对象存储 OSS：Java进度条

注意事项

• 本文以华东1（杭州）外网Endpoint为例。如果您希望通过与OSS同地域的其他阿里云产品访问OSS，请使用内网Endpoint。关于OSS支持的Region与Endpoint的对应关系，请参见OSS访问域名、数据中心、开放端口。

• 本文以从环境变量读取访问凭证为例。如何配置访问凭证，请参见Java配置访问凭证。

• 本文以OSS域名新建OSSClient为例。如果您希望通过自定义域名、STS等方式新建OSSClient，请参见新建OSSClient。

示例代码

以下代码用于演示通过ossClient.getObject下载文件时使用进度条的方法。

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.event.ProgressEvent;
import com.aliyun.oss.event.ProgressEventType;
import com.aliyun.oss.event.ProgressListener;
import com.aliyun.oss.model.GetObjectRequest;
import java.io.File;

public class GetObjectProgressListener implements ProgressListener {
    private long bytesRead = 0;
    private long totalBytes = -1;
    private boolean succeed = false;

    public static void main(String[] args) throws Exception {
        // Endpoint以华东1（杭州）为例，其它Region请按实际情况填写。
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // 从环境变量中获取访问凭证。运行本代码示例之前，请确保已设置环境变量OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // 填写Bucket名称，例如examplebucket。
        String bucketName = "examplebucket";
        // 填写不包含Bucket名称在内的Object完整路径，例如testfolder/exampleobject.txt。
        String objectName = "testfolder/exampleobject.txt";
      	// 填写本地文件的完整路径，例如D:\\localpath\\examplefile.txt。
        String pathName = "D:\\localpath\\examplefile.txt";
        // 填写Bucket所在地域。以华东1（杭州）为例，Region填写为cn-hangzhou。
        String region = "cn-hangzhou";

        // 创建OSSClient实例。
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // 下载文件的同时指定了进度条参数。
            ossClient.getObject(new GetObjectRequest(bucketName, objectName).
                            <GetObjectRequest>withProgressListener(new GetObjectProgressListener()),
                    new File(pathName));
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }

    @Override
    public void progressChanged(ProgressEvent progressEvent) {
        long bytes = progressEvent.getBytes();
        ProgressEventType eventType = progressEvent.getEventType();
        switch (eventType) {
            case TRANSFER_STARTED_EVENT:
                System.out.println("Start to download......");
                break;
            case RESPONSE_CONTENT_LENGTH_EVENT:
                this.totalBytes = bytes;
                System.out.println(this.totalBytes + " bytes in total will be downloaded to a local file");
                break;
            case RESPONSE_BYTE_TRANSFER_EVENT:
                this.bytesRead += bytes;
                if (this.totalBytes != -1) {
                    int percent = (int)(this.bytesRead * 100.0 / this.totalBytes);
                    System.out.println(bytes + " bytes have been read at this time, download progress: " +
                            percent + "%(" + this.bytesRead + "/" + this.totalBytes + ")");
                } else {
                    System.out.println(bytes + " bytes have been read at this time, download ratio: unknown" +
                            "(" + this.bytesRead + "/...)");
                }
                break;
            case TRANSFER_COMPLETED_EVENT:
                this.succeed = true;
                System.out.println("Succeed to download, " + this.bytesRead + " bytes have been transferred in total");
                break;
            case TRANSFER_FAILED_EVENT:
                System.out.println("Failed to download, " + this.bytesRead + " bytes have been transferred");
                break;
            default:
                break;
        }
    }
    public boolean isSucceed() {
        return succeed;
    }
}

相关文档

关于下载文件的进度条使用方法的完整示例代码，请参见GitHub示例。