一个通用的ajax程序（实现像百度一样自动提示功能）

1.jsp+javabean实现ajax

（1），<script type="text/javascript">
String.prototype.trim=function(){
return this.replace(/(^\s*)|(\s*$)/g, "");
}
//表名ajax
function ajaxTable(){

    var table_name=document.validateRule01.table_name.value;
    if(table_name==""){
     document.getElementById("result_display").style.visibility='hidden';
    return;
    }
var X = new ActiveXObject("MSXML2.XMLHTTP.3.0");
   //var X = new XMLHttpRequest();
   if(X)
   {
   X.onreadystatechange=function(){
    if(X.readyState==4)
    {
     if(X.status==200)
     {
      var mobanhtml=X.responseText;
      mobanhtml=mobanhtml.trim();
     var tableNames = mobanhtml.split(",");
     var s = document.getElementById('result_display') ;
                s.innerHTML = '';  
                if(tableNames.length>0){
                document.getElementById('result_display').style.visibility='visible';
                for(i=0; i < tableNames.length ; i++) {  
                   var suggest = '<div onmouseover="onmouseOver(this);" ';  
                   suggest += 'onmouseout="onmousetOut(this);" ';  
                   suggest += 'onclick="setSuggestValue(this.innerHTML);" ';  
                   suggest += 'class="onmouset_out">' + tableNames[i] + '</div>';  
                   s.innerHTML += suggest;
                }  
                }
     }
     else
     {
      
       }
    }

   };
   
    X.open("POST","getTableName.jsp?table_name="+table_name,true);
    X.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
    X.send();
   
   }
   else
   {
    alert("??");
   }
}
function onmouseOver(div) {  
         div.className = 'onmouse_over';  
      }  
      function onmousetOut(div) {  
         div.className = 'onmouset_out';  
      }  
      function setSuggestValue(value) {  
         document.validateRule01.table_name.value = value;  
         document.getElementById('result_display').innerHTML = '';
          document.getElementById("result_display").style.visibility='hidden';
      }    其中红色部分是要修改的部分，其他代码可以照搬

然后是促发这个ajax的text框代码：<input type='text' size='30' style="width:200px" id="txt" name='table_name' value='<%=InitBean.getTable_name()%>' onkeyup="ajaxTable();" >

在这个text框所在的table外面添加<div id="result_display" style="position:absolute; visibility:hidden; overflow:auto; top:70px; left:195px; width:200px; height:200px; background-color:#ffffff;">
           </div>

2.下面是getTableName.jsp的代码：

<%@ page contentType="text/html;charset=gb2312" %>
<%@ page language="java"
session="true"
         buffer="32kb"        
         autoFlush="true"        
%>

<%@ page import="
   com.hoperun.bi.quality.GetTableName,
   java.sql.Connection,
   java.sql.Statement,
   java.sql.ResultSet
   "
%>
<%--
response.setHeader("Cache-Control","no-cache"); //Forces caches to obtain a new copy of the page from the origin server
response.setHeader("Cache-Control","no-store"); //Directs caches not to store the page under any circumstance
response.setDateHeader("Expires", 0);           //Causes the proxy cache to see the page as "stale"
response.setHeader("Pragma","no-cache");        //HTTP 1.0 backward compatibility
--%>

<%
String table_name=request.getParameter("table_name");
GetTableName getTableName=new GetTableName();
String str=getTableName.getTableNames(table_name);

out.write(str);
%>

3.下面是GetTableName.java的bean代码：

/*
* com.hoperun.bi.beans.SqlEditorBean0101.java
*
* Created on 2006-5-22 14:16:59
*
* Version 1.0.0
*
* Copyright 2003-2005 by NanJing HopeRun(IT-FOREST) Information System Co., Ltd, CHINA and
*                        IT Forest Corporation
* All rights reserved.
*
* This software is the confidential and proprietary information of
* HopeRun(IT-FOREST) Information System Co., Ltd, CHINA and IT Forest Corporation.
* You shall not disclose such Confidential Information and shall use it only in
* accordance with the terms of the license agreement you entered into with
* HopeRun(IT-FOREST) Information System Co., Ltd, CHINA and IT Forest Corporation.
*/
package com.hoperun.bi.quality;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import com.webpump.sdk.datasource.DataSourceManager;

/**
* @author wei_yuhong
*
* 表格中文描述和字段描述定义画面Bean,选择数据源分别编辑
*/
public class GetTableName {

private Connection conn;
public GetTableName() throws SQLException{
   conn=DataSourceManager.findDataSource("").getConnection();
}
/**
* 执行添加、查询等动作的过程。
* @param objIn 保存有执行此操作所需的所有数据
* @param objOut 保存查询等操作的结果数据
*/
public String getTableNames(String table_name) throws SQLException {
   String str="";
   try{
    String sqlmodel = "select t.table_en_name from hpbi_tablestorage t where t.table_en_name like '"+table_name+"%' order by t.table_en_name";
    Statement pStmt = this.conn.createStatement();
    ResultSet rsmodel = pStmt.executeQuery(sqlmodel);
   
    while(rsmodel.next()){
     str+=rsmodel.getString("table_en_name")+",";
    }
   }catch(Exception e){
    System.out.print(e);
   }finally{
     try {
      if (conn!=null) {
        conn.close();
        conn = null;
      }
           } catch (Exception e) {
           }
   }
   return str;
}
}

这样就可以在输入框中输入表名的首字母，就可以自动提示所有以这个字母开头的表名

二.用struts2.0的实现：只要把X.open("POST","getTableName.jsp?table_name="+table_name,true);
中的。getTableName.jsp改成getTableName.action就ok了，还有就是下面的getTableName.action的代码：

package com.hoperun.action;

import java.io.PrintStream;
import java.util.HashMap;

import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;

import com.hoperun.service.GetCloseIdService;
import com.hoperun.service.SalesSearchService;
import com.opensymphony.xwork2.ActionSupport;

public class getCloseIdAction extends ActionSupport
{

    /** *//**
     *
     */
    private static final long serialVersionUID = 1L;
   
    /**//*
     */
    private GetCloseIdService getCloseIdService=new GetCloseIdService();
   
    private String clothesid="";
   
   

    public String getClothesid() {
   return clothesid;
}

public void setClothesid(String clothesid) {
   this.clothesid = clothesid;
}

@Override
    public void validate()
    {
    
    }
   
    @Override
    public String execute() throws Exception
    {
        HashMap<String,String> hmInput = new HashMap<String,String>();
       
        String reStr=getCloseIdService.getclothesIds(clothesid);
        HttpServletResponse response = ServletActionContext.getResponse();
        response.setContentType("text/html;charset=GBK");//解决中文乱码
        PrintStream out = new PrintStream(response.getOutputStream());//获取out输出对象
        out.println(reStr);
        return null;//这里返回的是null
    }

}

注意这里action返回的是null，千万记住