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MaxCompute用户指南：数据上传下载：批量数据通道SDK示例：简单下载示例

  1. import java.io.IOException;
  2. import java.util.Date;
  4. import com.aliyun.odps.Column;
  5. import com.aliyun.odps.Odps;
  6. import com.aliyun.odps.PartitionSpec;
  7. import com.aliyun.odps.TableSchema;
  8. import com.aliyun.odps.account.Account;
  9. import com.aliyun.odps.account.AliyunAccount;
  10. import com.aliyun.odps.data.Record;
  11. import com.aliyun.odps.data.RecordReader;
  12. import com.aliyun.odps.tunnel.TableTunnel;
  13. import com.aliyun.odps.tunnel.TableTunnel.DownloadSession;
  14. import com.aliyun.odps.tunnel.TunnelException;
  16. public class DownloadSample {
  17.          private static String accessId = "<your access id>";
  18.          private static String accessKey = "<your access Key>";
  19.          private static String odpsUrl = "http://service.odps.aliyun.com/api";
  22.          private static String project = "<your project>";
  23.          private static String table = "<your table name>";
  24.          private static String partition = "<your partition spec>";
  26.          public static void main(String args[]) {
  27.                  Account account = new AliyunAccount(accessId, accessKey);
  28.                  Odps odps = new Odps(account);
  29.                  odps.setEndpoint(odpsUrl);
  30.                  odps.setDefaultProject(project);
  31.                  TableTunnel tunnel = new TableTunnel(odps);
  32.                  PartitionSpec partitionSpec = new PartitionSpec(partition);
  33.                  try {
  34.                          DownloadSession downloadSession = tunnel.createDownloadSession(project, table,
  35.                                          partitionSpec);
  36.                          System.out.println("Session Status is : "
  37.                                          + downloadSession.getStatus().toString());
  39.                          long count = downloadSession.getRecordCount();
  40.                          System.out.println("RecordCount is: " + count);
  42.                          RecordReader recordReader = downloadSession.openRecordReader(0,
  43.                                          count);
  44.                          Record record;
  45.                          while ((record = recordReader.read()) != null) {
  46.                                  consumeRecord(record, downloadSession.getSchema());
  47.                          }
  48.                          recordReader.close();
  49.                  } catch (TunnelException e) {
  50.                          e.printStackTrace();
  51.                  } catch (IOException e1) {
  52.                          e1.printStackTrace();
  53.                  }
  54.          }
  56.          private static void consumeRecord(Record record, TableSchema schema) {
  57.                  for (int i = 0; i < schema.getColumns().size(); i++) {
  58.                          Column column = schema.getColumn(i);
  59.                          String colValue = null;
  60.                          switch (column.getType()) {
  61.                          case BIGINT: {
  62.                                  Long v = record.getBigint(i);
  63.                                  colValue = v == null ? null : v.toString();
  64.                                  break;
  65.                          }
  66.                          case BOOLEAN: {
  67.                                  Boolean v = record.getBoolean(i);
  68.                                  colValue = v == null ? null : v.toString();
  69.                                  break;
  70.                          }
  71.                          case DATETIME: {
  72.                                  Date v = record.getDatetime(i);
  73.                                  colValue = v == null ? null : v.toString();
  74.                                  break;
  75.                          }
  76.                          case DOUBLE: {
  77.                                  Double v = record.getDouble(i);
  78.                                  colValue = v == null ? null : v.toString();
  79.                                  break;
  80.                          }
  81.                          case STRING: {
  82.                                  String v = record.getString(i);
  83.                                  colValue = v == null ? null : v.toString();
  84.                                  break;
  85.                          }
  86.                          default:
  87.                                  throw new RuntimeException("Unknown column type: "
  88.                                                  + column.getType());
  89.                          }
  90.                          System.out.print(colValue == null ? "null" : colValue);
  91.                          if (i != schema.getColumns().size())
  92.                                  System.out.print("\t");
  93.                  }
  94.                  System.out.println();
  95.          }
  97. }

本示例中，为了方便测试，数据通过 System.out.println 直接打印出来，在实际使用时，您可改写为直接输出到文本文件。

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行者武松 2017-10-23 15:34:28 1908 分享 版权

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