英文:
Unable to read small compressed byte array from GZIPInputStream
问题
我遇到了一个问题，无法解决或找到一个有用的答案。我有一段压缩字节数组的代码：
try (final ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream()) {
final GZIPOutputStream gzip = new GZIPOutputStream(byteArrayOutputStream);
gzip.write(response.getBytes());
gzip.close();
response = byteArrayOutputStream.toByteArray();
} catch (IOException e) {
log.error("压缩时出现问题", e);
}
它运行得相当顺利，生成的压缩字节数组保存在数据库中。
我有另一段代码，将从数据库中获取压缩的字节数组并进行解压：
try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(compressed)) {
GZIPInputStream gzipInputStream = new GZIPInputStream(byteArrayInputStream, BUFFER_SIZE);
byte[] data = new byte[BUFFER_SIZE];
int bytesRead;
while ((bytesRead = gzipInputStream.read(data)) != -1) {
byteArrayOutputStream.write(data, 0, bytesRead);
}
gzipInputStream.close();
return byteArrayOutputStream.toByteArray();
} catch (IOException e) {
log.error("解压时出现问题", e);
}
解压对于“大型”字节数组（大于32字节）非常有效，但我有一个只有20字节的压缩数组，无法解压缩它。它永远不会进入while循环，因为read始终返回-1，因此没有读取任何内容。我尝试更改缓冲区大小等等，但什么都不起作用。我做错了什么？
提前感谢！
英文:
I struggle with a problem and I can't solve it or find a useful answer to it.
I have a piece of code that compress an array of bytes :
try (final ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream()) {
final GZIPOutputStream gzip = new GZIPOutputStream(byteArrayOutputStream);
gzip.write(response.getBytes());
gzip.close();
response = byteArrayOutputStream.toByteArray();
} catch (IOException e) {
log.error("Problem in compression", e);
}
It works pretty well, and the resulting compressed array of bytes is saved in a database.
I have another piece of code that will get the compressed array of bytes in the database and that will decompress it :
try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(compressed)) {
GZIPInputStream gzipInputStream = new GZIPInputStream(byteArrayInputStream, BUFFER_SIZE);
byte[] data = new byte[BUFFER_SIZE];
int bytesRead;
while ((bytesRead = gzipInputStream.read(data)) != -1) {
byteArrayOutputStream.write(data, 0, bytesRead);
}
gzipInputStream.close();
return byteArrayOutputStream.toByteArray();
} catch (IOException e) {
log.error("Problem in decompression", e);
}
The decompression works very well for "big" byte array (bigger than 32 bytes), but I have, for example a compressed array of 20 bytes and I cannot decompress it.
It never enters the while because the read always return -1 and so nothing is read.
I tried to change the buffer size, etc..., but nothing works.
What am I doing wrong ?
Thank you in advance !
答案1
得分: 1
这实际上是您的代码（尽管zip输入流应该在try-with-resources块中），您可以运行：
import java.util.*;
import java.util.zip.*;
import java.io.*;
public class Unzip {
public static void main(String[] args) throws Exception {
String s = "H4sIAAAAAAAAA3WRQW+CQBCF7/6K0dOSUNKeiYeaYMNJo+nFxjQrTHQTYMkwhNLG/95lESSIe9jDmzffm51lqkGsasZ3IllvSs5L3jOhTOE0qS4hwwomO4TjwwzM6athNoEbiiPaoCQineaERYGx48Cf5X4cwu2w+/yr8kfayCWmgl1Yfa7Xwe57Hx4Cx7f0xvd1hFiyvJGsMjAeW6PK2JaKHcrYn1mtuqgEQYheN4jReJ65YtHgzYPmS3h5697VpT9s1KtIMdoeF17de+pt5GsbPg6KEl2g+Y22SsglZU8CWPfLbxquEEmOLiDCTfATYc5KZ4DdnIk+e0ikSSy2pE8JpmYXEGP3Vca8cI3dcP4BN4CC8VgCAAA=";
final int BUFFER_SIZE = 32;
byte[] compressed = Base64.getDecoder().decode(s);
try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(compressed)) {
GZIPInputStream gzipInputStream = new GZIPInputStream(byteArrayInputStream, BUFFER_SIZE);
byte[] data = new byte[BUFFER_SIZE];
int bytesRead;
while ((bytesRead = gzipInputStream.read(data)) != -1) {
byteArrayOutputStream.write(data, 0, bytesRead);
}
gzipInputStream.close();
System.out.println(new String(byteArrayOutputStream.toByteArray()));
} catch (IOException e) {
e.printStackTrace();
}
}
}
英文:
This is essentially your code (though the zip input stream should be in the try-with-resources block), which you can run:
import java.util.*;
import java.util.zip.*;
import java.io.*;
public class Unzip {
public static void main(String[] args) throws Exception {
String s = "H4sIAAAAAAAAA3WRQW+CQBCF7/6K0dOSUNKeiYeaYMNJo+nFxjQrTHQTYMkwhNLG/95lESSIe9jDmzffm51lqkGsasZ3IllvSs5L3jOhTOE0qS4hwwomO4TjwwzM6athNoEbiiPaoCQineaERYGx48Cf5X4cwu2w+/yr8kfayCWmgl1Yfa7Xwe57Hx4Cx7f0xvd1hFiyvJGsMjAeW6PK2JaKHcrYn1mtuqgEQYheN4jReJ65YtHgzYPmS3h5697VpT9s1KtIMdoeF17de+pt5GsbPg6KEl2g+Y22SsglZU8CWPfLbxquEEmOLiDCTfATYc5KZ4DdnIk+e0ikSSy2pE8JpmYXEGP3Vca8cI3dcP4BN4CC8VgCAAA=";
final int BUFFER_SIZE = 32;
byte[] compressed = Base64.getDecoder().decode(s);
try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(compressed)) {
GZIPInputStream gzipInputStream = new GZIPInputStream(byteArrayInputStream, BUFFER_SIZE);
byte[] data = new byte[BUFFER_SIZE];
int bytesRead;
while ((bytesRead = gzipInputStream.read(data)) != -1) {
byteArrayOutputStream.write(data, 0, bytesRead);
}
gzipInputStream.close();
System.out.println(new String(byteArrayOutputStream.toByteArray()));
} catch (IOException e) {
e.printStackTrace();
}
}
}
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