找出解决方案。除了application.properties配置之外，我还必须创建一个配置类，当提供适当的凭证时，该类将使我能够访问AmazonS3Client对象。我在GitHub上遵循了以下示例：
https://github.com/brant-hwang/spring-cloud-aws-
example/blob/master/src/main/java/com/axisj/spring/cloud/aws/AWSConfiguration.java
AWSConfiguration.java：
import com.amazonaws.auth.AWSCredentials;import com.amazonaws.auth.BasicAWSCredentials;import com.amazonaws.regions.Region;import com.amazonaws.regions.Regions;import com.amazonaws.services.s3.AmazonS3Client;import org.springframework.beans.factory.annotation.Value;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configurationpublic class AWSConfiguration { @Value("${cloud.aws.credentials.accessKey}") private String accessKey; @Value("${cloud.aws.credentials.secretKey}") private String secretKey; @Value("${cloud.aws.region}") private String region; @Bean public BasicAWSCredentials basicAWSCredentials() { return new BasicAWSCredentials(accessKey, secretKey); } @Bean public AmazonS3Client amazonS3Client(AWSCredentials awsCredentials) { AmazonS3Client amazonS3Client = new AmazonS3Client(awsCredentials); amazonS3Client.setRegion(Region.getRegion(Regions.fromName(region))); return amazonS3Client; }}配置完成后，您可以在其他类中创建AmazonS3Client对象（自动装配），并使用客户端向您的S3云发出请求。该示例将包装器类用作服务，以简化其他控制器类的实现。
S3Wrapper.java：
import com.amazonaws.services.s3.AmazonS3Client;import com.amazonaws.services.s3.model.*;import org.apache.commons.io.IOUtils;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Value;import org.springframework.http.HttpHeaders;import org.springframework.http.HttpStatus;import org.springframework.http.MediaType;import org.springframework.http.ResponseEntity;import org.springframework.stereotype.Service;import org.springframework.util.StringUtils;import org.springframework.web.multipart.MultipartFile;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.net.URLEnprer;import java.util.ArrayList;import java.util.Arrays;import java.util.List;@Servicepublic class S3Wrapper { @Autowired private AmazonS3Client amazonS3Client; @Value("${cloud.aws.s3.bucket}") private String bucket; private PutObjectResult upload(String filePath, String uploadKey) throws FileNotFoundException { return upload(new FileInputStream(filePath), uploadKey); } private PutObjectResult upload(InputStream inputStream, String uploadKey) { PutObjectRequest putObjectRequest = new PutObjectRequest(bucket, uploadKey, inputStream, new Objectmetadata()); putObjectRequest.setCannedAcl(CannedAccessControlList.PublicRead); PutObjectResult putObjectResult = amazonS3Client.putObject(putObjectRequest); IOUtils.closeQuietly(inputStream); return putObjectResult; } public List<PutObjectResult> upload(MultipartFile[] multipartFiles) { List<PutObjectResult> putObjectResults = new ArrayList<>(); Arrays.stream(multipartFiles) .filter(multipartFile -> !StringUtils.isEmpty(multipartFile.getOriginalFilename())) .forEach(multipartFile -> { try { putObjectResults.add(upload(multipartFile.getInputStream(), multipartFile.getOriginalFilename())); } catch (IOException e) { e.printStackTrace(); } }); return putObjectResults; } public ResponseEntity<byte[]> download(String key) throws IOException { GetObjectRequest getObjectRequest = new GetObjectRequest(bucket, key); S3Object s3Object = amazonS3Client.getObject(getObjectRequest); S3ObjectInputStream objectInputStream = s3Object.getObjectContent(); byte[] bytes = IOUtils.toByteArray(objectInputStream); String fileName = URLEnprer.enpre(key, "UTF-8").replaceAll("\+", "%20"); HttpHeaders httpHeaders = new HttpHeaders(); httpHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM); httpHeaders.setContentLength(bytes.length); httpHeaders.setContentDispositionFormData("attachment", fileName); return new ResponseEntity<>(bytes, httpHeaders, HttpStatus.OK); } public List<S3ObjectSummary> list() { ObjectListing objectListing = amazonS3Client.listObjects(new ListObjectsRequest().withBucketName(bucket)); List<S3ObjectSummary> s3ObjectSummaries = objectListing.getObjectSummaries(); return s3ObjectSummaries; }}注意：为了使用Apache Commons IO库，需要将以下依赖项添加到pom.xml中。
pom.xml：
<dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-io</artifactId> <version>1.3.2</version></dependency>
