如何实现多文件上传至S3并返回文件URL及名称？

1. 单个文件上传后获取Object URL #

上传完成后，直接通过AmazonS3客户端的getUrl()方法即可获取文件的访问链接。如果你的S3对象是公开可读的，这个URL可以直接访问；如果是私有对象，可生成预签名URL提供临时访问权限。

修改后的单文件上传代码 #

import com.amazonaws.AmazonServiceException;
import com.amazonaws.SdkClientException;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.transfer.TransferManager;
import com.amazonaws.services.s3.transfer.TransferManagerBuilder;
import com.amazonaws.services.s3.transfer.Upload;
import java.io.File;
import java.net.URL;

public class S3Uploader {
    public static void main(String[] args) {
        String region = "your-region"; // 替换为你的S3区域，如us-east-1
        String mediaBucket = "your-bucket-name"; // 替换为你的存储桶名称
        String keyName = "your-object-key"; // 替换为S3中的对象键（文件名）
        String filePath = "local-file-path"; // 替换为本地文件路径

        try {
            AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                    .withRegion(region)
                    .withCredentials(new ProfileCredentialsProvider())
                    .build();
            TransferManager tm = TransferManagerBuilder.standard()
                    .withS3Client(s3Client)
                    .build();

            Upload upload = tm.upload(mediaBucket, keyName, new File(filePath));
            System.out.println("Object upload started");

            upload.waitForCompletion();
            System.out.println("Object upload complete");

            // 获取文件的访问URL
            URL objectUrl = s3Client.getUrl(mediaBucket, keyName);
            System.out.println("文件访问URL: " + objectUrl.toString());
            System.out.println("文件名称: " + keyName);

        } catch (AmazonServiceException e) {
            e.printStackTrace();
        } catch (SdkClientException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

2. 扩展为多文件上传并返回URL与名称 #

遍历本地文件列表，逐个执行上传逻辑，将每个文件的名称和URL收集到列表中返回即可。

多文件上传示例代码 #

import com.amazonaws.AmazonServiceException;
import com.amazonaws.SdkClientException;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.transfer.TransferManager;
import com.amazonaws.services.s3.transfer.TransferManagerBuilder;
import com.amazonaws.services.s3.transfer.Upload;
import java.io.File;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

// 存储上传结果的实体类
class UploadResult {
    private String fileName;
    private String fileUrl;

    public UploadResult(String fileName, String fileUrl) {
        this.fileName = fileName;
        this.fileUrl = fileUrl;
    }

    // Getter方法
    public String getFileName() {
        return fileName;
    }

    public String getFileUrl() {
        return fileUrl;
    }
}

public class S3MultiUploader {
    public static List<UploadResult> uploadFilesToS3(String region, String bucketName, List<File> localFiles) {
        List<UploadResult> results = new ArrayList<>();

        try {
            AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                    .withRegion(region)
                    .withCredentials(new ProfileCredentialsProvider())
                    .build();
            TransferManager tm = TransferManagerBuilder.standard()
                    .withS3Client(s3Client)
                    .build();

            for (File file : localFiles) {
                // 使用本地文件名作为S3对象键，也可自定义键名
                String keyName = file.getName();
                Upload upload = tm.upload(bucketName, keyName, file);
                System.out.println("开始上传文件: " + file.getName());

                upload.waitForCompletion();
                System.out.println("文件上传完成: " + file.getName());

                // 获取URL并添加到结果列表
                URL objectUrl = s3Client.getUrl(bucketName, keyName);
                results.add(new UploadResult(file.getName(), objectUrl.toString()));
            }

        } catch (AmazonServiceException e) {
            e.printStackTrace();
        } catch (SdkClientException | InterruptedException e) {
            e.printStackTrace();
        }

        return results;
    }

    // 测试方法
    public static void main(String[] args) {
        String region = "your-region";
        String bucketName = "your-bucket-name";

        // 构造本地文件列表
        List<File> files = new ArrayList<>();
        files.add(new File("path/to/file1.jpg"));
        files.add(new File("path/to/file2.pdf"));

        List<UploadResult> uploadResults = uploadFilesToS3(region, bucketName, files);

        // 打印所有上传结果
        System.out.println("\n所有文件上传结果:");
        for (UploadResult result : uploadResults) {
            System.out.println("文件名: " + result.getFileName() + " | 访问URL: " + result.getFileUrl());
        }
    }
}

3. 私有对象的预签名URL生成（可选） #

如果S3对象是私有访问权限，直接通过getUrl()获取的URL无法直接访问，可生成预签名URL提供临时访问权限：

// 生成有效期为1小时的预签名URL
java.util.Date expiration = new java.util.Date();
long expTimeMillis = expiration.getTime();
expTimeMillis += 1000 * 60 * 60; // 1小时
expiration.setTime(expTimeMillis);

URL presignedUrl = s3Client.generatePresignedUrl(bucketName, keyName, expiration);
System.out.println("预签名访问URL: " + presignedUrl.toString());

内容的提问来源于stack exchange，提问作者Teletubbies