Fragment跟Activity之间的通信

先在Activity定义接口和一个Handler,接口的作用是让碎片接收Activity的指令,而Handler用于接收碎片传来的指令,Activity在执行操作.如下所示:

package com.example.fragmentactivity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.app.Activity;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentActivity;import android.support.v4.app.FragmentTransaction;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.FrameLayout;public class MainActivity extends FragmentActivity implements OnClickListener {  private Button button1;  private String fragmentName;  private OnButtonClickedListener buttonClickedListener;  /**   * 定义一个Handler用于接收黄色碎片给Activity发出来的指令   */  public Handler handler=new Handler(){    @Override    public void handleMessage(Message msg) {      super.handleMessage(msg);      if(msg!=null){        switch (msg.what) {        case 100:          /**           * 接收到黄色碎片发来的指令,Activity执行替换操作           */          fragmentName=Fragment2.class.getName();          replaceFragment(R.id.FrameLayout1, fragmentName);          break;        default:          break;        }      }    }      };  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    button1=(Button) findViewById(R.id.button1);    button1.setOnClickListener(this);    /**     * 加载黄色碎片     */    fragmentName=Fragment1.class.getName();    replaceFragment(R.id.FrameLayout1, fragmentName);  }  @Override  public void onClick(View v) {    switch (v.getId()) {    case R.id.button1:      if(buttonClickedListener!=null){        buttonClickedListener.onclicked("Activity:我不想要这个黄色碎片了,点击下面的按钮给我换个绿色的碎片");      }      break;    default:      break;    }  }  /*   *    * 加载碎片   */  protected void replaceFragment(int viewResource, String fragmentName) {    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();    Fragment fragment = Fragment.instantiate(this, fragmentName);    ft.replace(viewResource, fragment);    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);    ft.commit();    getSupportFragmentManager().executePendingTransactions();  }  /**   * 定义一个接口   * @author zqy   *   */  public  interface OnButtonClickedListener{    /**     * 里面传个值     * @param s     */      public void onclicked(String s);  }  /**   *    * @param buttonClickedListener   * 写一个对外公开的方法   */  public void setButtonClickedListener(OnButtonClickedListener buttonClickedListener){    this.buttonClickedListener=buttonClickedListener;  }    }

这就是Activity里面的代码,我们在去写两个碎片如下所示:

Fragment1:

package com.example.fragmentactivity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.support.v4.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.widget.Button;import android.widget.TextView;import android.widget.Toast;import com.example.fragmentactivity.MainActivity.OnButtonClickedListener;public class Fragment1 extends Fragment implements OnClickListener {  private TextView textView;  private Button button;  private Handler handler;  @Override  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    MainActivity activity=(MainActivity) getActivity();    /**     * 得到Activity的Handler     */    handler=activity.handler;    /**     * 加监听     */    activity.setButtonClickedListener(new OnButtonClickedListener() {            @Override      public void onclicked(String s) {        /*         * 显示Activity传来的内容         */        textView.setText(s);        button.setVisibility(View.VISIBLE);      }    });  }  @Override  public View onCreateView(LayoutInflater inflater, ViewGroup container,      Bundle savedInstanceState) {    return inflater.inflate(R.layout.item1, null);  }  @Override  public void onActivityCreated(Bundle savedInstanceState) {    super.onActivityCreated(savedInstanceState);    textView=(TextView) getActivity().findViewById(R.id.textView1);    button=(Button) getActivity().findViewById(R.id.button2);    button.setOnClickListener(this);  }  @Override  public void onClick(View v) {    switch (v.getId()) {    case R.id.button2:      /**       * 发送指令到Activity       */      handler.sendEmptyMessage(100);      break;    default:      break;    }  }

这个碎片让它的Activity实现这个接口,在把接口里面的值显示到页面上,在点击这个碎片里面的Button给它的Activity发送一个消息.这里面我发的是100.

Fragment2:

package com.example.fragmentactivity;import android.os.Bundle;import android.support.v4.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;public class Fragment2 extends Fragment {  @Override  public View onCreateView(LayoutInflater inflater, ViewGroup container,      Bundle savedInstanceState) {    // TODO Auto-generated method stub    return inflater.inflate(R.layout.item2, null);  }}