我现在实现一个简单的server-client方式的calculator,client将计算请求序列化成protocol buffers形式然后发给server端,server端反序列化后将完成计算然后将结果序列化后返回给client端。
先看一下最后整体的package结构(模仿hadoop的包命名,便于比较)
package org.tao.pbtest.api:
org.tao.pbtest.api.Calculator
org.tao.pbtest.api.CalculatorPB
org.tao.pbtest.api.CalculatorPBServiceImpl
package org.tao.pbtest.server.business
org.tao.pbtest.server.business.CalculatorService
package org.tao.pbtest.ipc
org.tao.pbtest.ipc.Server
package org.tao.pbtest.proto
org.tao.pbtest.proto.Calculator
org.tao.pbtest.proto.CalculatorMsg
package org.tao.pbtest.proto.test
org.tao.pbtest.proto.test.TestCalculator
首先看一下Calculator这个接口:
package org.tao.pbtest.api; public interface Calculator { public int add(int a, int b); public int minus(int a, int b); }
这个计算器就进行简单的两种运算,两个整数的加减。
然后定义两个proto文件:CalculatorMsg.proto和Calculator.proto。
第一个是运算的参数消息、返回结果消息,输入时两个整数,返回结果是一个整数。具体protocol buffers的语法此处不做解释了,可以参看google的文档。
option java_package = "org.tao.pbtest.proto"; option java_outer_classname = "CalculatorMsg"; option java_generic_services = true; option java_generate_equals_and_hash = true; message RequestProto { required string methodName = 1; required int32 num1 = 2; required int32 num2 = 3; } message ResponseProto { required int32 result = 1; }
第二个proto文件定义service:
option java_package = "org.tao.pbtest.proto"; option java_outer_classname = "Calculator"; option java_generic_service = true; option java_generate_equals_and_hash = true; import "CalculatorMsg.proto" service CalculatorService { rpc add(RequestProto) returns (ResponseProto); rpc minus(RequestProto) returns (ResponseProto); }
然后用protoc将此两个文件编译,生成两个java文件:
org.tao.pbtest.proto.Calculator
org.tao.pbtest.proto.CalculatorMsg
然后定义一个CalculatorPB接口extends刚才生成的org.tao.pbtest.proto.Calculator.CalculatorService.BlockingInterface, 这是一个过渡作用的接口。
package org.tao.pbtest.server.api; import org.tao.pbtest.proto.Calculator.CalculatorService.BlockingService; public interface CalculatorPB extends BlockingInterface { }
还需要一个发送、接受信息的ipc server/client端。这里偷懒只实现一个最最简单的server端,什么并发啊,异常处理啊,nio啊统统不考虑,因为这不是重点。
package org.tao.pbtest.ipc; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.IOException; import java.net.*; import com.google.protobuf.*; import com.google.protobuf.Descriptors.MethodDescriptor; import org.tao.pbtest.proto.CalculatorMsg.RequestProto; import org.tao.pbtest.proto.CalculatorMsg.ResponseProto; public class Server extends Thread { private Class<?> protocol; private BlockingService impl; private int port; private ServerSocket ss; public Server(Class<?> protocol, BlockingService protocolImpl, int port){ this.protocol = protocol; this.impl = protocolImpl; this.port = port; } public void run(){ Socket clientSocket = null; DataOutputStream dos = null; DataInputStream dis = null; try { ss = new ServerSocket(port); }catch(IOException e){ } int testCount = 10; //进行10次计算后就退出 while(testCount-- > 0){ try { clientSocket = ss.accept(); dos = new DataOutputStream(clientSocket.getOutputStream()); dis = new DataInputStream(clientSocket.getInputStream()); int dataLen = dis.readInt(); byte[] dataBuffer = new byte[dataLen]; int readCount = dis.read(dataBuffer); byte[] result = processOneRpc(dataBuffer); dos.writeInt(result.length); dos.write(result); dos.flush(); }catch(Exception e){ } } try { dos.close(); dis.close(); ss.close(); }catch(Exception e){ }; } public byte[] processOneRpc (byte[] data) throws Exception { RequestProto request = RequestProto.parseFrom(data); String methodName = request.getMethodName(); MethodDescriptor methodDescriptor = impl.getDescriptorForType().findMethodByName(methodName); Message response = impl.callBlockingMethod(methodDescriptor, null, request); return response.toByteArray(); } }
package org.tao.pbtest.server.business; import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import org.tao.pbtest.ipc.Server; import org.tao.pbtest.server.api.Calculator; import com.google.protobuf.BlockingService; public class CalculatorService implements Calculator { private Server server = null; private final Class protocol = Calculator.class; private final ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); private final String protoPackage = "org.tao.pbtest.proto"; private final String host = "localhost"; private final int port = 8038; public CalculatorService (){ } @Override public int add(int a, int b) { // TODO Auto-generated method stub return a+b; } public int minus(int a, int b){ return a-b; } public void init(){ createServer(); } /* * return org.tao.pbtest.server.api.CalculatorPBServiceImpl */ public Class<?> getPbServiceImplClass(){ String packageName = protocol.getPackage().getName(); String className = protocol.getSimpleName(); String pbServiceImplName = packageName + "." + className + "PBServiceImpl"; Class<?> clazz = null; try{ clazz = Class.forName(pbServiceImplName, true, classLoader); }catch(ClassNotFoundException e){ System.err.println(e.toString()); } return clazz; } /* * return org.tao.pbtest.proto.Calculator$CalculatorService */ public Class<?> getProtoClass(){ String className = protocol.getSimpleName(); String protoClazzName = protoPackage + "." + className + "$" + className + "Service"; Class<?> clazz = null; try{ clazz = Class.forName(protoClazzName, true, classLoader); }catch(ClassNotFoundException e){ System.err.println(e.toString()); } return clazz; } public void createServer(){ Class<?> pbServiceImpl = getPbServiceImplClass(); Constructor<?> constructor = null; try{ constructor = pbServiceImpl.getConstructor(protocol); constructor.setAccessible(true); }catch(NoSuchMethodException e){ System.err.print(e.toString()); } Object service = null; // instance of CalculatorPBServiceImpl try { service = constructor.newInstance(this); }catch(InstantiationException e){ } catch (IllegalArgumentException e) { } catch (IllegalAccessException e) { } catch (InvocationTargetException e) { } /* * interface: org.tao.pbtest.server.CalculatorPB */ Class<?> pbProtocol = service.getClass().getInterfaces()[0]; /* * class: org.tao.pbtest.proto.Calculator$CalculatorService */ Class<?> protoClazz = getProtoClass(); Method method = null; try { // pbProtocol.getInterfaces()[] 即是接口 org.tao.pbtest.proto.Calculator$CalculatorService$BlockingInterface method = protoClazz.getMethod("newReflectiveBlockingService", pbProtocol.getInterfaces()[0]); method.setAccessible(true); }catch(NoSuchMethodException e){ System.err.print(e.toString()); } try{ createServer(pbProtocol, (BlockingService)method.invoke(null, service)); }catch(InvocationTargetException e){ } catch (IllegalArgumentException e) { } catch (IllegalAccessException e) { } } public void createServer(Class pbProtocol, BlockingService service){ server = new Server(pbProtocol, service, port); server.start(); } public static void main(String[] args){ CalculatorService cs = new CalculatorService(); cs.init(); } }
package org.tao.pbtest.server.api; import org.tao.pbtest.proto.CalculatorMsg.RequestProto; import org.tao.pbtest.proto.CalculatorMsg.ResponseProto; import com.google.protobuf.RpcController; import com.google.protobuf.ServiceException; public class CalculatorPBServiceImpl implements CalculatorPB { public Calculator real; public CalculatorPBServiceImpl(Calculator impl){ this.real = impl; } @Override public ResponseProto add(RpcController controller, RequestProto request) throws ServiceException { // TODO Auto-generated method stub ResponseProto proto = ResponseProto.getDefaultInstance(); ResponseProto.Builder build = ResponseProto.newBuilder(); int add1 = request.getNum1(); int add2 = request.getNum2(); int sum = real.add(add1, add2); ResponseProto result = null; build.setResult(sum); result = build.build(); return result; } @Override public ResponseProto minus(RpcController controller, RequestProto request) throws ServiceException { // TODO Auto-generated method stub ResponseProto proto = ResponseProto.getDefaultInstance(); ResponseProto.Builder build = ResponseProto.newBuilder(); int add1 = request.getNum1(); int add2 = request.getNum2(); int sum = real.minus(add1, add2); ResponseProto result = null; build.setResult(sum); result = build.build(); return result; } }
最后,偷懒没写客户端的东西,只是写了一个简单的测试例子:
package org.tao.pbtest.proto.test; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.IOException; import java.net.Socket; import java.util.Random; import org.tao.pbtest.proto.CalculatorMsg.RequestProto; import org.tao.pbtest.proto.CalculatorMsg.ResponseProto; import org.tao.pbtest.server.api.Calculator; public class TestCalculator implements Calculator { public int doTest(String op, int a, int b){ // TODO Auto-generated method stub Socket s = null; DataOutputStream out = null; DataInputStream in = null; int ret = 0; try { s= new Socket("localhost", 8038); out = new DataOutputStream(s.getOutputStream()); in = new DataInputStream(s.getInputStream()); RequestProto.Builder builder = RequestProto.newBuilder(); builder.setMethodName(op); builder.setNum1(a); builder.setNum2(b); RequestProto request = builder.build(); byte [] bytes = request.toByteArray(); out.writeInt(bytes.length); out.write(bytes); out.flush(); int dataLen = in.readInt(); byte[] data = new byte[dataLen]; int count = in.read(data); if(count != dataLen){ System.err.println("something bad happened!"); } ResponseProto result = ResponseProto.parseFrom(data); System.out.println(a + " " + op + " " + b + "=" + result.getResult()); ret = result.getResult(); }catch(Exception e){ e.printStackTrace(); System.err.println(e.toString()); }finally { try{ in.close(); out.close(); s.close(); }catch(IOException e){ e.printStackTrace(); } } return ret; } @Override public int add(int a, int b) { // TODO Auto-generated method stub return doTest("add", a, b); } @Override public int minus(int a, int b) { // TODO Auto-generated method stub return doTest("minus", a, b); } /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub TestCalculator tc = new TestCalculator(); int testCount = 5; Random rand = new Random(); while(testCount-- > 0){ int a = rand.nextInt(100); int b = rand.nextInt(100); tc.add(a,b); tc.minus(a, b); } } }
输出:
76 add 14=90
76 minus 14=62
20 add 84=104
20 minus 84=-64
4 add 16=20
4 minus 16=-12
56 add 4=60
56 minus 4=52
46 add 50=96
46 minus 50=-4