/**
* @param origPath 源图片文件路径
* @param width 缩略图设定宽度
* @param height 缩略图设定高度
* @return 返回缩略图,失败返回null
*/
public Bitmap getImageThumbFromMK(String origPath, int width, int height) {
// 产生缩略图，并把该文件存到指定目录下，更新数据库中图片信息
Bitmap thumbnail = null;
Log.d(TAG, origPath + ":make thumbnail and insert message in database");
ThumbnailCreator mCreator = new ThumbnailCreator(width, height);
thumbnail = mCreator.createThumbnail(origPath);
if (thumbnail == null) {
return null;
}
String name = null;
try {
name = origPath.substring(origPath.lastIndexOf("/") + 1, origPath.lastIndexOf("."));
} catch (IndexOutOfBoundsException e) {
e.printStackTrace();
return null;
}
try {
File f = new File(imageDB.getAppDir() + "/" + name);
FileOutputStream fOut = null;
fOut = new FileOutputStream(f);
thumbnail.compress(Bitmap.CompressFormat.JPEG, 100, fOut);
fOut.flush();
fOut.close();
imageDB.insert(origPath, f.getPath());
} catch (Exception e) {
// TODO Auto-generated catch block
Log.d(TAG, "create temp file false");
e.printStackTrace();
}
return thumbnail;
}
/** 清除数据库中暂存的缩略图信息及对应的缩略图文件，需要在每次退出程序前清除过时的信息，只保留MaxThumbnailNum个缩略图信息， 防止暂存区不断扩大 */
public void clearThumbnailData() {
final int ORIG_PATH_COLUMN = 0;
final int THUMB_PATH_COLUMN = 1;
final int CREATE_TIME = 2;
String[] columns = {
ImageDatabase.ORIG_PATH, ImageDatabase.THUMB_PATH, ImageDatabase.CREATE_TIME
};
String sort = ImageDatabase.CREATE_TIME + " DESC";
// 按降序整理查询的结果
Cursor c = imageDB.query(columns, null, null, sort);
int i = 0;
if (c != null) {
try {
while (c.moveToNext()) {
i++;
// 删除第MaxThumbnailNum以后个图片及其信息
if (i > MaxThumbnailNum) {
String thumbPath = c.getString(THUMB_PATH_COLUMN);
String origPath = c.getString(ORIG_PATH_COLUMN);
File file = new File(thumbPath);
try {
if (file.delete()) {
imageDB.delete(origPath);
}
} catch (SecurityException e) {
}
}
}
} finally {
c.close();
c = null;
}
} else {
Log.d(TAG, "cursor is null");
}
}
/**
* 从数据库中查询返回缩略图
*
* @param origPath
* @return null如果查询不到该缩略图文件
*/
public Bitmap getImageThumbFromDB(String origPath) {
final int ORIG_PATH_COLUMN = 0;
final int THUMB_PATH_COLUMN = 1;
String[] columns = {ImageDatabase.ORIG_PATH, ImageDatabase.THUMB_PATH};
String selection = ImageDatabase.ORIG_PATH + "=?";
String Args[] = {origPath};
Bitmap thumbnail = null;
Cursor c = imageDB.query(columns, selection, Args, null);
// 如果从数据库中找到该原图的缩量图，则直接使用
if (c != null) {
try {
while (c.moveToNext()) {
String thumbPath = c.getString(THUMB_PATH_COLUMN);
thumbnail = BitmapFactory.decodeFile(thumbPath);
break;
}
} finally {
c.close();
c = null;
}
}
return thumbnail;
}
public void closeDB() {
imageDB.closeDatabase();
}