我正在使用Java (JDO)在Google App Engine上构建一个项目。我正在使用Deflater对大型byte[]进行编程压缩，然后将压缩后的byte[]作为blobstore存储。这个方法非常有效：
public class Functions {
public static byte[] compress(byte[] input) throws UnsupportedEncodingException, IOException, MessagingException
{
Deflater df = new Deflater(); //this function mainly generate the byte code
df.setLevel(Deflater.BEST_COMPRESSION);
df.setInput(input);
ByteArrayOutputStream baos = new ByteArrayOutputStream(input.length); //we write the generated byte code in this array
df.finish();
byte[] buff = new byte[1024]; //segment segment pop....segment set 1024
while(!df.finished())
{
int count = df.deflate(buff); //returns the generated code... index
baos.write(buff, 0, count); //write 4m 0 to count
}
baos.close();
int baosLength = baos.toByteArray().length;
int inputLength = input.length;
//System.out.println("Original: "+inputLength);
// System.out.println("Compressed: "+ baosLength);
return baos.toByteArray();
}
public static byte[] decompress(byte[] input) throws UnsupportedEncodingException, IOException, DataFormatException
{
Inflater decompressor = new Inflater();
decompressor.setInput(input);
// Create an expandable byte array to hold the decompressed data
ByteArrayOutputStream bos = new ByteArrayOutputStream(input.length);
// Decompress the data
byte[] buf = new byte[1024];
while (!decompressor.finished()) {
try {
int count = decompressor.inflate(buf);
bos.write(buf, 0, count);
} catch (DataFormatException e) {
}
}
try {
bos.close();
} catch (IOException e) {
}
// Get the decompressed data
byte[] decompressedData = bos.toByteArray();
return decompressedData;
}
public static BlobKey putInBlobStore(String contentType, byte[] filebytes) throws IOException {
// Get a file service
FileService fileService = FileServiceFactory.getFileService();
AppEngineFile file = fileService.createNewBlobFile(contentType);
// Open a channel to write to it
boolean lock = true;
FileWriteChannel writeChannel = fileService.openWriteChannel(file, lock);
// This time we write to the channel using standard Java
BufferedInputStream in = new BufferedInputStream(new ByteArrayInputStream(filebytes));
byte[] buffer;
int defaultBufferSize = 524288;
if(filebytes.length > defaultBufferSize){
buffer = new byte[defaultBufferSize]; // 0.5 MB buffers
}
else{
buffer = new byte[filebytes.length]; // buffer the size of the data
}
int read;
while( (read = in.read(buffer)) > 0 ){ //-1 means EndOfStream
System.out.println(read);
if(read < defaultBufferSize){
buffer = new byte[read];
}
ByteBuffer bb = ByteBuffer.wrap(buffer);
writeChannel.write(bb);
}
writeChannel.closeFinally();
return fileService.getBlobKey(file);
}
}
使用我Functions类中的静态compress()和putInBlobStore()函数，我可以这样压缩并存储byte[]：
BlobKey dataBlobKey = Functions.putInBlobStore("MULTIPART_FORM_DATA", Functions.compress(orginalDataByteArray));
非常不错。我真的很喜欢GAE。
但现在，有一个问题：
我正在存储压缩的HTML，希望能够在JSP页面内的iframe中检索并解压缩以显示。压缩很快，但解压缩却需要很长时间！即使压缩的HTML只有15k，有时解压缩也会失败。
以下是我的解压缩方法：
URL file = new URL("/blobserve?key=" + htmlBlobKey);
URLConnection conn = file.openConnection();
conn.setReadTimeout(30000);
conn.setConnectTimeout(30000);
InputStream inputStream = conn.getInputStream();
byte[] data = IOUtils.toByteArray(inputStream);
return new String(Functions.decompress(data));
有没有什么好的方法可以从Blobstore中获取压缩后的HTML并将其解压并显示出来？即使我需要将它传递给任务队列，同时显示进度条并轮询完成 - 这也是可以的。 我真的不在乎，只要它高效并最终能够正常工作。您能在这里与我分享任何指导吗？
感谢您的帮助。