【达内课程】线程——Handler（三）

实现3s后跳转主界面

主要代码：

SplashActivity

public class SplashActivity extends AppCompatActivity {
    private Handler handler;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_splash);

        handler = new Handler(){
            @Override
            public void handleMessage(Message msg) {
                Intent intent = new Intent(SplashActivity.this,MainActivity.class);
                startActivity(intent);
            }
        };
        handler.sendEmptyMessageDelayed(0,3000);
    }
}

现在用方式2来做上一节进度条栗子

public class SecondActivity extends AppCompatActivity implements View.OnClickListener {
    private ProgressBar progressBar;
    private Button button;
    private TextView textView;
    private Handler handler;

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

        progressBar = (ProgressBar) findViewById(R.id.progressBar);
        button = (Button) findViewById(R.id.button);
        textView = (TextView) findViewById(R.id.tv_show_progress);
        button.setOnClickListener(this);

        InnerHandlerCallback innerHandlerCallback = new InnerHandlerCallback();
        handler = new Handler(innerHandlerCallback);
    }

    @Override
    public void onClick(View view) {
        InnerThread thread = new InnerThread();
        thread.start();
    }

    private class InnerHandlerCallback implements Handler.Callback{

        @Override
        public boolean handleMessage(Message msg) {
            if(msg.what == MESSAGE_UPDATE_PROGRESS) {
                Log.d("Handler","InnerHandlerCallback.handleMessage->"+MESSAGE_UPDATE_PROGRESS);
                progressBar.setProgress(msg.arg1);
                textView.setText(msg.arg1 + "/100");
            }else if(msg.what == MESSAGE_UPDATE_COMPLETE){
                Log.d("Handler","InnerHandlerCallback.handleMessage->"+MESSAGE_UPDATE_COMPLETE);
                Toast.makeText(SecondActivity.this,"更新进度完成",Toast.LENGTH_SHORT).show();
            }
            return false;
        }
    }

    public static final int MESSAGE_UPDATE_PROGRESS = 999;
    public static final int MESSAGE_UPDATE_COMPLETE = 998;
    private class InnerThread extends Thread{
        @Override
        public void run() {
            for(int i=0;i<=100;i++){
                //发消息，通知主线程更新UI
                Message msg = Message.obtain();
                msg.what = MESSAGE_UPDATE_PROGRESS;
                msg.arg1 = i;
                handler.sendMessage(msg);
                try {
                    Thread.sleep(50);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            //发出消息，标识更新进度完成
            Message msg = Message.obtain();
            msg.what = MESSAGE_UPDATE_COMPLETE;
            handler.sendMessage(msg);
        }
    }
}

如果InnerHandler增加一个构造方法，代码修改为

 private class InnerHandler extends Handler{
        public InnerHandler(Callback callback) {
            super(callback);
        }

        @Override
        public void handleMessage(Message msg) {
            if(msg.what == MESSAGE_UPDATE_PROGRESS) {
                Log.d("Handler","InnerHandler.handleMessage->"+MESSAGE_UPDATE_PROGRESS);
                progressBar.setProgress(msg.arg1);
                textView.setText(msg.arg1 + "/100");
            }else if(msg.what == MESSAGE_UPDATE_COMPLETE){
                Log.d("Handler","InnerHandler.handleMessage->"+MESSAGE_UPDATE_COMPLETE);
                Toast.makeText(SecondActivity.this,"更新进度完成",Toast.LENGTH_SHORT).show();
            }
        }
    }

在onCreate中

InnerHandlerCallback innerHandlerCallback = new InnerHandlerCallback();
        handler = new InnerHandler(innerHandlerCallback);

这两种方式同时存在，那么

InnerHandlerCallback.handleMessage->999
InnerHandler.handleMessage->999
......
InnerHandlerCallback.handleMessage->998
InnerHandler.handleMessage->998

如果

private class InnerHandlerCallback implements Handler.Callback{

        @Override
        public boolean handleMessage(Message msg) {
            ......
            }
            return true;
        }
    }

InnerHandlerCallback.handleMessage->999
InnerHandlerCallback.handleMessage->999
......
InnerHandlerCallback.handleMessage->998

方式3，反正不用……简单写

private class InnerThread extends Thread{
        @Override
        public void run() {
            for(int i=0;i<=100;i++){
                Message msg = Message.obtain(handler, new Runnable() {
                    @Override
                    public void run() {
                        Log.d("Handler", "Thread ID:"+currentThread().getId()+"Message.obtain->Runnable.run");
                    }
                });
                msg.sendToTarget();
                //发消息，通知主线程更新UI
               /* Message msg = Message.obtain();
                msg.what = MESSAGE_UPDATE_PROGRESS;
                msg.arg1 = i;
                handler.sendMessage(msg);*/
                try {
                    Thread.sleep(50);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            //发出消息，标识更新进度完成
            ......
        }
    }