共用方式為

Azure Tables client library for Java - version 12.5.0

  • 發行項

Azure Tables is a service that stores structured NoSQL data in the cloud, providing a key/attribute store with a schemaless design. Azure Tables gives developers flexibility and scalability with all the best parts of Azure cloud.

Source code | Package (Maven) | API reference documentation | Product documentation | Samples

Getting started

Include the package

Include the BOM file

Please include the azure-sdk-bom to your project to take dependency on the General Availability (GA) version of the library. In the following snippet, replace the {bom_version_to_target} placeholder with the version number. To learn more about the BOM, see the AZURE SDK BOM README.

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.azure</groupId>
            <artifactId>azure-sdk-bom</artifactId>
            <version>{bom_version_to_target}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

and then include the direct dependency in the dependencies section without the version tag as shown below.

<dependencies>
    <dependency>
        <groupId>com.azure</groupId>
        <artifactId>azure-data-tables</artifactId>
    </dependency>
</dependencies>

Include direct dependency

If you want to take dependency on a particular version of the library that is not present in the BOM, add the direct dependency to your project as follows.

<dependency>
  <groupId>com.azure</groupId>
  <artifactId>azure-data-tables</artifactId>
  <version>12.5.0</version>
</dependency>

Prerequisites

Create a Storage Account

To create a Storage Account you can use the Azure Portal or Azure CLI.

az storage account create \
    --resource-group <resource-group-name> \
    --name <storage-account-name> \
    --location <location>

Your storage account URL, subsequently identified as <your-table-account-url>, would be formatted as follows http(s)://<storage-account-name>.table.core.windows.net.

Create a Cosmos DB Table API account

To create a Cosmos DB Table API account you can use the Azure Portal or Azure CLI.

az cosmosdb create \
    --resource-group <resource-group-name> \
    --name <cosmosdb-account-name> \
    --capabilities EnableTable

Your Table API account URL, subsequently identified as <your-table-account-url>, would be formatted as follows http(s)://<cosmosdb-account-name>.table.cosmosdb.azure.com.

Authenticate the client

Every request made to the Tables service must be authorized using a connection string, named key credential, Shared Access Signature, or token credentials. The samples below demonstrate the usage of these methods.

Note: Only Azure Storage API endpoints currently support AAD authorization via token credentials.

Connection string

A connection string includes the authentication information required for your application to access data in an Azure table at runtime using Shared Key authorization. See Authenticate with a Connection String for an example of how to use a connection string with a TableServiceClient.

You can obtain your connection string from the Azure Portal (click Access keys under Settings in the Portal Storage account blade, or Connection String under Settings in the Portal Cosmos DB account blade) or using the Azure CLI:

# Storage account
az storage account show-connection-string \
    --resource-group <resource-group-name> \
    --name <storage-account-name>

# Cosmos DB Table API account
az cosmosdb list-connection-strings \
    --resource-group <resource-group-name> \
    --name <cosmosdb-account-name>

Shared Key credential

Shared Key authorization relies on your account access keys and other parameters to produce an encrypted signature string that is passed on the request in the Authorization header. See Authenticate with a Shared Key credential for an example of how to use Named Key authorization with a TableServiceClient.

To use Named Key authorization you'll need your account name and URL, as well as an account access key. You can obtain your primary access key from the Azure Portal (click Access keys under Settings in the Portal Storage account blade, or Connection String under Settings in the Portal Cosmos DB account blade) or using the Azure CLI:

# Storage account
az storage account keys list \
    --resource-group <resource-group-name> \
    --account-name <storage-account-name>

# Cosmos DB Table API account
az cosmosdb list-keys \
    --resource-group <resource-group-name> \
    --name <cosmosdb-account-name>

Shared Access Signature (SAS)

A Shared Access Signature allows administrators to delegate granular access to an Azure table without sharing the access key directly. You can control what resources the client may access, what permissions it has on those resources, and how long the SAS is valid, among other parameters. It relies on your account access keys and other parameters to produce an encrypted signature string that is passed on the request in the query string. See Authenticate with a Shared Access Signature (SAS) for an example of how to use shared access signatures with a TableServiceClient.

To use SAS token authorization you'll need your account name and URL, as well as the SAS. You can obtain your SAS from the Azure Portal (click Shared access signature under Settings in the Portal Storage account blade) or using the Azure CLI:

# Account-level SAS
az storage account generate-sas \
    --account-name <storage-or-cosmosdb-account-name> \
    --services t \
    --resource-types <resource-types> \
    --permissions <permissions> \
    --expiry <expiry-date>

# Table-level SAS
az storage table generate-sas \
    --name <table-name>

TokenCredential

Azure Tables provides integration with Azure Active Directory (AAD) for identity-based authentication of requests to the Table service when targeting a Storage endpoint. With AAD, you can use role-based access control (RBAC) to grant access to your Azure Table resources to users, groups, or applications.

To access a table resource with a TokenCredential, the authenticated identity should have either the "Storage Table Data Contributor" or "Storage Table Data Reader" role.

With the azure-identity package, you can seamlessly authorize requests in both development and production environments. To learn more about Azure AD integration in Azure Storage, see the Azure Identity README.

Key concepts

  • TableServiceClient - A TableServiceClient is a client object that enables you to interact with the Table Service in order to create, list, and delete tables.
  • TableClient - A TableClient is a client object that enables you to interact with a specific table in order to create, upsert, update, get, list, and delete entities within it.
  • Table - A table is a collection of entities. Tables don't enforce a schema on entities, which means a single table can contain entities that have different sets of properties.
  • Entity - An entity is a set of properties, similar to a database row. An entity in Azure Storage can be up to 1MB in size. An entity in Azure Cosmos DB can be up to 2MB in size. An entity has a partition key and a row key which together uniquely identify the entity within the table.
  • Properties - A property is a name-value pair. Each entity can include up to 252 properties to store data. Each entity also has three system properties that specify a partition key, a row key, and a timestamp.
  • Partition Key - An entity's partition key identifies the partition within the table to which the entity belongs. Entities with the same partition key can be queried more quickly, and inserted/updated in atomic operations.
  • Row Key - An entity's row key is its unique identifier within a partition.

Common uses of the Tables service include:

  • Storing TBs of structured data capable of serving web scale applications
  • Storing datasets that don't require complex joins, foreign keys, or stored procedures and can be de-normalized for fast access
  • Quickly querying data using a clustered index
  • Accessing data using the OData protocol

Examples

Authenticate a client

Authenticate with a connection string

To use a connection string to authorize your client, call the builder's connectionString method with your connection string.

TableServiceClient tableServiceClient = new TableServiceClientBuilder()
    .connectionString("<your-connection-string>")
    .buildClient();

Authenticate with a Shared Key

To use a Shared Key to authorize your client, create an instance of AzureNamedKeyCredential with your account name and access key. Call the builder's endpoint method with your account URL and the credential method with the AzureNamedKeyCredential object you created.

AzureNamedKeyCredential credential = new AzureNamedKeyCredential("<your-account-name>", "<account-access-key>");
TableServiceClient tableServiceClient = new TableServiceClientBuilder()
    .endpoint("<your-table-account-url>")
    .credential(credential)
    .buildClient();

Authenticate with a Shared Access Signature (SAS)

To use a SAS to authorize your client, call the builder's endpoint method with your account URL and the sasToken method with your SAS.

TableServiceClient tableServiceClient = new TableServiceClientBuilder()
    .endpoint("<your-table-account-url>")
    .sasToken("<sas-token-string>")
    .buildClient();

Authenticate with a Token Credentials

To authorize your client via AAD, create an instance of a credentials class that implements TokenCredential. Call the builder's endpoint method with your account URL and the credential method with the TokenCredential object you created.

TokenCredential tokenCredential = new DefaultAzureCredentialBuilder().build();
TableServiceClient tableServiceClient = new TableServiceClientBuilder()
    .endpoint("<your-table-account-url>")
    .credential(tokenCredential)
    .buildClient();

Create, List, and Delete Azure tables

Construct a TableServiceClient

Construct a TableServiceClient by creating an instance of TableServiceClientBuilder and then calling the builder's buildClient or buildAsyncClient methods.

TableServiceClient tableServiceClient = new TableServiceClientBuilder()
    .connectionString("<your-connection-string>") // or use any of the other authentication methods
    .buildClient();

Create a table

Create a table by calling the TableServiceClient's createTable method. A TableClient will be returned, this client allows performing operations on the table. An exception will be thrown if a table with the provided name exists.

TableClient tableClient = tableServiceClient.createTable(tableName);

Alternatively, you can call the createTableIfNotExists method which will create the table only if no such table exists, and does not throw an exception. A TableClient will be returned as well.

TableClient tableClient = tableServiceClient.createTableIfNotExists(tableName);

List tables

List or query the set of existing tables by calling the TableServiceClient's listTables method, optionally passing in a ListTablesOptions instance to filter or limit the query results. See Supported Query Options for details about supported query options.

ListTablesOptions options = new ListTablesOptions()
    .setFilter(String.format("TableName eq '%s'", tableName));

for (TableItem tableItem : tableServiceClient.listTables(options, null, null)) {
    System.out.println(tableItem.getName());
}

Delete a table

Delete a table by calling the TableServiceClient's deleteTable method.

tableServiceClient.deleteTable(tableName);

Create, List, and Delete table entities

Construct a TableClient

Construct a TableClient by creating an instance of TableClientBuilder, calling the builder's tableName method with the name of the table, and then calling its buildClient or buildAsyncClient methods.

TableClient tableClient = new TableClientBuilder()
    .connectionString("<your-connection-string>") // or use any of the other authentication methods
    .tableName(tableName)
    .buildClient();

Alternatively, a TableClient can be retrieved from an existing TableServiceClient by calling its getTableClient method.

TableClient tableClient = tableServiceClient.getTableClient(tableName);

Create an entity

Create a new TableEntity instance, providing the partition key and row key of the entity to create, optionally adding properties to the created object. Then pass the object to the TableClient's createEntity method. An exception will be thrown if an entity with the provided partition key and row key exists within the table.

TableEntity entity = new TableEntity(partitionKey, rowKey)
    .addProperty("Product", "Marker Set")
    .addProperty("Price", 5.00)
    .addProperty("Quantity", 21);

tableClient.createEntity(entity);

List entities

List or query the set of entities within the table by calling the TableClient's listEntities method, optionally passing in a ListEntitiesOptions instance to filter, select, or limit the query results. See Supported Query Options for details about supported query options.

List<String> propertiesToSelect = new ArrayList<>();
propertiesToSelect.add("Product");
propertiesToSelect.add("Price");

ListEntitiesOptions options = new ListEntitiesOptions()
    .setFilter(String.format("PartitionKey eq '%s'", partitionKey))
    .setSelect(propertiesToSelect);

for (TableEntity entity : tableClient.listEntities(options, null, null)) {
    Map<String, Object> properties = entity.getProperties();
    System.out.printf("%s: %.2f%n", properties.get("Product"), properties.get("Price"));
}

Delete an entity

Delete an entity by calling the TableClient's deleteEntity method.

tableClient.deleteEntity(partitionKey, rowKey);

Troubleshooting

General

When you interact with Tables service using the Azure Tables library for Java, errors returned by the service correspond to the same HTTP status codes returned for REST API requests.

For example, if you try to create a table that already exists, a 409 error is returned, indicating "Conflict".

// Create the table if it doesn't already exist.
tableServiceClient.createTableIfNotExists(tableName);

// Now attempt to create the same table unconditionally.
try {
    tableServiceClient.createTable(tableName);
} catch (TableServiceException e) {
    System.out.println(e.getResponse().getStatusCode()); // 409
}

Logging

Enabling logging may help uncover useful information about failures. In order to see a log of HTTP requests and responses, set the AZURE_LOG_LEVEL environment variable to the desired verbosity. See LogLevel for a description of available log levels.

Next steps

Get started with our Table samples.

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

Impressions