从aws中获取访问令牌，秘密访问密钥和会话令牌

AWS.config.credentials = new AWS.CognitoIdentityCredentials({ 
     IdentityPoolId: 'us-east-1:2ce7b2c2-898f-4a26-9066-d4feff8ebfe4' 
    }); 

    // Make the call to obtain credentials 
    AWS.config.credentials.get(function(){ 

     // Credentials will be available when this function is called. 
     var accessKeyId = AWS.config.credentials.accessKeyId; 
     var secretAccessKey = AWS.config.credentials.secretAccessKey; 
     var sessionToken = AWS.config.credentials.sessionToken; 
     //var identityId = AWS.config.credentials.identityId; 

     return res.send({ 
     accessKeyId: accessKeyId 
     }); 

    });

所有变量都有空值。为什么？我究竟做错了什么？有没有其他方法可以访问它？从aws中获取访问令牌，秘密访问密钥和会话令牌

而且我应该送一个秘密密钥和令牌来获取会话密钥

UPDATE：

当我尝试这种方法，我得到一个错误说： 错误：NotAuthorizedException：未认证此身份池不支持访问。

AWS.config.credentials.get(function(err) { 
    if (err) { 
     console.log("Error: "+err); 
     return; 
    } 
    console.log("Cognito Identity Id: " + AWS.config.credentials.identityId); 

    // Other service clients will automatically use the Cognito Credentials provider 
    // configured in the JavaScript SDK. 
    var cognitoSyncClient = new AWS.CognitoSync(); 
    cognitoSyncClient.listDatasets({ 
     IdentityId: AWS.config.credentials.identityId, 
     IdentityPoolId: "" 
    }, function(err, data) { 
     if (!err) { 
      console.log(JSON.stringify(data)); 
     } 
     return res.send({ 
      data: data 
     }); 
    }); 
    });

来源

2016-02-26 karankumar89