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首先浏览实现后的结果，输入一个a之后会出现包含a的下拉列表，当我们点击某一个的时候，搜索框中就会出现点击的值。实现所需要的主要是ajax+js。

前端search.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
   	
   
	   
    
		   
      		   
     	   
    
	   
    
	      
     
	         
      
	      
     
	   
    
	
   

后台searchServlet.java

package search;import java.io.IOException;import java.util.ArrayList;import java.util.List;import net.sf.json.JSONArray;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 searchServlet */@WebServlet("/searchServlet")public class searchServlet extends HttpServlet {	private static final long serialVersionUID = 1L;	static  List
   
     datas=new ArrayList
    
     ();    static {//假数据，模拟数据库读取    	datas.add("ajax");    	datas.add("bjax");    	datas.add("ajaxfd");    	datas.add("bfvd");    	datas.add("dafdx");    	datas.add("fdax");    	datas.add("ahg");    	datas.add("ddx");    }    /**     * @see HttpServlet#HttpServlet()     */    public searchServlet() {        super();        // 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		doPost(request, response);	}	/**	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)	 */	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {		// TODO Auto-generated method stub		request.setCharacterEncoding("UTF-8");		response.setCharacterEncoding("UTF-8");		String keyword=request.getParameter("keyword");		//System.out.println(keyword);		List
     
       listdata= getData(keyword);	//	返回json,以流的形式写到前台		response.getWriter().write(JSONArray.fromObject(listdata).toString());	}		//获取假数据中符合条件的值    public List
      
        getData(String keyword)    {    	List
       
         list=new ArrayList
        
         (); for(String data:datas) { if(data.contains(keyword)){ list.add(data); } } return list; }}
        
       
      
     
    
   

xml配置

   
     
        
     
      searchServlet
         
     
      search.searchServlet
       
      
        
     
      searchServlet
         
     
      /search/searchServlet
       
       
    
     DropMeum
      
        
     
      index.html
         
     
      index.htm
         
     
      index.jsp
         
     
      default.html
         
     
      default.htm
         
     
      default.jsp
       
    
   

目录结构