更新即使我没有从缓存中检索图像,我也试图通过Drawable检索,其中我将所有18个图像存储在“drawable-mdpi”夹。仍然显示一个空白屏幕。使用Android中的BitmapFactory.decodeStream()从缓存中加载图像
我能够从服务器检索图像并将图像(.GIF)保存到缓存中。但是,当我需要从缓存中加载该图像时,图像不会显示在屏幕上。下面是做的工作代码:
File cacheDir = context.getCacheDir();
File cacheMap = new File(cacheDir, smallMapImageNames.get(i).toString());
if(cacheMap.exists()){
FileInputStream fis = null;
try {
fis = new FileInputStream(cacheMap);
Bitmap local = BitmapFactory.decodeStream(fis);
puzzle.add(local);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}else{
Drawable smallMap = LoadImageFromWebOperations(mapPiecesURL.get(i).toString());
if(i==0){
height1 = smallMap.getIntrinsicHeight();
width1 = smallMap.getIntrinsicWidth();
}
if (smallMap instanceof BitmapDrawable) {
Bitmap bitmap = ((BitmapDrawable)smallMap).getBitmap();
FileOutputStream fos = null;
try {
cacheMap.createNewFile();
fos = new FileOutputStream(cacheMap);
bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.flush();
fos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
puzzle.add(bitmap);
}
}
ArrayList中存储的图片名称:smallMapImageNames(图像名称也可以在网址中找到)
ArrayList中存储的图像的URL :mapPiecesURL
总结它我有2个问题 1)如何从缓存中加载图像? 2)关于bitmap.compress(),来自服务器的图像是.GIF格式,但我应用Bitmap.CompressFormat.PNG。那么这会有什么问题吗?
任何人都可以帮助我吗?
两个功能
private Bitmap getBitMap(Context context) {
// TODO Auto-generated method stub
WifiPositioningServices wifiPositioningServices = new WifiPositioningServices();
String[] mapURLandCalibratedPoint1 = wifiPositioningServices.GetMapURLandCalibratedPoint("ERLab-1_1.GIF","ERLab"); //list of map pieces url in the first 9 pieces
String[] mapURLandCalibratedPoint2 = wifiPositioningServices.GetMapURLandCalibratedPoint("ERLab-4_1.GIF","ERLab"); //list of map pieces url in the last 9 pieces
ArrayList<String> smallMapImageNames = new ArrayList<String>();
ArrayList<String> mapPiecesURL = new ArrayList<String>();
for(int i=0; i<mapURLandCalibratedPoint1.length; i++){
if(mapURLandCalibratedPoint1[i].length()>40){ //image url
int len = mapURLandCalibratedPoint1[i].length();
int subStrLen = len-13;
smallMapImageNames.add(mapURLandCalibratedPoint1[i].substring(subStrLen, len-3)+"JPEG");
mapPiecesURL.add(mapURLandCalibratedPoint1[i]);
}
else{
//perform other task
}
}
for(int i=0; i<mapURLandCalibratedPoint2.length; i++){
if(mapURLandCalibratedPoint2[i].length()>40){ //image url
int len = mapURLandCalibratedPoint2[i].length();
int subStrLen = len-13;
smallMapImageNames.add(mapURLandCalibratedPoint2[i].substring(subStrLen, len-3)+"JPEG");
mapPiecesURL.add(mapURLandCalibratedPoint2[i]);
}
else{
//perform other task
}
}
Bitmap result = Bitmap.createBitmap(1029, 617, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(result);
ArrayList<Bitmap> puzzle = new ArrayList<Bitmap>();
int height1 = 0 ;
int width1 = 0;
File cacheDir = context.getCacheDir();
for(int i=0; i<18; i++){
File cacheMap = new File(cacheDir, smallMapImageNames.get(i).toString());
if(cacheMap.exists()){
//retrieved from cached
try {
FileInputStream fis = new FileInputStream(cacheMap);
Bitmap bitmap = BitmapFactory.decodeStream(fis);
puzzle.add(bitmap);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else{
//retrieve from server and cached it
Drawable smallMap = LoadImageFromWebOperations(mapPiecesURL.get(i).toString());
if(i==0){
height1 = smallMap.getIntrinsicHeight();
width1 = smallMap.getIntrinsicWidth();
}
if (smallMap instanceof BitmapDrawable) {
Bitmap bitmap = ((BitmapDrawable)smallMap).getBitmap();
FileOutputStream fos = null;
try {
cacheMap.createNewFile();
fos = new FileOutputStream(cacheMap);
bitmap.compress(CompressFormat.JPEG, 100, fos);
fos.flush();
fos.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
puzzle.add(bitmap);
}
}
}
Rect srcRect;
Rect dstRect;
int cnt =0;
for (int j = 0; j < 3; j++) {
int newHeight = height1 * (j % 3);
for (int k = 0; k < 3; k++) {
if (j == 0 && k == 0) {
srcRect = new Rect(0, 0, width1, height1);
dstRect = new Rect(srcRect);
} else {
int newWidth = width1 * k;
srcRect = new Rect(0, 0, width1, height1);
dstRect = new Rect(srcRect);
dstRect.offset(newWidth, newHeight);
}
canvas.drawBitmap(puzzle.get(cnt), srcRect, dstRect,null);
cnt++;
}
}
for(int a=0; a<3; a++){
int newHeight = height1 * (a % 3);
for (int k = 3; k < 6; k++) {
if (a == 0 && k == 0) {
srcRect = new Rect(0, 0, width1*3, height1);
dstRect = new Rect(srcRect);
} else {
int newWidth = width1 * k;
srcRect = new Rect(0, 0, width1, height1);
dstRect = new Rect(srcRect);
dstRect.offset(newWidth, newHeight);
}
canvas.drawBitmap(puzzle.get(cnt), srcRect, dstRect,
null);
cnt++;
}
}
return result;
}
private Drawable LoadImageFromWebOperations(String url) {
// TODO Auto-generated method stub
try
{
InputStream is = (InputStream) new URL(url).getContent();
Drawable d = Drawable.createFromStream(is, "src name");
return d;
}catch (Exception e) {
System.out.println("Exc="+e);
return null;
}
}
我实际上试图显示图像的18个(3X6),以形成一个平面布置图。所以要显示图像,我使用两个for-loop来显示它。两个.GIF图像,ERLab-1_1.GIF和ERLab-4_1.GIF是每个组的中心部分。例如,第一行将是ERLab-0_0.GIF,ERLab-1_0.GIF,ERLab-2_0.GIF,ERLab-3_0.GIF,ERLab-4_0.GIF,ERLab-5_0.GIF。第二行将是第三行的XXX-X_1.GIF和XXX-X_2.GIF。
最后,
Bitmap resultMap = getBitMap(this.getContext());
bmLargeImage = Bitmap.createBitmap(1029 , 617, Bitmap.Config.ARGB_8888);
bmLargeImage = resultMap;
在OnDraw函数
然后将图像绘制被在画布上。
什么是拼图? – Blackbelt
对不起,我忘了提这个。它只是另一个ArrayList,用于在从缓存(如果缓存中已存在图像)或从服务器中获取图像后存储所有位图图像。 – user918197
'decodeStream'成功返回一个位图? – Ronnie