<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"
  tools:context=".MainActivity" >

  <Button
    android:onClick="click"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:text="调用系统相机拍照" />

</RelativeLayout>

 <activity android:name="com.android.camera.Camera"
        android:configChanges="orientation|keyboardHidden"
        android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"
        android:screenOrientation="landscape"
        android:clearTaskOnLaunch="true"
        android:taskAffinity="android.task.camera">
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
      <intent-filter>
        <action android:name="android.media.action.IMAGE_CAPTURE" />
        <category android:name="android.intent.category.DEFAULT" />
      </intent-filter>
      <intent-filter>
        <action android:name="android.media.action.STILL_IMAGE_CAMERA" />
        <category android:name="android.intent.category.DEFAULT" />
      </intent-filter>
    </activity>

public class MainActivity extends Activity {

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

  public void click(View view) {
    /*
     * <intent-filter> <action
     * android:name="android.media.action.IMAGE_CAPTURE" /> <category
     * android:name="android.intent.category.DEFAULT" /> </intent-filter>
     */
    // 激活系统的照相机进行拍照
    Intent intent = new Intent();
    intent.setAction("android.media.action.IMAGE_CAPTURE");
    intent.addCategory("android.intent.category.DEFAULT");
    
    //保存照片到指定的路径
    File file = new File("/sdcard/image.jpg");
    Uri uri = Uri.fromFile(file);
    intent.putExtra(MediaStore.EXTRA_OUTPUT, uri);
    
    startActivity(intent);

  }

}

public class MainActivity extends Activity {

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

  public void click(View view) {
    /*
     * <intent-filter> <action
     * android:name="android.media.action.VIDEO_CAPTURE" /> <category
     * android:name="android.intent.category.DEFAULT" /> </intent-filter>
     */
    // 激活系统的照相机进行录像
    Intent intent = new Intent();
    intent.setAction("android.media.action.VIDEO_CAPTURE");
    intent.addCategory("android.intent.category.DEFAULT");

    // 保存录像到指定的路径
    File file = new File("/sdcard/video.3pg");
    Uri uri = Uri.fromFile(file);
    intent.putExtra(MediaStore.EXTRA_OUTPUT, uri);

    startActivityForResult(intent, 0);
  }
  
  @Override
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    Toast.makeText(this, "调用照相机完毕", 0).show();
    super.onActivityResult(requestCode, resultCode, data);
    
  }

}