码：</td>
			    	<td class="controler"><input type="password" name="mypassword" ></td>
			    	
			    </tr>
			    <tr>
			    	<td class="label">确认密码：</td>
			    	<td class="controler"><input type="password" name="confirmpass" ></td>
			    	
			    </tr>
			    <tr>
			    	<td class="label">电子邮箱：</td>
			    	<td class="controler"><input type="text" name="email" ></td>
			    	
			    </tr>
			    <tr>
			    	<td class="label">性别：</td>
			    	<td class="controler"><input type="radio" name="gender" checked="checked" value="Male">男<input type="radio" name="gender" value="Female">女</td>
			    	
			    </tr>
			   
			    <tr>
			    	<td class="label">出生日期：</td>
			    	<td class="controler">
			    	  <input name="birthday" type="text" id="control_date" size="10"
                      maxlength="10" onclick="new Calendar().show(this);" readonly="readonly" />
			    	</td>
			    </tr>
			    <tr>
			    	<td class="label">爱好：</td>
			    	<td class="controler">
			    	<input type="checkbox" name="favorite" value="nba"> NBA &nbsp;
			    	  <input type="checkbox" name="favorite" value="music"> 音乐 &nbsp;
			    	  <input type="checkbox" name="favorite" value="movie"> 电影 &nbsp;
			    	  <input type="checkbox" name="favorite" value="internet"> 上网 &nbsp;
			    	</td>
			    </tr>
			    <tr>
			    	<td class="label">自我介绍：</td>
			    	<td class="controler">
			    		<textarea name="introduce" rows="10" cols="40"></textarea>
			    	</td>
			    </tr>
			    <tr>
			    	<td class="label">接受协议：</td>
			    	<td class="controler">
			    		<input type="checkbox" name="isAccept" value="true">是否接受霸王条款
			    	</td>
			    </tr>
			    <tr>
			    	<td colspan="2" align="center">
			    		<input type="submit" value="注册"/>&nbsp;&nbsp;
			    	    <input type="reset" value="取消"/>&nbsp;&nbsp;
			    	</td>
			    </tr>
			  </table>
			</form>
  </body>
</html>

userinfo.jsp：用户注册成功之后，提交给userinfo显示用户注册成功的用户信息。

<%@ page language="java" import="java.util.*,java.text.*" contentType="text/html; charset=utf-8"%>

<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'userinfo.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
    <style type="text/css">
	 .title{
		 width: 30%;	
		 background-color: #CCC;
		 font-weight: bold;
	 }
	 .content{
	     width:70%;
	     background-color: #CBCFE5;
	 }
	 
   </style>  
  </head>
  
  <body>
    <h1>用户信息</h1>
    <hr>
    <center>
     <jsp:useBean  id="regUser" class="entity.Users" scope="session"/>   
     <table width="600" cellpadding="0" cellspacing="0" border="1">
        <tr>
          <td class="title">用户名：</td>
          <td class="content">&nbsp;<jsp:getProperty name="regUser" property="username"/></td>
        </tr>
        <tr>
          <td class="title">密码：</td>
          <td class="content">&nbsp;<jsp:getProperty name="regUser" property="mypassword"/></td>
        </tr>
        <tr>
          <td class="title">性别：</td>
          <td class="content">&nbsp;<jsp:getProperty name="regUser" property="gender"/></td>
        </tr>
        <tr>
          <td class="title">E-mail：</td>
          <td class="content">&nbsp;<jsp:getProperty name="regUser" property="email"/></td>
        </tr>
        <tr>
          <td class="title">出生日期：</td>
          <td class="content">&nbsp;
            <% 
               SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日");
               String date = sdf.format(regUser.getBirthday());
               
            %>
             <%=date%>
          </td>
        </tr>
        <tr>
          <td class="title">爱好：</td>
          <td class="content">&nbsp;
            <% 
               String[] favorites = regUser.getFavorites();
               for(String f:favorites)
               {
            %>
                <%=f%> &nbsp;&nbsp;
            <% 
               }
            %>
          </td>
        </tr>
        <tr>
          <td class="title">自我介绍：</td>
          <td class="content">&nbsp;<jsp:getProperty name="regUser" property="introduce"/></td>
        </tr>
        <tr>
          <td class="title">是否介绍协议：</td>
          <td class="content">&nbsp;<jsp:getProperty name="regUser" property="flag"/></td>
        </tr>
     </table>
    </center>
  </body>
</html>

建一个实体类提交公户注册表单：Users.java（用户实体类）

package entity;

import java.util.Date;

//用户实体类
public class Users {

	private String username; //用户名
	private String mypassword; //密码
	private String email; //电子邮箱
	private String gender; //性别
	private Date birthday; //出生日期
	private String[] favorites; //爱好
	private String introduce; //自我介绍
	private boolean flag; //是否接受协议
	
	public Users()
	{
		
	}
	
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getMypassword() {
		return mypassword;
	}
	public void setMypassword(String mypassword) {
		this.mypassword = mypassword;
	}
	public String getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	public Date getBirthday() {
		return birthday;
	}
	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}
	public String[] getFavorites() {
		return favorites;
	}
	public void setFavorites(String[] favorites) {
		this.favorites = favorites;
	}
	public String getIntroduce() {
		return introduce;
	}
	public void setIntroduce(String introduce) {
		this.introduce = introduce;
	}

	public boolean isFlag() {
		return flag;
	}

	public void setFlag(boolean flag) {
		this.flag = flag;
	}
	
	
	
	
	
}

处理用户注册的RegServlet类：

package servlet;

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

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

import entity.Users;

public class RegServlet extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public RegServlet() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doPost(request,response);
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		request.setCharacterEncoding("utf-8");
		
		Users u = new Users();
		String username,mypassword,gender,email,introduce,isAccept;
		Date birthday;
		String[] favorites;
		
		
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		try
		{
			username = request.getParameter("username");
			mypassword = request.getParameter("mypassword");
			gender = request.getParameter("gender");
			email = request.getParameter("email");
			introduce = request.getParameter("introduce");
			birthday = sdf.parse(request.getParameter("birthday"));
			if(request.getParameterValues("isAccept")!=null)
			{
			  isAccept = request.getParameter("isAccept");
			}
			else
			{
			  isAccept = "false";
			}
			//用来获取多个复选按钮的值
			favorites = request.getParameterValues("favorite");
			u.setUsername(username);
			u.setMypassword(mypassword);
			u.setGender(gender);
			u.setEmail(email);
			u.setFavorites(favorites);
			u.setIntroduce(introduce);//封装
			if(isAccept.equals("true"))
			{
				u.setFlag(true);
			}
			else
			{
				u.setFlag(false);
			}
			u.setBirthday(birthday);
			
			//把注册成功的用户对象保存在session中
			request.getSession().setAttribute("regUser", u);
			//跳转到注册成功页面
			request.getRequestDispatcher("../userinfo.jsp").forward(request,response);
		}
		catch(Exception ex)
		{
			ex.printStackTrace();
		}
		
		
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}

getParameterValues接收字符串数组，用来获取多个复选按钮的值。

 

注：本节课老师打的源代码有错，RegServlet里面的isAccept写成了isAccpet

 

在页面上调用Servlet时路径的写法

使用相对路径访问HelloServlet（超链接方式）： 

href="报错

如何解决删除servlet后The servlet name already exists

新建index.jsp：

<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
    <title>My JSP 'index.jsp' starting page</title>
  </head>
  
  <body>
    <h1>Servlet路径跳转</h1>
    <hr>
    <!--使用相对路径访问HelloServlet -->
    <!-- /servlet/HelloServlet 第一个/表示服务器的根目录 -->
    <a href="servlet/HelloServlet">访问HelloServlet!</a><br>
</body>
</html>

新建HelloServlet.jsp：

package servlet;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class HelloServlet
 */
@WebServlet("/HelloServlet")
public class HelloServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public HelloServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see Servlet#init(ServletConfig)
	 */
	public void init(ServletConfig config) throws ServletException {
		// TODO Auto-generated method stub
	}

	/**
	 * @see Servlet#destroy()
	 */
	public void destroy() {
		// TODO Auto-generated method stub
	}

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

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setContentType("text/html;charset=utf-8");
		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.println("<h1>您好，我是HelloServlet!</h1>");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}

}

新建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_2_5.xsd" version="2.5">
  <display-name></display-name>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>HelloServlet</servlet-name>
    <servlet-class>servlet.HelloServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>HelloServlet</servlet-name>
    <url-pattern>/servlet/HelloServlet</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

结果： 

使用绝对路径访问HelloServlet（超链接方式）：

index.jsp：

<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
    <title>My JSP 'index.jsp' starting page</title>
  </head>
  
  <body>
    <h1>Servlet路径跳转</h1>
    <hr>
    <!--使用相对路径访问HelloServlet -->
    <!-- /servlet/HelloServlet 第一个/表示服务器的根目录 -->
    <a href="servlet/HelloServlet">访问HelloServlet!</a><br>
    <!-- 使用绝对路径访问HelloServlet，可以使用path变量：path变量表示项目的根目录 -->
    <a href="<%=path %>/servlet/HelloServlet">访问HelloServlet!</a><br>
</body>
</html>

 

Servlet当中页面跳转问题

采用请求重定向的方式：

新建TestServlet：

package servlet;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class TestServlet
 */
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see Servlet#init(ServletConfig)
	 */
	public void init(ServletConfig config) throws ServletException {
		// TODO Auto-generated method stub
	}

	/**
	 * @see Servlet#destroy()
	 */
	public void destroy() {
		// TODO Auto-generated method stub
	}

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

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//请求重定向方式跳转到test.jsp，当前路径是ServletPathDirection/servlet/
		//response.sendRedirect("test.jsp");
		//使用request.getContextPath()获得上下文对象
		response.sendRedirect(request.getContextPath()+"/test.jsp");

	}

}

新建test.jsp：

<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
    <title>My JSP 'index.jsp' starting page</title>
  </head>
  
  <body>
    <h1>Test.jsp</h1>
    <hr>
   
</body>
</html>

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_2_5.xsd" version="2.5">
  <display-name></display-name>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>HelloServlet</servlet-name>
    <servlet-class>servlet.HelloServlet</servlet-class>
  </servlet>
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>TestServlet</servlet-name>
    <servlet-class>servlet.TestServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
    <servlet-name>HelloServlet</servlet-name>
    <!--url-pattern处必须以/开头，这里的/表示项目的根目录  -->
    <url-pattern>/servlet/HelloServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>TestServlet</servlet-name>
    <url-pattern>/servlet/TestServlet</url-pattern>
  </servlet-mapping>	
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

 

服务器内部跳转：

 TestServlet.jsp：

package servlet;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class TestServlet
 */
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see Servlet#init(ServletConfig)
	 */
	public void init(ServletConfig config) throws ServletException {
		// TODO Auto-generated method stub
	}

	/**
	 * @see Servlet#destroy()
	 */
	public void destroy() {
		// TODO Auto-generated method stub
	}

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

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//请求重定向方式跳转到test.jsp，当前路径是ServletPathDirection/servlet/
		//response.sendRedirect("test.jsp");
		//使用request.getContextPath()获得上下文对象
		//response.sendRedirect(request.getContextPath()+"/test.jsp");
		
		//服务器内部跳转，这里的斜线表示项目的根目录
		request.getRequestDispatcher("/test.jsp").forward(request, response);
	}

}

结果一样

网页获取资源文件方式：

TestServlet：

package servlet;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class TestServlet
 */
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see Servlet#init(ServletConfig)
	 */
	public void init(ServletConfig config) throws ServletException {
		// TODO Auto-generated method stub
	}

	/**
	 * @see Servlet#destroy()
	 */
	public void destroy() {
		// TODO Auto-generated method stub
	}

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

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//请求重定向方式跳转到test.jsp，当前路径是ServletPathDirection/servlet/
		//response.sendRedirect("test.jsp");
		//使用request.getContextPath()获得上下文对象
		//response.sendRedirect(request.getContextPath()+"/test.jsp");
		
		//服务器内部跳转，这里的斜线表示项目的根目录
		//request.getRequestDispatcher("/test.jsp").forward(request, response);
		request.getRequestDispatcher("../test.jsp").forward(request, response);
	}

}

结果一样

蔡姬
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