使用canvas实现图片压缩上传

就不描述了，直接贴代码。有需要的朋友可以直接拿

js 部分:

// 参数，最大高度

var MAX_HEIGHT = 200;

// 渲染

function render(src) {

    // 创建一个 Image 对象

    var image = new Image();

    // 绑定 load 事件处理器，加载完成后执行

    image.onload = function () {

        // 获取 canvas DOM 对象

         var canvas = document.createElement( "canvas" );

        // 如果高度超标

        if (image.height > MAX_HEIGHT) {

            // 宽度等比例缩放 *=

            image.width *= MAX_HEIGHT / image.height;

            image.height = MAX_HEIGHT;

        }

        // 获取 canvas的 2d 环境对象,

        // 可以理解Context是管理员，canvas是房子

        var ctx = canvas.getContext( "2d" );

        // canvas清屏

        ctx.clearRect(0, 0, canvas.width, canvas.height);

        // 重置canvas宽高

        canvas.width = image.width;

        canvas.height = image.height;

        // 将图像绘制到canvas上

        ctx.drawImage(image, 0, 0, image.width, image.height);

        // !!! 注意，image 没有加入到 dom之中

//        document.getElementById('img').src = canvas.toDataURL("image/png");

        var blob = dataURLtoBlob(canvas.toDataURL( "image/png" ));

        var fd = new FormData();

        fd.append( "image" , blob, "image.png" );

        imgCompressUpload(canvas.toDataURL( "image/png" ));

       

    };

    // 设置src属性，浏览器会自动加载。

    // 记住必须先绑定事件，才能设置src属性，否则会出同步问题。

    image.src = src;

};

// 加载 图像文件(url路径)

function loadImage(src) {

    // 过滤掉 非 image 类型的文件

    if (!src.type.match( /image.*/ )) {

        if (window.console) {

            console.log( "选择的文件类型不是图片: " , src.type);

        } else {

            window.confirm( "只能选择图片文件" );

        }

        return ;

    }

    // 创建 FileReader 对象 并调用 render 函数来完成渲染.

    var reader = new FileReader();

    // 绑定load事件自动回调函数

    reader.onload = function (e) {

        // 调用前面的 render 函数

        render(e.target.result);

    };

    // 读取文件内容

    reader.readAsDataURL(src);

};

function loadImageFile() {

  if (document.getElementById( "file" ).files.length === 0) { return ; }

  var oFile = document.getElementById( "file" ).files[0];

  loadImage(oFile)

}

function dataURLtoBlob(dataurl) {

    var arr = dataurl.split( ',' ), mime = arr[0].match( /:(.*?);/ )[1],

        bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);

    while (n--){

        u8arr[n] = bstr.charCodeAt(n);

    }

    return new Blob([u8arr], {type:mime});

}

function imgCompressUpload(formData){

    $.ajax({

        url: ctxJs+ "/mob/yezhu/voice/voUservoice/uploadBase64.json" ,

        data: {base64Data: formData},

        type: "post" ,

        dataType: "json" ,

        success: function (data){

            data = JSON.parse(data);

             if (data.status == "true" ){

                 var imgSrc=data.data;

                 var imgStart= "" ;

                 var inpStart= "" ;

                $( "#imgList" ).append(imgStart+ctxJs+imgSrc+imgEnd+inpStart+imgSrc+inpEnd);

                $( "#imgList img" ).css( "height" , $( "#imgList img" ).width());

            } else {

                

            }

            console.log(data);

        },

        error: function (e){

            console.log(e);

        }

    })

}

java后台部门，楼主后台用的是StringMVC

@RequestMapping (value= "/uploadBase64" ,method=RequestMethod. POST )

    @ResponseBody public ResponseEntity base64UpLoad( @RequestParam String base64Data, HttpServletRequest                                                                                      

     request, HttpServletResponse response){ 

        try { 

            String dataPrix = "" ;

            String data = "" ;

            if (base64Data == null || "" .equals(base64Data)){

                throw new Exception( "上传失败，上传图片数据为空" );

            } else {

                String [] d = base64Data.split( "base64," );

                if (d != null && d. length == 2){

                    dataPrix = d[0];

                    data = d[1];

                } else {

                    throw new Exception( "上传失败，数据不合法" );

                }

            }

            String suffix = "" ;

            if ( "data:image/jpeg;" .equalsIgnoreCase(dataPrix)){ //data:image/jpeg;base64,base64编码的jpeg图片数据

                suffix = ".jpg" ;

            } else if ( "data:image/x-icon;" .equalsIgnoreCase(dataPrix)){ //data:image/x-icon;base64,base64编码的icon图片数据

                suffix = ".ico" ;

            } else if ( "data:image/gif;" .equalsIgnoreCase(dataPrix)){ //data:image/gif;base64,base64编码的gif图片数据

                suffix = ".gif" ;

            } else if ( "data:image/png;" .equalsIgnoreCase(dataPrix)){ //data:image/png;base64,base64编码的png图片数据

                suffix = ".png" ;

            } else {

                throw new Exception( "上传图片格式不合法" );

            }

           

            File fImg = buildYuLanFolder(request);

            File fileUploadurl = new File(fImg.getCanonicalPath() + "/"

                    + Math.random() + suffix);

                    

             //进行解密

             byte [] result = Base64.decodeBase64(data);

            FileCopyUtils.copy(result, fileUploadurl);

            

            String strURL = fileUploadurl.getCanonicalPath();

            System. out .println(strURL);

            strURL = strURL.substring(request.getSession()

                    .getServletContext().getRealPath( "/" ).length() - 1);

            strURL = strURL.replace( "\\" , "/" ); // 转换正反斜杠

            System. out .println( "" + strURL);

            

             return renderData( true , "ok" , strURL);

        } catch (Exception e) {

            System. out .print(e.getMessage());

             return renderMsg( false , "ng" );

        } 

       

    }