android - 如何将数据从单个 Activity 传递到多个 fragment

Question

在我的应用程序中有一个具有多个 fragment 的 Activity 和一个具有微调器的 Activity ，当更改操作发生在微调器上时，所有 fragment 都应该改变值，假设

Activity 临时 --> fragment A --> fragment B --> fragment C

我可以使用 Intent 将数据从 Activity 传递到 fragment A --> B--> C，但是如果当前 fragment 是 C 并且值从微调器更改，那么 fragment C 应该有最新值，当我按下后退按钮时，流程是

fragment C --> fragment B --> fragment A 应该有最新的值，那么如何维护从单个 Activity 传递的多个 fragment 数据

Activity temp.java

public interface FragmentCommunicator {
        void passDataToFragment(String data);
    }

private class onItemSelect implements android.widget.AdapterView.OnItemSelectedListener {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

            Fragment f = getSupportFragmentManager().findFragmentById(R.id.fragment_container);

             if (f instanceof FragmentA) {

                fragmentCommunicator.passDataToFragment(data[position]);
            }

        }
}

fragment A.java

public class FragmentA extends Fragment implements temp.FragmentCommunicator {

@Override
    public void passDataToFragment(String data) {
        this.data = data;
    }


@Override
    public void onAttach(Context context) {
        super.onAttach(context);
        mContext = context;
        ((temp) context).fragmentCommunicator = this;
       }
}

Answer 1

使用接口(interface)我们可以实现它。我们可以简单地将其称为数据更改监听器。

只要按照我的代码来了解它是如何工作的。

1.TempActivity.java

public class TempActivity extends AppCompatActivity {

    public List<FragmentCommunicator> fragmentCommunicators = new ArrayList<>();

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

    final Spinner spinner1 = (Spinner) findViewById(R.id.spinner1);
    spinner1.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, new String[]{"Value One", "Value Two", "Value Three"}));
   spinner1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
       @Override
       public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {

           for (FragmentCommunicator fragmentCommunicator : fragmentCommunicators) {
               fragmentCommunicator.passDataToFragment(spinner1.getSelectedItem().toString());
           }

       }

       @Override
       public void onNothingSelected(AdapterView<?> adapterView) {

       }
   });

   ViewPager viewPager1 = (ViewPager) findViewById(R.id.viewPager1);
   FragmentAdapter adapter = new FragmentAdapter(getSupportFragmentManager());
   adapter.addFragment(new FirstFragment(), "FirstFragment");
   adapter.addFragment(new SecondFragment(), "SecondFragment");
   adapter.addFragment(new ThirdFragment(), "ThirdFragment");
   viewPager1.setAdapter(adapter);

   viewPager1.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
       @Override
       public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

       }

       @Override
       public void onPageSelected(int position) {

           for (FragmentCommunicator fragmentCommunicator : fragmentCommunicators) {
               fragmentCommunicator.passDataToFragment(spinner1.getSelectedItem().toString());
           }

       }

       @Override
       public void onPageScrollStateChanged(int state) {

       }
   });
 }
}

2.activity_temp.xml

<?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">

<Spinner
    android:id="@+id/spinner1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="16dp" />

<android.support.v4.view.ViewPager
    android:id="@+id/viewPager1"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
</LinearLayout>

3.FragmentCommunicator.java

public interface FragmentCommunicator {
    void passDataToFragment(String data);

}

4.FragmentAdapter.java

public class FragmentAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

public FragmentAdapter(FragmentManager manager) {
    super(manager);
}
@Override
public Fragment getItem(int position) {
    return mFragmentList.get(position);
}
@Override
public int getCount() {
    return mFragmentList.size();
}
public void addFragment(Fragment fragment, String title) {
    mFragmentList.add(fragment);
    mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
    return mFragmentTitleList.get(position);
}
}

5.FirstFragment.java

public class FirstFragment extends Fragment implements FragmentCommunicator {
private TextView textView1;
public FirstFragment() {
    // Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_first, container, false);
    textView1 = (TextView) view.findViewById(R.id.textView1);
    if (getActivity() instanceof TempActivity) {
        ((TempActivity) getActivity()).fragmentCommunicators.add(this);
    }
    return view;
}
@Override
public void passDataToFragment(String data) {
    textView1.setText(data);
}
}

6.fragment_first.xml

<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"
android:background="@android:color/holo_orange_light">
<!-- TODO: Update blank fragment layout -->
<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:textColor="@android:color/black"
    android:textSize="24sp" />
</FrameLayout>

7.对剩余的 fragment 执行相同的步骤。

Create new fragment. Implement FragmentCommunicator interface. Add implemented interface in Activity’s interface list.

8.构建并运行您的应用程序。我们实现了。

您可以获取我的示例项目 here .

快乐的编码......