在Hbase Endpoint Coprocessor中使用coprocessorProxy操作例子与问题解析

转载请注明原创为Michael Zhang：http://blog.csdn.net/matrixyy/article/details/46688467

一、先说注意事项吧：

1、Coprocessor启动有三种方式：配置文件、shell和程序中指定，我使用的是程序指定：

    static {        EP_TABLE_DISCRIPTOR = new HTableDescriptor("epTest");        HColumnDescriptor family = new HColumnDescriptor("_tis".getBytes());        family.setInMemory(true);        family.setMaxVersions(1);        EP_TABLE_DISCRIPTOR.addFamily(family);        try {            EP_TABLE_DISCRIPTOR.addCoprocessor("ict.wde.test.RowCountServer");        } catch (IOException ioe) {        }

上段代码中的addCoprocessor就是指定该表启动coprocessor操作。但前提是必须重启HBase才能把jar包载入进来。

2、如果客户端连接后出现如下问题：No matching handler **** for protocol  in *** region，说明jar包还没有载入到HBaes中，确保HBase已经重启，另外检查代码中addCoprocessor("ict.wde.test.RowCountServer");的类名“RowCountServer”是否写正确了

二、说下步骤

2.1编写服务端代码：

1）接口类（固定格式）

package ict.wde.test;import org.apache.hadoop.hbase.Coprocessor;import org.apache.hadoop.hbase.filter.Filter;import org.apache.hadoop.hbase.ipc.CoprocessorProtocol;import java.io.File;import java.io.IOException;/** * Created by Michael on 2015/6/22. */public interface RowCountProtocol extends Coprocessor, CoprocessorProtocol {    public long getRowCount() throws IOException;    public long getRowCount(Filter filter) throws IOException;    public String getStr() throws IOException;    //public long getKeyValue() throws IOException;}

2）真正起作用的类

package ict.wde.test;import org.apache.hadoop.hbase.CoprocessorEnvironment;import org.apache.hadoop.hbase.client.Scan;import org.apache.hadoop.hbase.filter.Filter;import org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter;import org.apache.hadoop.hbase.ipc.ProtocolSignature;import java.io.IOException;/** * Created by Michael on 2015/6/27. */public class RowCountServer implements RowCountProtocol {    @Override    public void start(CoprocessorEnvironment env) throws IOException {    }    @Override    public void stop(CoprocessorEnvironment env) throws IOException {    }    @Override    public ProtocolSignature getProtocolSignature(String protocol,                                                  long clientVersion, int clientMethodsHash) throws IOException {        return new ProtocolSignature(3, null);    }    @Override    public long getProtocolVersion(String protocol, long clientVersion) throws IOException {        return 3;    }    @Override    public long getRowCount() throws IOException {        return this.getRowCount(new FirstKeyOnlyFilter());    }    @Override    public long getRowCount(Filter filter) throws IOException {        return this.getRowCount(filter, false);    }    @Override    public String getStr() throws IOException {        String name = "Hello Doctor Michael Zhang, again!";        return name;    }//    @Override//    public long getKeyValueCount() {//        return 0;//    }    public long getRowCount(Filter filter, boolean countKeyValue) throws IOException {        Scan scan = new Scan();        scan.setMaxVersions(1);        if (filter != null) {            scan.setFilter(filter);        }        return 1;    }}

上述两个类打包jar后放入hbase的lib目录下

2.2客户端代码

import ict.wde.test.RowCountProtocol;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.hbase.HColumnDescriptor;import org.apache.hadoop.hbase.HTableDescriptor;import org.apache.hadoop.hbase.client.HBaseAdmin;import org.apache.hadoop.hbase.client.HTable;import org.apache.hadoop.hbase.client.HTableInterface;import org.apache.hadoop.hbase.filter.Filter;import java.io.IOException;/** * Created by Michael on 2015/6/30. */public class EndpointTestClient {    private final HTableInterface table;    private final Configuration conf;    private final RowCountProtocol server;    private static final HTableDescriptor EP_TABLE_DISCRIPTOR;    static {        EP_TABLE_DISCRIPTOR = new HTableDescriptor("epTest");        HColumnDescriptor family = new HColumnDescriptor("_tis".getBytes());        family.setInMemory(true);        family.setMaxVersions(1);        EP_TABLE_DISCRIPTOR.addFamily(family);        try {            EP_TABLE_DISCRIPTOR.addCoprocessor("ict.wde.test.RowCountServer");        } catch (IOException ioe) {        }    }    public EndpointTestClient(Configuration config) throws IOException {        conf = config;        table = initTidTable();        server = table.coprocessorProxy(RowCountProtocol.class, "0".getBytes());    }    private HTableInterface initTidTable() throws IOException {        HBaseAdmin admin = new HBaseAdmin(conf);        if (!admin.tableExists("epTest")) {            admin.createTable(EP_TABLE_DISCRIPTOR);        }        admin.close();        return new HTable(conf, "epTest");    }    public String getStr() throws IOException {        return server.getStr();    }}

启动类：

import org.apache.hadoop.conf.Configuration;import java.io.IOException;/** * Created by Michael on 2015/6/22. */public class EndpointExample {//    private final HTableInterface table;//    private static final Configuration conf;//    private static final HTableDescriptor EP_TABLE_DISCRIPTOR;////    static {//        conf = new Configuration();//        conf.set("hbase.zookeeper.quorum", "ccf04:2181");////        EP_TABLE_DISCRIPTOR = new HTableDescriptor("epTest");//        HColumnDescriptor family = new HColumnDescriptor("_tis".getBytes());//        family.setInMemory(true);//        family.setMaxVersions(1);//        EP_TABLE_DISCRIPTOR.addFamily(family);//        try {//            EP_TABLE_DISCRIPTOR.addCoprocessor("ict.wde.test.RowCountServer");//        } catch (IOException ioe) {////        }////        table = initTidTable();//    }////    private HTableInterface initTidTable() throws IOException {//        HBaseAdmin admin = new HBaseAdmin(conf);//        if (!admin.tableExists("epTest")) {//            admin.createTable(EP_TABLE_DISCRIPTOR);//        }//        admin.close();//        return new HTable(conf, "epTest");//    }    public static void main(String[] agrs) throws IOException {        Configuration conf = new Configuration();        conf.set("hbase.zookeeper.quorum", "ccf04:2181");        EndpointTestClient client = new EndpointTestClient(conf);        String name = client.getStr();        System.out.println(name);    }}