<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>