JSP详细篇——Servlet(二)

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Servlet开发

1.Servlet创建

Servlet创建很简单，主要有两种方法：一是创建一个普通的Java类使其继承HttpServlet类，在手动配置web.xml文件注册Servlet对象。另一种是直接通过IDE继承开发工具进行创建。

2.Servlet配置

（1）声明Servlet对象

在web.xml中，通过<servlet>标签声明一个Servlet对象。再此标签下主要包含两个子元素，分别为：<servlet-name>和<servlet-class>。其中<servlet-name>元素用于指定Servlet的名称，该名称可以是自定义的名称；<servlet-class>元素用于指定Servlet对象的完整位置。包括Servlet对象的包名和类名。其生命语法格式：

<servlet-name>SimpleServlet</servlet-name>

<servlet-class>com.zgy.servlet</servlet-class>

</servlet>

（2）映射Servlet

在web.xml文件中声明了Servlet对象后，需要映射访问Servlet的URL。该操作使用<servlet-mapping>标签进行配置。<servlet-mappig>标签包含两个子元素，分别为<servlet-name>和<url-pattern>。其中，<servlet-name>元素与<servlet>标签中的<servlet-name>元素相对应，不可以随便更改命名。<url-pattern>元素用于映射访问URL。其配置方法：

<servlet-mapping>

<servlet-name>SimpleServlet</servlet-name>

<url-pattern>/SimpleServlet</url-pattern>

</servlet-mapping>

范例：

package com.zgy.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;

public class MyServlet extends HttpServlet {

/**

* 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 {

response.setContentType("text/html");

response.setCharacterEncoding("GBK");

PrintWriter out = response.getWriter();

out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");

out.println("<HTML>");

out.println(" <HEAD><TITLE>Servlet 实例</TITLE></HEAD>");

out.println(" <BODY>");

out.print(" Servlet实例 ");

out.print(this.getClass());

out.println(", using the GET method");

out.println(" </BODY>");

out.println("</HTML>");

out.flush();

out.close();

}

web.xml配置

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="3.0"

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_3_0.xsd">

<display-name></display-name>

<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>MyServlet</servlet-name>

<servlet-class>com.zgy.servlet.MyServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>MyServlet</servlet-name>

<url-pattern>/servlet/MyServlet</url-pattern>

</servlet-mapping>

<welcome-file-list>

<welcome-file>index.jsp</welcome-file>

</welcome-file-list>

</web-app>

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