dwr:direct web remoting 是我们通过javascript方便的操作业务方法。我以一个三级联动下拉框的例子给大家演示dwr是如何实现的。我用到的技术有spring 2.0.5 ,dwr2.0.5,hibernate3.2.3.ga,struts1.2.9,主要涉及到dwr如何调用spring管理的业务方法,以及dwr如何处理返回的数据。
dwr的配置:
Code
<servlet>
<servlet-name>dwr-invoker</servlet-name>
<servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
<init-param>
<param-name>debug</param-name>
<param-value>true</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
我要实现的是地区,市县,社区的三级下拉,比如邯郸地区,邯郸县,明珠社区,这样的下拉框,数据库表设计是这样的:
id name pid
1 邯郸 0
2 邯郸县 1
3 明珠社区 2
.....
大家一看都明白了吧。
那么如何实现呢?第一个下了框显示地区,数据可以从action或者servlet中去,也可以用dwr来去,我采取第二种方式。
html代码:
Code
<script type="text/javascript">
function initCity(){
var cityObj = document.getElementById('city');
var areaObj = document.getElementById('area');
var street = document.getElementById('street');
cityObj.options[0] = new Option('请选择','-1');
areaObj.options[0] = new Option('请选择','-1');
street.options[0] = new Option('请选择','-1');
cityService.getBaseCities(cb);
function cb(cities){
for(var i=0;i<cities.length;i++){
cityObj.options[cityObj.options.length] =
new Option(cities[i].name,cities[i].id);
}
}
}
</script>
<BODY onload="initCity();">
城 市:
<select id=city name=city onchange="loadArea(this);"></select>
注意 cityService.getBaseCities(cb); 这行代码 cityService 是dwr暴漏给javascript的对象,用它可以操作业务方法。它是怎么设置的呢?实际上我们CityService是我们业务方法,代码如下
Code
public interface ICityService {
public List getBaseCities();
}
public class CityServiceImpl implements ICityService {
CityDao cityDao;
public List getBaseCities() {
return cityDao.getBaseCities();
}
}
那么javascript如何才能调用getBaseCities()方法,来填充第一个下拉框呢?
好,dwr一个重要的配置文件上演了。
dwr.xml
Code
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" "http://getahead.org/dwr/dwr20.dtd">
<dwr>
<allow>
<create creator="spring" javascript="cityService">
<param name="beanName" value="cityService"/>
</create>
<convert converter="bean" match="com.secondhand.hibernate.entity.TtArea"/>
</allow>
</dwr>
allow节点下面的create 有一个属性 creator="spring" 代表我们要暴漏的服务端代码是从spring中来的。param的beanName代表根据spring配置文件配置的id来取bean,哪个bean呢? value="cityService",就是cityService这个bean. 看一下spring配置文件
Code
<bean id="cityService" parent="txProxyTemplate">
<property name="target">
<bean class="com.secondhand.service.impl.CityServiceImpl">
<property name="cityDao">
<ref bean="TtAreaDAO" />
</property>
</bean>
</property>
</bean>
这个bean就有我们要调用的getBaseCities()方法。
那么javascript如何调用呢?
打开http://localhost:8080/项目名/dwr
点击暴漏的业务类,拷贝js引用,本例代码
Code
<script type='text/javascript' src='/secondhandhib/dwr/interface/cityService.js'></script>
<script type='text/javascript' src='/secondhandhib/dwr/engine.js'></script>
<script type='text/javascript' src='/secondhandhib/dwr/util.js'></script>
结合我上面的javascript的代码就可以用了。
下面我贴出全部html代码:
Code
<LINK href="css/main.css" type=text/css rel=stylesheet>
<script type='text/javascript' src='/secondhandhib/dwr/interface/cityService.js'></script>
<script type='text/javascript' src='/secondhandhib/dwr/engine.js'></script>
<script type='text/javascript' src='/secondhandhib/dwr/util.js'></script>
<META content="MSHTML 6.00.2900.5726" name=GENERATOR>
<script type="text/javascript">
function initCity(){
var cityObj = document.getElementById('city');
var areaObj = document.getElementById('area');
var street = document.getElementById('street');
cityObj.options[0] = new Option('请选择','-1');
areaObj.options[0] = new Option('请选择','-1');
street.options[0] = new Option('请选择','-1');
cityService.getBaseCities(cb);
function cb(cities){
for(var i=0;i<cities.length;i++){
cityObj.options[cityObj.options.length] = new Option(cities[i].name,cities[i].id);
}
}
}
function loadArea(obj){
var city = $("city").value;
var areaObj = document.getElementById('area');
var street = document.getElementById('street');
cityService.getAreaBySuper(city,areaCb);
areaObj.length=0;
street.length=0;
areaObj.options[0] = new Option('请选择','-1');
street.options[0] = new Option('请选择','-1');
function areaCb(areas){
for(var i=0;i<areas.length;i++){
areaObj.options[areaObj.options.length] = new Option(areas[i].name,areas[i].id);
}
}
}
function loadArea1(obj){
var area = $("area").value;
var street = document.getElementById('street');
cityService.getAreaBySuper(area,streetCb);
street.length=0;
street.options[0] = new Option('请选择','-1');
function streetCb(streets){
for(var i=0;i<streets.length;i++){
street.options[street.options.length] = new Option(streets[i].name,streets[i].id);
}
}
}
</script>
</HEAD>
<BODY onload="initCity();">
<select id=city name=city onchange="loadArea(this);"> </select>
<select id=area name=area onchange="loadArea1(this);"></select>
<select id=street name=street> </select>