ServletConfig接口

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ServletConfig接口

Servlet容器初始化Servlet对象时会为Servlet创建一个ServletConfig对象，在ServletConfig对象中包含了Servlet的初始化参数信息，此外ServletConfig对象还与当前web应用中的ServletContext对象关联，Servlet容器在调用Servlet对象的init(SevletConfig config)方法时会把ServletConfig对象作为一个参数传递给Servlet对象，这个方法是的Servlet和ServletConfig对象之间建立关联，

每个初始化参数包含一对参数名和参数值，在web.xml中初始化参数时可以用<init-param>来设置参数值，<param-name>表示参数名，<param-value>表示参数值。

以下代码为一个FontServlet类设置了两个初始化参数size和color.

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
           <servlet>
        <servlet-name>Font</servlet-name>
        <servlet-class>com.demo.servlet.FontServlet</servlet-class>
        <init-param>
            <param-name>color</param-name>
            <param-value>red</param-value>
        </init-param>
        <init-param>
            <param-name>size</param-name>
            <param-value>35</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>Font</servlet-name>
        <url-pattern>/font</url-pattern>
    </servlet-mapping>

</web-app>

FontServle.java

package com.demo.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

/**
* Created by 谭雪娇 on 2017/4/6.
*/
public class FontServlet extends HttpServlet {
    public void doGet(HttpServletRequest request,HttpServletResponse response)throws ServletException ,IOException{
        String word=request.getParameter("word");
        if(word==null){
            word="Hello";
        }
        //读取初始化参数
        String color=getInitParameter("color");
        String size=getInitParameter("size");
        System.out.println("ServletName:"+getServletName());//打印ServletName:Font
        /**设置HTTP响应正文得MIME类型及字符编码*/
        response.setContentType("text/html;charset=UTF-8");
        /*输出HTML文档*/
        PrintWriter out=response.getWriter();
        out.println("<html><head><title>FontServlet</title></head>");
        out.println("<font size='"+size+"'color='"+color+"'>"+word+"</font>");
        out.println("</body></html>");
        out.close();

    }
}