从Activity生命周期到handler线程通信

1.Activity生命周期：

onCreate（）> onStart() > onResume() > onPause() > onStop() > ( onRestart() ) > onDestroy()

2.Activity跳转及数据传递：

//显式跳转1
Intent intent = new Intent(AActivity.this,BActivity.class);
startActivity(intent);

//显式2
Intent intent = new Intent();
intent.setClass(AActivity.this,BActivity.class);
startActivity(intent);

//显式3
Intent intent = new Intent();
intent.setClassName(AActivity.this,"com.example.learnandroidfrominternet.jump.BActivity");
startActivity(intent);

//显式4
Intent intent = new Intent();
intent.setComponent(new ComponentName(AActivity.this,"com.example.learnandroidfrominternet.jump.BActivity"));
startActivity(intent);

//隐式
Intent intent = new Intent();
intent.setAction("AActivityToBActivity");//在要跳转的activity的xml配置下
startActivity(intent);

//Mainfest.xml配置
<intent-filter>
        <action android:name="AActivityToBActivity" />

        <category android:name="android.intent.category.DEFAULT" />
</intent-filter>

//数据传递
  Intent intent = new Intent(AActivity.this,BActivity.class);
  Bundle bundle = new Bundle();
  bundle.putString("name","name");
  bundle.putInt("number",66);
  intent.putExtras(bundle);
  //startActivity(intent);
  startActivityForResult(intent,0);//此方法可接收跳转的activity返回当前activity的回传数据，0为请求码，用于判断是谁发起的


//目标activity接收数据
    Bundle bundle = getIntent().getExtras();
    String name = bundle.getString("name");
    int number = bundle.getInt("number");
    title.setText("name:"+name+" number:"+number);

//目标activity结束当前activity，返回前一个activity，回传数据
    Intent intent = new Intent();
    Bundle bundle1 = new Bundle();
    bundle1.putString("title","我回来了");
    intent.putExtras(bundle1);
    setResult(Activity.RESULT_OK,intent);
    finish();


@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    ToastUtil.showMsg(this,data.getExtras().getString("title")+"---"+requestCode+"---"+resultCode);
}

Activity四种启动方式：

  • standard：标准，没启动一个activity就入栈。
  • singleTop：如果activity已经在栈中存在，且在栈顶，则不创建新的实例，直接复用。
  • singleTask: 如果栈中存在activity，则复用，但会移除上面的activity。
  • singleInstance：全局，一个activity实例就是一个栈（例如，支付宝）

3.Fragment

布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<!--<Button
    android:id="@+id/btn_change"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:text="更换fragment"
    android:textAllCaps="false"/>-->

  <TextView
    android:id="@+id/tv_title"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textColor="@color/colorBlack"
    android:textSize="20sp"
    android:text="Hello"/>
  <FrameLayout
    android:id="@+id/fl_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@+id/tv_title"/>
</RelativeLayout>

ContainerActivity：

public class ContainerActivity extends AppCompatActivity implements AFragment.IOnMessageClick {

    private AFragment aFragment;
    private BFragment bFragment;
    private Button btn_change;
    private TextView title;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_container);
//      btn_change = findViewById(R.id.btn_change);

        title = findViewById(R.id.tv_title);

        aFragment = AFragment.newInstance("我是参数");
        getSupportFragmentManager().beginTransaction().add(R.id.fl_container,aFragment,"afragment").commitAllowingStateLoss();

    /*  btn_change.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(bFragment == null){
                    bFragment = new BFragment();
                }
            getSupportFragmentManager().beginTransaction().replace(R.id.fl_container,bFragment).commitAllowingStateLoss();
            }
        });*/
    }

    public void setData(String text){
        title.setText(text);
    }

    @Override
    public void onClick(String text) {
        title.setText(text);
    }
}

AFragment:

public class AFragment extends Fragment {
    private TextView title;
    private Button btn_change,btn_reset,btn_message;
    private BFragment bFragment;
    private IOnMessageClick listener;

//  private Activity activity;

    public static AFragment newInstance(String title){
        AFragment aFragment = new AFragment();
        Bundle bundle = new Bundle();
        bundle.putString("title",title);
        aFragment.setArguments(bundle);
        return aFragment;
    }
    public interface IOnMessageClick{
        void onClick(String text);
    }
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_a,container,false);
        Log.d("AFragment","----onCreateView----");
        return view;
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        title = view.findViewById(R.id.tv_title);
        btn_change = view.findViewById(R.id.btn_change);
        btn_reset = view.findViewById(R.id.btn_reset);
        btn_message = view.findViewById(R.id.btn_message);

        btn_message.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
//          ((ContainerActivity)getActivity()).setData("你好");
                listener.onClick("你好");
            }
        });
        btn_change.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(bFragment == null){
                    bFragment = new BFragment();
                }
                Fragment fragment = getActivity().getSupportFragmentManager().findFragmentByTag("afragment");
                if(fragment != null){
                    getActivity().getSupportFragmentManager().beginTransaction().hide(fragment).add(R.id.fl_container,bFragment).addToBackStack(null).commitAllowingStateLoss();
                }else {
                    getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.fl_container, bFragment).addToBackStack(null).commitAllowingStateLoss();
                }
            }
        });
        btn_reset.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                title.setText("我是新文字");
            }
        });
        if(getArguments() != null){
            title.setText(getArguments().getString("title"));
        }
        /*if(getActivity()!=null){

            }else{

        }*/
    }

    //当fragment与activity绑定后就会调用该方法
    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
//      activity = (Activity) context;
        try {
            listener = (IOnMessageClick) context;
        }catch (ClassCastException e){
            throw new  ClassCastException("Activity 必须实现 IOnMessageClick接口");
        }
}

    @Override
    public void onDetach() {
        super.onDetach();
    }
}

fragment_a.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center">

  <Button
    android:id="@+id/btn_message"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:text="给Activity传递消息"
    android:textAllCaps="false"/>

  <Button
    android:id="@+id/btn_change"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:text="更换为Bfragment"
    android:textAllCaps="false"/>

  <Button
    android:id="@+id/btn_reset"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:text="更换textview的文字内容"
    android:textAllCaps="false"/>


  <TextView
    android:id="@+id/tv_title"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:textSize="20sp"
    android:gravity="center"
    android:textColor="@color/colorBlack"
    android:text="fragmentA"/>
</LinearLayout>

4.Event

点击事件5种：

  • 内部类；
  • 匿名内部类；
  • 通过事件源所在的类实现；
  • 通过外部类实现；
  • 布局文件引用。
    引用顺序：布局文件定义的优先级最低，最后一个定义的优先级最高

按钮的touch事件顺序：
dispatchTouchEvent > Listener >onTouchEvent

5.Handler线程通信：

public class HandlerActivity extends AppCompatActivity {

private Handler handler;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_handler);
    /*handler = new Handler();
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            Intent intent = new Intent(HandlerActivity.this,ButtonActivity.class);
            startActivity(intent);
        }
    }, 3000);*/

    handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what){
                case 1:
                    ToastUtil.showMsg(HandlerActivity.this,"线程通信成功");
                    break;
            }
        }
    };

    new Thread(){
        @Override
        public void run() {
            super.run();
            Message message = new Message();
            message.what = 1;
            handler.sendMessage(message);
        }
    }.start();
}

}

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