如何在没有代码分析警告的情况下一起使用StringWriter和HtmlWriter

Question

我正在使用.net并且需要获取一些html文本,所以我想我会一起使用HtmlTextWriter和StringWriter来获得格式正确的html.但是,尽管编写代码的方式各不相同,我仍然会收到静态代码分析器的警告(使用Microsoft All Rules).在下面的代码示例中,我在注释中显示代码分析器警告.为了简化代码,我实际上并没有对HtmlTextWriter进行任何调用(您将在每个函数中看到对该效果的注释).如何正确编写代码以避免警告？

// CA2000 : Microsoft.Reliability : In method 'Default.Func1()', object 'stringWriter' is not disposed along all exception paths. Call System.IDisposable.Dispose on object 'stringWriter' before all references to it are out of scope.
public static string Func1()
{
    string html;
    StringWriter stringWriter;
    using (var writer = new HtmlTextWriter(stringWriter = new StringWriter()))
    {
        // You would do some stuff with the writer here, but not for this example.

        html = stringWriter.ToString();
    }
    return html;
}

// CA2202 : Microsoft.Usage : Object 'stringWriter' can be disposed more than once in method 'Default.Func2()'. To avoid generating a System.ObjectDisposedException you should not call Dispose more than one time on an object.: Lines: 45
public static string Func2()
{
    string html;
    StringWriter stringWriter = null;
    try
    {
        using (var writer = new HtmlTextWriter(stringWriter = new StringWriter()))
        {
            // You would do some stuff with the writer here, but not for this example.

            html = stringWriter.ToString();
        }
    }
    finally
    {
        if (stringWriter != null)
            stringWriter.Dispose();
    }
    return html;
}

// CA2202 : Microsoft.Usage : Object 'stringWriter' can be disposed more than once in
// method 'Default.Func3()'. To avoid generating a System.ObjectDisposedException 
// you should not call Dispose more than one time on an object.: Lines: 61
public static string Func3()
{
    string html;
    using (var stringWriter = new StringWriter())
    {
        using (var writer = new HtmlTextWriter(stringWriter))
        {
            // You would do some stuff with the writer here, but not for this example.

            html = stringWriter.ToString();
        }
    }
    return html;
}

// CA2202 : Microsoft.Usage : Object 'stringWriter' can be disposed more than once in 
// method 'Default.Func4()'. To avoid generating a System.ObjectDisposedException you 
// should not call Dispose more than one time on an object.: Lines: 77
public static string Func4()
{
    string html;
    using (StringWriter stringWriter = new StringWriter())
    {
        using (HtmlTextWriter writer = new HtmlTextWriter(stringWriter))
        {
            // You would do some stuff with the writer here, but not for this example.

            html = stringWriter.ToString();
        }
    }
    return html;
}

// CA2202 : Microsoft.Usage : Object 'stringWriter' can be disposed more than once in 
// method 'Default.Func5()'. To avoid generating a System.ObjectDisposedException you 
// should not call Dispose more than one time on an object.: Lines: 100
public static string Func5()
{
    string html;
    StringWriter stringWriter = null;
    try
    {
        stringWriter = new StringWriter();
        using (HtmlTextWriter htmlTextWriter = new HtmlTextWriter(stringWriter))
        {
            // You would do some stuff with the writer here, but not for this example.

            html = stringWriter.ToString();
        }
    }
    finally
    {
        if (stringWriter != null)
            stringWriter.Dispose();
    }
    return html;
}

Answer 1

因为 StringWriter 是一次性的，所以您可以用其他用途包装您的内部编写器。

using (StringWriter stringWriter = new StringWriter())
{
    using (var writer = new HtmlTextWriter(stringWriter))
    {
         html = stringWriter.ToString();  
    }
}
return html;