Android实现一个简单的手电筒

添加手机权限

<uses-permission android:name="android.permission.FLASHLIGHT"></uses-permission>
<uses-permission android:name="android.permission.CAMERA"></uses-permission>
<uses-permission android:name="android.handware.camera"></uses-permission>
<uses-permission android:name="android.handware.autofocus"></uses-permission>

布局

<Button
android:id="@+id/btn_open"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>

代码

import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.camera2.CameraManager;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {
private Button btn_open;
private boolean status=false;
private CameraManager cm;
private Camera camera;
Camera.Parameters parameters;
MainActivity instance;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
instance=this;
btn_open= (Button) findViewById(R.id.btn_open);
btn_open.setText("open");
cm= (CameraManager) getSystemService(Context.CAMERA_SERVICE);
camera=Camera.open();
btn_open.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(!status){
btn_open.setText("close");
status=true;
new Thread(new TurnOnLight()).start();
}else{
parameters=camera.getParameters();
instance.parameters.setFlashMode("off");
camera.setParameters(instance.parameters);
btn_open.setText("open");
status=false;
}
}
});
}

@Override
protected void onDestroy() {
super.onDestroy();
camera.stopPreview();
camera.release();
camera = null;
}

private class TurnOnLight implements Runnable {
@Override
public void run() {
instance.parameters=instance.camera.getParameters();
instance.parameters.setFlashMode("torch");
instance.camera.setParameters(instance.parameters);
}
}
}

总结：

声明完调用系统硬件后，想要使用闪光灯则要创建CameraManager ,Camera，以及Camera.Parameters对象。顾名思义，前面两个不用解释，Parameters表示相机服务的参数（例如聚焦，闪关灯，滤镜等等的一些相关配置）

具体操作:
CameraManager cm= (CameraManager)getSystemService(Context.CAMERA_SERVICE)
Camera camera=Camera.open();
Camera.Parameters parameter=camera.getParameters();

//打开闪光灯
parameters.setFlashMode(“torch”);//打开
camera.setParameters(paramsters);
//关闭闪光灯

parameters.setFlashMode(“off”);//关闭
camera.setParameters(paramsters);