菜鸟学Android笔记（二十三）：ServletConfig

来源：互联网发布：工资软件下载编辑：程序博客网时间：2024/04/29 16:19

一、ServletConfig代表当前Servlet在web.xml中的配置信息

ServletConfig常见的方法：

String getServletName()---获取当前Servlet指定名称的初始化参数的值

Enumeration getInitParameterNames()---获取当前Servlet初始化信息的枚举

ServletConfig的作用：

1、

2、

3、

二、如何初始化ServletConfig

方法一：将ServletConfig设为成员方法，初始化类的时候初始化ServletConfig：

package com.java;import java.io.IOException;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class SconfigServlet extends HttpServlet{ServletConfig config=null;public void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {}@Overridepublic void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doGet(req,resp);}@Overridepublic void init(ServletConfig config) throws ServletException {this.config=config;}}

如果每次都这样初始化会很麻烦，所以我们可以直接配置

假设，在web应用中web.xml文件已经配置了：

<servlet>        <servlet-name>SconfigServlet</servlet-name>        <servlet-class>com.java.SconfigServlet</servlet-class>    </servlet>     <servlet-mapping>        <servlet-name>SconfigServlet</servlet-name>        <url-pattern>/java/SconfigServlet</url-pattern>    </servlet-mapping>

那么再classes文件夹中可以设置一个

SconfigServlet,java,里面的内容可以这样配置：

package com.java;import java.io.IOException;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class SconfigServlet extends HttpServlet{public void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {ServletConfig Congfig=this.getServletConfig();String sName=Congfig.getServletName();System.out.println(sName);}@Overridepublic void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doGet(req,resp);}}

这是在浏览器输入“http://localhost/Day02/java/SconfigServlet”，然后回车，那么Myeclipse变回会输出：

SconfigServlet

ServletConfig的其他功能，利用枚举方法getInitParameterNames：

加入web.xml是这样的：

<?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">  <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list>  <servlet>        <servlet-name>DemoServlet</servlet-name>        <servlet-class>com.java.DemoServlet</servlet-class>    </servlet>     <servlet-mapping>        <servlet-name>DemoServlet</servlet-name>        <url-pattern>/java/DemoServlet</url-pattern>    </servlet-mapping>        <servlet>        <servlet-name>SconfigServlet</servlet-name>        <servlet-class>com.java.SconfigServlet</servlet-class>        <init-param>        <param-name>>name1</param-name>        <param-value>value1</param-value>        </init-param>        <init-param>        <param-name>>name3</param-name>        <param-value>value3</param-value>        </init-param>    </servlet>     <servlet-mapping>        <servlet-name>SconfigServlet</servlet-name>        <url-pattern>/java/SconfigServlet</url-pattern>    </servlet-mapping></web-app>

而 SconfigServlet类是这样的时候，可以枚举：

package com.java;import java.io.IOException;import java.util.Enumeration;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class SconfigServlet extends HttpServlet{public void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {ServletConfig Congfig=this.getServletConfig();//String sName=Congfig.getServletName();//System.out.println(sName);//String value=Congfig.getInitParameter("name2");//System.out.println(value);Enumeration enumration=Congfig.getInitParameterNames();while((enumration).hasMoreElements()){String name=(String)enumration.nextElement();String value=Congfig.getInitParameter(name);System.out.println(name+"value");}}@Overridepublic void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doGet(req,resp);}}

作用：不想写死在程序中的东西可以在Servletconfig中配置，如：

1、换编码

2、数据库用户名和密码

0 0