如何将在javascript中创建的Blob传递给JSF Bean [英] How to pass a blob created in javascript to JSF bean

问题描述

我的客户端代码处理画布绘图，并且我使用JavaScript生成了形状的Blob zip文件. 我想在服务器端使用zip.但是，我找不到任何解决方案.

My client side code deals with canvas drawing, and i generate a blob zip file of the shapes using javascript. I want to use the zip at the server side. However, I am not able to find any solution.

我尝试使用远程命令，但是使用该命令我只能将字符串参数传递给JSF bean. 我试图以某种方式破解primefaces fileUpload插件，以便可以将我的Blob传递给支持bean，但这也没有解决.

I have tried using remote command, but using that i can only pass string parameters to the JSF bean. I tried hacking the primefaces fileUpload plugin somehow so that I could pass my blob to the backing bean, but that also didn't work out.

推荐答案

您可以通过将blob编码为某种字符串表示形式(例如，传递到 Base64 并将其传递给)来将blob从JavaScript传递到JSF bean. Primefaces p:remoteCommand，将其发送到托管bean，最后将其解码回字节数组.

You can pass blob from JavaScript to JSF bean by encoding blob to some string representation, for example, to Base64 and passing it to Primefaces p:remoteCommand, sending it to managed bean and finally decoding it there back to byte array.

操作步骤如下:

1. 将blob转换为Base64

1. Convert blob to Base64

 function prepareAndSendBlobToManagedBean(){
            //zipped file as blob
            var blob=...;
            ///convert blob to Base64 string
            var blobBase64String=convertToBase64(blob);
            sendBlobBase64([{name : 'blobBase64Name', value : blobBase64String}]);
        }

(用于从blob转换为base64，请参考此已接受的 answer )

(for converting from blob to base64 reffer to this accepted answer)

1. 在页面中添加p:remoteCommand

1. Add p:remoteCommand to your page

<p:remoteCommand name="sendBlobBase64" 
                 actionListener="#{yourBean.onBlobBase64Sent}" process="@this"/>

在名为 yourBean 的托管bean中，您可以使用

In managed bean named yourBean you can catch it with

public void onBlobBase64Sent() {
   String blobBase64 = (String)FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("blobBase64Name");
   byte[]blob=java.util.Base64.getDecoder().decode(blobBase64);
}

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