[Java SDK] Get Table Structure

1. Interface Description

Get table structure data from a specified table.

2. Version Requirements

This interface is provided in all versions without special requirements.

3. Preparations

Refer to Preparation document to complete the preparation before using this interface and create the following TDR table.

Get the following information after the preparation. These details will be used by the SDK:

Directory server address list
App ID
App access password
Game zone ID
Table name

4. Example Code

Basic execution process of example code:

Create a client;
Create a request;
Send a request;
Process the response;
Destroy the client.

4.1 Example Code for Synchronous Call

import com.tencent.tcaplus.client.Client;
import com.tencent.tcaplus.client.ClientFactory;
import com.tencent.tcaplus.client.Record;
import com.tencent.tcaplus.client.Request;
import com.tencent.tcaplus.client.Response;
import com.tencent.tcaplus.util.TdrType;
import com.tencent.tdr.tcaplus_protocol_cs.TcaplusProtocolCsConstants;

import java.util.ArrayList;
import java.util.List;

public class Example {

    public static void main(String[] arguments) {
        // 1. Prepare the environment information
        // 1.1. Directory server address list
        List<String> dirList = new ArrayList<String>();
        dirList.add("tcp://x.x.x.x:9999");
        dirList.add("tcp://y.y.y.y:9999");
        // 1.2. App ID
        int appId = 1;
        // 1.3. App password
        String appPassword = "****************";
        // 1.4. Table group ID
        int tableGroupId = 1;
        // 1.5. Table name
        String tableName = "test";

        // 2. Create a client
        Client client = ClientFactory.createClient(appId, tableGroupId, appPassword, dirList);
        try {
            // 3. Create a request to query data
            // 3.1. Get the request object. In order to improve the SDK's performance, the Request object is reused
            Request request = client.acquireRequest();
            // 3.2. Set the request type and target table name.
            req.setCmd(TcaplusProtocolCsConstants.TCAPLUS_CMD_METADATA_GET_REQ);
            request.setTableName(tableName);

            // 4. Send a request and get the result
            Response response = client.poll(request);

            // 5. Process the result
            if (response.getResult() == 0) {
                // Get table structure successfully
                ResponseLite rspLite = (ResponseLite) response;
                TableMetadata meta = rspLite.getMetadata();
                //Get table fields
                List<TableMetadata.KeyColumn> keyColumnList = meta.keyColumnList;
                //And table field type
                for (TableMetadata.KeyColumn keyColumn:keyColumnList) {
                    int type = keyColumn.type;
                    switch (type) {
                        case TdrType.TCAPLUS_RECORD_TYPE_BINARY:
                            //
                            break;
                        case TdrType.TCAPLUS_RECORD_TYPE_DOUBLE:
                            //
                            break;
                        default:
                            //
                            break;
                    }
                }
            } else {
                // Failed to get table structure. It may be that the table does not exist
            }
        } finally {
            // 6. Destroy the client object
            ClientFactory.destroyClient(client);
        }
    }

}

4.2 Example Code for Asynchronous Call

import com.tencent.tcaplus.client.Client;
import com.tencent.tcaplus.client.ClientFactory;
import com.tencent.tcaplus.client.Record;
import com.tencent.tcaplus.client.Request;
import com.tencent.tcaplus.client.Response;
import com.tencent.tcaplus.util.TdrType;
import com.tencent.tdr.tcaplus_protocol_cs.TcaplusProtocolCsConstants;

import java.util.ArrayList;
import java.util.List;

public class Example {

    public static void main(String[] arguments) {
        // 1. Prepare the environment information
        // 1.1. Directory server address list
        List<String> dirList = new ArrayList<String>();
        dirList.add("tcp://x.x.x.x:9999");
        dirList.add("tcp://y.y.y.y:9999");
        // 1.2. App ID
        int appId = 1;
        // 1.3. App password
        String appPassword = "****************";
        // 1.4. Table group ID
        int tableGroupId = 1;
        // 1.5. Table name
        String tableName = "test";

        // 2. Create a client
        Client client = ClientFactory.createClient(appId, tableGroupId, appPassword, dirList);
        try {
            // 3. Create a request to query data
            // 3.1. Get the request object. In order to improve the SDK's performance, the Request object is reused
            Request request = client.acquireRequest();
            // 3.2. Set the request type and target table name.
            req.setCmd(TcaplusProtocolCsConstants.TCAPLUS_CMD_METADATA_GET_REQ);
            request.setTableName(tableName);

            CountDownLatch latch = new CountDownLatch(1);

            // 4. Send the request asynchronously and specify the processor that returns the response. The post method will return the result immediately
            client.post(request, new Future() {

                @Override
                public void onResponse(Response response) {
                    // 5. Process the result
                    if (response.getResult() == 0) {
                        // Get table structure successfully
                        ResponseLite rspLite = (ResponseLite) response;
                        TableMetadata meta = rspLite.getMetadata();
                        //Get table fields
                        List<TableMetadata.KeyColumn> keyColumnList = meta.keyColumnList;
                        //And table field type
                        for (TableMetadata.KeyColumn keyColumn:keyColumnList) {
                            int type = keyColumn.type;
                            switch (type) {
                                case TdrType.TCAPLUS_RECORD_TYPE_BINARY:
                                    //
                                    break;
                                case TdrType.TCAPLUS_RECORD_TYPE_DOUBLE:
                                    //
                                    break;
                                default:
                                    //
                                    break;
                            }
                        }
                    } else {
                        // Failed to get table structure. It may be that the table does not exist
                    }
                }
            });

            latch.await();

        } finally {
            // 6. Destroy the client object
            ClientFactory.destroyClient(client);
        }
    }

}

5. Method Description in Request Object

Note: If a Request object method is not listed, it means that the method is invalid in the scenario of reading data.

Method signature	Method description
`void setCmd(int cmd)`	Set the request type (command). cmd: request type, fixed to TcaplusProtocolCsConstants.TCAPLUS_CMD_METADATA_GET_REQ
`void setTableName(String tableName)`	Set the target table name. TableName: target table name, which cannot be null.

6. Method Description in Response Object

Note: If a Response object method is not listed, it means that the method is invalid in the scenario of reading data.

Method signature	Method description
`int getResult()`	Get the response code of the data query request. 0 indicates that the operation succeeds. If the value is not 0, the operation is abnormal. Please refer to Response Code Meaning Description.

7. ResponseLite Object Method Description

Note: If there is an unlisted ResponseLite object method, it means that the method is invalid in the scenario of getting data.

Method signature	Method description
`TableMetadata getMetadata()`	Get the meta structure of the table. Non-null indicates that the operation is successful, and null indicates that the operation is abnormal.

8. TableMetadata Object Method Description

Note: If there is an unlisted TableMetadata object method, it means that the method is invalid in the scenario of getting data.

Member variable	Member variable description
type	Table type, TCAPLUS_TABLE_TYPE_GENERIC and TCAPLUS_TABLE_TYPE_LIST are supported currently.
listMaxElementNum	The maximum number of elements supported by a Key in the List.
keyColumnList	Metadata information of the Key field.
valueColumnList	Metadata information of the Value field.

9. TableMetadata.KeyColumn Object Method Description

Note: If there is an unlisted TableMetadata.KeyColumn object method, it means that the method is invalid in the scenario of getting data.

Member variable	Member variable description
type	Field type.
name	Field name.

10. TableMetadata.ValueColumn Object Method Description

Note: If there is an unlisted TableMetadata.ValueColumn object method, it means that the method is invalid in the scenario of getting data.

Member variable	Member variable description
type	Field type.
name	Field name.

Get Table Structure