Android中编写简单的手电筒小应用的实例教程

主要实现两个步骤：

1、实现打开和关闭闪光灯；而实现操作闪光灯主要通过Camera类

Camera camera = Camera.open();
Parameters mParameters = camera.getParameters();
mParameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);//打开Camera.Parameters.FLASH_MODE_OFF

则为关闭

amera.setParameters(mParameters)

2、自定义闪光灯的按钮；自定义控件主要是设置设置view的大小

onMeasure(int widthMeasureSpec, int heightMeasureSpec)

效果如下：

源码如下：

<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"
  android:gravity="center"
  android:background="@drawable/light"
  tools:context=".MainActivity" > 

  <com.android.xiong.xionglight.LightBkView
    android:id="@+id/light1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/> 

</RelativeLayout> 

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

package com.android.xiong.xionglight; 

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.Menu; 

public class MainActivity extends Activity { 

  private LightBkView light1; 

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    light1 = (LightBkView) findViewById(R.id.light1);
    //定义单击事件
    light1.setOnClickListener(light1); 

  } 

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

}

package com.android.xiong.xionglight; 

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.util.AttributeSet;
import android.view.View;
import android.view.View.OnClickListener; 

public class LightBkView extends View implements OnClickListener { 

  Camera camera = Camera.open();
  // 定义画皮
  Paint paint = new Paint();
  Paint paint1 = new Paint();
  int x = 0;
  int y = 0;
  // 打开闪光灯
  boolean islight; 

  public LightBkView(Context context, AttributeSet set) {
    super(context, set);
  } 

  @Override
  protected void onDraw(Canvas canvas) {
    // 获取控件的宽度和高度
    int width = this.getWidth();
    int heigth = this.getHeight();
    // 圆点的坐标
    x = width / 2;
    y = heigth / 2;
    //更换开关背景
    if(!islight){
    paint.setColor(Color.BLUE);
    canvas.drawCircle(x, y, 60, paint);
    paint1.setColor(Color.RED);
    paint1.setTextSize(20);
    canvas.drawText("打开闪光灯", x-50, y, paint1);
    invalidate();
    }else{
      paint.setColor(Color.WHITE);
      canvas.drawCircle(x, y, 60, paint);
      paint1.setColor(Color.RED);
      paint1.setTextSize(20);
      canvas.drawText("关闭闪光灯", x-50, y, paint1);
      invalidate();
    }
  } 

  // 定义View的大小
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    setMeasuredDimension(getWidth(widthMeasureSpec),
        getHeight(heightMeasureSpec)); 

  }
  //定义view的宽度
  public int getWidth(int widthMeasureSpec) {
    int reslut = 0;
    int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    if (widthMode == MeasureSpec.AT_MOST) {
      reslut = 120;
    }
    if (widthMode == MeasureSpec.EXACTLY) {
      reslut = MeasureSpec.getSize(widthMeasureSpec);
    }
    return reslut;
  }
  //定义view的高度
  public int getHeight(int heightMeasureSpec) {
    int reslut = 0;
    int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    if (heightMode == MeasureSpec.AT_MOST) {
      reslut = 120;
    }
    if (heightMode == MeasureSpec.EXACTLY) {
      reslut = MeasureSpec.getSize(heightMeasureSpec);
    }
    return reslut;
  } 

  // 实现闪光灯的的开关
  @Override
  public void onClick(View v) {
    if (!islight) {
      Parameters mParameters = camera.getParameters();
      mParameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
      camera.setParameters(mParameters);
      islight = true;
    } else {
      Parameters mParameters = camera.getParameters();
      mParameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
      camera.setParameters(mParameters);
      islight = false;
    }
  } 

}