xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">
    <TextView
        android:layout_width="50dp"
        android:layout_height="50dp" />
    <ToggleButton
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button"
        android:textOn="檢測當前手機電量"
        android:textOff="停止檢測"/>
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/text"/>
</LinearLayout>

 

java:

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.CompoundButton;
import android.widget.TextView;
import android.widget.ToggleButton;

import com.example.camera.R;

public class MainActivity extends AppCompatActivity {
    private ToggleButton button;
    private TextView text;
    BroadcastReceiver receiver = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (ToggleButton) findViewById(R.id.button);
        text = (TextView) findViewById(R.id.text);
        final BroadcastReceiver receiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                if (Intent.ACTION_BATTERY_CHANGED.equals(action)) {
                    int current = intent.getExtras().getInt("level");
                    int total = intent.getExtras().getInt("scale");
                    int value = current * 100 / total;
                    text.setText("當前電量是" + value + "%" + "");
                }
            }
        };
        button.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {
                if (isChecked) {
                    IntentFilter filter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
                    registerReceiver(receiver, filter);
                } else {
                    unregisterReceiver(receiver);
                    text.setText("");
                }
            }
        });
    }
}
 

1. BroadcastReceiver 用於監聽與接收App發出的廣播訊息並作出響應
2. onReceive 廣播接收器接收到相應廣播後，會自動回撥 onReceive() 方法
3. CompoundButton.OnCheckedChangeListener() 可選中按鈕的是否選中方法
4. registerReceiver(receiver, filter); 註冊廣播接收器