C# 本地图片缓存器ImageFileCache (www.csframework.com)|C/S框架网

C# 本地图片缓存器ImageFileCache (www.csframework.com)

作者:C/S框架网|www.cscode.ne 发布日期:2021/03/19 15:32:24

C# 本地图片缓存器ImageFileCache (www.csframework.com)

C# Code:

/// <summary>
/// C# 本地图片缓存器(www.csframework.com)
/// </summary>
public class ImageFileCache
{
//考虑异步应用，加锁
private object _Locker = new object();

//图片根目录
private string _baseFolder = "";

//图片数据库
private DataTable _Data;

/// <summary>
/// 构造器
/// </summary>
public ImageFileCache(string baseFolder = "")
{
//默认为应用程序目录下
if (String.IsNullOrWhiteSpace(baseFolder))
baseFolder = Path.Combine(Application.StartupPath, "ImageCache");

_baseFolder = baseFolder;

if (!Directory.Exists(baseFolder))
Directory.CreateDirectory(baseFolder);

//加载数据库
_Data = ReadDatabase();
}

#region Instance

static ImageFileCache _Instance = null;

public static ImageFileCache Instance
{
get
{
if (_Instance == null) _Instance = new ImageFileCache();
return _Instance;
}
}

#endregion;

internal bool Exists(ImageBuckleName buckle, string url)
{
url = ToMD5(url);

lock (_Locker)
{
return _Data.Select($"buckle='{buckle.ToString()}' AND url='{url}'").Length > 0;
}
}

/// <summary>
/// 数据库文件路径
/// </summary>
private string dbFile { get { return Path.Combine(_baseFolder, "cache_files.db"); } }

/// <summary>
/// 加载数据库
/// </summary>
/// <returns></returns>
private DataTable ReadDatabase()
{
lock (_Locker)
{
string path = this.dbFile;

if (File.Exists(path))
{
_Data = GetFileTable();
_Data.ReadXml(path);
return _Data;
}
else
{
_Data = GetFileTable();
return _Data;
}
}
}

/// <summary>
/// 保存数据库
/// </summary>
public void Save()
{
lock (_Locker)
{
_Data.WriteXml(this.dbFile, true);
}
}

/// <summary>
/// 获取图片
/// </summary>
/// <param name="buckle"></param>
/// <param name="url"></param>
/// <returns></returns>
public Bitmap GetImage(ImageBuckleName buckle, string url)
{
url = ToMD5(url);

lock (_Locker)
{
var rows = _Data.Select($"buckle='{buckle.ToString()}' AND url='{url}'");

if (rows.Length > 0)
{
string file = Path.Combine(_baseFolder, rows[0]["name"].ToString());

//C#加载图片文件，不占用文件句柄方式。
byte[] bs = File.ReadAllBytes(file);
MemoryStream ms = new MemoryStream(bs);
return new Bitmap(Image.FromStream(ms));
}
else
{
return null;
}
}
}

/// <summary>
/// 添加图片
/// </summary>
/// <param name="url"></param>
/// <param name="img"></param>
/// <param name="buckle"></param>
public void AddImage(string url, Image img, ImageBuckleName buckle)
{
lock (_Locker)
{
string md5 = ToMD5(url);

string dir = Path.Combine(_baseFolder, buckle.ToString());
if (!Directory.Exists(dir)) Directory.CreateDirectory(dir);

string ext = Path.GetExtension(url);
string fileName = md5 + ext;
fileName = buckle.ToString() + @"\" + fileName;

string file = Path.Combine(_baseFolder, fileName);
img.Save(file);

if (File.Exists(file))
{
DataRow row = _Data.Rows.Add();
row["buckle"] = buckle.ToString();
row["name"] = fileName;
row["url"] = md5;//将url转化为md5
row["time"] = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
_Data.AcceptChanges();
}
}
}

private DataTable GetFileTable()
{
DataTable dt = new DataTable("file");
dt.Columns.Add("isid", typeof(int));
dt.Columns.Add("buckle", typeof(String));
dt.Columns.Add("url", typeof(String));
dt.Columns.Add("name", typeof(String));
dt.Columns.Add("time", typeof(String));
return dt;
}

/// <summary>
/// MD5加密，不可逆
/// </summary>
/// <param name="clearText">明文字符串</param>
/// <returns></returns>
private string ToMD5(string clearText)
{
MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
byte[] encryptedBytes = md5.ComputeHash(UTF8Encoding.UTF8.GetBytes(clearText));
StringBuilder sb = new StringBuilder();
for (int i = 0; i < encryptedBytes.Length; i++)
{
sb.AppendFormat("{0:x2}", encryptedBytes[i]);
}
return sb.ToString().ToLower();
}
}

//来源:C/S框架网 | www.csframework.com | QQ:23404761

C# Code:

/// <summary>
/// 图片存储子目录(可自定义)
/// </summary>
public enum ImageBuckleName
{
large_images,
small_images
}

//来源:C/S框架网 | www.csframework.com | QQ:23404761

缓存图片文件目录结构，以及图片数据库文件：

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参考文档：

C#数据库本地缓存技术(Database local cache)
C# PictureBox设置背景图片及加载图片源码
C# 百度地图坐标获取详细地址
DevExpress表格打印预览及自定义页眉页脚并绘制图片(C# Winform)
C# 窗体上显示透明图片，制作已审核/未审核图标
C# 窗体上显示透明图片,PNG图片，已审核/未审核图标
C#切割图片自动填充工具栏按钮图片
C# RichTextbox中插入图片
Asp.Net(C#)发送带有附件及显示图片的邮件
C#.Net 上传图片,限制图片大小,检查类型完整版
C# Winform 制作可任意拖动的不规则背景图片窗体
C#图片转换类支持按比例缩放图片
C# 实现条码图片自动生成功能
开发应用-观察者模式之C#实现缓存数据更新
C#图片加水印(Generate Watermark Picture)

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