“定位查询”locate()方法，增加一个线程，在该线程中处理查询地点的功能，请参考代码清单16-10，完整代码请参考chapter16_7工程中src/com/work/map/MyMapActivity.java文件locate()方法代码部分。
【代码清单16-1】
/**
* 定位查询
*/
private void locate() {
LayoutInflater factory= LayoutInflater.from(MyMapActivity.this);
View locationView =factory.inflate(R.layout.find_dialog, null);
final EditTextfindText = (EditText) locationView
.findViewById(R.id.dailog_find);
newAlertDialog.Builder(this).setTitle(R.string.dialog_find).setView(
locationView).setPositiveButton(R.string.button_ok,
newDialogInterface.OnClickListener() {
public void onClick(DialogInterfacedialog, int whichButton) {
findString= findText.getText().toString();
progDialog =ProgressDialog.show(MyMapActivity.this,
"处理中...", "定位" +findString, true, false);
new Thread() {
@Override
publicvoid run() {
try{
Geocoder geocoder = new Geocoder(
MyMapActivity.this);
addresses =geocoder.getFromLocationName(
findString, 1);
if (addresses.size() > 0) {
List<OverlayItem>overlayitems = new ArrayList<OverlayItem>();
doublelat = addresses.get(0)
.getLatitude();
doublelng = addresses.get(0)
.getLongitude();
//设定中心点
centerPoit= new GeoPoint(
(int)(lat * 1E6),
(int)(lng * 1E6)); // 地理坐标
mc.setCenter(centerPoit);
Log.i(TAG," lat " + lat + " lng"
+lng);
intintMaxAddressLineIndex = addresses
.get(0)
.getMaxAddressLineIndex();
Stringaddress = "地址：";
for(int j = 0; j <= intMaxAddressLineIndex; j++) {
if (addresses.get(0) == null)
continue;
address += addresses.get(0)
.getAddressLine(j)
+ ",";
}
if(address.endsWith(",")) {
address = address.substring(0,
address.length() - 1);
}
Stringtitle = "";
if(addresses.get(0).getFeatureName() == null) {
title = "";
}else {
title = addresses.get(0)
.getFeatureName();
}
overlayitems.add(newOverlayItem(
centerPoit,title, address));
Drawablemarker = getResources()
.getDrawable(
R.drawable.markermap2);
locs= new LocationItemsOverlay(marker,
overlayitems);
handler.sendEmptyMessage(0);
} else {
handler.sendEmptyMessage(1);
}
}catch (Exception e) {
e.printStackTrace();
handler.sendEmptyMessage(1);
}
}
}.start();
}
}).setNegativeButton(R.string.button_cancel,
newDialogInterface.OnClickListener() {
public void onClick(DialogInterfacedialog, int which) {
}
}).show();
}
通过下面的代码是实现显示进度条：
progDialog =ProgressDialog.show(MyMapActivity.this, "处理中...", "定位" + findString, true, false);
启动一个子线程，在该线程中实现地点查询，但是不能有更新UI的处理，如果查询成功调用handler.sendEmptyMessage(0)，如果失败调用handler.sendEmptyMessage(1)。
new Thread() {
@Override
public void run() {
… …
}
}.start();
在Hander的handleMessage方法中处理更新UI操作，其中成功(case 0)时候清除屏幕上原来的图层，重新添加图层，最后progDialog.dismiss()方法关闭进度条对话框。如果是查询失败(case 1)弹出Toast说明一下，也要通过progDialog.dismiss()方法关闭进度条对话框，否则进度条对话框不会关闭。
private Handler handler = new Handler() {
@Override
public voidhandleMessage(Message msg) {
switch (msg.what) {
case 0:
mapView.getOverlays().clear();
mapView.getOverlays().add(locs);
progDialog.dismiss();
break;
case 1:
Toast.makeText(MyMapActivity.this,"暂时无法" + findString + "信息。",
Toast.LENGTH_SHORT).show();
progDialog.dismiss();
}
}
};
出自《Android开发案例驱动教程》第十六章
