1
更新即使我沒有從緩存中檢索圖像，我也試圖通過Drawable檢索，其中我將所有18個圖像存儲在「drawable-mdpi」夾。仍然顯示一個空白屏幕。使用Android中的BitmapFactory.decodeStream（）從緩存中加載圖像
我能夠從服務器檢索圖像並將圖像（.GIF）保存到緩存中。但是，當我需要從緩存中加載該圖像時，圖像不會顯示在屏幕上。下面是做的工作代碼：
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中存儲的圖片名稱：smallMapImageNames（圖像名稱也可以在網址中找到）
ArrayList中存儲的圖像的URL ：mapPiecesURL
總結它我有2個問題 1）如何從緩存中加載圖像？ 2）關於bitmap.compress（），來自服務器的圖像是.GIF格式，但我應用Bitmap.CompressFormat.PNG。那麼這會有什麼問題嗎？
任何人都可以幫助我嗎？
兩個功能
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;
}
}
我實際上試圖顯示圖像的18個（3X6），以形成一個平面佈置圖。所以要顯示圖像，我使用兩個for-loop來顯示它。兩個.GIF圖像，ERLab-1_1.GIF和ERLab-4_1.GIF是每個組的中心部分。例如，第一行將是ERLab-0_0.GIF，ERLab-1_0.GIF，ERLab-2_0.GIF，ERLab-3_0.GIF，ERLab-4_0.GIF，ERLab-5_0.GIF。第二行將是第三行的XXX-X_1.GIF和XXX-X_2.GIF。
最後，
Bitmap resultMap = getBitMap(this.getContext());
bmLargeImage = Bitmap.createBitmap(1029 , 617, Bitmap.Config.ARGB_8888);
bmLargeImage = resultMap;
然後將圖像繪製被在畫布上。
什麼是拼圖？ – Blackbelt
對不起，我忘了提這個。它只是另一個ArrayList，用於在從緩存（如果緩存中已存在圖像）或從服務器中獲取圖像後存儲所有位圖圖像。 – user918197
'decodeStream'成功返回一個位圖？ – Ronnie