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Merge pull request #9 from aliyun/dev
Add example of pagination read.
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‎src/test/java/examples/OTSPaginationReadSample.java‎

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package examples;
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import com.aliyun.openservices.ots.*;
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import com.aliyun.openservices.ots.model.*;
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import com.aliyun.openservices.ots.utils.Preconditions;
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import javafx.util.Pair;
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import java.util.ArrayList;
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import java.util.List;
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public class OTSPaginationReadSample {
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private static final String COLUMN_GID_NAME = "gid";
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private static final String COLUMN_UID_NAME = "uid";
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private static final String COLUMN_NAME_NAME = "name";
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private static final String COLUMN_ADDRESS_NAME = "address";
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private static final String COLUMN_AGE_NAME = "age";
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private static final String COLUMN_MOBILE_NAME = "mobile";
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public static void main(String args[]) {
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final String endPoint = "";
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final String accessId = "";
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final String accessKey = "";
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final String instanceName = "";
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OTSClient client = new OTSClient(endPoint, accessId, accessKey,
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instanceName);
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final String tableName = "sampleTable";
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try {
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// 创建表
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createTable(client, tableName);
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// 注意：创建表只是提交请求，OTS创建表需要一段时间。
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// 这里简单地等待5秒，请根据您的实际逻辑修改。
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Thread.sleep(5000);
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// 插入多行数据。
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putRows(client, tableName);
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// 分页查询数据，每一页取5条，直到全部查完.
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readByPage(client, tableName);
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} catch (ServiceException e) {
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System.err.println("操作失败，详情：" + e.getMessage());
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// 可以根据错误代码做出处理， OTS的ErrorCode定义在OTSErrorCode中。
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if (OTSErrorCode.QUOTA_EXHAUSTED.equals(e.getErrorCode())) {
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System.err.println("超出存储配额。");
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}
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// Request ID可以用于有问题时联系客服诊断异常。
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System.err.println("Request ID:" + e.getRequestId());
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} catch (ClientException e) {
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// 可能是网络不好或者是返回结果有问题
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System.err.println("请求失败，详情：" + e.getMessage());
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} catch (InterruptedException e) {
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System.err.println(e.getMessage());
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} finally {
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// 不留垃圾。
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try {
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deleteTable(client, tableName);
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} catch (ServiceException e) {
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System.err.println("删除表格失败，原因：" + e.getMessage());
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e.printStackTrace();
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} catch (ClientException e) {
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System.err.println("删除表格请求失败，原因：" + e.getMessage());
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e.printStackTrace();
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}
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client.shutdown();
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}
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}
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/**
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* 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。
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*/
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private static Pair<List<Row>, RowPrimaryKey> readByPage(OTSClient client, String tableName, RowPrimaryKey startKey, RowPrimaryKey endKey, int offset, int pageSize) {
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Preconditions.checkArgument(offset >= 0, "Offset should not be negative.");
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Preconditions.checkArgument(pageSize > 0, "Page size should be greater than 0.");
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List<Row> rows = new ArrayList<Row>(pageSize);
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int limit = pageSize;
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int skip = offset;
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RowPrimaryKey nextStart = startKey;
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while (limit > 0 && nextStart != null) {
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RangeRowQueryCriteria criteria = new RangeRowQueryCriteria(tableName);
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criteria.setInclusiveStartPrimaryKey(nextStart);
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criteria.setExclusiveEndPrimaryKey(endKey);
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criteria.setLimit(skip + limit);
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GetRangeRequest request = new GetRangeRequest();
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request.setRangeRowQueryCriteria(criteria);
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GetRangeResult response = client.getRange(request);
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for (Row row : response.getRows()) {
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if (skip > 0) {
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skip--;
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} else {
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rows.add(row);
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limit--;
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}
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}
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nextStart = response.getNextStartPrimaryKey();
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}
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return new Pair<List<Row>, RowPrimaryKey>(rows, nextStart);
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}
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private static void readByPage(OTSClient client, String tableName) {
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int pageSize = 8;
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int offset = 33;
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RowPrimaryKey startKey = new RowPrimaryKey();
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startKey.addPrimaryKeyColumn(COLUMN_GID_NAME, PrimaryKeyValue.INF_MIN);
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startKey.addPrimaryKeyColumn(COLUMN_UID_NAME, PrimaryKeyValue.INF_MIN);
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RowPrimaryKey endKey = new RowPrimaryKey();
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endKey.addPrimaryKeyColumn(COLUMN_GID_NAME, PrimaryKeyValue.INF_MAX);
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endKey.addPrimaryKeyColumn(COLUMN_UID_NAME, PrimaryKeyValue.INF_MAX);
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// 读第一页，从范围的offset=33的行开始读起
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Pair<List<Row>, RowPrimaryKey> result = readByPage(client, tableName, startKey, endKey, offset, pageSize);
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for (Row row : result.getKey()) {
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System.out.println(row.getColumns());
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}
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System.out.println("Total rows count: " + result.getKey().size());
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// 顺序翻页，读完范围内的所有数据
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startKey = result.getValue();
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while (startKey != null) {
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System.out.println("============= start read next page ==============");
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result = readByPage(client, tableName, startKey, endKey, 0, pageSize);
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for (Row row : result.getKey()) {
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System.out.println(row.getColumns());
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}
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startKey = result.getValue();
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System.out.println("Total rows count: " + result.getKey().size());
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}
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}
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private static void createTable(OTSClient client, String tableName)
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throws ServiceException, ClientException {
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TableMeta tableMeta = new TableMeta(tableName);
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tableMeta.addPrimaryKeyColumn(COLUMN_GID_NAME, PrimaryKeyType.INTEGER);
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tableMeta.addPrimaryKeyColumn(COLUMN_UID_NAME, PrimaryKeyType.INTEGER);
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// 将该表的读写CU都设置为0
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CapacityUnit capacityUnit = new CapacityUnit(0, 0);
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CreateTableRequest request = new CreateTableRequest();
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request.setTableMeta(tableMeta);
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request.setReservedThroughput(capacityUnit);
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client.createTable(request);
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System.out.println("表已创建");
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}
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private static void deleteTable(OTSClient client, String tableName)
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throws ServiceException, ClientException {
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DeleteTableRequest request = new DeleteTableRequest();
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request.setTableName(tableName);
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client.deleteTable(request);
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System.out.println("表已删除");
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}
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private static void putRows(OTSClient client, String tableName)
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throws OTSException, ClientException {
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int bid = 1;
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final int rowCount = 100;
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for (int i = 0; i < rowCount; ++i) {
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RowPutChange rowChange = new RowPutChange(tableName);
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RowPrimaryKey primaryKey = new RowPrimaryKey();
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primaryKey.addPrimaryKeyColumn(COLUMN_GID_NAME,
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PrimaryKeyValue.fromLong(bid));
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primaryKey.addPrimaryKeyColumn(COLUMN_UID_NAME,
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PrimaryKeyValue.fromLong(i));
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rowChange.setPrimaryKey(primaryKey);
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rowChange.addAttributeColumn(COLUMN_NAME_NAME,
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ColumnValue.fromString("小" + Integer.toString(i)));
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rowChange.addAttributeColumn(COLUMN_MOBILE_NAME,
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ColumnValue.fromString("111111111"));
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rowChange.addAttributeColumn(COLUMN_ADDRESS_NAME,
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ColumnValue.fromString("中国A地"));
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rowChange.addAttributeColumn(COLUMN_AGE_NAME,
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ColumnValue.fromLong(20));
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rowChange.setCondition(new Condition(
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RowExistenceExpectation.EXPECT_NOT_EXIST));
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PutRowRequest request = new PutRowRequest();
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request.setRowChange(rowChange);
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PutRowResult result = client.putRow(request);
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int consumedWriteCU = result.getConsumedCapacity()
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.getCapacityUnit().getWriteCapacityUnit();
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System.out.println("成功插入数据, 消耗的写CU为：" + consumedWriteCU);
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}
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System.out.println(String.format("成功插入%d行数据。", rowCount));
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}
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}

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