如何使用Tunnel SDK上传/下载MaxCompute复杂类型数据

基于Tunnel SDK如何上传复杂类型数据到MaxCompute？首先介绍一下MaxCompute复杂数据类型：

复杂数据类型
MaxCompute采用基于ODPS2.0的SQL引擎，丰富了对复杂数据类型类型的支持。MaxCompute支持ARRAY, MAP, STRUCT类型，并且可以任意嵌套使用并提供了配套的内建函数。

复杂类型构造与操作函数

Tunnel SDK 介绍
Tunnel 是 ODPS 的数据通道，用户可以通过 Tunnel 向 ODPS 中上传或者下载数据。
TableTunnel 是访问 ODPS Tunnel 服务的入口类，仅支持表数据（非视图）的上传和下载。

对一张表或 partition 上传下载的过程，称为一个session。session 由一或多个到 Tunnel RESTful API 的 HTTP Request 组成。
session 用 session ID 来标识，session 的超时时间是24小时，如果大批量数据传输导致超过24小时，需要自行拆分成多个 session。
数据的上传和下载分别由 TableTunnel.UploadSession 和 TableTunnel.DownloadSession 这两个会话来负责。
TableTunnel 提供创建 UploadSession 对象和 DownloadSession 对象的方法.

典型表数据上传流程：
1) 创建 TableTunnel
2) 创建 UploadSession
3) 创建 RecordWriter,写入 Record
4）提交上传操作

典型表数据下载流程：
1) 创建 TableTunnel
2) 创建 DownloadSession
3) 创建 RecordReader,读取 Record
基于Tunnel SDK构造复杂类型数据
代码示例：

        RecordWriter recordWriter = uploadSession.openRecordWriter(0);
  ArrayRecord record = (ArrayRecord) uploadSession.newRecord();

  // prepare data
  List arrayData = Arrays.asList(1, 2, 3);
  Map<String, Long> mapData = new HashMap<String, Long>();
  mapData.put("a", 1L);
  mapData.put("c", 2L);

  List<Object> structData = new ArrayList<Object>();
  structData.add("Lily");
  structData.add(18);

  // set data to record
  record.setArray(0, arrayData);
  record.setMap(1, mapData);
  record.setStruct(2, new SimpleStruct((StructTypeInfo) schema.getColumn(2).getTypeInfo(),
                                       structData));

  // write the record
  recordWriter.write(record);

从MaxCompute下载复杂类型数据
代码示例：

        RecordReader recordReader = downloadSession.openRecordReader(0, 1);

  // read the record
  ArrayRecord record1 = (ArrayRecord)recordReader.read();

  // get array field data
  List field0 = record1.getArray(0);
  List<Long> longField0 = record1.getArray(Long.class, 0);

  // get map field data
  Map field1 = record1.getMap(1);
  Map<String, Long> typedField1 = record1.getMap(String.class, Long.class, 1);

  // get struct field data
  Struct field2 = record1.getStruct(2);

运行实例
完整代码如下：

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.aliyun.odps.Odps;
import com.aliyun.odps.PartitionSpec;
import com.aliyun.odps.TableSchema;
import com.aliyun.odps.account.Account;
import com.aliyun.odps.account.AliyunAccount;
import com.aliyun.odps.data.ArrayRecord;
import com.aliyun.odps.data.RecordReader;
import com.aliyun.odps.data.RecordWriter;
import com.aliyun.odps.data.SimpleStruct;
import com.aliyun.odps.data.Struct;
import com.aliyun.odps.tunnel.TableTunnel;
import com.aliyun.odps.tunnel.TableTunnel.UploadSession;
import com.aliyun.odps.tunnel.TableTunnel.DownloadSession;
import com.aliyun.odps.tunnel.TunnelException;
import com.aliyun.odps.type.StructTypeInfo;

public class TunnelComplexTypeSample {

private static String accessId = "<your access id>";
private static String accessKey = "<your access Key>";
private static String odpsUrl = "<your odps endpoint>";
private static String project = "<your project>";

private static String table = "<your table name>";

// partitions of a partitioned table, eg: "pt='1',ds='2'"
// if the table is not a partitioned table, do not need it
private static String partition = "<your partition spec>";

public static void main(String args[]) {

Account account = new AliyunAccount(accessId, accessKey);
Odps odps = new Odps(account);
odps.setEndpoint(odpsUrl);
odps.setDefaultProject(project);

try {
  TableTunnel tunnel = new TableTunnel(odps);
  PartitionSpec partitionSpec = new PartitionSpec(partition);

  // ---------- Upload Data ---------------
  // create upload session for table
  // the table schema is {"col0": ARRAY<BIGINT>, "col1": MAP<STRING, BIGINT>, "col2": STRUCT<name:STRING,age:BIGINT>}
  UploadSession uploadSession = tunnel.createUploadSession(project, table, partitionSpec);
  // get table schema
  TableSchema schema = uploadSession.getSchema();

  // open record writer
  RecordWriter recordWriter = uploadSession.openRecordWriter(0);
  ArrayRecord record = (ArrayRecord) uploadSession.newRecord();

  // prepare data
  List arrayData = Arrays.asList(1, 2, 3);
  Map<String, Long> mapData = new HashMap<String, Long>();
  mapData.put("a", 1L);
  mapData.put("c", 2L);

  List<Object> structData = new ArrayList<Object>();
  structData.add("Lily");
  structData.add(18);

  // set data to record
  record.setArray(0, arrayData);
  record.setMap(1, mapData);
  record.setStruct(2, new SimpleStruct((StructTypeInfo) schema.getColumn(2).getTypeInfo(),
                                       structData));

  // write the record
  recordWriter.write(record);

  // close writer
  recordWriter.close();

  // commit uploadSession, the upload finish
  uploadSession.commit(new Long[]{0L});
  System.out.println("upload success!");

  // ---------- Download Data ---------------
  // create download session for table
  // the table schema is {"col0": ARRAY<BIGINT>, "col1": MAP<STRING, BIGINT>, "col2": STRUCT<name:STRING,age:BIGINT>}
  DownloadSession downloadSession = tunnel.createDownloadSession(project, table, partitionSpec);
  schema = downloadSession.getSchema();

  // open record reader, read one record here for example
  RecordReader recordReader = downloadSession.openRecordReader(0, 1);

  // read the record
  ArrayRecord record1 = (ArrayRecord)recordReader.read();

  // get array field data
  List field0 = record1.getArray(0);
  List<Long> longField0 = record1.getArray(Long.class, 0);

  // get map field data
  Map field1 = record1.getMap(1);
  Map<String, Long> typedField1 = record1.getMap(String.class, Long.class, 1);

  // get struct field data
  Struct field2 = record1.getStruct(2);

  System.out.println("download success!");
} catch (TunnelException e) {
  e.printStackTrace();
} catch (IOException e) {
  e.printStackTrace();
}

}
}