有关ServletConfig的用法

06820170907
1、在注解或者配置文件(web.xml)中写明初始化信息

2、通过getServletConfig().getInitParameter(name);返回参数值

3、代码如下：

package com.tiger.config.annotation;

import java.io.*;
import javax.servlet.*;
import javax.servlet.annotation.*;
import javax.servlet.http.*;
/**
 * 06820170907
 * 1、配置文件方式初始化信息
 * ServletConfig是每个Servelt都会产生一个ServletConfig对象与之对应
 * @author tiger
 * @time 2017年9月7日
 */
@WebServlet(name = "ServletConfig_annotation",
    urlPatterns = { "/servletConfig_annotation" },
    initParams = {@WebInitParam(name = "username",value = "tiger"),
        @WebInitParam(name = "password",value = "123456")})
public class ServletConfig_annotation extends HttpServlet {
  private static final long serialVersionUID = 1L;
  
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String username = getServletConfig().getInitParameter("username");
    String password = getServletConfig().getInitParameter("password");
    response.getWriter().append("username = ").
    append(username).append("   password = ").
    append(password);
    System.out.println("-------ServletConfig_annotation----------");
    System.out.println("username = " + username);
    System.out.println("password = " + password);
  }
  
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request, response);
  }
}
package com.tiger.config.web_xml;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
/**
 * 2、配置文件方式初始化信息
 * @author tiger
 * @time 2017年9月7日
 */
public class ServletConfig_xml extends HttpServlet {
  
  private static final long serialVersionUID = 1L;
  
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String username = getServletConfig().getInitParameter("username");
    String password = getServletConfig().getInitParameter("password");
    response.getWriter().append("username = ").
    append(username).append("   password = ").
    append(password);
    System.out.println("------ServletConfig_xml---------");
    System.out.println("username = " + username);
    System.out.println("password = " + password);
  }
  
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request, response);
  }
}

   

   
  
    
     20170906-servletConfig-配置文件方式实现
    
  
    
    
     
      index.html
     
    
     
      index.htm
     
    
     
      index.jsp
     
    
     
      default.html
     
    
     
      default.htm
     
    
     
      default.jsp
     
  
    
  
    
    
     
      ServletConfig
     
    
     
      com.tiger.config.web_xml.ServletConfig_xml
     
    
     
      
      
       username
      
      
      
       tiger
      
    
     
    
     
      
      
       password
      
      
      
       123456
      
    
     
  
    
  
    
    
     
      ServletConfig
     
    
     
      /servletConfig