CA2202，如何解决这种情况下， [英] CA2202, how to solve this case

问题描述

谁能告诉我如何从以下code所有CA2202警告？

 公共静态byte []的加密（字符串数据，字节[]键，byte []的IV）
{
    使用（MemoryStream的MemoryStream的=新的MemoryStream（））
    {
        使用（DESCryptoServiceProvider密=新DESCryptoServiceProvider（））
        {
            使用（CryptoStream的CryptoStream的=新的CryptoStream（的MemoryStream，cryptograph.CreateEncryptor（钥匙，四），CryptoStreamMode.Write））
            {
                使用（的StreamWriter StreamWriter的=新的StreamWriter（CryptoStream的））
                {
                    streamWriter.Write（数据）;
                }
            }
        }
        返回memoryStream.ToArray（）;
    }
}
 

  

警告7 CA2202：Microsoft.Usage：对象'的CryptoStream可以设置一次以上方法CryptoServices.Encrypt（字符串，字节[]，byte []的）'。为了避免产生System.ObjectDisposedException你不应该调用Dispose超过一次的对象上：行：34

     

警告8 CA2202：Microsoft.Usage：对象'的MemoryStream可以设置一次以上方法CryptoServices.Encrypt（字符串，字节[]，byte []的）'。为了避免产生System.ObjectDisposedException你不应该调用Dispose一个以上的时间在一个对象：行：34，37

您需要的Visual Studio code的分析，看看这些警告（这些都不是C＃编译器警告）。

解决方案

这个编译没有警告：

 公共静态byte []的加密（字符串数据，字节[]键，byte []的IV）
    {
        的MemoryStream MemoryStream的= NULL;
        DESCryptoServiceProvider密= NULL;
        CryptoStream的CryptoStream的= NULL;
        的StreamWriter的StreamWriter = NULL;
        尝试
        {
            MemoryStream的=新的MemoryStream（）;
            密=新DESCryptoServiceProvider（）;
            CryptoStream的=新的CryptoStream（的MemoryStream，cryptograph.CreateEncryptor（钥匙，四），CryptoStreamMode.Write）;
            VAR的结果= MemoryStream的;
            MemoryStream的= NULL;
            的StreamWriter =新的StreamWriter（CryptoStream的）;
            CryptoStream的= NULL;
            streamWriter.Write（数据）;
            返回result.ToArray（）;
        }
        最后
        {
            如果（MemoryStream的！= NULL）
                memoryStream.Dispose（）;
            如果（密文！= NULL）
                cryptograph.Dispose（）;
            如果（CryptoStream的！= NULL）
                cryptoStream.Dispose（）;
            如果（StreamWriter的！= NULL）
                streamWriter.Dispose（）;
        }
    }
 

修改回应的评论： 我只是再次验证了这code不会产生警告，而原来的一样。 在原来的code， CryptoStream.Dispose（）和的MemoryStream（）的Dispose（）的实际调用两次（其可以是或可以不是个问题）。

修改后的code的工作原理如下：引用设置为空，只要负有责任的处理转移到另一个对象。例如。 的MemoryStream 设置为空调用的CryptoStream 构造函数之后成功了。 的CryptoStream 设置为空，调用的StreamWriter 之后构造成功。如果没有异常发生，的StreamWriter 设置在最后块将依次部署的CryptoStream 和的MemoryStream 。

Can anybody tell me how to remove all CA2202 warnings from the following code?

public static byte[] Encrypt(string data, byte[] key, byte[] iv)
{
    using(MemoryStream memoryStream = new MemoryStream())
    {
        using (DESCryptoServiceProvider cryptograph = new DESCryptoServiceProvider())
        {
            using (CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptograph.CreateEncryptor(key, iv), CryptoStreamMode.Write))
            {
                using(StreamWriter streamWriter = new StreamWriter(cryptoStream))
                {
                    streamWriter.Write(data);
                }
            }
        }
        return memoryStream.ToArray();
    }
}

Warning 7 CA2202 : Microsoft.Usage : Object 'cryptoStream' can be disposed more than once in method 'CryptoServices.Encrypt(string, byte[], byte[])'. To avoid generating a System.ObjectDisposedException you should not call Dispose more than one time on an object.: Lines: 34

Warning 8 CA2202 : Microsoft.Usage : Object 'memoryStream' can be disposed more than once in method 'CryptoServices.Encrypt(string, byte[], byte[])'. To avoid generating a System.ObjectDisposedException you should not call Dispose more than one time on an object.: Lines: 34, 37

You need Visual Studio Code Analysis to see these warnings (these are not c# compiler warnings).

解决方案

This compiles without warning:

    public static byte[] Encrypt(string data, byte[] key, byte[] iv)
    {
        MemoryStream memoryStream = null;
        DESCryptoServiceProvider cryptograph = null;
        CryptoStream cryptoStream = null;
        StreamWriter streamWriter = null;
        try
        {
            memoryStream = new MemoryStream();
            cryptograph = new DESCryptoServiceProvider();
            cryptoStream = new CryptoStream(memoryStream, cryptograph.CreateEncryptor(key, iv), CryptoStreamMode.Write);
            var result = memoryStream;              
            memoryStream = null;
            streamWriter = new StreamWriter(cryptoStream);
            cryptoStream = null;
            streamWriter.Write(data);
            return result.ToArray();
        }
        finally
        {
            if (memoryStream != null)
                memoryStream.Dispose();
            if (cryptograph != null)
                cryptograph.Dispose();
            if (cryptoStream != null)
                cryptoStream.Dispose();
            if (streamWriter != null)
                streamWriter.Dispose();
        }
    }

Edit in response to the comments: I just verified again that this code does not generate the warning, while the original one does. In the original code, CryptoStream.Dispose() and MemoryStream().Dispose() are actually called twice (which may or may not be a problem).

The modified code works as follows: references are set to null, as soon as responsibilty for disposing is transferred to another object. E.g. memoryStream is set to null after the call to CryptoStream constructor succeeded. cryptoStream is set to null, after the call to StreamWriter constructor succeeded. If no exception occurs, streamWriter is disposed in the finally block and will in turn dispose CryptoStream and MemoryStream.

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