本文介绍如何进行跨域资源共享。

跨域资源共享（Cross-origin resource sharing，简称CORS）允许Web端的应用程序访问不属于本域的资源。OSS提供跨域资源共享接口，方便您控制跨域访问的权限。

更多关于跨域资源共享的介绍，请参见开发指南中的设置跨域访问和API参考中PutBucketcors。

跨域资源共享的完整代码请参见GitHub。

using Aliyun.OSS;
using Aliyun.OSS.Common;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
// 创建OSSClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    var request = new SetBucketCorsRequest(bucketName);
    var rule1 = new CORSRule();
    // 指定允许跨域请求的来源。
    rule1.AddAllowedOrigin("http://example.com");
    // 指定允许的跨域请求方法(GET/PUT/DELETE/POST/HEAD)。
    rule1.AddAllowedMethod("POST");
    // AllowedHeaders和ExposeHeaders不支持通配符。
    rule1.AddAllowedHeader("*");
    // 指定允许用户从应用程序中访问的响应头。
    rule1.AddExposeHeader("x-oss-test");
    // 最多允许10条规则。
    request.AddCORSRule(rule1);
    var rule2 = new CORSRule();
    // AllowedOrigins和AllowedMethods最多支持一个星号（*）通配符。星号（*）表示允许所有的域来源或者操作。
    rule2.AddAllowedOrigin("http://example.net");
    rule2.AddAllowedMethod("GET");
    // 是否允许预取指令（OPTIONS）中Access-Control-Request-Headers头中指定的Header。
    rule2.AddExposeHeader("x-oss-test2");
    // 指定浏览器对特定资源的预取（OPTIONS）请求返回结果的缓存时间，单位为秒。
    rule2.MaxAgeSeconds = 100;
    request.AddCORSRule(rule2);
    // 设置跨域资源共享规则。
    client.SetBucketCors(request);
    Console.WriteLine("Set bucket:{0} Cors succeeded ", bucketName);
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error info: {0}; Error info: {1}. \nRequestID:{2}\tHostID:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}

using Aliyun.OSS;
using Aliyun.OSS.Common;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
// 创建OSSClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    // 获取跨域资源共享规则。
    var result = client.GetBucketCors(bucketName);
    Console.WriteLine("Get bucket:{0} Cors succeeded ", bucketName);
    foreach (var rule in result)
    {
        foreach (var origin in rule.AllowedOrigins)
        {
            Console.WriteLine("Allowed origin:{0}", origin);
        }
    }
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error info: {0}; Error info: {1}. \nRequestID:{2}\tHostID:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}

using Aliyun.OSS;
using Aliyun.OSS.Common;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
// 创建OSSClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    // 删除跨域资源共享规则。
    client.DeleteBucketCors(bucketName);
    Console.WriteLine("Delete bucket:{0} Cors succeeded ", bucketName);
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error info: {0} ; Error info: {1}. \nRequestID:{2}\tHostID:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}