Android Fragment的使用 二 事务函数详解

我先把需要将的函数摆列出来
FragmentTransaction transaction = fm.benginTransatcion();//开启一个事务
transaction.add()
往Activity中添加一个Fragment
transaction.remove()
从Activity中移除一个Fragment，如果被移除的Fragment没有添加到回退栈（回退栈后面会详细说），这个Fragment实例将会被销毁。
transaction.replace()
使用另一个Fragment替换当前的，实际上就是remove()然后add()的合体~
transaction.hide()
隐藏当前的Fragment，仅仅是设为不可见，并不会销毁
transaction.show()
显示之前隐藏的Fragment
detach()
会将view从UI中移除,和remove()不同,此时fragment的状态依然由FragmentManager维护。
attach()
重建view视图，附加到UI上并显示。
transatcion.commit()//提交一个事务

使用例子如下：

public class MainActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        FragmentManager fm = getFragmentManager();        FragmentTransaction tx = fm.beginTransaction();        tx.add(R.id.id_content,new FragmentOne(),"ONE");        tx.commit();    }}public class FragmentOne extends Fragment implements View.OnClickListener {    private Button button;    @Override    public View onCreateView(LayoutInflater inflater,ViewGroup container,                             Bundle savedInstanceState){        View view = inflater.inflate(R.layout.fragment_one,container,false);        button = (Button) view.findViewById(R.id.id_fragment_one_btn);        button.setOnClickListener(this);        return view;    }    @Override    public void onClick(View v){        FragmentTwo fTwo = new FragmentTwo();        FragmentManager fm = getFragmentManager();        FragmentTransaction tx = fm.beginTransaction();        tx.replace(R.id.id_content,fTwo,"TWO");        tx.addToBackStack(null);        tx.commit();    }}public class FragmentTwo extends Fragment implements View.OnClickListener {    private Button button;    @Override    public View onCreateView(LayoutInflater inflater,ViewGroup container,                             Bundle savedInstanceState){        View view = inflater.inflate(R.layout.fragment_two,container,false);        button = (Button) view.findViewById(R.id.id_fragment_two_btn);        button.setOnClickListener(this);        return view;    }    @Override    public void onClick(View v){        FragmentThree fThree = new FragmentThree();        FragmentManager fm = getFragmentManager();        FragmentTransaction tx = fm.beginTransaction();        tx.hide(this);        tx.add(R.id.id_content,fThree,"THREE");        tx.addToBackStack(null);        tx.commit();    }}public class FragmentThree extends Fragment implements View.OnClickListener {    private Button button;    @Override    public View onCreateView(LayoutInflater inflater,ViewGroup container,                             Bundle savedInstanceState){        View view = inflater.inflate(R.layout.fragment_three,container,false);        button = (Button) view.findViewById(R.id.id_fragment_three_btn);        button.setOnClickListener(this);        return view;    }    @Override    public void onClick(View v){        Toast.makeText(getActivity(),"three",Toast.LENGTH_SHORT).show();    }}activity_main<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="android.com.myapplication.MainActivity">    <FrameLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/id_content"></FrameLayout></RelativeLayout>fragment_one<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent">    <Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="one"        android:id="@+id/id_fragment_one_btn"        android:layout_gravity="center"/>    <EditText        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>fragment_two<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent">    <Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="two"        android:id="@+id/id_fragment_two_btn"        android:layout_gravity="center"/>    <EditText        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>fragment_three<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent">    <Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="three"        android:id="@+id/id_fragment_three_btn"        android:layout_gravity="center"/>    <EditText        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>

我们在三个Fragment的输入栏都写入了数据，当我们从FragmentThree按下back键，回退到FragmentTwo，发现这输入栏还存在之前的数据，但再按下back键，FragmentOne的输入栏没有数据。
这是因为FragmentOne的replace将之前FragmentOne销毁了，然后添加了FragmenTwo，但在FragmentTwo使用了hide将FragmentTwo隐藏，将FragmentThree添加下来。

下期将Fragment与Activity的交互。
再见