在Amazon S3文件上传过程中，使用FileInputStream和InputStream都可以实现文件上传。以下是使用这两种方法的代码示例：

1. 使用FileInputStream上传文件：

import com.amazonaws.AmazonServiceException;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.model.PutObjectRequest;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class S3FileUploadExample {

    public static void main(String[] args) throws IOException {
        String bucketName = "your-bucket-name";
        String key = "your-object-key";
        String filePath = "path/to/your/file.jpg";

        AmazonS3 s3Client = new AmazonS3Client();

        try {
            File file = new File(filePath);
            FileInputStream fis = new FileInputStream(file);
            s3Client.putObject(new PutObjectRequest(bucketName, key, fis, null));
        } catch (AmazonServiceException e) {
            // Handle Amazon S3 service exception
            e.printStackTrace();
        } catch (IOException e) {
            // Handle file IO exception
            e.printStackTrace();
        }
    }
}

2. 使用InputStream上传文件：

import com.amazonaws.AmazonServiceException;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.model.PutObjectRequest;

import java.io.InputStream;

public class S3FileUploadExample {

    public static void main(String[] args) {
        String bucketName = "your-bucket-name";
        String key = "your-object-key";
        InputStream inputStream = null;

        AmazonS3 s3Client = new AmazonS3Client();

        try {
            // Get the input stream of your file from any source
            inputStream = getInputStream();

            s3Client.putObject(new PutObjectRequest(bucketName, key, inputStream, null));
        } catch (AmazonServiceException e) {
            // Handle Amazon S3 service exception
            e.printStackTrace();
        } finally {
            // Close the input stream
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private static InputStream getInputStream() {
        // Implement this method to return the input stream of your file
        // It could be a FileInputStream, ByteArrayInputStream, etc.
        return null;
    }
}

无论使用FileInputStream还是InputStream，都需要确保文件的输入流被正确关闭以避免资源泄漏。