JavaWeb基础 继承GenericServlet 简单示例

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web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID"
version="3.1">

<servlet>
<servlet-name>myGenericServlet</servlet-name>
<servlet-class>jizuiku.web.servlet.MyGenericServlet</servlet-class><!-- 执行的是这个类 -->

<init-param>
<param-name>minNum</param-name>
<param-value>10</param-value>
</init-param>

<init-param>
<param-name>maxNum</param-name>
<param-value>100</param-value>
</init-param>
</servlet>

<servlet-mapping>
<servlet-name>myGenericServlet</servlet-name> <!-- 两个name 相应就好 -->
<url-pattern>/MyGenericServletDemo</url-pattern><!-- 访问的是这个路径 -->
</servlet-mapping>

</web-app>

继承GenericServlet的类的代码

package jizuiku.web.servlet;

import java.io.IOException;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

/**
*
*
* @author 给最苦
* @version V17.10.20
*/
public class MyGenericServlet extends GenericServlet{

/**
*
*/
private static final long serialVersionUID = 1L;

@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {

System.out.println("执行service()...");

}

// 根据源代码可以推出 ，要重写的方法一定是 init()
@Override
public void init() throws ServletException {
// TODO Auto-generated method stub
System.out.println("你好，执行初始化程序");
}

@Override
public void destroy() {
// TODO Auto-generated method stub
System.out.println("执行destroy()...");
}

}

效果



　　如上浏览器访问指定页面 一次，控制台输出信息发生如下变化



扩展
　　为什么要重写 无参数的init()方法？请看源代码

/**
* Called by the servlet container to indicate to a servlet that the servlet
* is being placed into service. See {@link Servlet#init}.
* <p>
* This implementation stores the {@link ServletConfig} object it receives
* from the servlet container for later use. When overriding this form of
* the method, call <code>super.init(config)</code>.
*
* @param config
*            the <code>ServletConfig</code> object that contains
*            configuration information for this servlet
* @exception ServletException
*                if an exception occurs that interrupts the servlet's
*                normal operation
* @see UnavailableException
*/
@Override
public void init(ServletConfig config) throws ServletException {
this.config = config;
this.init();
}

　　 关于serialVersionUID的简单介绍



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