重溫Servlet之param-name參數

我們用springMVC時要在Servlet處配置一個contextConfigLocation參數

但是servlet怎么讀取呢

今天我們就來try一下

這是xml里的配置 我們在helloServlet里配置一個名為value的參數

<?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_3_0.xsd" metadata-complete="false" version="3.0">
<absolute-ordering/>
<display-name>test</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
<servlet>
    <servlet-name>hello</servlet-name>
    <servlet-class>Hello</servlet-class>
    <init-param>
    <param-name>value</param-name>
    <param-value>這是xml里配置的元素</param-value>
    </init-param>
</servlet>
<servlet-mapping>
<servlet-name>hello</servlet-name>
<url-pattern>/hello</url-pattern>

</servlet-mapping>
</web-app>

加下來創建Servlet

import java.io.IOException;

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 Hello
 */
@WebServlet("/Hello")
public class Hello extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * Default constructor. 
     */
    public Hello() {
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        ServletConfig config = getServletConfig();
        
        response.setCharacterEncoding("UTF-8");
        System.out.println(config.getInitParameter("value"));
        response.getWriter().append("Served at: ").append(request.getContextPath()).append(config.getInitParameter("value"));
        
    }

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

}

我們通過父類中的

getServletConfig（）方法獲取配置；
通過value獲取值
查看一下結果 訪問http://localhost:8080/test/hello
結果

Served at: /test這是xml里配置的元素

 

本來想繼續解析源碼 但是沒有源碼包 等下次用maven創建時在看看父類中的方法是怎么實現的