s3协议java签名 前端post方式上传文件

在Java中使用S3协议进行前端POST方式上传文件，通常需要以下几个步骤：

配置AWS凭证和权限：确保你有AWS的访问密钥ID和秘密访问密钥，并且这些凭证具有访问S3存储桶的权限。

生成预签名URL：使用AWS SDK for Java生成一个预签名的URL，这个URL包含了对特定S3存储桶和对象的临时访问权限。

前端上传文件：在前端使用生成的预签名URL，通过POST方式将文件上传到S3存储桶。

以下是一个示例代码，展示如何在Java中生成预签名URL：
import com.amazonaws.HttpMethod;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.GeneratePresignedUrlRequest;

import java.util.Date;

public class S3Presigner {
private static final String AWS_ACCESS_KEY = "your-access-key";
private static final String AWS_SECRET_KEY = "your-secret-key";
private static final String BUCKET_NAME = "your-bucket-name";
private static final String OBJECT_KEY = "your-object-key";
private static final long EXPIRATION_TIME = 1000 * 60 * 10; // 10 minutes

public static void main(String[] args) {
BasicAWSCredentials awsCreds = new BasicAWSCredentials(AWS_ACCESS_KEY, AWS_SECRET_KEY);
AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
.withRegion("your-region")
.withCredentials(new AWSStaticCredentialsProvider(awsCreds))
.build();

Date expiration = new Date();
expiration.setTime(expiration.getTime() + EXPIRATION_TIME);

GeneratePresignedUrlRequest generatePresignedUrlRequest =
new GeneratePresignedUrlRequest(BUCKET_NAME, OBJECT_KEY)
.withMethod(HttpMethod.POST)
.withExpiration(expiration);

URL presignedUrl = s3Client.generatePresignedUrl(generatePresignedUrlRequest);

System.out.println("Pre-signed URL: " + presignedUrl.toString());
}
}
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在前端，你可以使用JavaScript的fetch API或XMLHttpRequest来上传文件：
const presignedUrl = 'https://your-presigned-url.com';
const fileInput = document.getElementById('fileInput');

fileInput.addEventListener('change', () => {
const file = fileInput.files[0];
const formData = new FormData();
formData.append('file', file);

fetch(presignedUrl, {
method: 'POST',
body: formData
})
.then(response => {
if (response.ok) {
console.log('File uploaded successfully');
} else {
console.error('File upload failed');
}
})
.catch(error => {
console.error('Error:', error);
});
});
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