本篇文章给大家带来的内容是介绍io帮助类是什么？io帮助类的实例介绍（附代码）。有一定的参考价值，有需要的朋友可以参考一下，希望对你们有所帮助。
using system;using system.io;using system.web;using system.drawing;using system.drawing.imaging;using system.drawing.drawing2d;using system.xml.serialization;namespace zmm.core{    /// <summary>    /// io帮助类    /// </summary>    public class iohelper    {        //是否已经加载了jpeg编码解码器        private static bool _isloadjpegcodec = false;        //当前系统安装的jpeg编码解码器        private static imagecodecinfo _jpegcodec = null;        /// <summary>        /// 获得文件物理路径        /// </summary>        /// <returns></returns>        public static string getmappath(string path)        {            if (httpcontext.current != null)            {                return httpcontext.current.server.mappath(path);            }            else            {                return system.web.hosting.hostingenvironment.mappath(path);            }        }        #region  序列化        /// <summary>        /// xml序列化        /// </summary>        /// <param name="obj">序列对象</param>        /// <param name="filepath">xml文件路径</param>        /// <returns>是否成功</returns>        public static bool serializetoxml(object obj, string filepath)        {            bool result = false;            filestream fs = null;            try            {                fs = new filestream(filepath, filemode.create, fileaccess.write, fileshare.readwrite);                xmlserializer serializer = new xmlserializer(obj.gettype());                serializer.serialize(fs, obj);                result = true;            }            catch (exception ex)            {                throw ex;            }            finally            {                if (fs != null)                    fs.close();            }            return result;        }        /// <summary>        /// xml反序列化        /// </summary>        /// <param name="type">目标类型(type类型)</param>        /// <param name="filepath">xml文件路径</param>        /// <returns>序列对象</returns>        public static object deserializefromxml(type type, string filepath)        {            filestream fs = null;            try            {                fs = new filestream(filepath, filemode.open, fileaccess.read, fileshare.readwrite);                xmlserializer serializer = new xmlserializer(type);                return serializer.deserialize(fs);            }            catch (exception ex)            {                throw ex;            }            finally            {                if (fs != null)                    fs.close();            }        }        #endregion        #region  水印,缩略图        /// <summary>        /// 获得当前系统安装的jpeg编码解码器        /// </summary>        /// <returns></returns>        public static imagecodecinfo getjpegcodec()        {            if (_isloadjpegcodec == true)                return _jpegcodec;            imagecodecinfo[] codecslist = imagecodecinfo.getimageencoders();            foreach (imagecodecinfo codec in codecslist)            {                if (codec.mimetype.indexof(jpeg) > -1)                {                    _jpegcodec = codec;                    break;                }            }            _isloadjpegcodec = true;            return _jpegcodec;        }        /// <summary>        /// 生成缩略图        /// </summary>        /// <param name="imagepath">图片路径</param>        /// <param name="thumbpath">缩略图路径</param>        /// <param name="width">缩略图宽度</param>        /// <param name="height">缩略图高度</param>        /// <param name="mode">生成缩略图的方式</param>           public static void generatethumb(string imagepath, string thumbpath, int width, int height, string mode)        {            image image = image.fromfile(imagepath);            string extension = imagepath.substring(imagepath.lastindexof(.)).tolower();            imageformat imageformat = null;            switch (extension)            {                case .jpg:                case .jpeg:                    imageformat = imageformat.jpeg;                    break;                case .bmp:                    imageformat = imageformat.bmp;                    break;                case .png:                    imageformat = imageformat.png;                    break;                case .gif:                    imageformat = imageformat.gif;                    break;                default:                    imageformat = imageformat.jpeg;                    break;            }            int towidth = width > 0 ? width : image.width;            int toheight = height > 0 ? height : image.height;            int x = 0;            int y = 0;            int ow = image.width;            int oh = image.height;            switch (mode)            {                case hw://指定高宽缩放（可能变形）                               break;                case w://指定宽，高按比例                                 toheight = image.height * width / image.width;                    break;                case h://指定高，宽按比例                    towidth = image.width * height / image.height;                    break;                case cut://指定高宽裁减（不变形）                               if ((double)image.width / (double)image.height > (double)towidth / (double)toheight)                    {                        oh = image.height;                        ow = image.height * towidth / toheight;                        y = 0;                        x = (image.width - ow) / 2;                    }                    else                    {                        ow = image.width;                        oh = image.width * height / towidth;                        x = 0;                        y = (image.height - oh) / 2;                    }                    break;                default:                    break;            }            //新建一个bmp            image bitmap = new bitmap(towidth, toheight);            //新建一个画板            graphics g = graphics.fromimage(bitmap);            //设置高质量插值法            g.interpolationmode = interpolationmode.high;            //设置高质量,低速度呈现平滑程度            g.smoothingmode = smoothingmode.highquality;            //清空画布并以透明背景色填充            g.clear(color.transparent);            //在指定位置并且按指定大小绘制原图片的指定部分            g.drawimage(image,                        new rectangle(0, 0, towidth, toheight),                        new rectangle(x, y, ow, oh),                        graphicsunit.pixel);            try            {                bitmap.save(thumbpath, imageformat);            }            catch (exception ex)            {                throw ex;            }            finally            {                if (g != null)                    g.dispose();                if (bitmap != null)                    bitmap.dispose();                if (image != null)                    image.dispose();            }        }        /// <summary>        /// 生成图片水印        /// </summary>        /// <param name="originalpath">源图路径</param>        /// <param name="watermarkpath">水印图片路径</param>        /// <param name="targetpath">保存路径</param>        /// <param name="position">位置</param>        /// <param name="opacity">透明度</param>        /// <param name="quality">质量</param>        public static void generateimagewatermark(string originalpath, string watermarkpath, string targetpath, int position, int opacity, int quality)        {            image originalimage = null;            image watermarkimage = null;            //图片属性            imageattributes attributes = null;            //画板            graphics g = null;            try            {                originalimage = image.fromfile(originalpath);                watermarkimage = new bitmap(watermarkpath);                if (watermarkimage.height >= originalimage.height || watermarkimage.width >= originalimage.width)                {                    originalimage.save(targetpath);                    return;                }                if (quality < 0 || quality > 100)                    quality = 80;                //水印透明度                float iii;                if (opacity > 0 && opacity <= 10)                    iii = (float)(opacity / 10.0f);                else                    iii = 0.5f;                //水印位置                int x = 0;                int y = 0;                switch (position)                {                    case 1:                        x = (int)(originalimage.width * (float).01);                        y = (int)(originalimage.height * (float).01);                        break;                    case 2:                        x = (int)((originalimage.width * (float).50) - (watermarkimage.width / 2));                        y = (int)(originalimage.height * (float).01);                        break;                    case 3:                        x = (int)((originalimage.width * (float).99) - (watermarkimage.width));                        y = (int)(originalimage.height * (float).01);                        break;                    case 4:                        x = (int)(originalimage.width * (float).01);                        y = (int)((originalimage.height * (float).50) - (watermarkimage.height / 2));                        break;                    case 5:                        x = (int)((originalimage.width * (float).50) - (watermarkimage.width / 2));                        y = (int)((originalimage.height * (float).50) - (watermarkimage.height / 2));                        break;                    case 6:                        x = (int)((originalimage.width * (float).99) - (watermarkimage.width));                        y = (int)((originalimage.height * (float).50) - (watermarkimage.height / 2));                        break;                    case 7:                        x = (int)(originalimage.width * (float).01);                        y = (int)((originalimage.height * (float).99) - watermarkimage.height);                        break;                    case 8:                        x = (int)((originalimage.width * (float).50) - (watermarkimage.width / 2));                        y = (int)((originalimage.height * (float).99) - watermarkimage.height);                        break;                    case 9:                        x = (int)((originalimage.width * (float).99) - (watermarkimage.width));                        y = (int)((originalimage.height * (float).99) - watermarkimage.height);                        break;                }                //颜色映射表                colormap colormap = new colormap();                colormap.oldcolor = color.fromargb(255, 0, 255, 0);                colormap.newcolor = color.fromargb(0, 0, 0, 0);                colormap[] newcolormap = { colormap };                //颜色变换矩阵,iii是设置透明度的范围0到1中的单精度类型                float[][] newcolormatrix ={                                             new float[] {1.0f,  0.0f,  0.0f,  0.0f, 0.0f},                                            new float[] {0.0f,  1.0f,  0.0f,  0.0f, 0.0f},                                            new float[] {0.0f,  0.0f,  1.0f,  0.0f, 0.0f},                                            new float[] {0.0f,  0.0f,  0.0f,  iii, 0.0f},                                            new float[] {0.0f,  0.0f,  0.0f,  0.0f, 1.0f}                                           };                //定义一个 5 x 5 矩阵                colormatrix matrix = new colormatrix(newcolormatrix);                //图片属性                attributes = new imageattributes();                attributes.setremaptable(newcolormap, coloradjusttype.bitmap);                attributes.setcolormatrix(matrix, colormatrixflag.default, coloradjusttype.bitmap);                //画板                g = graphics.fromimage(originalimage);                //绘制水印                g.drawimage(watermarkimage, new rectangle(x, y, watermarkimage.width, watermarkimage.height), 0, 0, watermarkimage.width, watermarkimage.height, graphicsunit.pixel, attributes);                //保存图片                encoderparameters encoderparams = new encoderparameters();                encoderparams.param[0] = new encoderparameter(encoder.quality, new long[] { quality });                if (getjpegcodec() != null)                    originalimage.save(targetpath, _jpegcodec, encoderparams);                else                    originalimage.save(targetpath);            }            catch (exception ex)            {                throw ex;            }            finally            {                if (g != null)                    g.dispose();                if (attributes != null)                    attributes.dispose();                if (watermarkimage != null)                    watermarkimage.dispose();                if (originalimage != null)                    originalimage.dispose();            }        }        /// <summary>        /// 生成文字水印        /// </summary>        /// <param name="originalpath">源图路径</param>        /// <param name="targetpath">保存路径</param>        /// <param name="text">水印文字</param>        /// <param name="textsize">文字大小</param>        /// <param name="textfont">文字字体</param>        /// <param name="position">位置</param>        /// <param name="quality">质量</param>        public static void generatetextwatermark(string originalpath, string targetpath, string text, int textsize, string textfont, int position, int quality)        {            image originalimage = null;            //画板            graphics g = null;            try            {                originalimage = image.fromfile(originalpath);                //画板                g = graphics.fromimage(originalimage);                if (quality < 0 || quality > 100)                    quality = 80;                font font = new font(textfont, textsize, fontstyle.regular, graphicsunit.pixel);                sizef sizepair = g.measurestring(text, font);                float x = 0;                float y = 0;                switch (position)                {                    case 1:                        x = (float)originalimage.width * (float).01;                        y = (float)originalimage.height * (float).01;                        break;                    case 2:                        x = ((float)originalimage.width * (float).50) - (sizepair.width / 2);                        y = (float)originalimage.height * (float).01;                        break;                    case 3:                        x = ((float)originalimage.width * (float).99) - sizepair.width;                        y = (float)originalimage.height * (float).01;                        break;                    case 4:                        x = (float)originalimage.width * (float).01;                        y = ((float)originalimage.height * (float).50) - (sizepair.height / 2);                        break;                    case 5:                        x = ((float)originalimage.width * (float).50) - (sizepair.width / 2);                        y = ((float)originalimage.height * (float).50) - (sizepair.height / 2);                        break;                    case 6:                        x = ((float)originalimage.width * (float).99) - sizepair.width;                        y = ((float)originalimage.height * (float).50) - (sizepair.height / 2);                        break;                    case 7:                        x = (float)originalimage.width * (float).01;                        y = ((float)originalimage.height * (float).99) - sizepair.height;                        break;                    case 8:                        x = ((float)originalimage.width * (float).50) - (sizepair.width / 2);                        y = ((float)originalimage.height * (float).99) - sizepair.height;                        break;                    case 9:                        x = ((float)originalimage.width * (float).99) - sizepair.width;                        y = ((float)originalimage.height * (float).99) - sizepair.height;                        break;                }                g.drawstring(text, font, new solidbrush(color.white), x + 1, y + 1);                g.drawstring(text, font, new solidbrush(color.black), x, y);                //保存图片                encoderparameters encoderparams = new encoderparameters();                encoderparams.param[0] = new encoderparameter(encoder.quality, new long[] { quality });                if (getjpegcodec() != null)                    originalimage.save(targetpath, _jpegcodec, encoderparams);                else                    originalimage.save(targetpath);            }            catch (exception ex)            {                throw ex;            }            finally            {                if (g != null)                    g.dispose();                if (originalimage != null)                    originalimage.dispose();            }        }        #endregion    }}
以上就是io帮助类是什么？io帮助类的实例介绍（附代码）的详细内容。