<Android 基础（二十八）> Fragment (1)

简介

Fragment，碎片，常用的内容，但是一直没有系统的学习下它的使用方法，花几天抽空看看随便记录一下。

生命周期

来自官网的图片一目了然。
自测试结果：

基本使用

1.自定义一个Fragment：BaseFragment

/*带参数构造方法*/
public static BaseFragment newInstance(String content) {
    Bundle args = new Bundle();
    args.putString("CONTENT", content);
    BaseFragment fragment = new BaseFragment();
    fragment.setArguments(args);//传递参数，设置内容文本
    return fragment;
}

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    Log.i(TAG, "onCreateView");
    View view = inflater.inflate(R.layout.content_fragment
            , container, false);
    Bundle args = getArguments();//获取参数并设置文本内容
    if (args != null) {
        String content = args.getString("CONTENT");
        tv = (TextView) view.findViewById(R.id.tv_content);
        tv.setText(content);
    }
    return view;
}

2.对应布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:id="@+id/tv_content"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:gravity="center"
        android:textColor="@color/colorAccent"
        android:textSize="30sp"
        android:textStyle="italic|bold" />

</LinearLayout>

3.主Activity布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="jzfp.gs.com.animationdemo.MainActivity">

    <!-- 工具栏-->
    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/colorPrimary"></android.support.v7.widget.Toolbar>
    <!-- 内容区域-->
    <FrameLayout
        android:id="@+id/fl_content"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></FrameLayout>
</LinearLayout>

4.Fragment切换

public class MainActivity extends AppCompatActivity {
    BaseFragment leftFragment = null;//左侧fragment
    BaseFragment rightFragment = null;//右侧Fragment
    BaseFragment defaultFragment= null;//默认Fragment

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        toolbar.setNavigationIcon(R.drawable.left);
        setSupportActionBar(toolbar);//设置ActionBar
        toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                showLeftFragment();
            }
        });
        defaultFragment = BaseFragment.newInstance("This is default fragment");
        FragmentManager fm = getSupportFragmentManager();
        FragmentTransaction transaction = fm.beginTransaction();
        transaction.replace(R.id.fl_content, defaultFragment);
        transaction.commit();//显示默认碎片
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.toolbar, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        switch(id){
            case R.id.right:
                showRightFragment();break;
            default:break;
        }
        return true;
    }

    public void showLeftFragment(){
        FragmentManager fm = getSupportFragmentManager();
        FragmentTransaction transaction = fm.beginTransaction();
        if(leftFragment == null) {
            leftFragment = BaseFragment.newInstance("This is Left Fragment");
        }
        transaction.replace(R.id.fl_content, leftFragment);
        transaction.commit();
    }

    public void showRightFragment(){
        FragmentManager fm = getSupportFragmentManager();
        FragmentTransaction transaction = fm.beginTransaction();
        if(rightFragment == null) {
            rightFragment = BaseFragment.newInstance("This is Right Fragment");
        }
        transaction.replace(R.id.fl_content, rightFragment);
        transaction.commit();
    }
}

5.结果
点击左右按钮切换fragment