Activity 与 Fragment通信方式-Android

Fragment 与 Activity 通信存在三种情形：

Activity 操作内嵌的 Fragment
Fragment 操作宿主 Activity
Fragment 操作同属 Activity中的其他 Fragment

Fragment 与 Activity 通信方式：

Bundle
接口回调
广播
EventBus
Handler
ViewModel

一、Bundle

1、Activity 传递数据到 Fragment

activity_main.xml

<?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:id="@+id/button"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="Activity" />

    <FrameLayout
        android:layout_below="@+id/button"
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

activity_my_fragment.xml

<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:id="@+id/change"
        android:layout_gravity="center"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="change消息" />

    <Button
        android:id="@+id/get"
        android:layout_gravity="center"
        android:text="get消息"
        android:layout_centerInParent="true"
        android:textSize="20dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

MainActivity.java

public class MainActivity extends AppCompatActivity {

    Button button;

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

        button = (Button) findViewById(R.id.button);

        // 步骤1：获取FragmentManager
        FragmentManager fragmentManager = getFragmentManager();

        // 步骤2：获取FragmentTransaction
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        // 步骤3：创建需要添加的Fragment
        final MyFragment fragment = new MyFragment();

        // 步骤4:创建Bundle对象
        // 作用:存储数据，并传递到Fragment中
        Bundle bundle = new Bundle();

        // 步骤5:往bundle中添加数据
        bundle.putString("msg", "change成功");

        // 步骤6:把数据设置到Fragment中
        fragment.setArguments(bundle);

        // 步骤7：动态添加fragment
        // 即将创建的fragment添加到Activity布局文件中定义的占位符中（FrameLayout）
        fragmentTransaction.add(R.id.fragment_container,fragment);
        fragmentTransaction.commit();

    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37

MyFragment.java

public class MyFragment extends Fragment {

    Button change;
    Button get;
    Bundle bundle;
    String message;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View contentView = inflater.inflate(R.layout.activity_my_fragment, container, false);
        // 设置布局文件

        change = (Button) contentView.findViewById(R.id.change);
        get = (Button) contentView.findViewById(R.id.get);

        // 步骤1:通过getArgments()获取从Activity传过来的全部值
        bundle = this.getArguments();

        // 步骤2:获取某一值
        message = bundle.getString("msg");

        // 步骤3:设置按钮,将设置的值显示出来
        get.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 显示传递过来的值
                change.setText(message);
            }
        });
        return contentView;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33

二、接口回调

1、Fragment 传递数据到 Activity

方法一：

接口用于Activity与Fragment通信
ICallBack.java

public interface ICallBack {
    void get_message_from_Fragment(String string);
}

1
2
3
4

activity_main.xml

<?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:id="@+id/button"
        android:layout_gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="Activity接受消息前" />

    <Button
        android:id="@+id/get"
        android:layout_gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="get消息" />

    <FrameLayout
        android:layout_below="@+id/button"
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28

activity_my_fragment.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    >

    <Button
        android:id="@+id/fragment"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="fragment消息:发送成功"
        />
</LinearLayout>
1
2
3
4
5
6
7
8
9
10
11
12
13
14

MainActivity.java

public class MainActivity extends AppCompatActivity {
    Button button;
    Button get;

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

        button = (Button) findViewById(R.id.button);
        get = (Button) findViewById(R.id.get);

        // 步骤1：获取FragmentManager
        FragmentManager fragmentManager = getFragmentManager();

        // 步骤2：获取FragmentTransaction
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        // 步骤3：创建需要添加的Fragment
        final MyFragment fragment = new MyFragment();

        // 步骤4：动态添加fragment
        // 即将创建的fragment添加到Activity布局文件中定义的占位符中（FrameLayout）
        fragmentTransaction.add(R.id.fragment_container, fragment);
        fragmentTransaction.commit();
        get.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                fragment.sendMessage(new ICallBack() {
                    @Override
                    public void get_message_from_Fragment(String string) {
                        button.setText(string);
                    }
                });
            }
        });

    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39

MyFragment.java

public class MyFragment extends Fragment {


    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View contentView = inflater.inflate(R.layout.activity_my_fragment, container, false);
        return contentView;
    }
    public void sendMessage(ICallBack iCallBack){
        iCallBack.get_message_from_Fragment("发送成功");
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13

在这里插入图片描述

方法二：

FragmentListener.java

public interface FragmentListener {
    void process(String str);
}
1
2
3

activity_main.xml

<?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:id="@+id/button"
        android:layout_gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="Activity接受消息前" />

    <Button
        android:id="@+id/get"
        android:layout_gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="get消息" />

    <FrameLayout
        android:layout_below="@+id/button"
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28

activity_my_fragment.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    >

    <Button
        android:id="@+id/fragment2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="fragment发送消息"
        />
</LinearLayout>
1
2
3
4
5
6
7
8
9
10
11
12
13
14

MainActivity.java

public class MainActivity extends AppCompatActivity implements FragmentListener{
    Button button;
    Button get;
    String getstring;

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

        button = (Button) findViewById(R.id.button);
        get = (Button) findViewById(R.id.get);
        // 步骤1：获取FragmentManager
        FragmentManager fragmentManager = getFragmentManager();
        // 步骤2：获取FragmentTransaction
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        final MyFragment2 myFragment2 = new MyFragment2();
        fragmentTransaction.add(R.id.fragment_container,myFragment2);
        fragmentTransaction.commit();
        get.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                button.setText(getstring);
            }
        });
    }

    @Override
    public void process(String str) {
        getstring = str;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32

MyFragment2.java

public class MyFragment2 extends Fragment {
    Button button;
    private FragmentListener listener;
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        if(activity instanceof FragmentListener){
            listener = (FragmentListener) activity;
        }else{
            throw new IllegalArgumentException("activity must implements Fragment interface");
        }

    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.activity_my_fragment2, container, false);
        button = (Button) view.findViewById(R.id.fragment2);
        listener.process("发送消息：我是接口");
        return view;
    }

    @Override
    public void onDetach() {
        super.onDetach();
        listener = null;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

在这里插入图片描述

三、EventBus

正常发送消息

简化组件之间的通信
解耦事件发送者和接收者
在活动、片段和后台线程中表现良好
避免复杂且容易出错的依赖关系和生命周期问题
让你的代码更简单

使用

1、添加依赖

implementation("org.greenrobot:eventbus:3.3.1")
1

2、EventBus 五步走

注册：EventBus.getDefault().register(this);
解注册：EventBus.getDefault().unregister(this);
构造发送消息类：public class MessageEvent
发布消息：EventBus.getDefault().post(new MessageEvent(“Fragment发送成功”));
接受消息：显示接受消息
activity_main.xml

<?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:id="@+id/button"
        android:layout_gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="Activity接受消息前" />

    <Button
        android:id="@+id/get"
        android:layout_gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="get消息" />

    <FrameLayout
        android:id="@+id/fragment_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/button" />
</LinearLayout>


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

activity_event_bus_fragment.xml

<?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:id="@+id/bt_send"
        android:layout_gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="Fragment发送数据" />

    <Button
        android:id="@+id/bt_get"
        android:layout_gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:text="Fragment接受数据" />

    <Button
        android:id="@+id/msg"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:textSize="20dp"
        android:text="显示数据"/>
</LinearLayout>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

MainActivity.java

public class MainActivity extends AppCompatActivity {
    Button button;
    Button get;

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

        button = (Button) findViewById(R.id.button);
        get = (Button) findViewById(R.id.get);
        // 步骤1：获取FragmentManager
        FragmentManager fragmentManager = getFragmentManager();

        // 步骤2：获取FragmentTransaction
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        // 步骤3：创建需要添加的Fragment
        final EventBusFragment fragment = new EventBusFragment();
        initData();

        // 步骤7：动态添加fragment
        // 即将创建的fragment添加到Activity布局文件中定义的占位符中（FrameLayout）
        fragmentTransaction.add(R.id.fragment_container,fragment);
        fragmentTransaction.commit();

    }

    //初始化
    public void initData(){
        //1.注册广播
        EventBus.getDefault().register(this);
    }

    //5.接受消息
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onMessageEvent(MessageEvent event) {
        // Do something
        // 显示接受消息
        button.setText(event.name);


    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        //2.解注册
        EventBus.getDefault().unregister(this);

    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52

EventBusFragment.java

public class EventBusFragment extends Fragment {
    Button bt_send;
    Button bt_get;
    Button msg;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.activity_event_bus_fragment, container, false);
        bt_send = view.findViewById(R.id.bt_send);
        bt_get = view.findViewById(R.id.bt_get);
        msg = view.findViewById(R.id.msg);
        bt_send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //4.发送消息
                EventBus.getDefault().post(new MessageEvent("Fragment发送成功"));
            }
        });

        return view;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

发送粘性事件

构造发送消息类：public class MessageEvent
发布消息：EventBus.getDefault().post(new MessageEvent(“Fragment发送成功”));
接受消息：显示接受消息
注册： EventBus.getDefault().register(EventBusFragment.this);
解注册：EventBus.getDefault().unregister(EventBusFragment.this);

MainActivity.java

public class MainActivity extends AppCompatActivity {
    Button button;
    Button get;

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

        button = (Button) findViewById(R.id.button);
        get = (Button) findViewById(R.id.get);
        // 步骤1：获取FragmentManager
        FragmentManager fragmentManager = getFragmentManager();

        // 步骤2：获取FragmentTransaction
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        // 步骤3：创建需要添加的Fragment
        final EventBusFragment fragment = new EventBusFragment();
        initData();

        // 步骤7：动态添加fragment
        // 即将创建的fragment添加到Activity布局文件中定义的占位符中（FrameLayout）
        fragmentTransaction.add(R.id.fragment_container,fragment);
        fragmentTransaction.commit();

    }

    //初始化
    public void initData(){
        //2. 发送消息
        EventBus.getDefault().postSticky(new StickyMessageEvent("发送粘性事件成功"));
    }

    //5.接受消息
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onMessageEvent(MessageEvent event) {
        // Do something
        // 显示接受消息
        button.setText(event.name);


    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        //2.解注册
        EventBus.getDefault().unregister(this);

    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52

EventBusFragment.java

public class EventBusFragment extends Fragment {
    Button bt_send;
    Button bt_get;
    Button msg;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.activity_event_bus_fragment, container, false);
        bt_send = view.findViewById(R.id.bt_send);
        bt_get = view.findViewById(R.id.bt_get);
        msg = view.findViewById(R.id.msg);
        bt_send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //4.发送消息
                EventBus.getDefault().post(new MessageEvent("Fragment发送成功"));
            }
        });

        //4.接受粘性事件注册
        bt_get.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                EventBus.getDefault().register(EventBusFragment.this);
            }
        });


        return view;
    }
    //3，接受粘性事件
    @Subscribe(sticky = true, threadMode = ThreadMode.MAIN)
    public void onEvent(StickyMessageEvent event) {
        msg.setText(event.name);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        //5.解注册
        MessageEvent stickyEvent = EventBus.getDefault().getStickyEvent(MessageEvent.class);
// Better check that an event was actually posted before
        if(stickyEvent != null) {
            // "Consume" the sticky event
            EventBus.getDefault().removeStickyEvent(stickyEvent);
            // Now do something with it
        }
        EventBus.getDefault().unregister(EventBusFragment.this);
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51

在这里插入图片描述

四、Handler

Fragment对具体的Activity存在耦合，不利于Fragment复用

相关阅读:
微服务架构 | 分布式事务 - [Seata]
python3 简易 http server：实现本地与远程服务器传大文件
 Spring更加简单地存储Bean
leetcode - 1930. Unique Length-3 Palindromic Subsequences
MogaFX外汇市场保持相对稳定
 MFC Windows 程序设计[136]之文件属性统计(附源码)
【计算机组成课程笔记】7.2 DRAM和SRAM
sql中如何实现递归
 【C语言 |预处理指令】预处理指令详解（包括编译与链接）
Matlab论文插图绘制模板第124期—三维气泡图
原文地址：https://blog.csdn.net/hequnwang10/article/details/124948946