Android更新UI界面的幾種方法的使用

更新UI界面：由於性能要求，Android不能在子線程中訪問UI控件，只能在UI線程中更新UI，如果要想在其他線程中更新UI，可以通過以下幾種方法更新UI：

1、使用Handler的handleMessage(Message msg)方法；

public class MainActivity extends AppCompatActivity {

    private TextView mTextView;

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            mTextView.setText("子線程通過handleMessage更新後的UI");
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextView = (TextView) findViewById(R.id.text_view_handle_send);
        new MyThread().start();
    }

    class MyThread extends Thread {
        @Override
        public void run() {
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            Message message = Message.obtain();
            handler.sendMessage(message);
        }
    }
}

2、使用Handler的post(new Runnable())方法；

public class MainActivity extends AppCompatActivity {

    private TextView mTextView;

    private Handler handler = new Handler();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextView = (TextView) findViewById(R.id.text_view_handle_post);
        handler.post(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                mTextView.setText("子線程通過post方法更新後的UI");
            }
        });
    }
}

3、使用runOnUiThread(new Runnable())方法，此方法只能運行在Activity當中；

public class MainActivity extends AppCompatActivity {
    private TextView mTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextView = (TextView) findViewById(R.id.text_view_run_on_ui);
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                mTextView.setText("子線程通過runOnUiThread方法更新後的UI");
            }
        });
    }
}

4、使用View的post(new Runnable())方法，其底層也是調用Handler.post(new Runnable())方法；

public class MainActivity extends AppCompatActivity {

    private TextView mTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextView = (TextView) findViewById(R.id.text_view_post);
        mTextView.post(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                mTextView.setText("子線程通過view.post方法更新後的UI");
            }
        });
    }
}

5、使用AsyncTask異步任務類；

public class MainActivity extends AppCompatActivity {

    private TextView mTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextView = (TextView) findViewById(R.id.text_view_async_task);
        new MyAsyncTask().execute();
    }

    class MyAsyncTask extends AsyncTask<String, String, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected String doInBackground(String... params) {
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            String str = "子線程通過AsyncTask異步更新後的UI";
            // 返回結果給到onPostExecute方法
            return str;
        }

        @Override
        protected void onProgressUpdate(String... values) {
            super.onProgressUpdate(values);
        }

        @Override
        protected void onPostExecute(String result) {
            mTextView.setText(result);
            super.onPostExecute(result);
        }
    }
}