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我在Android開發網站上閱讀了關於使用反射的內容。但我真的不知道如何使用它。我需要這個Java文件在1.5（SDK3）設備上運行，但只是忽略新的代碼，它在2.0（SDK5）或更高版本的手機上運行良好。我有這個活動（在下面發佈），它是一個簡單的web視圖。但是，我希望啓用地理定位（即使它僅適用於2.0及更高版本的手機），因爲這些API在SDK 5之前未引入，並且我希望webview至少能夠加載在1.5手機而不是隻是崩潰。我如何獲取我的代碼並使用反射進行設置？在Android中使用反射以實現向後兼容性
package com.my.app;
import com.facebook.android.R;
//NEEDS TO BE IGNORED**********************************************************
import android.webkit.GeolocationPermissions;
import android.webkit.GeolocationPermissions.Callback;
//END**************************************************************************
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.webkit.CookieSyncManager;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;
//GeolocationPermissionsCallback NEEDS TO BE IGNORED**********************************************************
public class Places extends Activity implements GeolocationPermissions.Callback {
private ProgressDialog progressBar;
public WebView webview;
private static final String TAG = "Main";
String geoWebsiteURL = "http://google.com";
@Override
public void onStart()
{
super.onStart();
CookieSyncManager.getInstance().sync();
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
CookieSyncManager.createInstance(this);
CookieSyncManager.getInstance().startSync();
webview = (WebView) findViewById(R.id.webview);
webview.setWebViewClient(new testClient());
webview.getSettings().setJavaScriptEnabled(true);
webview.getSettings().setPluginsEnabled(true);
webview.loadUrl("http://google.com");
progressBar = ProgressDialog.show(Places.this, "", "Loading Page...");
//START GROUP OF CODE THAT NEEDS TO BE IGNORED************************************************************
webview.getSettings().setGeolocationEnabled(true);
GeoClient geo = new GeoClient();
webview.setWebChromeClient(geo);
}
public void invoke(String origin, boolean allow, boolean remember) {
}
final class GeoClient extends WebChromeClient {
@Override
public void onGeolocationPermissionsShowPrompt(String origin,
Callback callback) {
super.onGeolocationPermissionsShowPrompt(origin, callback);
callback.invoke(origin, true, false);
}
//END OF CODE THAT NEEDS TO BE IGNORED************************************************
}
private class testClient extends WebViewClient {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
Log.i(TAG, "Processing webview url click...");
view.loadUrl(url);
return true;
}
public void onPageFinished(WebView view, String url) {
Log.i(TAG, "Finished loading URL: " +url);
if (progressBar.isShowing()) {
progressBar.dismiss();
}
if (url.startsWith("mailto:") || url.startsWith("geo:") ||
url.startsWith("tel:")) {
Intent intent = new Intent
(Intent.ACTION_VIEW, Uri.parse(url));
startActivity(intent);
}
}
}
//What's here????
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK) && webview.canGoBack()) {
webview.goBack();
return true;
}
if (keyCode == KeyEvent.KEYCODE_SEARCH) {
Intent z = new Intent(this, Search.class);
startActivity(z);
}
return super.onKeyDown(keyCode, event);
}
public boolean onCreateOptionsMenu (Menu menu) {
super.onCreateOptionsMenu(menu);
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected (MenuItem item) {
switch (item.getItemId()) {
case R.id.home:
Intent m = new Intent(this, Home.class);
startActivity(m);
return true;
case R.id.refresh:
webview.reload();
Toast.makeText(this, "Refreshing...", Toast.LENGTH_SHORT).show();
return true;
}
return false;
}
public void onStop()
{
super.onStop();
CookieSyncManager.getInstance().sync();
}
}