Hbase Java API：检索与部分行键匹配的所有行
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原文地址: http://stackoverflow.com/questions/21842469/
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Hbase Java API: Retrieving all rows that match a Partial Row Key
提问by Matthew Moisen
In the Python module happybase, I can retrieve all rows that have a row key starting with a given string (i.e, search using a partial row key).
在 Python 模块happybase 中，我可以检索具有以给定字符串开头的行键的所有行（即，使用部分行键进行搜索）。
Let's say I have a rowkey in the format of (ID|TYPE|DATE), I would be able to find all rows with an ID of 1 and a TYPE of A by:
假设我有一个 (ID|TYPE|DATE) 格式的行键，我将能够通过以下方式找到 ID 为 1 和 TYPE 为 A 的所有行：
import happybase
connection = happybase.Connection('hmaster-host.com')
table = connection.table('table_name')
for key, data in table.scan(row_prefix="1|A|"):
print key, data
This is what I have so far as a totally client side Java program for anyone trying to do the basics using the Java HBase API, but I can only search for a row using the full row key:
到目前为止，这就是我拥有的完全客户端 Java 程序，适用于任何尝试使用Java HBase API进行基础操作的人，但我只能使用完整的行键搜索一行：
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.util.Bytes;
//class foo {
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.addResource(new Path("C:\core-site.xml"));
conf.addResource(new Path("C:\hbase-site.xml"));
HTable table = new HTable(conf, "table_name");
Result row = table.get(new Get(Bytes.toBytes("1|A|2014-01-01 00:00")));
printRow(row);
}
public static void printRow(Result result) {
String returnString = "";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("id"))) + ", ";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("type"))) + ", ";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("date")));
System.out.println(returnString);
}
//}
Where "cf" is the name of the column family.
其中“cf”是列族的名称。
ANSWER:
回答：
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.PrefixFilter;
import org.apache.hadoop.hbase.util.Bytes;
//class foo {
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.addResource(new Path("C:\core-site.xml"));
conf.addResource(new Path("C:\hbase-site.xml"));
HTable table = new HTable(conf, "table_name");
byte[] prefix = Bytes.toBytes("1|A|");
Scan scan = new Scan(prefix);
Filter prefixFilter = new PrefixFilter(prefix);
scan.setFilter(prefixFilter);
ResultScanner resultScanner = table.getScanner(scan);
printRows(resultScanner);
//Result row = table.get(new Get(Bytes.toBytes("1|A|2014-01-01 00:00")));
//printRow(row);
}
public static void printRows(ResultScanner resultScanner) {
for (Iterator<Result> iterator = results.iterator(); iterator.hasNext();) {
printRow(iterator.next();
}
}
public static void printRow(Result result) {
String returnString = "";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("id"))) + ", ";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("type"))) + ", ";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("date")));
System.out.println(returnString);
}
//}
Note that I use the setFiltermethod, whereas the answer below uses the addFiltermethod, on account of us using different APIs.
请注意，我使用了该setFilter方法，而下面的答案使用了该addFilter方法，因为我们使用了不同的 API。
采纳答案by Arnon Rotem-Gal-Oz
You are using the HTable getoperation so you're only getting back one row (note that you can specify a prefix here as well and you don't have to give the complete key)
您正在使用 HTableget操作，因此您只返回一行（请注意，您也可以在此处指定前缀，而不必提供完整的键）
If you want to get back multiple rows you should use a Scan
如果你想取回多行，你应该使用 Scan
byte[] prefix=Bytes.toBytes("1|A|");
Scan scan = new Scan(prefix);
PrefixFilter prefixFilter = new PrefixFilter(prefix);
scan.addFilter(prefixFilter);
ResultScanner resultScanner = table.getScanner(scan);
