[Android] 開啟關閉閃光燈/手電筒 ~S－葛瑞斯肯樂活筆記

這個方法適用於Android API 24 以下(包含)，API 25以上用別的方法，預計成果的畫面:

Step1: 建立一個empty activity並且在 AndroidManifest.xml 中加入下述權限:

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

Step2: 在MainActivity.java 的onCreate中加入取得權限的程式碼，如下:

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    private static final int REQUEST = 1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        int readPermission = ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA);
        if(readPermission!= PackageManager.PERMISSION_GRANTED){
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.CAMERA}, REQUEST);
        } else {
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.CAMERA}, REQUEST);
        }
    }
}

Step3: 在layout的activity_main.xml中建立兩個按鈕，程式碼如下:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/on"
        android:layout_width="125dp"
        android:layout_height="61dp"
        android:layout_marginStart="160dp"
        android:layout_marginLeft="160dp"
        android:layout_marginTop="184dp"
        android:text="開手電筒"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/off"
        android:layout_width="117dp"
        android:layout_height="57dp"
        android:layout_marginBottom="40dp"
        android:text="關手電筒"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="@+id/on"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="@+id/on"
        app:layout_constraintTop_toBottomOf="@+id/on"
        app:layout_constraintVertical_bias="1.0" />

</androidx.constraintlayout.widget.ConstraintLayout>

Step4: 之後在MainActivity.java的onCreate()中產生兩個按鈕類別來連結layout上的兩個按鈕，跟Step2的程式碼只差在紅色字部分。

private static final int REQUEST = 1;
Button flashlightOn, flashlightOff;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
    int readPermission = ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA);
    if(readPermission!= PackageManager.PERMISSION_GRANTED){
        ActivityCompat.requestPermissions(this,
                new String[]{Manifest.permission.CAMERA}, REQUEST);
    } else {
        ActivityCompat.requestPermissions(this,
                new String[]{Manifest.permission.CAMERA}, REQUEST);
    }

    //取得layout上的連結
    flashlightOn = findViewById(R.id.on);
   flashlightOff = findViewById(R.id.off);
}

Step5: 將兩個按鈕分別註冊Listener事件，並且撰寫開啟閃光燈與關閉閃光燈的觸發程式，最後完整版程式碼如下:

package tw.idv.ken.flashlightdemo;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import android.Manifest;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    private static final int REQUEST = 1;
    Button flashlightOn, flashlightOff;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        int readPermission = ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA);
        if(readPermission!= PackageManager.PERMISSION_GRANTED){
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.CAMERA}, REQUEST);
        } else {
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.CAMERA}, REQUEST);
        }

        //取得layout上的連結
        flashlightOn = findViewById(R.id.on);
        flashlightOff = findViewById(R.id.off);

        //註冊listener
        flashlightOn.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                open();
            }
        });

        flashlightOff.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                close();
            }
        });

    }

    Camera mCamera = null; //設定為全域變數
    Camera.Parameters parameters; //camera參數

    //開啟閃光燈
    public void open() {
        mCamera = Camera.open();
        parameters = mCamera.getParameters(); //取得Camera的參數
        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
        mCamera.setParameters(parameters);
    }

  //關閉閃光燈
    public void close() {
        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF); //取得Camera的參數
        mCamera.setParameters(parameters);
        mCamera.release(); //使用完記得釋放掉

    }
}