我有一些将文件压缩的代码通过网络发送,然后在另一端解压缩。我仍在测试代码,并且源和目标都相同。压缩文件需要一分钟的时间。解压缩文件需要一个小时。我认为我的代码中必然存在一个缺陷,以产生如此大的差异。下面的代码来解压缩:Java:解压缩明显慢于压缩
public String uncompressLocalZip(String filename,String strUUID,ParentEntry pe,boolean bControlFileProgress) {
final int BUFFER = 2048;
BufferedOutputStream out = null;
ZipInputStream zis = null;
try {
FileInputStream fis = new FileInputStream(Constants.conf.getFileDirectory() + Constants.PATH_SEPARATOR + strUUID + Constants.PATH_SEPARATOR + filename);
zis = new ZipInputStream(new BufferedInputStream(fis));
ZipEntry entry;
long totallength = 0;
long size = 0;
if (pe !=null)
size = pe.getSize();
while((entry = zis.getNextEntry()) != null) {
System.out.println("Extracting: " +entry);
int count;
byte data[] = new byte[BUFFER];
// write the files to the disk
File fileOutput = new File(Constants.conf.getFileDirectory() + Constants.PATH_SEPARATOR + strUUID + Constants.PATH_SEPARATOR + Constants.conf.getUncompressFolderName() + Constants.PATH_SEPARATOR + entry.getName());
new File(fileOutput.getParent()).mkdirs();
BufferedOutputStream fos = new BufferedOutputStream(new FileOutputStream(fileOutput));
out = new BufferedOutputStream(fos, BUFFER);
while ((count = zis.read(data, 0, BUFFER)) != -1) {
out.write(data, 0, count);
totallength += count;
}
out.flush();
}
}
catch(Exception e) {
e.printStackTrace();
return("FAILED");
}
finally {
try {if (out!= null) out.close();} catch (IOException ioe) {}
try {if (zis!= null) zis.close();} catch (IOException ioe) {}
}
return("SUCCESS");
}
下面的代码到拉链:
public void createLocalZip(String filename,ProcessEntry pe) {
ZipOutputStream out=null;
try {
File fileOutput = new File (filename);
out = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(fileOutput)));
long totallength=0;
long size = pe.getParentEntry().getSize();
String strStartDirectory;
if (pe.getParentEntry().isDirectory())
strStartDirectory=pe.getParentEntry().getUrl();
else
strStartDirectory=pe.getParentEntry().getFolder();
for (int i=0;i<pe.getParentEntry().tableModel3.getRowCount();i++) {
FileEntry fe = pe.getParentEntry().tableModel3.getFileEntry(i);
File fileInput = new File (fe.getUrl());
FileInputStream input = new FileInputStream(fileInput);
BufferedInputStream in = new BufferedInputStream(input);
String strRelativeDir = fe.getUrl().substring(strStartDirectory.length()+1,fe.getUrl().length());
ZipEntry entry = new ZipEntry(strRelativeDir);
out.putNextEntry(entry);
byte[] bbuf = new byte[2048];
int length=0;
while ((in != null) && ((length = in.read(bbuf)) != -1)) {
out.write(bbuf,0,length);
totallength += length;
pe.setProgress((int) (totallength*100/size));
}
in.close();
}
}
catch (Exception e) {
System.out.println(e.getMessage());
}
finally {
try {if (out!=null) out.close();} catch(IOException ioe){}
}
}
更新:对于该特定试验中的压缩比为约90%(1.2GB到大约100MB)。所以我想这可能是额外写入磁盘解压缩与压缩,虽然我预计接近10倍差距与60倍。
你有没有尝试过分析你的解压缩代码? – 2011-06-17 01:08:53
从命令行(jar或unzip)运行它时,解压缩同一文件需要多长时间? – Thilo 2011-06-17 01:10:36
另外,请尝试观察内存使用情况。难道你的系统交换的太多了,因为你的文件不适合内存,并且不知怎的,你的程序试图把它放在那里? – 2011-06-17 01:15:18