使用OSGI写一个简单得Telnet聊天程序.(参考TutorialEclipseCon06)

最近使用OSGI原理写一个简单得聊天程序.
首先新建一个equinox得Plugin.再创建一个接口:

public interface IChannel ...{
    String CHANNEL_NAME = "channel.name";

    void send(String form, String msg) throws IOException;
}

这个接口主要作用是一个频道发送信息.以此只定义了一个send方法.
再新建另一个equinox的Plugin,使用Component的方式创建一个OSGI-INF/telnet_component.xml.代码如下:

<?xml version="1.0" encoding="UTF-8"?>
<component name="Telenet_Component">
    <implementation class="org.dengues.zos.chat.telnet.TelnetChatComponent"></implementation>
    <reference name="LOG" interface="org.osgi.service.log.LogService"></reference>
</component>

这样一来它的实现类就是TelnetChatComponent.java: 它的代码如下:

public class TelnetChatComponent extends Thread ...{

    protected LogService log;

    protected boolean quite;

    protected List<Handler> handlers = new ArrayList<Handler>();

    protected ServerSocket server;

    private ComponentContext context;

    protected void activate(ComponentContext context) ...{
        this.context = context;
        log = (LogService) context.locateService("LOG");
        log.log(LogService.LOG_INFO, "Component active!!!!!");
        start();
    }

    protected void deactivate(ComponentContext context) throws Exception ...{
        log.log(LogService.LOG_INFO, "Component deactive!!!!!");
        quite = true;
        for (Handler handler : handlers) ...{
            handler.close();
        }
        server.close();
    }

    @Override
    public void run() ...{
        super.run();
        while (!quite) ...{
            try ...{
                server = new ServerSocket(55555);
                loop();
            } catch (Exception e) ...{
                log.log(LogService.LOG_ERROR, "[TelnetChat] Inner loop", e);
            }
        }
    }

    private void loop() throws Exception ...{
        while (!quite) ...{
            try ...{
                Socket accept = server.accept();
                Handler handler = new Handler(context.getBundleContext(),
                        accept, this);
                handlers.add(handler);
                handler.start();
            } catch (Exception e) ...{
                e.printStackTrace();
            }
        }
    }

    public void remove(IChannel channel) ...{
        this.handlers.remove(channel);
    }

    protected void sleep(int ms) ...{
        try ...{
            Thread.sleep(ms);
        } catch (Exception e) ...{
        }
    }

}

由于使用的Component在激活的时候会默认调用activate方法.这里为了记录激活日志.在记录日志之后.我们先新建一个ServerSocket端口是55555.另外还有一个类实现IChannel.就是Handler.java:

public class Handler extends Thread implements IChannel ...{
    private BundleContext context;
    private Socket socket;
    private TelnetChatComponent component;

    private PrintWriter writer;

    private boolean quit;
    private String user;
    private IChannel channel;

    public Handler(BundleContext context, Socket socket,
            TelnetChatComponent component) throws Exception ...{
        this.context = context;
        this.socket = socket;
        this.component = component;
        writer = new PrintWriter(new OutputStreamWriter(socket
                .getOutputStream()));
    }

    @Override
    public void send(String form, String msg) throws IOException ...{
        writer.println(form + " -> " + msg);
        writer.flush();
    }

    public void close() ...{
        try ...{
            quit = true;
            this.writer.close();
            this.socket.close();
        } catch (Exception e) ...{
            e.printStackTrace();
        }
    }

    public void run() ...{
        super.run();
        writer.println("Welcome... Chat!");
        writer.print("Enter Name: ");
        writer.flush();
        try ...{
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    socket.getInputStream()));
            String line = "";
            while (!quit && (line = reader.readLine()) != null) ...{
                line = line.trim();
                process(line);
            }
        } catch (Exception e) ...{
            if (!quit) ...{
                component.log.log(LogService.LOG_ERROR, "Reading User Name: ",
                        e);
            }
        } finally ...{
            if(channel!=null) ...{
                component.remove(channel);
            }
        }
    }

    private void process(String line) throws Exception ...{
        if (user == null) ...{
            user = line;
            Hashtable<String, String> props = new Hashtable<String, String>();
            props.put(CHANNEL_NAME, user);
            channel = (IChannel) context.registerService(IChannel.class
                    .getName(), this, props);
            send("info", "set User to" + user);
        } else if (line.endsWith("/quit")) ...{
            writer.println("bye!!!");
        } else ...{
            dispatch(line);
        }
    }

    private void dispatch(String line) throws Exception ...{
        String[] parts = line.split("/W");
        ServiceReference[] channels = context.getServiceReferences(
                IChannel.class.getName(), "(" + CHANNEL_NAME + "=" + parts[0]
                        + ")");
        if (channels != null) ...{
            IChannel channel = (IChannel) context.getService(channels[0]);
            channel.send(user, line.substring(parts[0].length()));
            context.ungetService(channels[0]);
        } else ...{
            send("error", "not such user" + user);
        }
    }
}

当有一个客户请求的时候,它就新建以个Handler.要发送信息的功能在Handler中实现.
就这么简单了,还有几个问题要注意:
这个Component插件的META-INF/MANIFEST.MF:

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Telnet Plug-in
Bundle-SymbolicName: org.dengues.zos.chat.telnet
Service-Component: OSGI-INF/telnet_component.xml
Bundle-Version: 1.0.0
Bundle-Activator: org.dengues.zos.chat.telnet.TelnetActivator
Import-Package: org.dengues.zos.chat.channel,
 org.osgi.framework;version="1.3.0",
 org.osgi.service.component;version="1.0.0",
 org.osgi.service.log;version="1.3.0"
Eclipse-LazyStart: true

还有在运行的时候要选中两个插件:org.eclipse.equinox.ds(如果没有这个需要到Eclipse官网下),org.eclipse.equinox.log.这样运行后的结果:

osgi> ss

Framework is launched.

id    State       Bundle
0    ACTIVE      org.eclipse.osgi_3.3.0.v20070530
1    ACTIVE      javax.servlet_2.4.0.v200706111738
8    ACTIVE      org.eclipse.osgi.services_3.1.200.v20070605
17    ACTIVE      org.dengues.zos.chat_1.0.0
18    ACTIVE      org.dengues.zos.chat.telnet_1.0.0
19    ACTIVE      org.eclipse.equinox.ds_1.0.0.v20070226
20    ACTIVE      org.eclipse.equinox.log_1.0.100.v20070226

osgi> log
>Info [20] Log created; Log Size=100; Log Threshold=4 initial@reference:file:plugins/org.eclipse.equinox.log_1.0.100.v20070226.jar/
>Info [20] ServiceEvent REGISTERED {service.id=22}
>Info [20] ServiceEvent REGISTERED {service.id=23}
>Info [20] ServiceEvent REGISTERED {service.id=24}
>Info [20] BundleEvent STARTED initial@reference:file:plugins/org.eclipse.equinox.log_1.0.100.v20070226.jar/
>Info [0] FrameworkEvent STARTLEVEL CHANGED System Bundle
>Info [18] Component active!!!!! initial@reference:file:../workspaces/org.dengues.zos.chat.telnet/

osgi> 

可以看到Info[18],说明这个Component已经运行.
然后再打开两个Telnet, 使用 open localhost 55555.就可以聊天了!
注明：整个Dengues的代码文件太多，无法上传，如果需要源代码。请到用一下方式联系:
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