DynamoDB AmazonServiceException：提供的关键元素与模式不匹配

Question

因此，某些人可以指导我为什么会收到此异常。 下面是其中的应用程序已经停止异常BCZ名单： - 11-11 17:54:22.724 5048-5171/com.creation.ceaggregation1 E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #3 Process: com.creation.ceaggregation1, PID: 5048 java.lang.RuntimeException: An error occured while executing doInBackground() at android.os.AsyncTask$3.done(AsyncTask.java:304) at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355) at java.util.concurrent.FutureTask.setException(FutureTask.java:222) at java.util.concurrent.FutureTask.run(FutureTask.java:242) at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) at java.lang.Thread.run(Thread.java:818) Caused by: com.amazonaws.AmazonServiceException: The provided key element does not match the schema (Service: AmazonDynamoDB; Status Code: 400; Error Code: ValidationException; Request ID: C8BTD5J7Q2477PSOK1F9G3FUTFVV4KQNSO5AEMVJF66Q9ASUAAJG) at com.amazonaws.http.AmazonHttpClient.handleErrorResponse(AmazonHttpClient.java:712) at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:388) at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:199) at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.invoke(AmazonDynamoDBClient.java:4181) at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.updateItem(AmazonDynamoDBClient.java:1582) at com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper$SaveObjectHandler.doUpdateItem(DynamoDBMapper.java:1173) at com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper$2.executeLowLevelRequest(DynamoDBMapper.java:873) at com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper$SaveObjectHandler.execute(DynamoDBMapper.java:1056) at com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper.save(DynamoDBMapper.java:904) at com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper.save(DynamoDBMapper.java:688) at com.creation.ceaggregation1.EnterUser$UpdateTable.doInBackground(EnterUser.java:64) at com.creation.ceaggregation1.EnterUser$UpdateTable.doInBackground(EnterUser.java:40) at android.os.AsyncTask$2.call(AsyncTask.java:292) at java.util.concurrent.FutureTask.run(FutureTask.java:237) at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)  at java.lang.Thread.run(Thread.java:818)  11-11 17:54:24.769 5048-5171/com.creation.ceaggregation1 I/Process: Sending signal. PID: 5048 SIG: 9

继承人我映射类： -

@DynamoDBTable(tableName = "agation1") 
public class AWSDynamDBMapperClass { 
String username; 
String password; 

@DynamoDBHashKey(attributeName="username")//username 
public String getUsername() { 
    return username; 
} 

public void setUsername(String username) { 
    this.username = username; 
} 

@DynamoDBAttribute(attributeName = "password")//password 
public String getPassword() { 
    return password; 
} 

public void setPassword(String password) { 
    this.password = password; 
} 
} 

这里是mainActivity代码： - 私有类UpdateTable扩展的AsyncTask {

@Override 
    protected String doInBackground(String... params) { 
     String name = params[0]; 
     String password = params[1]; 

     try { 
      AWSDynamoDBManagerClass manager = new  AWSDynamoDBManagerClass(); 
      CognitoCredentialsProvider credentialsProvider = manager.getCredentials(EnterUser.this); 
      AWSDynamDBMapperClass mapperClass = new AWSDynamDBMapperClass(); 
      mapperClass.setUsername(name); 
      mapperClass.setPassword(password); 

      if (credentialsProvider != null && mapperClass != null) { 
       DynamoDBMapper dynamoDBMapper = manager.initDynamoClient((CognitoCachingCredentialsProvider) credentialsProvider); 
       dynamoDBMapper.save(mapperClass);//gives error over here 

      } else { 
       return "ss"; 
      } 
      return "rr"; 

     } catch (DynamoDBMappingException ex) { 
      ex.printStackTrace(); 
      return "exception"; 
     } 
    } 

    @Override 
    protected void onPostExecute(String result) { 
     super.onPostExecute(result); 
     if(result.equals("ss")){ 
      Toast.makeText(EnterUser.this, "Entered successfully :) ", Toast.LENGTH_LONG).show(); 
     }else if(result.equals("rr")){ 
      Toast.makeText(EnterUser.this, "Already Existing", Toast.LENGTH_SHORT).show(); 
     }else{ 
      Toast.makeText(EnterUser.this, "**Exception Caught**", Toast.LENGTH_SHORT).show(); 
     } 
    } 
} 

2分区键，主键散列键和排序键有什么区别？

3请建议您是否需要AsyncTask。另外请建议其优点和缺点（通过例子，如果可能的话会更好）

谢谢你的帮助。

Answer 1

1）这可能是因为表“agation1”没有设定为“用户名”分区键，或者它是不是字符串

2）分区键是主密钥散列+排序的组合键。两者一起唯一标识一行。但是你的表不需要有一个排序键。如果它没有排序键，则分区键与散列键相同。

3）您必须在另一个线程上进行保存调用，AsyncTask是一种方法。