Fragment Arguments

一个Fragment可以通过两种方式进行配置，一个是Bundle类型参数，一个是layout中的属性。请看下面的例子：

1.主activity的布局文件

<?xml version="1.0" encoding="utf-8"?>


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:padding="4dip"
    android:gravity="center_horizontal"
    android:layout_width="match_parent" android:layout_height="match_parent">

    <TextView
            android:id="@+id/text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="0"
            android:padding="4dip"
            android:layout_gravity="center_vertical|center_horizontal"
            android:gravity="top|center_horizontal"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="@string/fragment_arguments_msg" />

    <LinearLayout android:orientation="horizontal" android:padding="4dip"
        android:layout_width="match_parent" android:layout_height="wrap_content">


        <fragment class="com.example.android.apis.app.FragmentArguments$MyFragment"
                android:id="@+id/embedded"
                android:layout_width="0px" android:layout_height="wrap_content"
                android:layout_weight="1"
                android:label="From Layout" />


        <FrameLayout
                android:id="@+id/created"
                android:layout_width="0px"
                android:layout_height="wrap_content"
                android:layout_weight="1" />

    </LinearLayout>

</LinearLayout>

2.主Activity:

**
 * Demonstrates a fragment that can be configured through both Bundle arguments
 * and layout attributes.
 */
public class FragmentArguments extends Activity {

    @Override protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_arguments);

        if (savedInstanceState == null) {
            // First-time init; create fragment to embed in activity.
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            Fragment newFragment = MyFragment.newInstance("From Arguments");
            ft.add(R.id.created, newFragment);
            ft.commit();
        }
    }



    public static class MyFragment extends Fragment {
        CharSequence mLabel;

        /**
         * Create a new instance of MyFragment that will be initialized
         * with the given arguments.
         */
        static MyFragment newInstance(CharSequence label) {
            MyFragment f = new MyFragment();
            Bundle b = new Bundle();
            b.putCharSequence("label", label);
            f.setArguments(b);
            return f;
        }

        /**
         * Parse attributes during inflation from a view hierarchy into the
         * arguments we handle.
         */
        @Override public void onInflate(Activity activity, AttributeSet attrs,
                Bundle savedInstanceState) {
            super.onInflate(activity, attrs, savedInstanceState);

            TypedArray a = activity.obtainStyledAttributes(R.styleable.FragmentArguments);
            mLabel = a.getText(R.styleable.FragmentArguments_android_label);
            a.recycle();//不能忘记
        }

        /**
         * During creation, if arguments have been supplied to the fragment
         * then parse those out.
         */
        @Override public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            Bundle args = getArguments();
            if (args != null) {
                mLabel = args.getCharSequence("label", mLabel);
            }
        }

        /**
         * Create the view for this fragment, using the arguments given to it.
         */
        @Override public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View v = inflater.inflate(R.layout.hello_world, container, false);
            View tv = v.findViewById(R.id.text);
            ((TextView)tv).setText(mLabel != null ? mLabel : "(no label)");
           
            return v;
        }
    }

}

 3.MyFragment中的布局文件hello_world.xml

<TextView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/text"
    android:layout_width="match_parent" android:layout_height="match_parent"
    android:gravity="center_vertical|center_horizontal"
    android:textAppearance="?android:attr/textAppearanceMedium"
    android:text="hello_world"/>

<?xml version="1.0" encoding="utf-8"?>
 

<resources>

    <!-- These are the attributes that we want to retrieve for
         app/FragmentArguments.java -->

    <declare-styleable name="FragmentArguments">
        <attr name="android:label" />
    </declare-styleable>

</resources>

总结：

这个示例展示了如何configure 一个Fragment， 其中展示了2种方法：1. setArguments()方法

   这里要记住Fragment的Life cycle:   onAttach --- onCreate --- onCreateView --- onActivityCreated.

本例中定义了一个新的属性：android:label.

定义新属性的方法---在res/values/attr.xml中添加

<fragment class="com.example.android.apis.app.FragmentArguments$MyFragment"
                android:id="@+id/embedded"
                android:layout_width="0px" android:layout_height="wrap_content"
                android:layout_weight="1"
                android:label="@string/fragment_arguments_embedded" />