前面两篇文章说了怎样使用单个Filter来过滤数据，但是很多情况下我们需要做一下组合过滤，比如有逻辑与和逻辑或的查询，此时我们可以使用FilterList来实现了。
FilterList也是实现了Filter接口，因此我们可以通过多个过滤器组合来实现某些效果。
看下面的例子，我们创建了两个filter，第一个是过滤 username=user_0，第二个是过滤 password=password_0，然后我们将这两个filter组合到一个FilterList对象中，并且制定组合操作符为MUST_PASS_ALL，意思是过滤满足这两个条件的记录。然后就可以像使用普通过滤器一样来扫描记录了。
Filter filter1 = new SingleColumnValueFilter(Bytes.toBytes("base"), Bytes.toBytes("username"),
CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("user_0")));
Filter filter2 = new SingleColumnValueFilter(Bytes.toBytes("base"), Bytes.toBytes("password"),
CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("password_0")));
FilterList filterList = new FilterList(FilterList.Operator.MUST_PASS_ALL, filter1, filter2);
Table table = connection.getTable(TableName.valueOf(TABLE_NAME));
Scan scan = new Scan();
scan.setFilter(filterList);
ResultScanner resultScanner = table.getScanner(scan);
Iterator<Result> it = resultScanner.iterator();
while (it.hasNext()) {
Result result = it.next();
printRow(result);
}
resultScanner.close();
table.close();
下面是完整代码示例
package my.hbasestudy;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.CompareOperator;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.*;
import org.apache.hadoop.hbase.filter.*;
import org.apache.hadoop.hbase.util.Bytes;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class TestFilterList {
private static final String TABLE_NAME = "user";
private static final String COLUMN_FAMILY_BASE = "base";
private static final String COLUMN_FAMILY_ADDRESS = "address";
private static final String COLUMN_USERNAME = "username";
private static final String COLUMN_PASSWORD = "password";
private static final String COLUMN_HOME = "home";
private static final String COLUMN_OFFICE = "office";
private Connection connection;
public static void main(String[] args) throws Exception {
Configuration config = HBaseConfiguration.create();
Connection connection = ConnectionFactory.createConnection(config);
TestFilterList t = new TestFilterList(connection);
t.test();
connection.close();
}
public TestFilterList(Connection connection) {
this.connection = connection;
}
private void test() throws IOException {
createTable();
prepare();
filterMustPassAll();
filterMustPassOne();
deleteTable();
}
private void filterMustPassAll() throws IOException {
System.out.println("---------- must pass all ----------");
Filter filter1 = new SingleColumnValueFilter(Bytes.toBytes("base"), Bytes.toBytes("username"),
CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("user_0")));
Filter filter2 = new SingleColumnValueFilter(Bytes.toBytes("base"), Bytes.toBytes("password"),
CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("password_0")));
FilterList filterList = new FilterList(FilterList.Operator.MUST_PASS_ALL, filter1, filter2);
Table table = connection.getTable(TableName.valueOf(TABLE_NAME));
Scan scan = new Scan();
scan.setFilter(filterList);
ResultScanner resultScanner = table.getScanner(scan);
Iterator<Result> it = resultScanner.iterator();
while (it.hasNext()) {
Result result = it.next();
printRow(result);
}
resultScanner.close();
table.close();
}
private void filterMustPassOne() throws IOException {
System.out.println("---------- must pass one ----------");
Filter filter1 = new SingleColumnValueFilter(Bytes.toBytes("base"), Bytes.toBytes("username"),
CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("user_0")));
Filter filter2 = new SingleColumnValueFilter(Bytes.toBytes("base"), Bytes.toBytes("username"),
CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("user_10")));
Filter filter3 = new SingleColumnValueFilter(Bytes.toBytes("base"), Bytes.toBytes("username"),
CompareOperator.EQUAL, new BinaryComparator(Bytes.toBytes("user_99")));
FilterList filterList = new FilterList(FilterList.Operator.MUST_PASS_ONE, filter1, filter2, filter3);
Table table = connection.getTable(TableName.valueOf(TABLE_NAME));
Scan scan = new Scan();
scan.setFilter(filterList);
ResultScanner resultScanner = table.getScanner(scan);
Iterator<Result> it = resultScanner.iterator();
while (it.hasNext()) {
Result result = it.next();
printRow(result);
}
resultScanner.close();
table.close();
}
private void createTable() throws IOException {
Admin admin = connection.getAdmin();
try {
TableDescriptor tableDesc = TableDescriptorBuilder.newBuilder(TableName.valueOf(TABLE_NAME))
.addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes(COLUMN_FAMILY_BASE)).build())
.addColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(Bytes.toBytes(COLUMN_FAMILY_ADDRESS)).build())
.build();
admin.createTable(tableDesc);
} finally {
admin.close();
}
}
private void deleteTable() throws IOException {
Admin admin = connection.getAdmin();
try {
admin.disableTable(TableName.valueOf(TABLE_NAME));
admin.deleteTable(TableName.valueOf(TABLE_NAME));
} finally {
admin.close();
}
}
private void prepare() throws IOException {
Table table = connection.getTable(TableName.valueOf(TABLE_NAME));
List<Row> actions = new ArrayList<Row>();
for (int i = 0; i < 100; i++) {
Put put = new Put(Bytes.toBytes("row_" + i));
put.addColumn(Bytes.toBytes(COLUMN_FAMILY_BASE), Bytes.toBytes(COLUMN_USERNAME), Bytes.toBytes("user_" + i));
put.addColumn(Bytes.toBytes(COLUMN_FAMILY_BASE), Bytes.toBytes(COLUMN_PASSWORD), Bytes.toBytes("password_" + i));
put.addColumn(Bytes.toBytes(COLUMN_FAMILY_ADDRESS), Bytes.toBytes(COLUMN_HOME), Bytes.toBytes("home_" + i));
put.addColumn(Bytes.toBytes(COLUMN_FAMILY_ADDRESS), Bytes.toBytes(COLUMN_OFFICE), Bytes.toBytes("office_" + i));
actions.add(put);
}
Object[] results = new Object[actions.size()];
try {
table.batch(actions, results);
} catch (InterruptedException e) {
e.printStackTrace();
}
table.close();
}
private void printRow(Result result) {
if (Bytes.toString(result.getRow()) != null) {
StringBuilder sb = new StringBuilder();
sb.append(Bytes.toString(result.getRow()));
sb.append("[");
sb.append("base:username=" + Bytes.toString(result.getValue(Bytes.toBytes("base"), Bytes.toBytes("username"))));
sb.append(", base:password=" + Bytes.toString(result.getValue(Bytes.toBytes("base"), Bytes.toBytes("password"))));
sb.append(", address:home=" + Bytes.toString(result.getValue(Bytes.toBytes("address"), Bytes.toBytes("home"))));
sb.append(", address:office=" + Bytes.toString(result.getValue(Bytes.toBytes("address"), Bytes.toBytes("office"))));
sb.append("]");
System.out.println(sb.toString());
}
}
}
最后，对于更复杂的过滤规则，可以通过实现自己的过滤器来实现。
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