杨老师课堂之Servlet的抽取为BaseServlet设计

package cn.javabs.smalltools.servlet;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * 
 * @author Mryang
 *
 */
public class BaseServlet extends HttpServlet {

  @Override
  public void service(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {

    //获取路径  本项目获取到的是smallTools/servlet/UserServlet/add
    String uri = request.getRequestURI();
    
    // 具体内容可以进行打印输出
    System.out.println("uri: "+uri);
    
    // 目的是为了获取add三个字母，可以进行截取uri
    //uri.lastIndexOf('/') 是获取‘/’在uri最后一次出写的位置
    // 另外substring()该方法的规律是 包含开头索引位置、但不包括结束索引位置，有不想要‘/’，因此要在截取后的索引值上+1
    String methodName = uri.substring(uri.lastIndexOf('/')+1);// methodName 就是截取后的  add
    
    try {
      // this指的是谁调用、谁就是this 那么this.getClass()是采用反射机制获取调用的类名称
      // 举例：如果是UserServlet继承了BaseServlet 那么UserServlet就是调用的类，也就是UserServlet的字节码 = this.getClass() 
      Method method = this.getClass().getMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);

        // invoke方法：调用包装在当前Method对象中的方法
        method.invoke(this,request,response);
      
    } catch (Exception e) {
      throw new RuntimeException(e);
    } 
  }
}

package cn.javabs.smalltools.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * 
 * @author Mryang
 * 以下方法书写技巧是： 在原有的doGet或doPost方法上，
 * 只需要将doGet单词换为addBook、findBook等等即可
 */
public class BookServlet extends BaseServlet {

  /**
   * 添加图书模块
   * @param request
   * @param response
   * @throws ServletException
   * @throws IOException
   */
  public void addBook(HttpServletRequest  request, 
            HttpServletResponse response)
            throws ServletException, IOException {
    
    String name = request.getParameter("name");
    // 通过输出的结果来检验get方式和post方式 是都可以接受的到！
    System.out.println("这个是BookServlet中的addBook方法"+name);
  }

  /**
   * 查询图书模块
   * @param request
   * @param response
   * @throws ServletException
   * @throws IOException
   */
  public void findBook(HttpServletRequest  request, 
            HttpServletResponse response)
            throws ServletException, IOException {
    System.out.println("这个是BookServlet中的findBook方法" );
  }
  
  /**
   * 删除图书模块
   * @param request
   * @param response
   * @throws ServletException
   * @throws IOException
   */
  public void delBook(HttpServletRequest  request, 
            HttpServletResponse response)
            throws ServletException, IOException {
    System.out.println("这个是BookServlet中的delBook方法" );
  }
  
  /**
   * 编辑图书模块
   * @param request
   * @param response
   * @throws ServletException
   * @throws IOException
   */
  public void editBook(HttpServletRequest  request, 
            HttpServletResponse response)
            throws ServletException, IOException {
    System.out.println("这个是BookServlet中的editBook方法" );
  }
  
  /**
   * 图书数据回显模块
   * @param request
   * @param response
   * @throws ServletException
   * @throws IOException
   */
  public void editBookView(HttpServletRequest  request, 
            HttpServletResponse response)
            throws ServletException, IOException {
    System.out.println("这个是BookServlet中的editBookView方法" );
  }

}

<?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">
  
  <display-name>Servlet的抽取为BaseServlet设计</display-name>
  
  <servlet>
    <servlet-name>BaseServlet</servlet-name>
    <servlet-class>cn.javabs.smalltools.servlet.BaseServlet</servlet-class>
  </servlet>


  <servlet-mapping>
    <servlet-name>BaseServlet</servlet-name>
    <url-pattern>/servlet/BaseServlet</url-pattern>
  </servlet-mapping>
  
  <servlet>
    <servlet-name>BookServlet</servlet-name>
    <servlet-class>cn.javabs.smalltools.servlet.BookServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
    <servlet-name>BookServlet</servlet-name>
    <url-pattern>/servlet/BookServlet/*</url-pattern>
  </servlet-mapping>  
  
  
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

/* 将basePath存储到pageContext作用域中 */

pageContext.setAttribute("basePath", basePath);

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>

    <title>测试</title>

  </head>
  
  <body>
      <h4>测试使用post方式提交</h4>
      <form action="${basePath}servlet/BookServlet/addBook" method="post" >
        <input type="text"  name="name" >
        <input type="submit" >
      </form>
      
  <hr color="deepskyblue"><!-- 这是一个水平线 -->
  
      <h4>测试使用get方式提交</h4>
      <form action="${basePath}servlet/BookServlet/addBook" method="get" >
        <input type="text"  name="name" >
        <input type="submit" >
      </form>
      
  <hr color="deepskyblue"><!-- 这是一个水平线 -->
  
  <a href="${basePath}servlet/BookServlet/findBook">点击是去寻找findBook方法</a>

  <br/><br/>  
      
      注意：“$ {basePath} =${basePath}”代表的是 项目的绝对路径！！！前面的$后故意加一个空格
  </body>
</html>