hadoopRPC的使用

1模拟namenode的查询元数据

public interface ClientNamenodeProtocol {
	public static final long versionID=1L; //会读取这个版本号， 但可以和客户端的不一样， 没有校验
	public String getMetaData(String path);
}


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public class MyNameNode implements ClientNamenodeProtocol{
	
	//模拟namenode的查询元数据
	@Override
	public String getMetaData(String path){
		if("/a.txt".equals(path)){
			return path+": dataNode3 - {BLK_1,BLK_2}";
		} 
		 return null;
	}
}
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服务端（先启动）

public class PublishServiceUtil {

	public static void main(String[] args) throws Exception {
		Builder builder = new RPC.Builder(new Configuration());
		builder.setBindAddress("127.0.0.1")
		.setPort(4578)
		.setProtocol(ClientNamenodeProtocol.class)
		.setInstance(new MyNameNode());
		Server server = builder.build();
		server.start();
	}
	
}
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客户端（后启动）
public class MyHdfsClient {

	public static void main(String[] args) throws Exception {
		ClientNamenodeProtocol namenode = RPC.getProxy(ClientNamenodeProtocol.class, 1L,
				new InetSocketAddress("127.0.0.1", 4578), new Configuration());
		String metaData = namenode.getMetaData("/a.txt");
		System.out.println("客户端获取的数据："+metaData);
		 
	}
}

结果

2业务的RPC简单模拟

代码

public interface IUserService {

	public static final long versionID = 100L;
	public String getUserName();
	
}
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public class UserServiceImpl implements IUserService{

	@Override
	public String getUserName() {
		return  "小明";
	}
}

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服务端
public class PublishServiceUtil {
	public static void main(String[] args) throws Exception {
		Builder builder2 = new RPC.Builder(new Configuration());
		builder2.setBindAddress("127.0.0.1")
		.setPort(9999)
		.setProtocol(IUserService.class)
		.setInstance(new UserServiceImpl());
		Server server2 = builder2.build();
		server2.start();
	}
}

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客户端
public class UserClient {
	public static void main(String[] args) throws Exception {
		//版本号要和IUserLoginService的版本号统一
		IUserService userLoginService = RPC.getProxy(IUserService.class, 100L, new InetSocketAddress("127.0.0.1", 9999), new Configuration());
		String userName = userLoginService.getUserName();
		System.out.println("用户名是："+userName);
	}
}


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