英文:
Creating files from ByteArrayOutputStream
问题
我正在尝试从ByteArrayOutputStream创建单独的文件（这里的byteOut是我的ByteOutputStream）。以下代码完成了这个任务：
final InputStream targetStream = new ByteArrayInputStream(byteOut.toByteArray());
final File destDir = new File(System.getProperty("user.dir"));
final byte[] buffer = new byte[1024];
ZipInputStream zis = new ZipInputStream(targetStream);
ZipEntry zipEntry = zis.getNextEntry();
while (zipEntry != null) {
File newFile = new File(destDir, zipEntry.getName());
FileOutputStream fos = new FileOutputStream(newFile);
int len;
while ((len = zis.read(buffer)) > 0) {
fos.write(buffer, 0, len);
}
fos.close();
zipEntry = zis.getNextEntry();
}
但我想优化这段代码，我尝试使用IOUtils.copy，就像这样：
final InputStream targetStream = new ByteArrayInputStream(byteOut.toByteArray());
final File destDir = new File(System.getProperty("user.dir"));
ZipInputStream zis = new ZipInputStream(targetStream);
ZipEntry zipEntry = zis.getNextEntry();
while (zipEntry != null) {
File newFile = new File(destDir, zipEntry.getName());
try(InputStream is = new FileInputStream(newFile);
OutputStream fos = new FileOutputStream(newFile)) {
IOUtils.copy(is, fos);
}
zipEntry = zis.getNextEntry();
}
但是文件的内容没有被复制，而且在第二次迭代时我还遇到了FileNotFoundException。我做错了什么？
英文:
I am trying to create separate files from ByteArrayOutputStream (Here byteOut is my ByteOutputStream). The following code does the job
final InputStream targetStream = new ByteArrayInputStream(byteOut.toByteArray());
final File destDir = new File(System.getProperty("user.dir"));
final byte[] buffer = new byte[1024];
ZipInputStream zis = new ZipInputStream(targetStream);
ZipEntry zipEntry = zis.getNextEntry();
while (zipEntry != null) {
File newFile = new File(destDir, zipEntry.getName());
FileOutputStream fos = new FileOutputStream(newFile);
int len;
while ((len = zis.read(buffer)) > 0) {
fos.write(buffer, 0, len);
}
fos.close();
zipEntry = zis.getNextEntry();
}
But I want to optimize the code, I tried using IOUtils.copy like this
final InputStream targetStream = new ByteArrayInputStream(byteOut.toByteArray());
final File destDir = new File(System.getProperty("user.dir"));
ZipInputStream zis = new ZipInputStream(targetStream);
ZipEntry zipEntry = zis.getNextEntry();
while (zipEntry != null) {
File newFile = new File(destDir, zipEntry.getName());
try(InputStream is = new FileInputStream(newFile);
OutputStream fos = new FileOutputStream(newFile)) {
IOUtils.copy(is, fos);
}
zipEntry = zis.getNextEntry();
}
But the contents of the file aren't getting copied and I also get a FileNotFoundException in the second iteration. What am I doing wrong?
答案1
得分: 1
这是一个更通用的Path＆Files类的用例。使用zip文件系统，它变成了高级别的复制。
Map<String, String> env = new HashMap<>();
//env.put("create", "true");
URI uri = new URI("jar:file:/foo/bar.zip");
FileSystem zipfs = FileSystems.newFileSystem(uri, env);
Path targetDir = Paths.get("C:/Temp");
Path pathInZip = zipfs.getPath("/");
Files.list(pathInZip)
.forEach(p -> {
Path targetP = Paths.get(targetDir.toString(), p.getFileName().toString());
try {
Files.createDirectories(targetP.getParent());
Files.copy(p, targetP);
} catch (IOException e) {
// Handle IOException
e.printStackTrace();
}
});
使用底层的Input/OutputStream时，必须确保is没有被关闭，可以使用库（例如IOUtils）/ InputStream.transferTo(OutputStream)来处理所有这些细节。
英文:
This is a use-case for the more generalized Path & Files classes. With a zip file system it becomes a high level copying.
Map<String, String> env = new HashMap<>();
//env.put("create", "true");
URI uri = new URI("jar:file:/foo/bar.zip");
FileSystem zipfs = FileSystems.newFileSystem(uri, env);
Path targetDir = Paths.get("C:/Temp");
Path pathInZip = zipfs.getPath("/");
Files.list(pathInZip)
.forEach(p -> {
Path targetP = Paths.get(targetDir, p.toString();
Files.createDirectories(targetP.getParent());
Files.copy(p, targetP);
});
Using the underlying Input/OutputStream one must ensure that is is not closed, revert to a library (IOUtils) / InputStream.transferTo(OutputStream) and all those details.
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