GZipStream COM pression问题（丢失字节） [英] GZipStream compression problem ( Lost Byte )
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问题描述
我有一些奇怪的问题，用gzip串行。
试图序列化对象，在它的数据。
随着code得出的结果（在POINT1在调试）：ms.Length = 100028和uncom pressedStream.Length = 100027
POINT1后有异常流的末尾遇到解析完成之前。，我认为这是失去的字节的结果。
我使用.NET 4.0。
//生成数据
INT长度= 100000;
byte []的数据=新的字节[长度];
的for（int i = 0; I＆LT;长度;我++）
{
数据[I] = System.Convert.ToByte（ⅰ％100 + I％50）;
}
//序列化到内存流
IFormatter格式化=新的BinaryFormatter（）;
VAR毫秒=新的MemoryStream（）;
formatter.Serialize（毫秒，数据）;
ms.Seek（0，SeekOrigin.Begin）;
// GZip压缩ZIP
MemoryStream的COM pressedStream =新的MemoryStream（）;
变种的COM preSS =新GZipStream（COM pressedStream，COM pressionMode.Com preSS）;
ms.CopyTo（比较preSS）;
COM pressedStream.Seek（0，SeekOrigin.Begin）;
// GZip压缩解压
MemoryStream的uncom pressedStream =新的MemoryStream（）;
VAR DECOM preSS =新GZipStream（COM pressedStream，COM pressionMode.Decom preSS）;
DECOM press.CopyTo（uncom pressedStream）;
uncom pressedStream.Seek（0，SeekOrigin.Begin）;
//从内存流反序列化
// POINT1
VAR 600 = formatter.Deserialize（uncom pressedStream）;
变种O =（byte []的）面向对象;
//检查
Assert.AreEqual（data.Length，o.Length）;
的for（int i = 0; I＆LT; data.Length;我++）
Assert.AreEqual（数据[I]，邻[I]）;
解决方案
的COM pression流不冲水（而无法正常冲水），直到它们被关闭。您将需要关闭 GZipStream 。告诉它不要关闭底层流（的构造函数的一个参数）将使它更容易些。
//生成数据
INT长度= 100000;
byte []的数据=新的字节[长度];
的for（int i = 0; I＆LT;长度;我++）
{
数据[I] = System.Convert.ToByte（ⅰ％100 + I％50）;
}
字节[] 0;
//序列化到内存流
IFormatter格式化=新的BinaryFormatter（）;
使用（VAR毫秒=新的MemoryStream（））
{
formatter.Serialize（毫秒，数据）;
ms.Seek（0，SeekOrigin.Begin）;
// GZip压缩ZIP
使用（MemoryStream的COM pressedStream =新的MemoryStream（））
{
使用（VAR的COM preSS =新GZipStream（COM pressedStream，COM pressionMode.Com preSS，真））
{
ms.CopyTo（比较preSS）;
}
COM pressedStream.Seek（0，SeekOrigin.Begin）;
// GZip压缩解压
使用（MemoryStream的uncom pressedStream =新的MemoryStream（））
{
使用（VAR DECOM preSS =新GZipStream（COM pressedStream，COM pressionMode.Decom preSS，真））
{
DECOM press.CopyTo（uncom pressedStream）;
}
uncom pressedStream.Seek（0，SeekOrigin.Begin）;
VAR 600 = formatter.Deserialize（uncom pressedStream）;
O =（byte []的）面向对象;
}
}
//从内存流反序列化
// POINT1
}
//检查
Debug.Assert的（data.Length == o.Length）;
的for（int i = 0; I＆LT; data.Length;我++）
Debug.Assert的（数据[I] ==问题o [I]）;
I've got some strange problem with GZip Serializer.
Trying serializing object with data in it.
Following code give results(at POINT1 in debug): ms.Length = 100028 and uncompressedStream.Length=100027
After POINT1 there is exception "End of Stream encountered before parsing was completed.", which i think is result of this lost byte.
I am using .net 4.0.
//generating data
int length = 100000;
byte[] data = new byte[length];
for (int i = 0; i < length; i++)
{
data[i] = System.Convert.ToByte(i % 100 + i % 50);
}
//serialization into memory stream
IFormatter formatter = new BinaryFormatter();
var ms = new MemoryStream();
formatter.Serialize(ms, data);
ms.Seek(0, SeekOrigin.Begin);
//GZip zip
MemoryStream compressedStream = new MemoryStream();
var Compress = new GZipStream(compressedStream, CompressionMode.Compress);
ms.CopyTo(Compress);
compressedStream.Seek(0, SeekOrigin.Begin);
//GZip Unzip
MemoryStream uncompressedStream = new MemoryStream();
var Decompress = new GZipStream(compressedStream, CompressionMode.Decompress);
Decompress.CopyTo(uncompressedStream);
uncompressedStream.Seek(0, SeekOrigin.Begin);
//deserialization from memory stream
//POINT1
var oo = formatter.Deserialize(uncompressedStream);
var o = (byte[])oo;
//checking
Assert.AreEqual(data.Length, o.Length);
for (int i = 0; i < data.Length; i++)
Assert.AreEqual(data[i], o[i]);
解决方案
Compression streams don't flush (and can't properly flush) until they are closed. You will need to close the GZipStream. Telling it not to close the underlying stream (one of the constructor arguments) will make this easier.
//generating data
int length = 100000;
byte[] data = new byte[length];
for (int i = 0; i < length; i++)
{
data[i] = System.Convert.ToByte(i % 100 + i % 50);
}
byte[] o;
//serialization into memory stream
IFormatter formatter = new BinaryFormatter();
using (var ms = new MemoryStream())
{
formatter.Serialize(ms, data);
ms.Seek(0, SeekOrigin.Begin);
//GZip zip
using(MemoryStream compressedStream = new MemoryStream())
{
using (var Compress = new GZipStream(compressedStream, CompressionMode.Compress, true))
{
ms.CopyTo(Compress);
}
compressedStream.Seek(0, SeekOrigin.Begin);
//GZip Unzip
using (MemoryStream uncompressedStream = new MemoryStream())
{
using (var Decompress = new GZipStream(compressedStream, CompressionMode.Decompress, true))
{
Decompress.CopyTo(uncompressedStream);
}
uncompressedStream.Seek(0, SeekOrigin.Begin);
var oo = formatter.Deserialize(uncompressedStream);
o = (byte[])oo;
}
}
//deserialization from memory stream
//POINT1
}
//checking
Debug.Assert(data.Length == o.Length);
for (int i = 0; i < data.Length; i++)
Debug.Assert(data[i] == o[i]);
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