“定位查询”loca......
推荐链接 20-30......
“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16-10】
/**
* 定位查询
*/
private void locate() {
LayoutInflater factory = LayoutInflater.from(MyMapActivity.this);
View locationView = factory.inflate(R.layout.find_dialog, null);
final EditText findText = (EditText) locationView
.findViewById(R.id.dailog_find);
new AlertDialog.Builder(this).setTitle(R.string.dialog_find).setView(
locationView).setPositiveButton(R.string.button_ok,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
findString = findText.getText().toString();
progDialog = ProgressDialog.show(MyMapActivity.this,
"处理中...", "定位" + findString, true, false);
new Thread() {
@Override
public void run() {
try {
Geocoder geocoder = new Geocoder(
MyMapActivity.this);
addresses = geocoder.getFromLocationName(
findString, 1);
if (addresses.size() > 0) {
List<OverlayItem> overlayitems = new ArrayList<OverlayItem>();
double lat = addresses.get(0)
.getLatitude();
double lng = 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);
int intMaxAddressLineIndex = addresses
.get(0)
.getMaxAddressLineIndex();
String address = "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);
}
String title = "";
if (addresses.get(0).getFeatureName() == null) {
title = "";
} else {
title = addresses.get(0)
.getFeatureName();
}
overlayitems.add(new OverlayItem(
centerPoit, title, address));
Drawable marker = 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,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, 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 void handleMessage(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
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