<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

    <Button
        android:id="@+id/button_open"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/textView1"
        android:layout_below="@+id/textView1"
        android:layout_marginTop="38dp"
        android:text="open" />

    <Button
        android:id="@+id/button_close"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/button_open"
        android:layout_below="@+id/button_open"
        android:layout_marginTop="50dp"
        android:text="close" />

</RelativeLayout>

package com.qiantu.flashlight;

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

public class MainActivity extends Activity {
 private Camera camera;
 private Button openBtn;
 private Button closeBtn;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  openBtn = (Button) findViewById(R.id.button_open);
  openBtn.setOnClickListener(new OnClickListener() {
   @Override
   public void onClick(View v) {
    if (null != camera) {
     Parameters parameters = camera.getParameters();
     parameters.setFlashMode(Parameters.FLASH_MODE_TORCH);
     camera.setParameters(parameters);
    }
   }
  });

  closeBtn = (Button) findViewById(R.id.button_close);
  closeBtn.setOnClickListener(new OnClickListener() {
   @Override
   public void onClick(View v) {
    if (null != camera) {
     Parameters parameters = camera.getParameters();
     parameters.setFlashMode(Parameters.FLASH_MODE_OFF);
     camera.setParameters(parameters);
    }
   }
  });
 }

 @Override
 protected void onStart() {
  super.onStart();
  camera = Camera.open();
 }

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

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

}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.qiantu.flashlight"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />
   
    <!-- 添加的部分 -->
    <uses-feature android:name="android.hardware.camera" />
 <uses-feature android:name="android.hardware.autofocus" />
    <uses-permission android:name="android.permission.CAMERA" />
 <uses-permission android:name="android.permission.FLASHLIGHT" />
 <uses-permission android:name="android.permission.DISABLE_KEYGUARD" />
 <!-- end -->

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.qiantu.flashlight.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>