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FileItem.cs
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166 lines (152 loc) · 5.07 KB
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using System;
using System.IO;
namespace Smallcode.Net
{
/// <summary>
/// 文件元数据。
/// 可以使用以下几种构造方法：
/// 本地路径：new FileItem("C:/temp.jpg");
/// 本地文件：new FileItem(new FileInfo("C:/temp.jpg"));
/// 字节流：new FileItem("abc.jpg", bytes);
/// </summary>
public class FileItem
{
private readonly FileInfo fileInfo;
private byte[] content;
private string fileName;
private string mimeType;
/// <summary>
/// 基于本地文件的构造器。
/// </summary>
/// <param name="fileInfo">本地文件</param>
public FileItem(FileInfo fileInfo)
{
if (fileInfo == null || !fileInfo.Exists)
{
throw new ArgumentException("fileInfo is null or not exists!");
}
this.fileInfo = fileInfo;
}
/// <summary>
/// 基于本地文件全路径的构造器。
/// </summary>
/// <param name="filePath">本地文件全路径</param>
public FileItem(string filePath)
: this(new FileInfo(filePath))
{
}
/// <summary>
/// 基于文件名和字节流的构造器。
/// </summary>
/// <param name="fileName">文件名称（服务端持久化字节流到磁盘时的文件名）</param>
/// <param name="content">文件字节流</param>
public FileItem(string fileName, byte[] content)
{
if (string.IsNullOrEmpty(fileName)) throw new ArgumentNullException("fileName");
if (content == null || content.Length == 0) throw new ArgumentNullException("content");
this.fileName = fileName;
this.content = content;
}
/// <summary>
/// 基于文件名、字节流和媒体类型的构造器。
/// </summary>
/// <param name="fileName">文件名（服务端持久化字节流到磁盘时的文件名）</param>
/// <param name="content">文件字节流</param>
/// <param name="mimeType">媒体类型</param>
public FileItem(String fileName, byte[] content, String mimeType)
: this(fileName, content)
{
if (string.IsNullOrEmpty(mimeType)) throw new ArgumentNullException("mimeType");
this.mimeType = mimeType;
}
public string GetFileName()
{
if (fileName == null && fileInfo != null && fileInfo.Exists)
{
fileName = fileInfo.FullName;
}
return fileName;
}
public string GetMimeType()
{
if (mimeType == null)
{
mimeType = GetMimeType(GetContent());
}
return mimeType;
}
public byte[] GetContent()
{
if (content == null && fileInfo != null && fileInfo.Exists)
{
using (Stream fileStream = fileInfo.OpenRead())
{
content = new byte[fileStream.Length];
fileStream.Read(content, 0, content.Length);
}
}
return content;
}
/// <summary>
/// 获取文件的真实媒体类型。目前只支持JPG, GIF, PNG, BMP四种图片文件。
/// </summary>
/// <param name="fileData">文件字节流</param>
/// <returns>媒体类型</returns>
public static string GetMimeType(byte[] fileData)
{
var suffix = GetFileSuffix(fileData);
string mimeType;
switch (suffix)
{
case "JPG":
mimeType = "image/pjpeg";
break;
case "GIF":
mimeType = "image/gif";
break;
case "PNG":
mimeType = "image/png";
break;
case "BMP":
mimeType = "image/bmp";
break;
default:
mimeType = "application/octet-stream";
break;
}
return mimeType;
}
/// <summary>
/// 获取文件的真实后缀名。目前只支持JPG, GIF, PNG, BMP四种图片文件。
/// </summary>
/// <param name="fileData">文件字节流</param>
/// <returns>JPG, GIF, PNG or null</returns>
public static string GetFileSuffix(byte[] fileData)
{
if (fileData == null || fileData.Length < 10)
{
return null;
}
if (fileData[0] == 'G' && fileData[1] == 'I' && fileData[2] == 'F')
{
return "GIF";
}
else if (fileData[1] == 'P' && fileData[2] == 'N' && fileData[3] == 'G')
{
return "PNG";
}
else if (fileData[6] == 'J' && fileData[7] == 'F' && fileData[8] == 'I' && fileData[9] == 'F')
{
return "JPG";
}
else if (fileData[0] == 'B' && fileData[1] == 'M')
{
return "BMP";
}
else
{
return null;
}
}
}
}