AWS-Java SDK を介してブラウザの S3 アップロード リクエストに署名する

私はこれを解決し、そのための小さな guice モジュールを作成しました。これは、バックエンドへの get リクエストで Repository クラスから呼び出されます。

// 資源

public class SignResource {

    private final SignRepository repository;

    @Inject
    public SignResource(SignRepository repository) {
        this.repository = repository;
    }

    @GET
    public Response signPOST(@QueryParam("type") String type) {
        String signRequest = repository.signRequest(type);
        return Response.status(Response.Status.OK).entity(signRequest).build();
    }
}

// リポジトリ

public class SignRepository {

    @Inject
    private SignService signService;

    public SignRepository() {
    }

    public String signRequest(String contentType) {
        return signService.signRequest(contentType);
    }
}

// 実装

public class SignServiceImpl implements SignService {

    private String awsBucket;
    private String awsAccessKey;
    private String awsSecretKey;

    SignServiceImpl(AmazonConfiguration amazon) {
        awsSecretKey = amazon.getSecret();
        awsAccessKey = amazon.getAccess();
        awsBucket = amazon.getBucket();
    }

    @Override
    public String signRequest(String contentType) {
        final String randomFileName = createRandomName();

        String policy = createPolicy(randomFileName, contentType);

        SignRequest signRequest = new SignRequest();
        signRequest.setAwsAccessKeyId(awsAccessKey);
        signRequest.setPolicy(policy);
        signRequest.setSignature(ServiceUtils.signWithHmacSha1(awsSecretKey, policy));
        signRequest.setBucket(awsBucket);
        signRequest.setKey(randomFileName);
        signRequest.setAcl("public-read");
        signRequest.setContentType(contentType);
        signRequest.setExpires(createExpireTime().toString());
        signRequest.setSuccessActionStatus("201");

        return createJsonString(signRequest);
    }

    private String createPolicy(String randomFileName, String contentType) {
        try {
            String[] conditions = {
                S3Service.generatePostPolicyCondition_Equality("bucket", awsBucket),
                S3Service.generatePostPolicyCondition_Equality("key", randomFileName),
                S3Service.generatePostPolicyCondition_Equality("acl", "public-read"),
                S3Service.generatePostPolicyCondition_Equality("expires", createExpireTime().toString()),
                S3Service.generatePostPolicyCondition_Equality("content-Type", contentType),
                S3Service.generatePostPolicyCondition_Equality("success_action_status", "201"),
                S3Service.generatePostPolicyCondition_AllowAnyValue("cache-control")
            };

            String policyDocument = "{\"expiration\": \"" + ServiceUtils.formatIso8601Date(createExpireTime()) + "\", \"conditions\": [" + ServiceUtils.join(conditions, ",") + "]}";

            return ServiceUtils.toBase64(policyDocument.getBytes(Constants.DEFAULT_ENCODING));
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }

        return null;
    }

    private String createRandomName() {
        return UUID.randomUUID().toString();
    }

    private Date createExpireTime() {
        Calendar cal = Calendar.getInstance();
        cal.add(Calendar.HOUR, 24);

        return cal.getTime();
    }

    private String createJsonString(SignRequest request) {
        ObjectMapper mapper = new ObjectMapper();
        String json = null;

        try {
            json = mapper.writeValueAsString(request);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }

        return json;
    }
}

// サービス

public interface SignService {
    String signRequest(String contentType);
}

// モジュール

public class SignServiceModule extends AbstractModule {

    @Override
    protected void configure() {
        bind(SignService.class).toProvider(SignServiceProvider.class).asEagerSingleton();
    }
}

// プロバイダー

public class SignServiceProvider implements Provider<SignService> {

    @Inject
    private SwordfishConfiguration configuration;

    @Override
    public SignService get() {
        return new SignServiceImpl(configuration.getAmazon());
    }
}