android 獲取視頻和圖片的縮略圖
要得到圖片的縮略圖，可以有兩種方法：
一種是利用BitmapFactory中的decodeFile對圖片進行壓縮。
一種是直接取縮略圖
直接訪問 android.provider.MediaStore.Images.Thumbnails 和android.provider.MediaStore.Video.Thumbnails這兩個數據庫，可以獲得設備中圖片和視頻的縮略圖
// 取縮略圖的方法
cr = getContentResolver();
String[] projection = { Thumbnails._ID, Thumbnails.IMAGE_ID, Thumbnails.DATA };
Cursor cursor = cr.query(Thumbnails.EXTERNAL_CONTENT_URI, projection, null, null, null);
getColumnData(cursor);
private void getColumnData(Cursor cur) {
if (cur.moveToFirst()) {
int _id;
int image_id;
String image_path;
int _idColumn = cur.getColumnIndex(Thumbnails._ID);
int image_idColumn = cur.getColumnIndex(Thumbnails.IMAGE_ID);
int dataColumn = cur.getColumnIndex(Thumbnails.DATA);
do {
// Get the field values
_id = cur.getInt(_idColumn);
image_id = cur.getInt(image_idColumn);
image_path = cur.getString(dataColumn);
// Do something with the values.
Log.i(TAG, _id + " image_id:" + image_id + " path:"
+ image_path + "---");
HashMap<String, String> hash = new HashMap<String, String>();
hash.put("image_id", image_id + "");
hash.put("path", image_path);
list.add(hash);
} while (cur.moveToNext());
}
}
// 取實際圖片的方法
String columns[] = new String[] { Media.DATA, Media._ID, Media.TITLE, Media.DISPLAY_NAME, Media.SIZE };
// 得到一個游標
cursor = this.getContentResolver().query(Media.EXTERNAL_CONTENT_URI, columns, null, null, null);
// 獲取指定列的索引
photoIndex = cursor.getColumnIndexOrThrow(Media.DATA);
photoNameIndex = cursor.getColumnIndexOrThrow(Media.DISPLAY_NAME);
photoIDIndex = cursor.getColumnIndexOrThrow(Media._ID);
photoTitleIndex = cursor.getColumnIndexOrThrow(Media.TITLE);
photoSizeIndex = cursor.getColumnIndexOrThrow(Media.SIZE);
// 獲取圖片總數
totalNum = cursor.getCount();
// 因為縮略圖數據庫和實際圖數據庫的id是相同的，所以可以根據取出的縮略圖的id去找開真正的圖片
OnItemClickListener listener = new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// TODO Auto-generated method stub
String image_id = list.get(position).get("image_id");
Log.i(TAG, "---(^o^)----" + image_id);
String[] projection = { Media._ID, Media.DATA };
Cursor cursor = cr.query(Media.EXTERNAL_CONTENT_URI, projection,
Media._ID + "=" + image_id, null, null);
if (cursor != null) {
cursor.moveToFirst();
String path = cursor.getString(cursor.getColumnIndex(Media.DATA));
Intent intent = new Intent(ThumbnailActivity.this, ImageViewer.class);
intent.putExtra("path", path);
startActivity(intent);
} else {
Toast.makeText(ThumbnailActivity.this, "Image doesn't exist!",
Toast.LENGTH_SHORT).show();
}
}
};
有關具體的縮略圖可以通過getThumbnail(ContentResolver cr, long origId, int kind, BitmapFactory.Options options) 或getThumbnail(ContentResolver cr, long origId, long groupId, int kind, BitmapFactory.Options options) 方法獲取，這兩種方法返回Bitmap類型，而縮略圖的分辨率可以從HEIGHT和WIDTH兩個字段提取，在Android上縮略圖分為兩種，通過讀取 KIND字段來獲得，分別為MICRO_KIND和MINI_KIND 分別為微型和迷你兩種縮略模式，前者的分辨率更低。這樣我們平時獲取文件系統的某個圖片預覽時，可以直接調用系統縮略圖，而不用自己重新計算。
縮略圖保存在SD卡的DCIM目錄，里面的.thumbnails是圖片的，而.video_thumbnails是視頻的，這兩個文件夾為隱藏屬性
--------------------------------------------------------------------------------------
從Android2.2開始系統新增了一個縮略圖ThumbnailUtils類，位于framework的 android.media.ThumbnailUtils位置，可以幫助我們從mediaprovider中獲取系統中的視頻或圖片文件的縮略圖，該類提供了三種靜態方法可以直接調用獲取。
1. static Bitmap createVideoThumbnail(String filePath, int kind)
//獲取視頻文件的縮略圖，第一個參數為視頻文件的位置，比如/sdcard/android123.3gp，而第二個參數可以為MINI_KIND或 MICRO_KIND最終和分辨率有關
2. static Bitmap extractThumbnail(Bitmap source, int width, int height, int options)
//直接對Bitmap進行縮略操作，最后一個參數定義為OPTIONS_RECYCLE_INPUT，來回收資源
3. static Bitmap extractThumbnail(Bitmap source, int width, int height)
// 這個和上面的方法一樣，無options選項
--------------------------------------------------------------------------------------
獲取音頻文件：
Cursor cursor = getContentResolver().query(
MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null, null,
MediaStore.Audio.Media.DEFAULT_SORT_ORDER);
cursor.moveToFirst();
int counter = cursor.getCount();
String title = cursor.getString(cursor
.getColumnIndexOrThrow(MediaStore.Audio.Media.TITLE));
Log.w("tag", "before looping,title=" + title);
for (int j = 0; j < counter; j++) {
Log.w("tag", "title=" + cursor.getString(cursor
.getColumnIndex(MediaStore.Audio.Media.TITLE)));
cursor.moveToNext();
}
cursor.close();
---------------------------------------------------------------------------------------
增加，代碼如下所以：
ContentValues values = new ContentValues();
values.put(MediaStore.Audio.Playlists.Members.PLAY_ORDER,0);
resolver.insert(_uri, values);
ContentValues values = new ContentValues();
values.put(MediaStore.Audio.Playlists.Members.PLAY_ORDER,0);
resolver.insert(_uri, values);
這個insert傳遞的參數只有兩個，一個是Uri(同查詢那個Uri)，另一個是ContentValues。這個ContentValuses對應于數據庫的一行數據，只要用put方法把每個列的設置好之后，直接利用insert方
法去插入就好了。
更新，代碼如下：
ContentResolver resolver = ctx.getContentResolver();
Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
ContentValues values = new ContentValues();
values.put(MediaStore.Audio.Media.DATE_MODIFIED, sid);
resolver.update(MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI,values, where, selectionArgs);
ContentResolver resolver = ctx.getContentResolver();
Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
ContentValues values = new ContentValues();
values.put(MediaStore.Audio.Media.DATE_MODIFIED, sid);
resolver.update(MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI,values, where, selectionArgs);
上面update方法和查詢還有增加里的參數都很類似，這里就不再重復敘述了，大家也可直接參考google的文檔，那里也寫的很清楚。
刪除，代碼如下：
ContentResolver resolver = ctx.getContentResolver();
resolver.delete(MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI,where, selectionArgs);
ContentResolver resolver = ctx.getContentResolver();
resolver.delete(MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI,where, selectionArgs);
//--------------------------------------------------------------------------------
在實際開發中遇到一個問題，只能讀出一個文件的縮略圖，在/mnt/sdcard/DCIM/.Thumbnails下，也只有一個縮略圖文件
另外還有一個文件 image_last_thumb
因時間太緊張沒有清楚查到原因，網上有說是和sd卡的類型有關，因為不明白原因，無奈之下只有使用取原圖壓縮的辦法。
http://forum.xda-developers.com/showthread.php?t=558168&page=2
// -------------------------------------------------------------------------------
http://www.netmite.com/android/mydroid/donut/packages/apps/Camera/src/com/android/camera/ImageManager.java
/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.camera;
import com.android.camera.gallery.BaseCancelable;
import com.android.camera.gallery.BaseImageList;
import com.android.camera.gallery.Cancelable;
import com.android.camera.gallery.DrmImageList;
import com.android.camera.gallery.IImage;
import com.android.camera.gallery.IImageList;
import com.android.camera.gallery.Image;
import com.android.camera.gallery.ImageList;
import com.android.camera.gallery.ImageListUber;
import com.android.camera.gallery.SingleImageList;
import com.android.camera.gallery.VideoList;
import com.android.camera.gallery.VideoObject;
import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.ContentValues;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.location.Location;
import android.net.Uri;
import android.os.Environment;
import android.os.Parcel;
import android.provider.DrmStore;
import android.provider.MediaStore;
import android.provider.MediaStore.Images;
import android.provider.MediaStore.Images.ImageColumns;
import android.util.Log;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.concurrent.ExecutionException;
/**
* ImageManager is used to retrieve and store images
* in the media content provider.
*/
public class ImageManager {
private static final String TAG = "ImageManager";
private static final Uri STORAGE_URI = Images.Media.EXTERNAL_CONTENT_URI;
private static final Uri THUMB_URI
= Images.Thumbnails.EXTERNAL_CONTENT_URI;
private static final Uri VIDEO_STORAGE_URI =
Uri.parse("content://media/external/video/media");
/**
* Enumerate type for the location of the images in gallery.
*/
public static enum DataLocation { NONE, INTERNAL, EXTERNAL, ALL }
public static final Bitmap DEFAULT_THUMBNAIL =
Bitmap.createBitmap(32, 32, Bitmap.Config.RGB_565);
public static final Bitmap NO_IMAGE_BITMAP =
Bitmap.createBitmap(1, 1, Bitmap.Config.RGB_565);
public static final int SORT_ASCENDING = 1;
public static final int SORT_DESCENDING = 2;
public static final int INCLUDE_IMAGES = (1 << 0);
public static final int INCLUDE_DRM_IMAGES = (1 << 1);
public static final int INCLUDE_VIDEOS = (1 << 2);
public static final String CAMERA_IMAGE_BUCKET_NAME =
Environment.getExternalStorageDirectory().toString()
+ "/DCIM/Camera";
public static final String CAMERA_IMAGE_BUCKET_ID =
getBucketId(CAMERA_IMAGE_BUCKET_NAME);
/**
* Matches code in MediaProvider.computeBucketValues. Should be a common
* function.
*/
public static String getBucketId(String path) {
return String.valueOf(path.toLowerCase().hashCode());
}
/**
* OSX requires plugged-in USB storage to have path /DCIM/NNNAAAAA to be
* imported. This is a temporary fix for bug#1655552.
*/
public static void ensureOSXCompatibleFolder() {
File nnnAAAAA = new File(
Environment.getExternalStorageDirectory().toString()
+ "/DCIM/100ANDRO");
if ((!nnnAAAAA.exists()) && (!nnnAAAAA.mkdir())) {
Log.e(TAG, "create NNNAAAAA file: " + nnnAAAAA.getPath()
+ " failed");
}
}
public static int roundOrientation(int orientationInput) {
int orientation = orientationInput;
if (orientation == -1) {
orientation = 0;
}
orientation = orientation % 360;
int retVal;
if (orientation < (0 * 90) + 45) {
retVal = 0;
} else if (orientation < (1 * 90) + 45) {
retVal = 90;
} else if (orientation < (2 * 90) + 45) {
retVal = 180;
} else if (orientation < (3 * 90) + 45) {
retVal = 270;
} else {
retVal = 0;
}
return retVal;
}
/**
* @return true if the mimetype is an image mimetype.
*/
public static boolean isImageMimeType(String mimeType) {
return mimeType.startsWith("image/");
}
/**
* @return true if the mimetype is a video mimetype.
*/
public static boolean isVideoMimeType(String mimeType) {
return mimeType.startsWith("video/");
}
/**
* @return true if the image is an image.
*/
public static boolean isImage(IImage image) {
return isImageMimeType(image.getMimeType());
}
/**
* @return true if the image is a video.
*/
public static boolean isVideo(IImage image) {
// This is the right implementation, but we use instanceof for speed.
//return isVideoMimeType(image.getMimeType());
return (image instanceof VideoObject);
}
public static void setImageSize(ContentResolver cr, Uri uri, long size) {
ContentValues values = new ContentValues();
values.put(Images.Media.SIZE, size);
cr.update(uri, values, null, null);
}
public static Uri addImage(ContentResolver cr, String title,
long dateTaken, Location location,
int orientation, String directory, String filename) {
ContentValues values = new ContentValues(7);
values.put(Images.Media.TITLE, title);
// That filename is what will be handed to Gmail when a user shares a
// photo. Gmail gets the name of the picture attachment from the
// "DISPLAY_NAME" field.
values.put(Images.Media.DISPLAY_NAME, filename);
values.put(Images.Media.DATE_TAKEN, dateTaken);
values.put(Images.Media.MIME_TYPE, "image/jpeg");
values.put(Images.Media.ORIENTATION, orientation);
if (location != null) {
values.put(Images.Media.LATITUDE, location.getLatitude());
values.put(Images.Media.LONGITUDE, location.getLongitude());
}
if (directory != null && filename != null) {
String value = directory + "/" + filename;
values.put(Images.Media.DATA, value);
}
return cr.insert(STORAGE_URI, values);
}
private static class AddImageCancelable extends BaseCancelable<Void> {
private final Uri mUri;
private final ContentResolver mCr;
private final int mOrientation;
private final Bitmap mSource;
private final byte [] mJpegData;
public AddImageCancelable(Uri uri, ContentResolver cr,
int orientation, Bitmap source, byte[] jpegData) {
if (source == null && jpegData == null || uri == null) {
throw new IllegalArgumentException("source cannot be null");
}
mUri = uri;
mCr = cr;
mOrientation = orientation;
mSource = source;
mJpegData = jpegData;
}
@Override
protected Void execute() throws InterruptedException,
ExecutionException {
boolean complete = false;
try {
long id = ContentUris.parseId(mUri);
BaseImageList il = new ImageList(
STORAGE_URI, THUMB_URI, SORT_ASCENDING, null);
il.open(mCr);
// TODO: Redesign the process of adding new images. We should
// create an <code>IImage</code> in "ImageManager.addImage"
// and pass the image object to here.
Image image = new Image(il, mCr, id, 0, il.contentUri(id), null,
0, null, 0, null, null, 0);
String[] projection = new String[] {
ImageColumns._ID,
ImageColumns.MINI_THUMB_MAGIC, ImageColumns.DATA};
Cursor c = mCr.query(mUri, projection, null, null, null);
String filepath;
try {
c.moveToPosition(0);
filepath = c.getString(2);
} finally {
c.close();
}
runSubTask(image.saveImageContents(
mSource, mJpegData, mOrientation, true, filepath));
ContentValues values = new ContentValues();
values.put(ImageColumns.MINI_THUMB_MAGIC, 0);
mCr.update(mUri, values, null, null);
complete = true;
return null;
} finally {
if (!complete) {
try {
mCr.delete(mUri, null, null);
} catch (Throwable t) {
// ignore it while clean up.
}
}
}
}
}
public static Cancelable<Void> storeImage(
Uri uri, ContentResolver cr, int orientation,
Bitmap source, byte [] jpegData) {
return new AddImageCancelable(
uri, cr, orientation, source, jpegData);
}
public static IImageList makeImageList(Uri uri, ContentResolver cr,
int sort) {
String uriString = (uri != null) ? uri.toString() : "";
// TODO: we need to figure out whether we're viewing
// DRM images in a better way. Is there a constant
// for content://drm somewhere??
IImageList imageList;
if (uriString.startsWith("content://drm")) {
imageList = ImageManager.allImages(
cr, ImageManager.DataLocation.ALL,
ImageManager.INCLUDE_DRM_IMAGES, sort);
} else if (uriString.startsWith("content://media/external/video")) {
imageList = ImageManager.allImages(
cr, ImageManager.DataLocation.EXTERNAL,
ImageManager.INCLUDE_VIDEOS, sort);
} else if (isSingleImageMode(uriString)) {
imageList = new SingleImageList(uri);
((SingleImageList) imageList).open(cr);
} else {
String bucketId = uri.getQueryParameter("bucketId");
imageList = ImageManager.allImages(
cr, ImageManager.DataLocation.ALL,
ImageManager.INCLUDE_IMAGES, sort, bucketId);
}
return imageList;
}
static boolean isSingleImageMode(String uriString) {
return !uriString.startsWith(
MediaStore.Images.Media.EXTERNAL_CONTENT_URI.toString())
&& !uriString.startsWith(
MediaStore.Images.Media.INTERNAL_CONTENT_URI.toString());
}
private static class EmptyImageList implements IImageList {
public static final Creator<EmptyImageList> CREATOR =
new Creator<EmptyImageList>() {
public EmptyImageList createFromParcel(Parcel in) {
return new EmptyImageList();
}
public EmptyImageList[] newArray(int size) {
return new EmptyImageList[size];
}
};
public void open(ContentResolver resolver) {
}
public void close() {
}
public void checkThumbnail(int index) {
}
public void deactivate() {
}
public HashMap<String, String> getBucketIds() {
return new HashMap<String, String>();
}
public int getCount() {
return 0;
}
public boolean isEmpty() {
return true;
}
public IImage getImageAt(int i) {
return null;
}
public IImage getImageForUri(Uri uri) {
return null;
}
public boolean removeImage(IImage image) {
return false;
}
public boolean removeImageAt(int i) {
return false;
}
public int getImageIndex(IImage image) {
throw new UnsupportedOperationException();
}
public int describeContents() {
return 0;
}
public void writeToParcel(Parcel dest, int flags) {
}
}
public static IImageList emptyImageList() {
return new EmptyImageList();
}
public static IImageList allImages(ContentResolver cr,
DataLocation location, int inclusion, int sort) {
return allImages(cr, location, inclusion, sort, null);
}
public static IImageList allImages(ContentResolver cr,
DataLocation location, int inclusion, int sort, String bucketId) {
if (cr == null) {
return null;
}
// false ==> don't require write access
boolean haveSdCard = hasStorage(false);
// use this code to merge videos and stills into the same list
ArrayList<BaseImageList> l = new ArrayList<BaseImageList>();
if (haveSdCard && location != DataLocation.INTERNAL) {
if ((inclusion & INCLUDE_IMAGES) != 0) {
l.add(new ImageList(
STORAGE_URI, THUMB_URI, sort, bucketId));
}
if ((inclusion & INCLUDE_VIDEOS) != 0) {
l.add(new VideoList(VIDEO_STORAGE_URI, sort, bucketId));
}
}
if (location == DataLocation.INTERNAL || location == DataLocation.ALL) {
if ((inclusion & INCLUDE_IMAGES) != 0) {
l.add(new ImageList(
Images.Media.INTERNAL_CONTENT_URI,
Images.Thumbnails.INTERNAL_CONTENT_URI,
sort, bucketId));
}
if ((inclusion & INCLUDE_DRM_IMAGES) != 0) {
l.add(new DrmImageList(
DrmStore.Images.CONTENT_URI, sort, bucketId));
}
}
// Optimization: If some of the lists are empty, remove them.
// If there is only one remaining list, return it directly.
Iterator<BaseImageList> iter = l.iterator();
while (iter.hasNext()) {
BaseImageList sublist = iter.next();
sublist.open(cr);
if (sublist.isEmpty()) iter.remove();
sublist.close();
}
if (l.size() == 1) {
BaseImageList list = l.get(0);
list.open(cr);
return list;
}
ImageListUber uber = new ImageListUber(
l.toArray(new IImageList[l.size()]), sort);
uber.open(cr);
return uber;
}
private static boolean checkFsWritable() {
// Create a temporary file to see whether a volume is really writeable.
// It's important not to put it in the root directory which may have a
// limit on the number of files.
String directoryName =
Environment.getExternalStorageDirectory().toString() + "/DCIM";
File directory = new File(directoryName);
if (!directory.isDirectory()) {
if (!directory.mkdirs()) {
return false;
}
}
File f = new File(directoryName, ".probe");
try {
// Remove stale file if any
if (f.exists()) {
f.delete();
}
if (!f.createNewFile()) {
return false;
}
f.delete();
return true;
} catch (IOException ex) {
return false;
}
}
public static boolean hasStorage() {
return hasStorage(true);
}
public static boolean hasStorage(boolean requireWriteAccess) {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
if (requireWriteAccess) {
boolean writable = checkFsWritable();
return writable;
} else {
return true;
}
} else if (!requireWriteAccess
&& Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
return true;
}
return false;
}
private static Cursor query(ContentResolver resolver, Uri uri,
String[] projection, String selection, String[] selectionArgs,
String sortOrder) {
try {
if (resolver == null) {
return null;
}
return resolver.query(
uri, projection, selection, selectionArgs, sortOrder);
} catch (UnsupportedOperationException ex) {
return null;
}
}
public static boolean isMediaScannerScanning(ContentResolver cr) {
boolean result = false;
Cursor cursor = query(cr, MediaStore.getMediaScannerUri(),
new String [] {MediaStore.MEDIA_SCANNER_VOLUME},
null, null, null);
if (cursor != null) {
if (cursor.getCount() == 1) {
cursor.moveToFirst();
result = "external".equals(cursor.getString(0));
}
cursor.close();
}
return result;
}
public static String getLastImageThumbPath() {
return Environment.getExternalStorageDirectory().toString() +
"/DCIM/.thumbnails/image_last_thumb";
}
public static String getLastVideoThumbPath() {
return Environment.getExternalStorageDirectory().toString() +
"/DCIM/.thumbnails/video_last_thumb";
}
}
//--------------------------------------------------------------------------------------------------------------------
禁止.thumbnails自動生成
~/.thumbnails
避免生成tumbnails文件夾的方法是在電腦上新建一個txt文件，并把這個文本文件的后綴名.txt去掉，電腦會提示“如果改變文件擴展名，可能導致文件不可用，確實要更改嗎”這樣的提示，點擊確定，把得到的這個文件拷貝到TF卡的根目錄，在安卓系統下將這個文件重命名為.nomedia（注意！nomedia單詞前面有一個"."）因windows系統不支持新建.與_開頭的文件，所以重命名必須在WM系統下進行。按照以上步驟，DCIM文件夾下就不會再生成tumbnails文件夾。
~/.thumbnails
你打開看這個文件夾，是不是很奇怪。有好多你瀏覽過的圖片，包括u盤等移動介質。還有預覽的圖片也在其中，隨著時間可能達到1～2G
有些個人隱私，也跑這個文件夾中了。比如我喜歡使用 ecryptfs-ulit 一個商用級別（免費）的加密數據層。這下也白干了。
所以要對付它。刪除它是不可能的，有些程序會自動生成它作為臨時文件夾?？墒菂s忘了刪它……
/tmp是系統指定的臨時文件夾，有個很好的特性——關閉系統會自動清空遮這個文件夾。
當然我把它扔到內存中，更保護硬盤。那只要啟動前把/tmp 指定為tmpfs文件系統即可
把.thumbnails 刪除了。復制/tmp文件夾 作為鏈接到～目錄，命名為.thumbnails
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