Android开发中Fragment主要用来提供更灵活的界面构造形式,顾名思义,英语中fragment一词就是片段的意思。我们可以创建一个扩展自Fragment的类,在重载的onCreateView方法中填充xml定义的布局,然后在其容器Activity所使用的xml布局文件中,像引入其它视图组件一样对其进行引入。在作为容器的Activity代码中使用FragmentManager可以获取到对这个Fragment的引用。
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.new_item_fragment, container, false);
}
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<fragment android:name="com.test.NewFragment"
android:id="@+id/NewFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
FragmentManager fm = getSupportFragmentManager();
NewFragment newFragment = (NewFragment)fm.findFragmentById(R.id.NewFragment);
容器Activity可以实现Fragment类中定义的一个接口,同时在Fragment类中定义该接口类型的一个成员,在重载的onAttach中获取容器activity引用,赋值给该成员。这样当触发了Fragment中的某个组件的事件时,就能调用该接口的方法,实现Fragment向容器Activity传递消息和数据了。
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
public class NewFragment extends Fragment {
/**
* 自定义事件接口
*/
public interface OnXXXListener {
public void onXXX(String msg);
}
/**
* 事件接口实例
*/
private OnXXXListener onXXXListener;
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
onXXXListener = (OnXXXListener)activity;//获取容器Activity
} catch (ClassCastException e) {
throw new ClassCastException(
activity.toString() + "must inplement OnXXXListener"
);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.xxx_fragment, container, false);
final EditText myEditText = (EditText)view.findViewById(R.id.my_edit_text);
myEditText.setOnKeyListener(new View.OnKeyListener() {
@Override
public boolean onKey(View view, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_DOWN) {
if (
(keyCode == KeyEvent.KEYCODE_DPAD_CENTER) ||
(keyCode == KeyEvent.KEYCODE_ENTER)
) {
String msg = myEditText.getText().toString();
onXXXListener.onXXX(msg);//向容器Activity传递消息
myEditText.setText("");
return true;
}
}
return false;
}
});
return view;
}
}
public class MainActivity extends ActionBarActivity
implements NewFragment.OnXXXListener{
@Override
public void onXXX(String msg) {
//TODO
}
}