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ajax怎么显示数据库的数据在jsp页面上？（ajax那里不能发表）

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ajax怎么显示数据库的数据在jsp页面上？（ajax那里不能发表）[已结贴,结贴人:sessionfactory]

发表于：2007-08-10 15:57:58 楼主

请各位高手帮帮忙，找了好长时间了，大部分是关于.net的，而关于java的，
又没讲清楚，如果谁知道怎么做，麻烦把代码贴出来，小弟在这里先谢啦！

发表于：2007-08-10 16:05:301楼得分:10

//下面是一个用ajax实现下拉列表的例子,楼主可以试试

import java.io.printwriter;

import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;

import org.apache.commons.logging.log;
import org.apache.commons.logging.logfactory;

import org.apache.struts.action.action;
import org.apache.struts.action.actionform;
import org.apache.struts.action.actionforward;
import org.apache.struts.action.actionmapping;

public abstract class baseajaxaction extends action {

public final actionforward ＥＸＥＣute（actionmapping mapping, actionform form,
httpservletrequest request,
httpservletresponse response)
throws exception {

string xml = null;
try {
xml = getxmlcontent（mapping, form, request, response);
}
catch （exception ex) {
response.senderror（httpservletresponse.sc_internal_server_error,
"can not create response ");
return null;
}

response.setcontenttype（ "text/xml; charset=utf-8 ");
response.setheader（ "cache-control ", "no-cache ");
printwriter pw = response.getwriter（);
pw.write（xml);
pw.close（);

return null;
}

public abstract string getxmlcontent（actionmapping mapping,
actionform form,
httpservletrequest request,
httpservletresponse response)
throws exception;
}

import java.util.arraylist;

import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;

import org.apache.struts.action.actionform;
import org.apache.struts.action.actionmapping;

public class dictionaryaction extends baseajaxaction {

public string getxmlcontent（actionmapping mapping, actionform form,
httpservletrequest request, httpservletresponse response)
throws exception {

string responseid = request.getparameter（ "responseid ");
string tablename = request.getparameter（ "tablename ");
string columnname = request.getparameter（ "columnname ");

string selectcolumnvalue = request.getparameter（ "selectcolumnvalue ");

arraylist result = new arraylist（);
//here get data from db
return new ajaxxmlbuilder（responseid).additems（result, "label ", "value ").tostring（);
}

public static void main（string args[]) throws exception {
dictionaryaction ac = new dictionaryaction（);
ac.ＥＸＥＣute（null, null, null, null);
}
}

import java.util.collection;
import java.util.list;
import java.util.arraylist;
import java.util.iterator;
import java.lang.reflect.invocationtargetexception;

import org.apache.commons.beanutils.beanutils;
import org.apache.struts.util.labelvaluebean;

public class ajaxxmlbuilder {

private string encoding = "utf-8 ";
private list items = new arraylist（);
private string responseid;

public ajaxxmlbuilder（) {
}

public ajaxxmlbuilder（string responseid) {
this.responseid = responseid;
}

public string getresponseid（) {
return responseid;
}

public void setresponseid（string responseid) {
this.responseid = responseid;
}

public string getencoding（) {
return encoding;
}

public void setencoding（string encoding) {
this.encoding = encoding;
}

/**
* add item to xml.
*
* @param name
* the name of the item
* @param value
* the value of the item
* @return
*/
public ajaxxmlbuilder additem（string name, string value) {
items.add（new labelvaluebean（name, value));
return this;
}

/**
* add item wrapped with inside a cdata element.
*
* @param name
* the name of the item
* @param value
* the value of the item
* @return
*/
public ajaxxmlbuilder additemascdata（string name, string value) {
items.add（new labelvaluebean（name, value));
return this;
}

/**
* add items from a collection.
*
* @param collection
* @param nameproperty
* @param valueproperty
* @return
* @throws illegalaccessexception
* @throws invocationtargetexception
* @throws nosuchmethodexception
*/
public ajaxxmlbuilder additems（collection collection, string nameproperty,
string valueproperty) throws illegalaccessexception,
invocationtargetexception, nosuchmethodexception {
return additems2（collection, nameproperty, valueproperty);
}

/**
* add items from a collection.
*
* @param collection
* @param nameproperty
* @param valueproperty
* @return
* @throws illegalaccessexception
* @throws invocationtargetexception
* @throws nosuchmethodexception
*/
public ajaxxmlbuilder additems2（collection collection, string nameproperty,
string valueproperty)
throws illegalaccessexception, invocationtargetexception,
nosuchmethodexception {
for （iterator iter = collection.iterator（); iter.hasnext（);) {
object element = （object) iter.next（);
string name = beanutils.getproperty（element, nameproperty);
string value = beanutils.getproperty（element, valueproperty);
items.add（new labelvaluebean（name, value));
}
return this;
}

/**
* add items from a collection as cdata element.
*
* @param collection
* @param nameproperty
* @param valueproperty
* @return
* @throws illegalaccessexception
* @throws invocationtargetexception
* @throws nosuchmethodexception
*/
public ajaxxmlbuilder additemsascdata（collection collection,
string nameproperty, string valueproperty)
throws illegalaccessexception, invocationtargetexception,
nosuchmethodexception {
return additems2（collection, nameproperty, valueproperty);
}

/**
* @see java.lang.object#tostring（)
*/
public string tostring（) {
stringbuffer xml = new stringbuffer（).append（ " <?xml version=\ "1.0\ " ");
if （encoding != null) {
xml.append（ " encoding=\ " ");
xml.append（encoding);
xml.append（ "\ " ");
}
xml.append（ " ?> ");

xml.append（ " <ajax-response> ");
xml.append（ " <response type=\ "object\ " id=\ " "+responseid+ "\ "> ");
for （iterator iter = items.iterator（); iter.hasnext（);) {
labelvaluebean item = （labelvaluebean) iter.next（);
xml.append（ " <item> ");
xml.append（ " <name> ");
// if （item.isascdata（)) {
// xml.append（ " <![cdata[ ");
// }
xml.append（item.getlabel（));
// if （item.isascdata（)) {
// xml.append（ "]]> ");
// }
xml.append（ " </name> ");
xml.append（ " <value> ");
// if （item.isascdata（)) {
// xml.append（ " <![cdata[ ");
// }
xml.append（item.getvalue（));
// if （item.isascdata（)) {
// xml.append（ "]]> ");
// }
xml.append（ " </value> ");
xml.append（ " </item> ");
}
xml.append（ " </response> ");
xml.append（ " </ajax-response> ");

return xml.tostring（);

}
}

发表于：2007-08-10 16:06:532楼得分:0

客户端用的是rico

发表于：2007-08-10 16:26:473楼得分:10

来晚了，顶
客户端通过xmlhttp.responsexml进行解析

发表于：2007-08-10 16:29:514楼得分:10

简单的方法：
xmlhttprequest即可，不需要什么复杂的框架

发表于：2007-08-10 16:54:075楼得分:20

从数据库得到的数据会写在xml中，然后返回给前台。通过xmlhttp.responsexml将数据进行解析。得到解析的结果放在页面中显示。
多看看ajax，我想楼主还没完全理解ajax

发表于：2007-08-10 18:23:496楼得分:0

首先谢谢大家的帮忙，按照大家的意思，我试了下
jsp:

<script type= "text/javascript ">
var xmlhttpreq; //创建xmlhttprequest对象

function createxmlhttprequest（) {
if （window.activexobject) {
xmlhttpreq = new activexobject（ "microsoft.xmlhttp ");
}
else if （window.xmlhttprequest) {
xmlhttpreq = new xmlhttprequest（);
}
}

function sendrequest（) {

createxmlhttprequest（);
var url = "track.do?method=init ";
xmlhttpreq.open（ "get ", url, true);
xmlhttpreq.onreadystatechange = processresponse;
xmlhttpreq.send（null);
}

function processresponse（) {

if （xmlhttpreq.readystate == 4) { // 判断对象状态
if （xmlhttpreq.status == 200) { // 信息已经成功返回，开始处理信息
alert（ "123 "+xmlhttpreq.responsexml);
settimeout（ "sendrequest（) ",4000);
}
}
}

</script>

</head>

<body bgcolor= "white " background= "image/right.gif ">
<input type= "button " value= "开始接收 " onclick= "sendrequest（) ">

</body>

------------------------------------------------------------------------------------
action:
trackshow show=new trackshow（vo.getworktype（),vo.getid（),vo.getusername（));
result_list.add（show);
response.setcontenttype（ "text/xml ");
printwriter out=response.getwriter（);
out.println（parsetoxml（result_list));
}

public string parsetoxml（list list){
stringbuffer sb=new stringbuffer（);
sb.append（ " <?xml version=\ "1.0\ " encoding=\ "utf-8\ "?> ");
sb.append（ " <track> ");
for（int i=0;i <list.size（);i++){
trackshow show=（trackshow)list.get（i);

sb.append（ " <track> ");
sb.append（ " <cardid> "+show.getcardid（)+ " </cardid> ");
sb.append（ " <antenna> "+show.getantenna（)+ " </antenna> ");
sb.append（ " </track> ");
}
sb.append（ " </track> ");
return sb.tostring（);
}

但是页面上就只是弹出了一个对话框，上面显示123，却没有显示我想要的数据
请问这是为什么？（show.getcardid（)和getantenna能输出数据）

发表于：2007-08-10 18:28:577楼得分:10

用ajax调用了controller 以后，会根据条件把你所要的数据写成xml ,通过xmlhttp.responsexml 就能得到你所要的了

发表于：2007-08-10 18:40:568楼得分:0

用ajaxanywhere啊

发表于：2007-08-10 18:44:379楼得分:0

楼上的能说说，我什么地方的错了吗？

发表于：2007-08-10 18:55:3710楼得分:40

xmlhttp.responsexml是一个document对象，要调用它的一些方法才能获得数据，如
var xmldoc = xmlhttp.responsexml;
//得到父节点
var org = xmldoc.getelementsbytagname（ "parentnode ")[0];
//父节点组织机构代码
var orgcode = org.childnodes[0].firstchild.nodevalue;
//父节点的名字
var name = org.childnodes[1].firstchild.nodevalue;

发表于：2007-08-10 19:29:1911楼得分:0

帮顶

发表于：2007-08-10 23:29:5412楼得分:0

收藏了

发表于：2007-08-11 16:13:5313楼得分:0

按照大家的意思我改了改，还是不行，一点开始按钮，过了会页面就死了，
并且也也没有弹出对话框 “4”,以下是我的代码，麻烦高手给看看
jsp:

<script type= "text/javascript ">
var xmlhttpreq; //创建xmlhttprequest对象

function createxmlhttprequest（) {
if （window.activexobject) {
xmlhttpreq = new activexobject（ "microsoft.xmlhttp ");
}
else if （window.xmlhttprequest) {
xmlhttpreq = new xmlhttprequest（);
}
}

//发送请求函数

function sendrequest（) {
createxmlhttprequest（);
var url = "track.do?method=init ";
xmlhttpreq.open（ "get ", url, true);
xmlhttpreq.onreadystatechange = processresponse;//指定响应函数
xmlhttpreq.send（null); // 发送请求
}

// 处理返回信息函数

function processresponse（) {
if （xmlhttpreq.readystate == 4) { // 判断对象状态
alert（ "4 ");
if （xmlhttpreq.status == 200) { // 信息已经成功返回，开始处理信息
alert（ "200 ");
showpage（);
settimeout（ "sendrequest（) ",4000);
}
}
}
function showpage（){
var xmldoc = xmlhttpreq.responsexml;
var tracks = xmldoc.getelementsbytagname（ "track ");
var result= " <table border=1> <tr> <td> 卡号 </td> <td> 天线 </td> </tr> ";
for（var i=0;i <tracks.length;i++){
result += " <tr> ";
var track=tracks[i];
result += " <td> "+track.getelementsbytagname（ "cardid ")[0].firstchild.nodevalue+ " </td> "
result += " <td> "+track.getelementsbytagname（ "antenna ")[0].firstchild.nodevalue+ " </td> "
result += " </tr> ";
}
result += " </table> ";
document.getelementbyid（ "data ").innerhtml=result;
}

</script>

</head>

<body bgcolor= "white " background= "image/right.gif ">
<input type= "button " value= "开始接收 " onclick= "sendrequest（) ">
<div id= "data "> </div>
</body>

=================================================================================
action:
result_list.add（show);

}
}

// request.setattribute（ "trackshow ", result_list);
// return mapping.findforward（ "trackshow ");
}
}
response.setcontenttype（ "text/xml ");
printwriter out=response.getwriter（);
out.println（parsetoxml（result_list));
}catch（exception e){
e.printstacktrace（);
}
return null;
}

public string parsetoxml（list list){
stringbuffer sb=new stringbuffer（);
sb.append（ " <?xml version=\ "1.0\ " encoding=\ "utf-8\ "?> ");
sb.append（ " <tracks> ");
for（int i=0;i <list.size（);i++){
trackshow show=（trackshow)list.get（i);
sb.append（ " <track> ");
sb.append（ " <cardid> "+show.getcardid（)+ " </cardid> ");
sb.append（ " <antenna> "+show.getantenna（)+ " </antenna> ");
sb.append（ " </track> ");
}
sb.append（ " </tracks> ");
return sb.tostring（);
}
}

发表于：2007-08-12 13:51:2014楼得分:0

在后台打个断点调试一下，感觉var url = "track.do?method=init "; 这个地方有点问题

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