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/*
观察者 */
public
interface
Observer {
void
update(Object... objs);
}
/*
被观察者 使用一个抽象类方便扩展 */
public
abstract
class
Observable<T> {
public
final
transient
ArrayList<HashMap<String, T>> obserList = new
ArrayList<HashMap<String,T>>();
/*
添加观察者 包括名称及本生 */
public
void
attachObserver(String obName, T ob) {
if(obName
== null
|| ob == null)
throw
new
NullPointerException();
synchronized(obserList)
{
HashMap<String,
T> map = new
HashMap<String, T>();
map.put(obName,
ob);
int
index = obserList.indexOf(map);
if(index
== -1)
{
obserList.add(map);
}
}
}
/*
删除观察者 */
public
void
detachObserver(String obName) {
if(obName
== null)
throw
new
NullPointerException();
synchronized(obserList){
Iterator<HashMap<String,
T>> iteratorMap = obserList.iterator();
while(iteratorMap.hasNext())
{
Iterator<Entry<String,
T>> iterator = iteratorMap.next().entrySet().iterator();
while(iterator.hasNext()){
if(iterator.next().getKey().equals(obName)){
iteratorMap.remove();
break;
}
}
}
}
}
/**
detach all observers */
public
void
detachObservers() {
synchronized(obserList)
{
obserList.removeAll(obserList);
}
}
/**
Ruturn the size of observers */
public
int
countObservers() {
synchronized(obserList)
{
return
obserList.size();
}
}
public
abstract
void
notifyObservers();
public
abstract
void
notifyObserver(String obserName, boolean
flag, Object... objs);
}
/*
被观察者实例 */
public
class
CommonObservable<T extends
Observer> extends
Observable<T> {
/*
实现抽象方法通知观察者， 第一个参数为观察者名字，第二个参数flag标志表示如果没有找到观察者是否通知其他所有观察者（true是false否），第三个为需要传递的参数 */
@Override
public
void
notifyObserver(String obserName, boolean
flag, Object... objs) {
//
TODO Auto-generated method stub
if(obserName
!= null
&& !(obserName instanceof
String)) return;
for(HashMap<String,
T> map : obserList){
if(map.containsKey(obserName))
{
((T)map.get(obserName)).update(objs);
break;
}
}
if(flag)
{
for(HashMap<String,
T> map : obserList){
Iterator<Entry<String,
T>> iterator = map.entrySet().iterator();
((T)iterator.next().getValue()).update(objs);
}
}
}
@Override
public
void
notifyObservers() {
//
TODO Auto-generated method stub
notifyObserver(null,
false,
null,
null);
}
}
/*
使用实例，如：在点击一个Activity中listview数据后进入另一个Activity，此时对另一个Activity作出改动后需要在不重新从服务器中下载数据后能够看到修改状态 */
public
class
FireTrainCoursewareActivity extends
Activity implements
Observer{
@Override
protected
void
onCreate(Bundle savedInstanceState) {
//
TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.firetrain_courseware);
/*在oncreate中注册观察者
*/
((BMapApiDemoApp)getApplication()).getCommonObservable().attachObserver("FireTrainCourseware",
this);
(ListViewImpl)findViewById(R.id.firetarin_courseware_listview);
listItem
= new
ArrayList<HashMap<String,Object>>();
simpleAdapter
= new
SimpleAdapter(FireTrainCoursewareActivity.this,
listItem,
R.layout.list_items_peixun, new
String[] {
"ItemImage",
"ItemTitle",
"ItemReadTimes","ItemDownloadTimes"
}, new
int[]
{
R.id.ItemImage_peixun,
R.id.ItemTitle_peixun, R.id.ItemRead_peixun,R.id.ItemLoad_peixun });
listView.setAdapter(simpleAdapter);
listView.setOnrefreshListener(this);
listView.setOnItemClickListener(this);
}
@Override
protected
void
onDestroy() {
//
TODO Auto-generated method stub
super.onDestroy();
/*最好在ondestory中注销之
*/
((BMapApiDemoApp)getApplication()).getCommonObservable().detachObserver("FireTrainCourseware");
}
/*
在update中更新数据 */
@Override
public
void
update(Object... objs) {
//
TODO Auto-generated method stub
mTempList.get(Integer.parseInt(objs[0].toString())).setDownloadTimes(Integer.parseInt(objs[1].toString()));
for(int
i = 0;
i < mAllList.size(); i++) {
if(mAllList.get(i).getId()
== mAllList.get(Integer.parseInt(objs[0].toString())).getId())
{
mAllList.get(i).setDownloadTimes(Integer.parseInt(objs[1].toString()));
mAllList.get(i).setReadTimes(mTempList.get(Integer.parseInt(objs[0].toString())).getReadTimes());
}
}
}
}
/*
使用观察者实例 在想要修改数据的时候调用notify方法即可 */
((BMapApiDemoApp)getApplication()).getCommonObservable()
.notifyObserver("FireTrainCourseware",
false,
getIntent().getIntExtra("position",
0),
downloadTimes_.getText().toString());
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