如何将 azure-storage 实现到 vaadin 框架中

Question

我正在尝试将文件上传到 Azure Blob。我正在尝试通过 vaadin 框架中的上传来实现。 Vaadin 版本：6.7.8

我能够开发将文件上传到 azure blob 的代码。

我的问题陈述如下：

我写了一个 class UploadToBlob.java 来上传文件到 azure blob。
如果我运行 class UploadToBlob.java 单独（运行来自 eclipse 运行作为 java 应用程序），我能够将文件上传到 azure blob。
如果我在另一个 class[ModifyComplaintComponent.java] 中创建 UploadToBlob class 的对象，storageAccount = CloudStorageAccount.parse(storageConnectionString); 不会执行。

下面是UploadToBlob.java代码：

    package com.---.trs.scms.ui.components;

import com.microsoft.azure.storage.CloudStorageAccount;
import com.microsoft.azure.storage.StorageCredentials;
import com.microsoft.azure.storage.blob.CloudBlobContainer;

public class UploadToBlob {

    public static void main(String[] args) {

        try {

            final String storageConnectionString = "DefaultEndpointsProtocol=https;AccountName=abcd;AccountKey=bmiA7+****==;EndpointSuffix=core.windows.net";
            System.out.println("---I am getting called Main-1 ");

            CloudStorageAccount storageAccount;

            storageAccount = CloudStorageAccount.parse(storageConnectionString);

            com.microsoft.azure.storage.blob.CloudBlobClient blobClient = storageAccount.createCloudBlobClient();

            CloudBlobContainer container = blobClient.getContainerReference("container2");

            container.createIfNotExists();

            String filePath = "C:\Users\----\Desktop\Timesheet - 19th Aug,2019.pdf";

            com.microsoft.azure.storage.blob.CloudBlockBlob blob = container.getBlockBlobReference("Timesheet.pdf");

            java.io.File source = new java.io.File(filePath);

            java.io.FileInputStream fileInputStream = new java.io.FileInputStream(source);

            blob.upload(fileInputStream, source.length());

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

现在，我正在传递手动文件 PATH 如上所述上传到 azure blob，正如我上面所说的，这个 class 被调用直到代码行 System.out.println("---I am getting called Main-1 ");

这是我调用的 ModifyComplaintComponent 代码 UploadToBlob.java:

import com.vaadin.ui.HorizontalLayout;
import com.vaadin.ui.Upload;

public class ModifyComplaintComponent extends CustomComponent {


//other component  code which I haven't pasted here
    private Upload uploadnew;

    try {
            System.out.println("------Inside try block-----------");
            UploadToBlob fileReceiver= new UploadToBlob ();

            uploadnew = new Upload("Upload a file", fileReceiver);

            uploadnew.setReceiver(fileReceiver);
            uploadnew.addListener(fileReceiver);

            System.out.println("------end of try block-----------");
        }  catch (Exception e) {
            System.out.println("------catch block-----------");
            e.printStackTrace();

        } 

        HorizontalLayout hlayout = new HorizontalLayout();
        hlayout.setSpacing(true);
        hlayout.addComponent(uploadnew);

}

我在 UploadToBlob 代码中给出手动文件路径的原因是因为我首先想让这段代码从 ModifyComplaintComponent class.

其次，当我尝试浏览文件时，文件被选中但是当我点击上传时，我在 Vaadin 上传 UI 部分得到 NullPointerException，即使我选择了文件，UI说 "no file choosen"

我面临的挑战是如果我单独运行 Upload.java 文件，我可以将静态文件上传到 azure blob 中，但我想浏览 vaadin 框架中的文件并将其上传到天蓝色的 blob 存储。

Answer 1

首先，上传是Vaadin的一个组件。您不应该创建自己的上传 class。

其次，public静态main方法是程序启动的入口。如果你想使用class的方法，你需要显式地调用它。

TheClassName.MethodName(...) // For static method
new TheClassName(...).MethodName(...) //For non-static method

第三，我做了一些测试，下面是一个成功的例子。将创建两个 classes:

Class 上传接收器

这个 class 实现了 Receiver 接口和一些侦听器。

import com.microsoft.azure.storage.CloudStorageAccount;
import com.microsoft.azure.storage.StorageException;
import com.microsoft.azure.storage.blob.CloudBlobClient;
import com.microsoft.azure.storage.blob.CloudBlobContainer;
import com.microsoft.azure.storage.blob.CloudBlockBlob;
import com.vaadin.ui.Upload;
import org.springframework.stereotype.Component;

import java.io.OutputStream;
import java.net.URISyntaxException;
import java.security.InvalidKeyException;

@Component
public class UploadReceiver implements Upload.Receiver, Upload.StartedListener, Upload.SucceededListener, Upload.ProgressListener {
    // Storage account connection string.
    public static String conn = "DefaultEndpointsProtocol=https;AccountName=stora***789;AccountKey=G3***w==;EndpointSuffix=core.windows.net";

    @Override
    public OutputStream receiveUpload(String filename, String mimeType) {
        System.out.println("Uploading -> " + mimeType + " ; File name -> " + filename);
        return GetOutputStream("vaadin",filename);
    }

    @Override
    public void uploadStarted(Upload.StartedEvent startedEvent) {
        System.out.println("Upload started!");
    }

    @Override
    public void uploadSucceeded(Upload.SucceededEvent succeededEvent) {
        System.out.println("Upload succeeded!");
    }


    public OutputStream GetOutputStream(String container, String blob){
        OutputStream outputStream = null;
        try{
            CloudStorageAccount storageAccount = CloudStorageAccount.parse(conn);
            CloudBlobClient blobClient = storageAccount.createCloudBlobClient();
            CloudBlobContainer blobContainer = blobClient.getContainerReference(container);
            CloudBlockBlob cloudBlockBlob = blobContainer.getBlockBlobReference(blob);
            outputStream = cloudBlockBlob.openOutputStream();
        } catch (StorageException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (URISyntaxException e) {
            e.printStackTrace();
        }
        return outputStream;
    }

    @Override
    public void updateProgress(long readBytes, long contentLength) {
        System.out.println("Progress: readBytes -> " + readBytes + " ; contentLength -> " + contentLength);
    }
}

Class 主要UI

这是 UI 页面。我只是添加了一个上传组件。

import com.vaadin.server.VaadinRequest;
import com.vaadin.spring.annotation.SpringUI;
import com.vaadin.ui.Alignment;
import com.vaadin.ui.UI;
import com.vaadin.ui.Upload;
import com.vaadin.ui.VerticalLayout;
import org.springframework.beans.factory.annotation.Autowired;

@SpringUI
public class MainUI extends UI {

    private VerticalLayout layout;
    private Upload upload;

    private UploadReceiver uploadReceiver;

    @Autowired
    public MainUI(UploadReceiver uploadReceiver){
        this.uploadReceiver = uploadReceiver;
    }

    @Override
    protected void init(VaadinRequest vaadinRequest) {

        // Set layout
        layout = new VerticalLayout();
        layout.setDefaultComponentAlignment(Alignment.MIDDLE_CENTER);
        setContent(layout);


        // Add upload
        upload = new Upload("Upload a file", uploadReceiver);
        upload.addStartedListener(uploadReceiver);
        upload.addSucceededListener(uploadReceiver);
        upload.addProgressListener(uploadReceiver);
        layout.addComponent(upload);
    }
}

结果： 单击上传按钮并选择要上传的文件后，我可以从控制台获得以下输出：

并且，通过使用存储资源管理器检查存储帐户，我可以看到文件已成功上传：

更新：

上传是这样的：

不知道你的代码是怎么通过编译的。要构建上传 object，您需要传递一个标题字符串和一个实现 Upload.Receiver 接口的接收器。

public Upload(String caption, Receiver uploadReceiver)

要实现Upload.Receiver 接口，您必须重写receiveUpload 方法。

OutputStream receiveUpload(String filename, String mimeType)

receiveUpload 将 return 一个输出流，vaadin 最终会将内容写入其中。

就是这样。给 vaadin 一个输出流，它会将所有内容写入流。

输入文件从您的浏览器发送并由 vaadin 处理。我没有找到在vaadin中手动设置输入内容的方法。对不起。

如何将 azure-storage 实现到 vaadin 框架中

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