Implementar CORS usando o OSS SDK for Java - Object Storage Service: Central de Documentação do Alibaba Cloud

Devido à política de mesma origem dos navegadores, solicitações entre origens podem ser rejeitadas durante a troca de dados ou o compartilhamento de recursos entre domínios diferentes. Para resolver esse problema, configure regras de compartilhamento de recursos entre origens (CORS). Nessas regras, especifique os domínios de origem das solicitações, os métodos permitidos e os cabeçalhos autorizados.

Observações de uso

Este tópico utiliza o endpoint público da região China (Hangzhou). Para acessar o OSS a partir de outros serviços da Alibaba Cloud na mesma região, use um endpoint interno. Para obter detalhes sobre as regiões e endpoints compatíveis, consulte Regiões e endpoints.
As credenciais de acesso neste tópico são obtidas de variáveis de ambiente. Para mais informações, consulte Configurar credenciais de acesso.
Este tópico demonstra a criação de uma instância OSSClient com um endpoint do OSS. Para configurações alternativas, como uso de domínio personalizado ou autenticação com credenciais do Security Token Service (STS), consulte Configuração do cliente.
A configuração de regras CORS exige a permissão oss:PutBucketCors. A consulta requer a permissão oss:GetBucketCors, e a exclusão demanda a permissão oss:DeleteBucketCors. Para mais informações, consulte Conceder uma política personalizada.

Configure uma regra CORS

O código de exemplo a seguir mostra como configurar uma regra CORS para um bucket específico:

import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.SetBucketCORSRequest;
import java.util.ArrayList;

public class Demo {

    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        // Call the shutdown method to release resources when the OSSClient is no longer in use.
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            SetBucketCORSRequest request = new SetBucketCORSRequest(bucketName);

            // You can configure up to 10 CORS rules for a bucket. 
            ArrayList<SetBucketCORSRequest.CORSRule> putCorsRules = new ArrayList<SetBucketCORSRequest.CORSRule>();

            SetBucketCORSRequest.CORSRule corRule = new SetBucketCORSRequest.CORSRule();

            ArrayList<String> allowedOrigin = new ArrayList<String>();
            // Specify the origins from which cross-origin requests are allowed. 
            allowedOrigin.add( "http://example.com");

            ArrayList<String> allowedMethod = new ArrayList<String>();
            // Specify the methods that can be used to send cross-origin requests, including GET, PUT, DELETE, POST, and HEAD. 
            allowedMethod.add("GET");

            ArrayList<String> allowedHeader = new ArrayList<String>();
            // Specify whether the headers that are specified by Access-Control-Request-Headers in the OPTIONS preflight request are allowed. 
            allowedHeader.add("x-oss-test");

            ArrayList<String> exposedHeader = new ArrayList<String>();
            // Specify the response headers for allowed access requests from applications. 
            exposedHeader.add("x-oss-test1");
            // You can use only one asterisk (*) as a wildcard character for AllowedOrigins and AllowedMethods in a CORS rule. The asterisk (*) wildcard character specifies that all origins or operations are allowed. 
            corRule.setAllowedMethods(allowedMethod);
            corRule.setAllowedOrigins(allowedOrigin);
            // AllowedHeaders and ExposeHeaders do not support wildcard characters. 
            corRule.setAllowedHeaders(allowedHeader);
            corRule.setExposeHeaders(exposedHeader);
            // Specify the period of time in which the browser can cache the response for an OPTIONS preflight request for specific resources. Unit: seconds. 
            corRule.setMaxAgeSeconds(10);

            // You can configure up to 10 CORS rules for the bucket. 
            putCorsRules.add(corRule);
            // The existing CORS rules are overwritten. 
            request.setCorsRules(putCorsRules);
            // Specify whether to return the "Vary: Origin" header. If you set this parameter to TRUE, the Vary: Origin header is returned regardless of whether the request is a cross-origin request or whether the cross-origin request is successful. If you set this parameter to False, the Vary: Origin header is not returned. 
            // request.setResponseVary(Boolean.TRUE);
            ossClient.setBucketCORS(request);
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

Consultar regras CORS

O código de exemplo a seguir mostra como consultar as regras CORS de um bucket específico:

import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.SetBucketCORSRequest;
import java.util.ArrayList;

public class Demo {

    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        // Call the shutdown method to release resources when the OSSClient is no longer in use.
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            ArrayList<SetBucketCORSRequest.CORSRule> corsRules;
            // Query the CORS rules. 
            corsRules =  (ArrayList<SetBucketCORSRequest.CORSRule>) ossClient.getBucketCORSRules(bucketName);
            for (SetBucketCORSRequest.CORSRule rule : corsRules) {
                for (String allowedOrigin1 : rule.getAllowedOrigins()) {
                    // Query the origins from which cross-origin requests are allowed. 
                    System.out.println(allowedOrigin1);
                }

                for (String allowedMethod1 : rule.getAllowedMethods()) {
                    // Query the HTTP methods that cross-origin requests are allowed to use. 
                    System.out.println(allowedMethod1);
                }

                if (rule.getAllowedHeaders().size() > 0){
                    for (String allowedHeader1 : rule.getAllowedHeaders()) {
                        // Query the response headers that are included in the cross-origin requests. 
                        System.out.println(allowedHeader1);
                    }
                }

                if (rule.getExposeHeaders().size() > 0) {
                    for (String exposeHeader : rule.getExposeHeaders()) {
                        // Query the response headers for allowed access requests from applications. 
                        System.out.println(exposeHeader);
                    }
                }

                if ( null != rule.getMaxAgeSeconds()) {
                    System.out.println(rule.getMaxAgeSeconds());
                }
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

Exclua regras CORS

O código de exemplo a seguir mostra como excluir todas as regras CORS de um bucket específico:

import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;

public class Demo {

    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou.
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        // Call the shutdown method to release resources when the OSSClient is no longer in use.
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // Delete all CORS rules of the bucket. 
            ossClient.deleteBucketCORSRules(bucketName);
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

Referências

Para obter o código de exemplo completo de gerenciamento de regras CORS, acesse o GitHub.
Para obter mais informações sobre a operação de API usada para configurar regras CORS, consulte PutBucketCors.
Para obter mais informações sobre a operação de API usada para consultar regras CORS, consulte GetBucketCors.
Para obter mais informações sobre a operação de API usada para excluir regras CORS, consulte DeleteBucketCors.