同一个应用程序中的Activity切换通常一个应用程序中需要多个UI 屏幕,也就需要多个Activity 类,并且在这些 Activity 之间进行切换,这种切换就是通过 Intent 机制来实现的。
例如
Intent intent = new Intent(getActivity(), DetailActivity.class);//
intent.putExtra(Intent.EXTRA_TEXT, forecast);//添加附带信息
startActivity(intent);//开启Activity
在DetailActivity.class里面接受intent传来的附加信息
例如
Intent intent = getActivity().getIntent();
if(intent != null && intent.hasExtra(Intent.EXTRA_TEXT)){
String forecast = intent.getStringExtra(Intent.EXTRA_TEXT);
((TextView)rootView.findViewById(R.id.forecastDetail)).setText(forecast);//something to do
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开启其它应用的intent,系统如何知道其它应用可以处理此intent
比如地图应用
在它的manifest.xml里面 activity 有个 intent筛选器
<intent-filter >
<action:name ="android.intent.action.VIEW"/>
<data android:scheme="geo"/>
</intent-filter>
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读取默认配置信息
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
position = prefs.getString(getString(R.string.pref_location_key),getString(R.string.pref_location_default));
weatherTask.execute(position);
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对于PreferenceActivity中addPreferencesFromResource(R.xml.pref_general)函数的弃用
public static class SettingsFragment extends PreferenceFragment {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Load the preferences from an XML resource
addPreferencesFromResource(R.xml.preferences);
}
}
然后将其添加到Activity
public class SettingsActivity extends PreferenceActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Display the fragment as the main content.
getFragmentManager().beginTransaction().replace(android.R.id.content, new SettingsFragment()).commit();
}
}
在安卓布局文件中添加控件<Fragment />,系统定义的此Fragment的id为android.R.id.content,根视图
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Basic Activity 创建项目时候带fragment.xml 有个选项勾选的,use a fragment 。luancher activity 作为点击应用进去的主界面。 ------------------------------------------------------------------------------------------------------------------- 分享菜单 fragment可以通过实现 onCreateOptionMenu() 提供菜单项给activity的选项菜单。为了使这个方法接收调用,无论如何, 你必须在 onCreate() 期间调用 setHasOptionsMenu() 来指出fragment愿意添加item到选项菜单(否则, fragment将接收不到对 onCreateOptionsMenu()的调用).
随后从fragment添加到Option菜单的任何项,都会被追加到现有菜单项的后面.当一个菜单项被选择, fragment也会接收到对onOptionsItemSelected() 的回调.就是说fragment中的菜单项包含了活动中定义的菜单。
class DetailFragment
public DetailFragment() {
setHasOptionsMenu(true);
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.detailfragment,menu);
MenuItem menuItem = menu.findItem(R.id.action_share);
ShareActionProvider mShareActionProvider = (ShareActionProvider) MenuItemCompat.getActionProvider(menuItem);
if(mShareActionProvider != null){
mShareActionProvider.setShareIntent(createShareForecastIntent());
}else{
Log.e(LOG_TAG,"share action provider is null!");
}
}
//FLAG_ACTIVITY_NEW_DOCUMENT instead of FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET
private Intent createShareForecastIntent(){
Intent shareIntent = new Intent(Intent.ACTION_SEND);
shareIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_DOCUMENT);
shareIntent.setType("text/plain");
shareIntent.putExtra(Intent.EXTRA_TEXT,mForecastStr+FORECAST_SHARE_TAG);
return shareIntent;
}
菜单配置文件
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
tools:context="com.example.android.sunshine.app.DetailActivity">
<item
android:id="@+id/action_share"
android:title="@string/action_share"
app:showAsAction="always"
app:actionProviderClass=
"android.support.v7.widget.ShareActionProvider" />
</menu>