利用Camera实现手电筒功能

现在，手机上一般都有相机功能，可以利用相机的闪光灯制作一个手电筒的小程序。

在AndroidManifest中注册相应的权限：

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

打开闪光灯关键代码：

camera = Camera.open();

final Parameters p = camera.getParameters();

p.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(p);
camera.stopPreview();

关闭闪关灯关键代码：

camera = Camera.open();

final Parameters p = camera.getParameters();

p.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(p);
camera.stopPreview();

我的测试代码：

AndroidManifest.xml文件

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.spread.flashlight"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="15" />

    <uses-permission android:name="android.permission.CAMERA" />

    <uses-feature android:name="android.hardware.camera" />

 

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".FlashLightActivity"
            android:label="@string/title_activity_flash_light" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Layout文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <!--
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world"
        tools:context=".FlashLightActivity" />
    -->

<Button
        android:id="@+id/buttonFlashlight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/torch" />

</RelativeLayout>

java测试代码文件

package com.spread.flashlight;

import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class FlashLightActivity extends Activity {

    private boolean isLighOn = false;
    private Camera camera;
    private Button button;

    @Override
    protected void onStop() {
        super.onStop();
if (camera != null) {
            camera.release();
        }
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
setContentView(R.layout.activity_flash_light);

        button = (Button) findViewById(R.id.buttonFlashlight);

        Context context = this;
        PackageManager pm = context.getPackageManager();

        // if device support camera?
        if (!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
            Log.e("err", "Device has no camera!");
            return;
        }

        camera = Camera.open();
        final Parameters p = camera.getParameters();

        button.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {

                if (isLighOn) {
                    Log.i("info", "torch is turn off!");

p.setFlashMode(Parameters.FLASH_MODE_OFF);
                    camera.setParameters(p);
                    camera.stopPreview();
                    isLighOn = false;
                } else {
                    Log.i("info", "torch is turn on!");

                    p.setFlashMode(Parameters.FLASH_MODE_TORCH);
                    camera.setParameters(p);
                    camera.stopPreview();
                    isLighOn = true;
                }
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_flash_light, menu);
        return true;
    }
}

可惜我的手机硬件上不支持闪光灯亮度的设置；如果支持的话，就可以调节这一参数，达到手电筒亮度档位的效果了。