Fragment高级进阶

最新推荐文章于 2021-10-15 09:52:11 发布

liuguitong_BK

最新推荐文章于 2021-10-15 09:52:11 发布

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分类专栏： Fragment高级进阶文章标签： Android2

本文链接：https://blog.youkuaiyun.com/liuguitong_BK/article/details/95379668

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Fragment 回退栈

radioGroupId.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                switch (checkedId) {
                    case R.id.person_id:
                        manager = getSupportFragmentManager();
                        fragmentTransaction = manager.beginTransaction();
                        //add(R.id.frame_layout_id,new FristFragment());
						//入栈
                        fragmentTransaction.addToBackStack("11");
                        fragmentTransaction.commit();
                        break;
                    case R.id.message_id:
                        manager = getSupportFragmentManager();
						
						//出栈
                        manager.popBackStack(); 
                        SelectActivity.this.fragmentTransaction = manager.beginTransaction();
                        SelectActivity.this.fragmentTransaction.replace(R.id.frame_layout_id,new SecondFragment());
                        // fragmentTransaction.addToBackStack(null);
                        SelectActivity.this.fragmentTransaction.commit();
                        break;

                    default:
                        break;
                }
            }
        });

case R.id.message_id:
    manager = getSupportFragmentManager();
//  manager.popBackStack();
    fragmentTransaction = manager.beginTransaction();
    fragmentTransaction.replace(R.id.frame_layout_id,new SecondFragment());
    //添加了返回栈,点击back的时候,不会退出activity,而会返回到之前的fragment界面.
//  fragmentTransaction.addToBackStack(null);
    fragmentTransaction.commit();
     break;

Fragment 传值介绍

不同页面间传值是最基本的要求.(这是页面间的联动,交互)

activity 给 fragment传值

在这里插入图片描述

主要涉及到一个方法是getArguments()和setArguments().
一个设置属性值,一个去取属性值.

步骤：要传的值，放到bundle对象里；在Activity中创建该Fragment的对象fragment，通过调用
fragment.setArguments()传递到fragment中；然后更新fragment.
在该Fragment中通过调用getArguments()得到bundle对象，就能得到里面的值。

fragment_first.xml的布局

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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"
    tools:context=".fragment.FirstFragment">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment" />

</FrameLayout>

FirstFragment.java代码

public class FirstFragment extends Fragment {

    private TextView textView;

    public FirstFragment() {

    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View inflate = inflater.inflate(R.layout.fragment_first, container, false);
        textView = inflate.findViewById(R.id.textView);
        Bundle arguments = getArguments();
        if (arguments!=null) {
            String key = arguments.getString("key");
            textView.setText(key);
        }
        return inflate;
    }

}

activity_main.xml布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/edit_id"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:drawable/edit_text"/>
    <Button
        android:id="@+id/button_id"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/select"
        android:onClick="click"
        android:text="发   送"/>
    <LinearLayout
        android:id="@+id/linear_id"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:orientation="vertical"
        android:layout_weight="1"></LinearLayout>

</LinearLayout>

MainActivity.java代码

public class MainActivity extends AppCompatActivity {

    private EditText editId;
    private Button buttonId;
    private LinearLayout linearId;
    private FragmentManager manager;
    private FragmentTransaction beginTransaction;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editId = (EditText) findViewById(R.id.edit_id);
        buttonId = (Button) findViewById(R.id.button_id);
        linearId = (LinearLayout) findViewById(R.id.linear_id);

        manager = getSupportFragmentManager();
        beginTransaction = manager.beginTransaction();
        beginTransaction.add(R.id.linear_id,new FirstFragment());
        beginTransaction.commit();
    }

    public void click(View view) {
        String string = editId.getText().toString();
        FirstFragment firstFragment = new FirstFragment();
        Bundle bundle = new Bundle();
        bundle.putString("key",string);
        firstFragment.setArguments(bundle);

        manager = getSupportFragmentManager();
        beginTransaction = manager.beginTransaction();
        beginTransaction.replace(R.id.linear_id,firstFragment);
        beginTransaction.commit();
    }
}

fragment 给 activity传值

第一种：
在Activity中调用getFragmentManager()得到fragmentManager,，调用findFragmentByTag(tag)或者通过findFragmentById(id)

FragmentManager fragmentManager = getFragmentManager()；
Fragment fragment = fragmentManager.findFragmentByTag(tag)；

第二种：
通过回调的方式，定义一个接口（可以在Fragment类中定义），接口中有一个空的方法，在fragment中需要的时候调用接口的方法，值可以作为参数放在这个方法中，然后让Activity实现这个接口，必然会重写这个方法，这样值就传到了Activity中.
大白话,就是java的父类引用指向了子类对象
在这里插入图片描述
fragment的xml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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".fragment.SecoundFragment">

    <EditText
        android:id="@+id/editView_id"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:drawable/edit_text"
        android:hint="请输入内容"/>
    <Button
        android:id="@+id/button_two_id"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="发   送"
        android:background="@drawable/select"/>

</LinearLayout>

fragment中的代码

public class SecoundFragment extends Fragment {

    private Button mButton;
    private EditText mEditText;
    private MyListener mMyListener;

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        mMyListener=(MyListener) getActivity();
    }

    public SecoundFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View inflate = inflater.inflate(R.layout.fragment_secound, container, false);
       mEditText= inflate.findViewById(R.id.editView_id);
       mButton= inflate.findViewById(R.id.button_two_id);
       mButton.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View view) {
               String string = mEditText.getText().toString();
               mMyListener.sendMessage(string);
           }
       });
        return inflate;
    }
    public interface MyListener{
        void sendMessage(String string);
    }

}

Activity中的xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".activitys.Main2Activity">

    <TextView
        android:id="@+id/textView_id"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:text="换掉我吧"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:id="@+id/lin"
        android:orientation="vertical"
        android:layout_weight="9">
    </LinearLayout>
</LinearLayout>

Activity中的代码

public class Main2Activity extends AppCompatActivity implements SecoundFragment.MyListener {

    private TextView textViewId;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        textViewId = (TextView) findViewById(R.id.textView_id);

        FragmentManager supportFragmentManager = getSupportFragmentManager();
        FragmentTransaction beginTransaction = supportFragmentManager.beginTransaction();
        beginTransaction.add(R.id.lin,new SecoundFragment());
        beginTransaction.commit();
    }

    @Override
    public void sendMessage(String string) {
        textViewId.setText(string);
    }
}

fragment 给 fragment 传值

第一种：
动态创建的fragment通过findFragmentByTag得到另一个的Fragment的对象，这样就可以调用另一个的方法了。
静态创建的fragment通过findFragmentById得到另一个的Fragment的对象，这样就可以调用另一个的方法了。
在这里插入图片描述

public class LeftFragment extends Fragment {

    private EditText editText;
    private Button send_button;

    public LeftFragment() {
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View inflate = inflater.inflate(R.layout.fragment_left, container, false);
        editText = inflate.findViewById(R.id.left_textView_id);
        send_button = inflate.findViewById(R.id.left_button_id);

        send_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String string = editText.getText().toString();
                
                **了解一种即可,不重点**
                //1 fragment传值方式1
                // 通过id找的指定fragment,调用他的方法,给他的组件赋值.
                FragmentManager fragmentManager = getFragmentManager(); //注意,这个manager是v4包下的.
                RightFragment rightFragment=(RightFragment) fragmentManager.findFragmentById(R.id.right_fragment_id);
                rightFragment.setTextView(string);

                //2 通过id找的指定fragment,得到他所有的view.在通过findViewById 找到组件.赋值
                TextView textView = getFragmentManager().findFragmentById(R.id.right_fragment_id).getView().findViewById(R.id.right_textview_id);
                textView.setText(string);

                //3
                //因为两个fragment在一个activity里面,所有可以通过拿到activity里面所有的指定组件.
                TextView textView = (TextView) getActivity().findViewById(R.id.right_textview_id);
                textView.setText(string);

            }
        });
        return inflate;
    }
}

第二种(重点)

通过接口回调的方式。
与上面的接口回调用法相同

第三种：

通过setArguments，getArguments的方式。

fragment 多层嵌套

 FragmentManager childFragmentManager = getChildFragmentManager();
 FragmentTransaction fragmentTransaction = childFragmentManager.beginTransaction();
 fragmentTransaction.add(R.id.left_fragment_id,new RightFragment());
 fragmentTransaction.commit();

案例(微信底部按钮与fragment实现界面切换)

Activity的Java代码

public class SelectActivity extends AppCompatActivity {
    private FrameLayout frameLayoutId;
    private RadioGroup radioGroupId;
    private RadioButton personId;
    private RadioButton messageId;
    private static final String TAG = "SelectActivity";
    private FragmentManager manager;
    private FragmentTransaction fragmentTransaction;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_select);

        frameLayoutId = findViewById(R.id.frame_layout_id);
        radioGroupId = findViewById(R.id.radio_group_id);

        radioGroupId.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                switch (checkedId) {
                    case R.id.person_id:
                        manager = getSupportFragmentManager();
                        fragmentTransaction = manager.beginTransaction();
//                        fragmentTransaction.replace(R.id.frame_layout_id,new FristFragment());
                        fragmentTransaction.add(R.id.frame_layout_id,new FristFragment());
                        fragmentTransaction.addToBackStack("11");
                        Log.i(TAG, "onCheckedChanged: "+SelectActivity.class.getName());
                        fragmentTransaction.commit();
                        break;
                    case R.id.message_id:
                        manager = getSupportFragmentManager();
                        manager.popBackStack();
                        SelectActivity.this.fragmentTransaction = manager.beginTransaction();
                        SelectActivity.this.fragmentTransaction.replace(R.id.frame_layout_id,new SecondFragment());
//                        fragmentTransaction.addToBackStack(null);
                        SelectActivity.this.fragmentTransaction.commit();
                        break;
                    default:
                        break;
                }
            }
        });
    }
}

activity的xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".activities.SelectActivity">

    <FrameLayout
        android:id="@+id/frame_layout_id"
        android:layout_weight="9"
        android:layout_width="match_parent"
        android:layout_height="0dp">
    </FrameLayout>

    <RadioGroup
        android:id="@+id/radio_group_id"
        android:layout_weight="1"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="0dp">

        <RadioButton
            android:layout_weight="1"
            android:id="@+id/person_id"
            android:button="@null"
            android:text="联系人"
            android:gravity="center"
            android:checked="true"
            android:drawableTop="@drawable/select_pserson"
            android:textColor="@drawable/select_text"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            />

        <RadioButton
            android:layout_weight="1"
            android:id="@+id/message_id"
            android:button="@null"
            android:gravity="center"
            android:drawableTop="@drawable/select_message"
            android:textColor="@drawable/select_text"
            android:text="信息"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            />
    </RadioGroup>

</LinearLayout>

说明
android:drawableTop="@drawable/select_message"
android:textColor="@drawable/select_text"
这两个属性,参照下面链接创建
https://blog.youkuaiyun.com/qq_34178710/article/details/91411003
java代码中的fragment,右键创建即可.