Salesforce图片上传

Salesforce图片上传的方式可通过自带组件apex:inputFile及html标签input type="file"实现。

1、效果

2、apex:inputFile实现

采用标准组件inputFile并将值赋给页面变量（view state）Picture

<apex:pageBlockSection columns="1">
	<apex:inputFile value="{!Picture}" accept="image/*" />
</apex:pageBlockSection>
<apex:pageBlockButtons>
	<apex:commandButton value="Save" action="{!save}" />
</apex:pageBlockButtons>

public with sharing class Test_HpcUploadImg {
public blob Picture { get; set; }

public PageReference save() {
	ErrorMessage = '';
	try {
		if (picture != null) {
			String url = CN_SPR_UploadAzureHelper.UploadToAzure(picture,'.jpg','application/octet-stream');
			ErrorMessage=url;

注意：

此种方式图片大小限制为170KB，超过则提示“Maximum view state size limit (170KB) exceeded. Actual view state size for this page was 293.157KB”

3、input type="file"实现

<div class="slds-col slds-size_1-of-1 slds-p-horizontal_medium">
    <img id="imgPreview_csp" style="180px;height:180px;" src="{!URLFOR($Resource.India_Content, 'img/sample_picture.png')}" />
</div>
<div class="slds-col slds-size_1-of-1 slds-p-horizontal_medium" style="margin-top:5px;">
    <input type="file" id="fileImg_csp" value="" filename="fileImg_csp" style="display:none;" accept=".jpg,.jpeg,.png" />
    <button class="slds-button slds-button_neutral" id="btnSelecttPic" style="display:none;">Select a Picture</button>
    <input type="Button" value="Upload" id="btnSave_csp" class="slds-button slds-button_brand" style="display:none;" />
</div>

//选择图片，马上预览
function changeImg(obj) {
    var file = obj.files[0];
    var reader = new FileReader();

    //读取文件过程方法
    reader.onloadstart = function (e) { //开始读取
    }
    reader.onprogress = function (e) { //正在读取中
    }
    reader.onabort = function (e) { //中断读取
    }
    reader.onerror = function (e) { //读取异常
    }
    reader.onload = function (e) { //成功读取
        var files = document.getElementById('fileImg_csp').files;
        var fileName = files[0].name;
        //判断文件后缀
        if (!(/.jpg$/.test(fileName) || /.jpeg$/.test(fileName) || /.png$/.test(fileName))) {
            Messages.add(Messages.Type.error, "JPG,PNG images only supported");
            return;
        }
        var img = document.getElementById("imgPreview_csp");
        img.src = e.target.result;
        //或者 img.src = this.result;  //e.target == this
    }

    reader.readAsDataURL(file);//必须要加
}

//上传
function saveImg() {
    Messages.clear();

    var maxFileSize = 1572864;      //1.5M=1.5*1024*1024
    var attachmentBody;                //附件内容
    var attachmentName;                //附件名称
    var fileSize;                     //附件大小

    var Files = document.getElementById('fileImg_csp').files;
    var File = Files[0];

    if (File != undefined) {
        if (File.size <= maxFileSize) {
            attachmentName = File.name;
            //判断文件后缀
            if (!(/.jpg$/.test(attachmentName) || /.jpeg$/.test(attachmentName) || /.png$/.test(attachmentName))) {
                Messages.add(Messages.Type.error, "JPG,PNG images only supported");
                return;
            }
            // debugger;
            var fileReader = new FileReader();
            fileReader.readAsBinaryString(File);
            fileReader.onloadend = function (e) {
                Spinner.show();
                //原始对象
                // attachmentBody = this.result;
                //Base64（btoa用于将对象创建为base-64 编码的字符串）
                attachmentBody = window.btoa(this.result);
                //Base64编码转换为Blob
                // attachmentBody=getBlob(window.btoa(this.result));

                Visualforce.remoting.Manager.invokeAction(
                    '{!$RemoteAction.IN_ChillerStandardPicture_Controller.UploadPicture}',
                    attachmentName,
                    attachmentBody,
                    getQueryParams(),
                    function (result, event) {
                        Spinner.hide();
                        console.log(result);
                        // alert('Upload Successfully');
                        Messages.add(Messages.Type.info, "Upload Successfully");
                    });

            }
            fileReader.onerror = function (e) {
                // alert("Upload failed");
                Messages.add(Messages.Type.error, "Upload failed");
            }
            fileReader.onabort = function (e) {
                // alert("Upload failed");
                Messages.add(Messages.Type.error, "Upload failed");
            }
            fileReader.onload = function (e) {

            }
        } else {
            // alert("Maximum upload of 1.5M files is allowed");
            Messages.add(Messages.Type.error, "Maximum upload of 1.5M files is allowed");
        }
    } else {
        // alert("Please select a file first");
        Messages.add(Messages.Type.error, "Please select a file first");
    }
}

//上传图片
@RemoteAction
public static String UploadPicture(String attachmentName,String attachmentBody,String queryParam) {
    try {
        //反序列化
        IN_AvailablilityAbi_Controller.QueryRequestParam req = (IN_AvailablilityAbi_Controller.QueryRequestParam)JSON.deserialize(queryParam, IN_AvailablilityAbi_Controller.QueryRequestParam.class);

        //上传图片到Azure
        // Blob blobFile= Blob.valueOf(attachmentBody);//将Base64编码的字符串转换为Blob【此处有问题】
        Blob blobFile = EncodingUtil.base64Decode(attachmentBody);//将Base64编码的字符串转换为Blob
        string fileSuffix= attachmentName.substring(attachmentName.indexOf('.'));//后缀
        String url = CN_SPR_UploadAzureHelper.UploadToAzure(blobFile,fileSuffix,'application/octet-stream');

注意：

此种方式测试了1.7M的图片可正常上传，5M则提示超出了大小限制（具体限制大小需再做测试）

4、建议

建议采用input type="file"实现的方式，且将图片以Base64传输到后端再进行流的转换。如果在前端进行Blob的转换需要考虑后端接收流的方式。

JS将Base64编码转换为Blob的实现如下：

//Base64编码转换为Blob
function getBlob(text) {
 var buffer = new Uint8Array(text.length);
 var pecent = 0, loop = null;
 for (var i = 0; i < text.length; i++) {
     buffer[i] = text.charCodeAt(i);
 }
 var format = 'image/jpeg';

 try {
     return new Blob([buffer], { type: format });
 } catch (e) {
     var bb = new (window.BlobBuilder || window.WebKitBlobBuilder || window.MSBlobBuilder);
     buffer.forEach(function (buf) {
         bb.append(buf);
     });
     return bb.getBlob(format);
 }
}