Apache Thrift学习小记
参考：
http://incubator.apache.org/thrift/
http://wiki.apache.org/thrift/FrontPage
http://jnb.ociweb.com/jnb/jnbJun2009.html 非常好的入门教程
http://developers.facebook.com/thrift/thrift-20070401.pdf thrift开发者写的论文
Thrift是个啥东东？
来自wiki.apache.org/thrift/FrontPage的定义
Thrift is a software framework for scalable cross-language services development.
Thrift是为了实现跨语言服务访问的一个框架
Thrift allows you to define data types and service interfaces in a simple definition file.
Thrift定义了数据和服务的描述方式，是一种IDL
Taking that file as input, the compiler generates code to be used to easily build RPC clients and servers that communicate seamlessly across programming languages.
写一个定义文件，就可以使用thrift来生成某种语言RPC客户端和服务端程序框架。你只需要考虑如何实现你的服务就可以了。并且它支持很多种语言。
这有点像web service, 定义好一个web service服务描述文件后，可以使用如axis等工具生成服务器端或客户端的框架程序。
为什么还需要Thrift
thrift-20070401.pdf中有解释。
1、多语言开发的需要
比如其中提到的搜索服务，LAMP本身没有这个功能，开发者可能使用C++开发，php如何访问这个服务呢？于是需要有一种高效的跨语言访问的方法。
2、性能问题
web service也可以实现多语言互访问的功能，但xml文件太大，性能不行。Thrift可以使用二进值的格式。
开始测试
实现一个简单的服务，就是根据loginName得到User, user中有userId,loginName, name, password
第一步，写Thrift IDL文件 ，user.thrift，
namespace java mytest.thrift.gen namespace py mytest.thrift struct User { 1: i32 userId, 2: string loginName, 3: string password, 4: string name } exception UserNotFound { 1: string message } service UserService { User getUser(1:string loginName) throws (1:UserNotFound unf), list<User> getUsers() }
第二步，生成java和python代码
thrift --gen java user.thrift
thrift --gen py user.thrift
第三步，实现java服务端
参见：http://wiki.apache.org/thrift/ThriftUsageJava
服务实现 UserServiceHandler.java
package myserver; import java.util.ArrayList; import java.util.List; import mytest.thrift.gen.User; import mytest.thrift.gen.UserNotFound; import mytest.thrift.gen.UserService; import org.apache.thrift.TException; public class UserServiceHandler implements UserService.Iface { @Override public User getUser(String loginName) throws UserNotFound, TException { if (!"login1".equals(loginName)) { UserNotFound e = new UserNotFound("User not Found!"); throw e; } User user = new User(); user.setUserId(100); user.setLoginName("login1"); user.setPassword("pwd1"); user.setName("user1"); return user; } @Override public List<User> getUsers() throws TException { List<User> list = new ArrayList<User>(); User user = new User(); user.setUserId(100); user.setLoginName("login1"); user.setPassword("pwd1"); user.setName("user1"); list.add(user); User user2 = new User(); user2.setUserId(200); user2.setLoginName("login2"); user2.setPassword("pwd2"); user2.setName("user2"); list.add(user2); return list; } }
主程序 Server.java
package myserver; import mytest.thrift.gen.UserService; import org.apache.thrift.server.TServer; import org.apache.thrift.server.TSimpleServer; import org.apache.thrift.transport.TServerSocket; import org.apache.thrift.transport.TServerTransport; public class Server { public static void main(String[] args) { try { UserServiceHandler handler = new UserServiceHandler(); UserService.Processor processor = new UserService.Processor(handler); TServerTransport serverTransport = new TServerSocket(9090); TServer server = new TSimpleServer(processor, serverTransport); // Use this for a multithreaded server // server = new TThreadPoolServer(processor, serverTransport); System.out.println("Starting the server..."); server.serve(); } catch (Exception x) { x.printStackTrace(); } System.out.println("done."); } }
第四步，实现java客户端
package myclient; import java.util.Iterator; import java.util.List; import mytest.thrift.gen.User; import mytest.thrift.gen.UserNotFound; import mytest.thrift.gen.UserService; import org.apache.thrift.TException; import org.apache.thrift.protocol.TBinaryProtocol; import org.apache.thrift.protocol.TProtocol; import org.apache.thrift.transport.TSocket; import org.apache.thrift.transport.TTransport; public class Client { public static void main(String[] args) { try { TTransport transport = new TSocket("localhost", 9090); TProtocol protocol = new TBinaryProtocol(transport); UserService.Client client = new UserService.Client(protocol); transport.open(); System.out.println("test1"); try { User user1 = client.getUser("login1"); System.out.println("name=" + user1.getName()); } catch (UserNotFound e) { System.out.println(e.getMessage()); } System.out.println("test2"); try { User user2 = client.getUser("login10"); System.out.println("name=" + user2.getName()); } catch (UserNotFound e) { System.out.println(e.getMessage()); } System.out.println("test3"); List<User> list = client.getUsers(); Iterator<User> it = list.iterator(); while(it.hasNext()){ User u = it.next(); System.out.println("name=" + u.getName()); } transport.close(); } catch (TException x) { x.printStackTrace(); } } }