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Merge pull request #9 from aliyun/dev
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Add example of pagination read.
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@zhouzf05
zhouzf05 authored Jun 22, 2016
2 parents fa64836 + e133d77 commit e06b883
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197 changes: 197 additions & 0 deletions src/test/java/examples/OTSPaginationReadSample.java
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package examples;

import com.aliyun.openservices.ots.*;
import com.aliyun.openservices.ots.model.*;
import com.aliyun.openservices.ots.utils.Preconditions;
import javafx.util.Pair;

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

public class OTSPaginationReadSample {
private static final String COLUMN_GID_NAME = "gid";
private static final String COLUMN_UID_NAME = "uid";
private static final String COLUMN_NAME_NAME = "name";
private static final String COLUMN_ADDRESS_NAME = "address";
private static final String COLUMN_AGE_NAME = "age";
private static final String COLUMN_MOBILE_NAME = "mobile";

public static void main(String args[]) {
final String endPoint = "";
final String accessId = "";
final String accessKey = "";
final String instanceName = "";

OTSClient client = new OTSClient(endPoint, accessId, accessKey,
instanceName);
final String tableName = "sampleTable";

try {
// 创建表
createTable(client, tableName);

// 注意：创建表只是提交请求，OTS创建表需要一段时间。
// 这里简单地等待5秒，请根据您的实际逻辑修改。
Thread.sleep(5000);

// 插入多行数据。
putRows(client, tableName);

// 分页查询数据，每一页取5条，直到全部查完.
readByPage(client, tableName);
} catch (ServiceException e) {
System.err.println("操作失败，详情：" + e.getMessage());
// 可以根据错误代码做出处理， OTS的ErrorCode定义在OTSErrorCode中。
if (OTSErrorCode.QUOTA_EXHAUSTED.equals(e.getErrorCode())) {
System.err.println("超出存储配额。");
}
// Request ID可以用于有问题时联系客服诊断异常。
System.err.println("Request ID:" + e.getRequestId());
} catch (ClientException e) {
// 可能是网络不好或者是返回结果有问题
System.err.println("请求失败，详情：" + e.getMessage());
} catch (InterruptedException e) {
System.err.println(e.getMessage());
} finally {
// 不留垃圾。
try {
deleteTable(client, tableName);
} catch (ServiceException e) {
System.err.println("删除表格失败，原因：" + e.getMessage());
e.printStackTrace();
} catch (ClientException e) {
System.err.println("删除表格请求失败，原因：" + e.getMessage());
e.printStackTrace();
}
client.shutdown();
}
}

/**
* 范围查询指定范围内的数据，返回指定页数大小的数据，并能根据offset跳过部分行。
*/
private static Pair<List<Row>, RowPrimaryKey> readByPage(OTSClient client, String tableName, RowPrimaryKey startKey, RowPrimaryKey endKey, int offset, int pageSize) {
Preconditions.checkArgument(offset >= 0, "Offset should not be negative.");
Preconditions.checkArgument(pageSize > 0, "Page size should be greater than 0.");

List<Row> rows = new ArrayList<Row>(pageSize);
int limit = pageSize;
int skip = offset;

RowPrimaryKey nextStart = startKey;
while (limit > 0 && nextStart != null) {
RangeRowQueryCriteria criteria = new RangeRowQueryCriteria(tableName);
criteria.setInclusiveStartPrimaryKey(nextStart);
criteria.setExclusiveEndPrimaryKey(endKey);
criteria.setLimit(skip + limit);

GetRangeRequest request = new GetRangeRequest();
request.setRangeRowQueryCriteria(criteria);
GetRangeResult response = client.getRange(request);
for (Row row : response.getRows()) {
if (skip > 0) {
skip--;
} else {
rows.add(row);
limit--;
}
}

nextStart = response.getNextStartPrimaryKey();
}

return new Pair<List<Row>, RowPrimaryKey>(rows, nextStart);
}

private static void readByPage(OTSClient client, String tableName) {
int pageSize = 8;
int offset = 33;

RowPrimaryKey startKey = new RowPrimaryKey();
startKey.addPrimaryKeyColumn(COLUMN_GID_NAME, PrimaryKeyValue.INF_MIN);
startKey.addPrimaryKeyColumn(COLUMN_UID_NAME, PrimaryKeyValue.INF_MIN);

RowPrimaryKey endKey = new RowPrimaryKey();
endKey.addPrimaryKeyColumn(COLUMN_GID_NAME, PrimaryKeyValue.INF_MAX);
endKey.addPrimaryKeyColumn(COLUMN_UID_NAME, PrimaryKeyValue.INF_MAX);
// 读第一页，从范围的offset=33的行开始读起
Pair<List<Row>, RowPrimaryKey> result = readByPage(client, tableName, startKey, endKey, offset, pageSize);
for (Row row : result.getKey()) {
System.out.println(row.getColumns());
}
System.out.println("Total rows count: " + result.getKey().size());

// 顺序翻页，读完范围内的所有数据
startKey = result.getValue();
while (startKey != null) {
System.out.println("============= start read next page ==============");
result = readByPage(client, tableName, startKey, endKey, 0, pageSize);
for (Row row : result.getKey()) {
System.out.println(row.getColumns());
}
startKey = result.getValue();
System.out.println("Total rows count: " + result.getKey().size());
}
}

private static void createTable(OTSClient client, String tableName)
throws ServiceException, ClientException {
TableMeta tableMeta = new TableMeta(tableName);
tableMeta.addPrimaryKeyColumn(COLUMN_GID_NAME, PrimaryKeyType.INTEGER);
tableMeta.addPrimaryKeyColumn(COLUMN_UID_NAME, PrimaryKeyType.INTEGER);
// 将该表的读写CU都设置为0
CapacityUnit capacityUnit = new CapacityUnit(0, 0);

CreateTableRequest request = new CreateTableRequest();
request.setTableMeta(tableMeta);
request.setReservedThroughput(capacityUnit);
client.createTable(request);

System.out.println("表已创建");
}

private static void deleteTable(OTSClient client, String tableName)
throws ServiceException, ClientException {
DeleteTableRequest request = new DeleteTableRequest();
request.setTableName(tableName);
client.deleteTable(request);

System.out.println("表已删除");
}

private static void putRows(OTSClient client, String tableName)
throws OTSException, ClientException {
int bid = 1;
final int rowCount = 100;
for (int i = 0; i < rowCount; ++i) {
RowPutChange rowChange = new RowPutChange(tableName);
RowPrimaryKey primaryKey = new RowPrimaryKey();
primaryKey.addPrimaryKeyColumn(COLUMN_GID_NAME,
PrimaryKeyValue.fromLong(bid));
primaryKey.addPrimaryKeyColumn(COLUMN_UID_NAME,
PrimaryKeyValue.fromLong(i));
rowChange.setPrimaryKey(primaryKey);
rowChange.addAttributeColumn(COLUMN_NAME_NAME,
ColumnValue.fromString("小" + Integer.toString(i)));
rowChange.addAttributeColumn(COLUMN_MOBILE_NAME,
ColumnValue.fromString("111111111"));
rowChange.addAttributeColumn(COLUMN_ADDRESS_NAME,
ColumnValue.fromString("中国A地"));
rowChange.addAttributeColumn(COLUMN_AGE_NAME,
ColumnValue.fromLong(20));
rowChange.setCondition(new Condition(
RowExistenceExpectation.EXPECT_NOT_EXIST));

PutRowRequest request = new PutRowRequest();
request.setRowChange(rowChange);

PutRowResult result = client.putRow(request);
int consumedWriteCU = result.getConsumedCapacity()
.getCapacityUnit().getWriteCapacityUnit();

System.out.println("成功插入数据, 消耗的写CU为：" + consumedWriteCU);
}

System.out.println(String.format("成功插入%d行数据。", rowCount));
}
}

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