Android Camera系列开发 (一): 通过Intent拍照

概述

使用Camera有两种方式：通过Intent使用已有的app和通过Camera构建自己的app。

Camera相关声明

如果你的应用程序要使用Camera，则必须获得使用许可，需要在AndroidManifest.xml中加入如下声明。

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

如果你的应用程序必须有Camera才能使用，则声明如下：

<uses-featureandroid:name="android.hardware.camera" />

否则应声明如下：

<uses-featureandroid:name="android.hardware.camera"android:required="false" />

其他相关声明：

存储：<uses-permissionandroid:name="android.permission.WRITE_EXTERNAL_STORAGE" />

语音：<uses-permissionandroid:name="android.permission.RECORD_AUDIO" />

位置：<uses-permissionandroid:name="android.permission.ACCESS_FINE_LOCATION" />

核心类

Itent：通过它进行Camera编程更简单。

Camera：通过它可以控制相机，构建功能更强大的Camera应用。

SurfaceView：提供实时预览功能。

通过Itent来实现拍照

第一步：在Eclipse中创建一个名为Photo的Android工程，可参见Hello world的例子；

第二步：在AndroidManifest.xml中添加使用Camera相关的声明如下：

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

第三步：编写MainActivity类。

(1) 添加成员变量

(2) 修改OnCreate方法

(3) 增加onActivityResult方法

(4) 新增两个辅助方法

类的源代码如下：

[java]
public class MainActivity extends Activity {
    private static final int MEDIA_TYPE_IMAGE = 1;
    private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE = 100;

    private Intent intent = null;
    private Uri fileUri    = null;

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

        intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);//create a intent to take picture
        fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE); // create a file to save the image
        intent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri); // set the image file name

        // start the image capture Intent
        startActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
            if (resultCode == RESULT_OK) {
                // Image captured and saved to fileUri specified in the Intent
                Toast.makeText(this, "Image saved to:\n" +
                         data.getData(),
                         Toast.LENGTH_LONG).show();
            } else if (resultCode == RESULT_CANCELED) {
                // User cancelled the image capture
            } else {
                // Image capture failed, advise user
            }
        }
    }

    /** Create a file Uri for saving an image or video */
    private static Uri getOutputMediaFileUri(int type){
          return Uri.fromFile(getOutputMediaFile(type));
    }

    /** Create a File for saving an image or video */
    private static File getOutputMediaFile(int type){
        // To be safe, you should check that the SDCard is mounted
        // using Environment.getExternalStorageState() before doing this.
        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
                  Environment.DIRECTORY_PICTURES), "MyCameraApp");
        // This location works best if you want the created images to be shared
        // between applications and persist after your app has been uninstalled.

        if (! mediaStorageDir.exists()){
            if (! mediaStorageDir.mkdirs()){
                Log.d("MyCameraApp", "failed to create directory");
                return null;
            }
        }

        // Create a media file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File mediaFile = null;
        if (type == MEDIA_TYPE_IMAGE){
            mediaFile = new File(mediaStorageDir.getPath() + File.separator +
            "IMG_"+ timeStamp + ".jpg");
        }

        return mediaFile;
    }
}

public class MainActivity extends Activity {
private static final int MEDIA_TYPE_IMAGE = 1;
private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE

补充：移动开发 , Android ,