我可以解压缩和反序列化使用流文件？ [英] Can I decompress and deserialize a file using streams?

问题描述

我的应用程序序列化使用Json.Net对象，压缩产生的JSON，然后保存该到文件。此外，应用程序可以从这些文件中的一个加载的对象。这些对象可以在大小几十MB，我很担心内存使用情况，由于路现有的代码创建大型字符串和字节数组： -

My application serializes an object using Json.Net, compresses the resulting JSON, then saves this to file. Additionally the application can load an object from one of these files. These objects can be tens of Mb in size and I'm concerned about memory usage, due to the way the existing code creates large strings and byte arrays:-

public void Save(MyClass myObject, string filename)
{
    var json = JsonConvert.SerializeObject(myObject);
    var bytes = Compress(json);
    File.WriteAllBytes(filename, bytes);
}

public MyClass Load(string filename)
{    
    var bytes = File.ReadAllBytes(filename);
    var json = Decompress(bytes);
    var myObject = JsonConvert.DeserializeObject<MyClass>(json);
}

private static byte[] Compress(string s)
{
    var bytes = Encoding.Unicode.GetBytes(s);

    using (var ms = new MemoryStream())
    {
        using (var gs = new GZipStream(ms, CompressionMode.Compress))
        {
            gs.Write(bytes, 0, bytes.Length);
            gs.Close();
            return ms.ToArray();
        }
    }
}

private static string Decompress(byte[] bytes)
{
    using (var msi = new MemoryStream(bytes))
    {
        using (var mso = new MemoryStream())
        {
            using (var gs = new GZipStream(msi, CompressionMode.Decompress))
            {
                gs.CopyTo(mso);
                return Encoding.Unicode.GetString(mso.ToArray());
            }
        }
    } 
}

我想知道如果保存/载入的方法可以用流来代替？我发现使用带有Json.Net流的例子，但我在努力让我围绕如何以适应额外的压缩东西头。

I was wondering if the Save/Load methods could be replaced with streams? I've found examples of using streams with Json.Net but am struggling to get my head around how to fit in the additional compression stuff.

推荐答案

JsonSerializer 的方法从 JsonTextReader 并到 的StreamWriter 时，两者都可以对任何类型的数据流的顶部被创建，包括一个 GZipStream 。使用它们，您可以创建以下扩展方法：

JsonSerializer has methods to serialize from a JsonTextReader and to a StreamWriter, both of which can be created on top of any sort of stream, including a GZipStream. Using them, you can create the following extension methods:

public static class JsonExtensions
{
    public static void SerializeToFileCompressed(object value, string path, JsonSerializerSettings settings = null)
    {
        using (var fs = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.Read))
            SerializeCompressed(value, fs, settings);
    }

    public static void SerializeCompressed(object value, Stream stream, JsonSerializerSettings settings = null)
    {
        using (var compressor = new GZipStream(stream, CompressionMode.Compress))
        using (var writer = new StreamWriter(compressor))
        {
            var serializer = JsonSerializer.CreateDefault(settings);
            serializer.Serialize(writer, value);
        }
    }

    public static T DeserializeFromFileCompressed<T>(string path, JsonSerializerSettings settings = null)
    {
        using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
            return DeserializeCompressed<T>(fs, settings);
    }

    public static T DeserializeCompressed<T>(Stream stream, JsonSerializerSettings settings = null)
    {
        using (var compressor = new GZipStream(stream, CompressionMode.Decompress))
        using (var reader = new StreamReader(compressor))
        using (var jsonReader = new JsonTextReader(reader))
        {
            var serializer = JsonSerializer.CreateDefault(settings);
            return serializer.Deserialize<T>(jsonReader);
        }
    }
}

请参阅的性能提示：优化Json.NET文档中的内存使用量

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