1. 程式人生 > >【Servlet】利用反射原理實現專案中的Servlet結構優化、減少Servlet數量

【Servlet】利用反射原理實現專案中的Servlet結構優化、減少Servlet數量

在我們日常的JavaWeb專案開發過程中,充當Controller角色的Servlet需要對於客戶端的請求進行處理或者轉發,所以在實際的專案中,我們所遇到的Servlet的邏輯處理內容將會非常之多,於是乎有了本片文章,利用反射簡化Servlet的業務邏輯結構。實現過程如下:

需要實現的業務程式碼:(Servlet需要自己配置web.xml,本文已省略)

Servlet程式碼如下:

package cn.totalo.servlet;

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


public class ServletDemo01 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
   
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String md = request.getParameter("method");
		if("addInfo".equals(md)) {
			System.out.println("增加學生");
		}
		if("delInfo".equals(md)) {
			System.out.println("刪除學生");
		}
		
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

由上可知,如果業務功能越來越多會導致if語句的增加,這是我們不想看到的,下面我們使用反射對於業務邏輯優化。程式碼如下:

package cn.totalo.servlet;

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

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class ServletDemo02 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
   
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String md = request.getParameter("method");
		String path = null;
		Class clazz = this.getClass();//獲取帶當前類的位元組碼物件
		try {
            //獲取請求的位元組碼檔案中對應的方法
			Method mds = clazz.getMethod(md, HttpServletRequest.class,HttpServletResponse.class);
		
		if(null!=mds) {
		path = (String)mds.invoke(this, request,response);
		}
		if(null!=path) {
			request.getRequestDispatcher(path).forward(request, response);
		}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}
	public String addInfo(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.print("新增資訊");
		return "/add.html";
		
	}
	public String delInfo(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.print("刪除資訊");
		return "del.html";
		
	}
}

此方式還可以進一步優化,通過Servlet的生命週期,抽取一個父類的Servlet,讓後面的Servlet繼承此父類。然後後面的Servlet只需要謝業務邏輯即可。