Android 打开闪光灯（手电筒）

package com.example.openBackLight;

import android.app.Activity;
import android.hardware.Camera;
import android.os.Bundle;
import android.view.View;
import android.hardware.Camera.Parameters;
import android.widget.Button;

public class MyActivity extends Activity {
    private Button button;
    private Camera camera;
    private Parameters parameters;
    public boolean hasClosed = true; // 定义开关状态，状态为false，打开状态，状态为true，关闭状态

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        button = (Button) findViewById(R.id.button);
    }

    public void toggleLight(View view) {
        if (hasClosed) {
            camera = Camera.open();
            parameters = camera.getParameters();
            parameters.setFlashMode(Parameters.FLASH_MODE_TORCH);// 开启
            camera.setParameters(parameters);
            button.setText("关闭闪光灯");
            hasClosed = false;
        } else {
            parameters.setFlashMode(Parameters.FLASH_MODE_OFF);// 关闭
            camera.setParameters(parameters);
            button.setText("开启闪光灯");
            hasClosed = true;
            camera.release();
        }
    }
    
}

布局文件很简单，就一个button，点击的时候会调用toggleLight()方法.

要加入以下权限：

    <uses-permission android:name="android.permission.FLASHLIGHT" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" />