c# - 通用处理程序不返回值

Question

处理程序未返回图像。如果我删除条件语句，处理程序将返回图像。这是我的代码

public void ProcessRequest(HttpContext context)
    {
        string sid = "JUN15MBACHN001";
        SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
        connection.Open();
        SqlCommand command = new SqlCommand("select suppassportphoto from studdetails where sregno=" + sid, connection);
        SqlDataReader dr = command.ExecuteReader();
        dr.Read();
        Byte[] br = (Byte[])dr[0];
        if (br.Length > 1)
        {
            context.Response.BinaryWrite((Byte[])dr[0]);
        }          
        else
        {
            string path = context.Server.MapPath("~/image/emptymalepic.jpg");
            byte[] byteArray = File.ReadAllBytes(path);
            context.Response.BinaryWrite(byteArray);
        }
        connection.Close();
        context.Response.End();
    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }

我不知道我哪里错了？任何帮助将不胜感激。

Answer 1

首先，我建议以不同的方式进行转换，因为您的代码可能会导致无效转换异常:

Byte[] br = dr[0] as Byte[];

然后检查是否为空

if (br != null && br.Length > 1)

然后写入文件:

context.Response.ContentType = "image/jpeg"; // or whatever type you're using
context.Response.BinaryWrite(br);

并替换

context.Response.End();

与

HttpContext.Current.ApplicationInstance.CompleteRequest();

因为我注意到有些浏览器不喜欢 Response.End()

希望这是有用的。祝你好运!