手机上的本地图片资源分为两种,一种是从本地相册获取,一种是从本地相机拍照获取。
1、获取图片很简单,调用系统提供的Intent对象,启动本地相册和照相机功能。
代码如下:
//开始拍照
private void startCamera() {
try{
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if(intent.resolveActivity(getPackageManager()) != null){
imageUri = setFileURI();//给即将拍照获取的照片命名,并返回它的uri
intent.setAction(MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(MediaStore.EXTRA_OUTPUT,imageUri);
startActivityForResult(intent,CAMERA_REQUEST);
}
}catch (ActivityNotFoundException e){
e.printStackTrace();
}
}
//给图片统一定义一个存放位置
private Uri setFileURI(){
//创建照片的存储目录
PHOTO_DIR.mkdirs();
String fileName = getFileName();
//给照片命名
File file = new File(PHOTO_DIR,fileName);
return Uri.fromFile(file);
}
//用当前时间作为拍照得到的照片的名字
protected String getFileName(){
Date date = new Date(System.currentTimeMillis());
SimpleDateFormat sdf = new SimpleDateFormat("'img'_yyyy-MM-dd HH:mm:ss", Locale.CHINA);
return sdf.format(date)+".jpg";
}
//从相册获取图片
private void getPhotoFromAlbum() {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/*");
startActivityForResult(intent,PHOTOALBUM_REQUEST);
}
2、获取图片的路径。
对于拍照获取的图片,我们前面已经把图片的uri放到imgeUri里了,直接取出即可使用。
对于从本地相册取回的图片,可以从OnActivityResult方法中的Intent data中取回图片Uri
imageUri = data.getData()。
下面就是获取图片的路径了。
int sdkVersion = Build.VERSION.SDK_INT;
if(sdkVersion >= 19){//android 5.0以上直接返回的是图片的路径
path = getPath_above19(this,imgUri);//或者直接使用path = imgUri.getPath();
}else{
path = getPath_below19(imgUri);
}
/**
* API19以下获取图片路径的方法
* @param uri
*/
private String getFilePath_below19(Uri uri) {
//这里开始的第二部分,获取图片的路径:低版本的是没问题的,但是sdk>19会获取不到
String[] proj = {MediaStore.Images.Media.DATA};
//好像是android多媒体数据库的封装接口,具体的看Android文档
Cursor cursor = getContentResolver().query(uri, proj, null, null, null);
//获得用户选择的图片的索引值
int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
System.out.println("***************" + column_index);
//将光标移至开头 ,这个很重要,不小心很容易引起越界
cursor.moveToFirst();
//最后根据索引值获取图片路径 结果类似:/mnt/sdcard/DCIM/Camera/IMG_20151124_013332.jpg
String path = cursor.getString(column_index);
System.out.println("path:" + path);
return path;
}
/**
* APIlevel 19以上才有
* 创建项目时,我们设置了最低版本API Level,比如我的是10,
* 因此,AS检查我调用的API后,发现版本号不能向低版本兼容,
* 比如我用的“DocumentsContract.isDocumentUri(context, uri)”是Level 19 以上才有的,
* 自然超过了10,所以提示错误。
* 添加 @TargetApi(Build.VERSION_CODES.KITKAT)即可。
*
* @param context
* @param uri
* @return
*/
@TargetApi(Build.VERSION_CODES.KITKAT)
public static String getPath_above19(final Context context, final Uri uri) {
final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
// DocumentProvider
if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
// ExternalStorageProvider
if (isExternalStorageDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];
if ("primary".equalsIgnoreCase(type)) {
return Environment.getExternalStorageDirectory() + "/" + split[1];
}
// TODO handle non-primary volumes
}
// DownloadsProvider
else if (isDownloadsDocument(uri)) {
final String id = DocumentsContract.getDocumentId(uri);
final Uri contentUri = ContentUris.withAppendedId(
Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));
return getDataColumn(context, contentUri, null, null);
}
// MediaProvider
else if (isMediaDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];
Uri contentUri = null;
if ("image".equals(type)) {
contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
} else if ("video".equals(type)) {
contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
} else if ("audio".equals(type)) {
contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
}
final String selection = "_id=?";
final String[] selectionArgs = new String[]{
split[1]
};
return getDataColumn(context, contentUri, selection, selectionArgs);
}
}
// MediaStore (and general)
else if ("content".equalsIgnoreCase(uri.getScheme())) {
// Return the remote address
if (isGooglePhotosUri(uri))
return uri.getLastPathSegment();
return getDataColumn(context, uri, null, null);
}
// File
else if ("file".equalsIgnoreCase(uri.getScheme())) {
return uri.getPath();
}
return null;
}
/**
* Get the value of the data column for this Uri. This is useful for
* MediaStore Uris, and other file-based ContentProviders.
*
* @param context The context.
* @param uri The Uri to query.
* @param selection (Optional) Filter used in the query.
* @param selectionArgs (Optional) Selection arguments used in the query.
* @return The value of the _data column, which is typically a file path.
*/
public static String getDataColumn(Context context, Uri uri, String selection,
String[] selectionArgs) {
Cursor cursor = null;
final String column = "_data";
final String[] projection = {column};
try {
cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
null);
if (cursor != null && cursor.moveToFirst()) {
final int index = cursor.getColumnIndexOrThrow(column);
return cursor.getString(index);
}
} finally {
if (cursor != null)
cursor.close();
}
return null;
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is ExternalStorageProvider.
*/
public static boolean isExternalStorageDocument(Uri uri) {
return "com.android.externalstorage.documents".equals(uri.getAuthority());
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is DownloadsProvider.
*/
public static boolean isDownloadsDocument(Uri uri) {
return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is MediaProvider.
*/
public static boolean isMediaDocument(Uri uri) {
return "com.android.providers.media.documents".equals(uri.getAuthority());
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is Google Photos.
*/
public static boolean isGooglePhotosUri(Uri uri) {
return "com.google.android.apps.photos.content".equals(uri.getAuthority());
}
3、处理图片。
从本地获取的图片大小往往不符合我们的要求,我们可以做一些压缩处理。
/**
* 压缩图片大小
* @param path 图片的路径
* @return
*/
private Bitmap decodeSampleBitmap(String path) {
//refundPhoto是将要呈现图片的ImageView控件
int targetW = refundPhoto.getWidth();
int targetH = refundPhoto.getHeight();
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(path,options);
int photoW = options.outWidth;
int photoH = options.outHeight;
//获取图片的最大压缩比
int scaleFactor = Math.max(photoW/targetW,photoH/targetH);
options.inJustDecodeBounds = false;
options.inSampleSize = scaleFactor;
options.inPurgeable = true;
Bitmap bitmap = BitmapFactory.decodeFile(path,options);
return bitmap;
}
Bitmap bm = decodeSampleBitmap(path);
refundPhoto.setImageBitmap(bm);