android如何从系统或相机中获取照片

public class MainActivity extends Activity
{

private static final int PHOTO_REQUEST_CAREMA = 1;// 拍照
private static final int PHOTO_REQUEST_GALLERY = 2;// 从相册中选择
private static final int PHOTO_REQUEST_CUT = 3;// 结果

private ImageView iv_image;

/* 头像名称 */
private static final String PHOTO_FILE_NAME = "temp_photo.jpg";
private File tempFile;

@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this.iv_image = (ImageView) this.findViewById(R.id.iv_image);
}

/*
* 从相册获取
*/
public void gallery(View view)
{
// 激活系统图库，选择一张图片
Intent intent = new Intent(Intent.ACTION_PICK);
intent.setType("image/*");
// 开启一个带有返回值的Activity，请求码为PHOTO_REQUEST_GALLERY
startActivityForResult(intent, PHOTO_REQUEST_GALLERY);
}

/*
* 从相机获取
*/
public void camera(View view)
{
// 激活相机
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
// 判断存储卡是否可以用，可用进行存储
if (hasSdcard())
{
tempFile = new File(Environment.getExternalStorageDirectory(),
PHOTO_FILE_NAME);
// 从文件中创建uri
Uri uri = Uri.fromFile(tempFile);
intent.putExtra(MediaStore.EXTRA_OUTPUT, uri);
}
// 开启一个带有返回值的Activity，请求码为PHOTO_REQUEST_CAREMA
startActivityForResult(intent, PHOTO_REQUEST_CAREMA);
}

/*
* 剪切图片
*/
private void crop(Uri uri)
{
// 裁剪图片意图
Intent intent = new Intent("com.android.camera.action.CROP");
intent.setDataAndType(uri, "image/*");
intent.putExtra("crop", "true");
// 裁剪框的比例，1：1
intent.putExtra("aspectX", 1);
intent.putExtra("aspectY", 1);
// 裁剪后输出图片的尺寸大小
intent.putExtra("outputX", 250);
intent.putExtra("outputY", 250);

intent.putExtra("outputFormat", "JPEG");// 图片格式
intent.putExtra("noFaceDetection", true);// 取消人脸识别
intent.putExtra("return-data", true);
// 开启一个带有返回值的Activity，请求码为PHOTO_REQUEST_CUT
startActivityForResult(intent, PHOTO_REQUEST_CUT);
}

/*
* 判断sdcard是否被挂载
*/
private boolean hasSdcard()
{
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED))
{
return true;
} else
{
return false;
}
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
if (requestCode == PHOTO_REQUEST_GALLERY)
{
// 从相册返回的数据
if (data != null)
{
// 得到图片的全路径
Uri uri = data.getData();
crop(uri);
}

} else if (requestCode == PHOTO_REQUEST_CAREMA)
{
// 从相机返回的数据
if (hasSdcard())
{
crop(Uri.fromFile(tempFile));
} else
{
Toast.makeText(MainActivity.this, "未找到存储卡，无法存储照片！", 0).show();
}

} else if (requestCode == PHOTO_REQUEST_CUT)
{
// 从剪切图片返回的数据
if (data != null)
{
Bitmap bitmap = data.getParcelableExtra("data");
this.iv_image.setImageBitmap(bitmap);
}
try
{
// 将临时文件删除
tempFile.delete();
} catch (Exception e)
{
e.printStackTrace();
}

}

super.onActivityResult(requestCode, resultCode, data);
}
}