Android 之Fragment

Android 之 Fragment（三）

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Fragment与Activity的消息传递

1. 从Activity将消息传递到Fragment中：

在Activity中创建Bundle数据包，并调用Fragment的setArguments()方法

//Activity_main.java 中的onCreate()方法
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //在Activity中给Button设置事件监听
    findViewById(R.id.activity_main_btn).setOnClickListener(new OnClickListener() {
           @Override
           public void onClick(View v) {
            //获取编辑框的输入数据
               String text = ((EditText)findViewById(R.id.activity_main_et)).getText().toString();
               Fragment_main fragment = new Fragment_main(); //动态创建自己定义的Fragment_main的对象
               Bundle bundle = new Bundle(); //创建Bundle数据包对象
               bundle.putString("message", text); //向Bundle数据包中放入编辑框中的数据
               fragment.setArguments(bundle);//将数据传递给自定义的Fragment_main对象

              //获取系统的FragmentManager的FragmentTransaction事物
               FragmentTransaction beginTransaction = getFragmentManager().beginTransaction();

               beginTransaction.add(R.id.activity_main_layout, fragment, "fragment");//向事物中添加Fragment

               beginTransaction.commit();//向Activity提交事物
               Toast.makeText(Activity_main.this, "向Fragment发送" + text + " 消息", Toast.LENGTH_SHORT).show();
           }
       });
｝



//Fragment_main.java中的onCreateView()方法
public View onCreateView(LayoutInflater inflater, ViewGroup conainer, Bundle savedInstanceState) {
    //解析Fragment的Layout文件
    View view = inflater.inflate(R.layout.fragment_main, conainer, false);
    //绑定Fragment的TextView控件
    textView = (TextView) view.findViewById(R.id.fragment_main_tv);

    //获取从Activity传递过来数据包中的数据
    String message = getArguments().get("message") + "";
    textView.setText(message); //设置到TextView上

    Toast.makeText(getActivity(), "收到来自Activity的消息：" + message, Toast.LENGTH_SHORT).show();
    return view;
}

2. 从Fragment将消息传递到Activity中：

在Fragment中定义一个内部回调接口，在让包含该Fragment的Activity实现该回调接口。这样Fragment可调用该回调方法将数据传递给Activity

public class Fragment_main extends Fragment {
    private TextView textView;
    private SendMessage sendMessage; //创建回调接口的对象
    private String code = "Fragment向Activity发送消息.....";

    //在Fragment中创建一个回调接口
    public interface SendMessage { 
        void send(String code);
    }

    @Override
    public void onAttach(Context context) {
        sendMessage  = (SendMessage) context; //实例化回调接口对象
        super.onAttach(context);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup conainer, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_main, conainer, false);

        textView = (TextView) view.findViewById(R.id.fragment_main_tv);
        String message = getArguments().get("message") + "";
        textView.setText(message);

        Toast.makeText(getActivity(), "收到来自Activity的消息：" + message, Toast.LENGTH_SHORT).show();

        Toast.makeText(getActivity(), code, Toast.LENGTH_SHORT).show();
        sendMessage.send(code); //向Activity传递数据
        return view;
    }
}

//让Activity_main实现Fragment_main中的回调接口
public class Activity_main extends Activity implements SendMessage{

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

        findViewById(R.id.activity_main_btn).setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                String text = ((EditText)findViewById(R.id.activity_main_et)).getText().toString();
                Fragment_main fragment = new Fragment_main();
                Bundle bundle = new Bundle();
                bundle.putString("message", text);
                fragment.setArguments(bundle);

                FragmentTransaction beginTransaction = getFragmentManager().beginTransaction();
                beginTransaction.add(R.id.activity_main_layout, fragment, "fragment");
                beginTransaction.commit();
                Toast.makeText(Activity_main.this, "向Fragment发送" + text + " 消息", Toast.LENGTH_SHORT).show();
            }
        });
    }

    //实现回调接口中的方法，直接获取数据
    public void send(String code) {
        Toast.makeText(this, "收到来自Fragment的消息：" + code, Toast.LENGTH_SHORT).show();
    }
}