servletconfig对象获取配置信息

1，servletconfig对象：
@1，它代表当前Servlet在web.xml中的配置信息。servlet在配置初始化信息时，web容器在创建servlet对象时，会将这些初始化参数封装到servletconfig中，在调用servlet中的init方法时，会将servletconfig对象传给servlet。程序员可以通过servletconfig对象来获取初始化参数。
@2，如何获取servletconfig对象：该对像开始是在init方法里，GenericServlet中的getServletConfig方法中可以返回Config对象.
获取servlet在web.xml中配置的名称：

import java.io.IOException;
import java.io.PrintWriter;

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 Myfirstservlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.getWriter().write("hello my name is lishuai");
        //servlet在web.xml中的名称
        ServletConfig config=this.getServletConfig();
        String name=config.getServletName();
        System.out.println(name);
        
        

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            doGet(request,response);
    }

}

获取当前servlet中配置的初始化参数：

import java.io.IOException;
import java.io.PrintWriter;
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 Myfirstservlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        
        ServletConfig config=this.getServletConfig();
        
        //获取在servlet的web.xml的配置信息
        String value=config.getInitParameter("name1");
        System.out.println(value);
        Enumeration e=config.getInitParameterNames();
        while(e.hasMoreElements()){
            String name1=(String)e.nextElement();
            String value1=config.getInitParameter(name1);
            System.out.println(name1+":"+value1);
        }
        
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            doGet(request,response);
    }

}

servlet中配置信息可以在<init-param>中配置。

 <servlet>
    <servlet-name>Myfirstservlet</servlet-name>
    <servlet-class>Myfirstservlet</servlet-class>
    <init-param>
    <param-name>name1</param-name>
    <param-value>value1</param-value>
    </init-param>
    <init-param>
    <param-name>name2</param-name>
    <param-value>value2</param-value>
    </init-param>
    <init-param>
    <param-name>name3</param-name>
    <param-value>value3</param-value>
    </init-param>
  </servlet> <servlet>
    <servlet-name>Myfirstservlet</servlet-name>
    <servlet-class>Myfirstservlet</servlet-class>
    <init-param>
    <param-name>name1</param-name>
    <param-value>value1</param-value>
    </init-param>
    <init-param>
    <param-name>name2</param-name>
    <param-value>value2</param-value>
    </init-param>
    <init-param>
    <param-name>name3</param-name>
    <param-value>value3</param-value>
    </init-param>
  </servlet>