• 编译和运行 Echo 服务器和客户端
    • 编译
    • 运行 Echo 服务器 和 客户端

    编译和运行 Echo 服务器和客户端

    编译

    本例涉及到多模块 Maven 项目的组织

    在例子 chapter2 目录下，执行

    1. mvn clean package

    输出如下

    Listing 2.6 Build Output

    1. chapter2>mvn clean package
    2. [INFO] Scanning for projects...
    3. [INFO] --------------------------------------------------------------------
    4. [INFO] Reactor Build Order:
    5. [INFO]
    6. [INFO] Echo Client and Server
    7. [INFO] Echo Client
    8. [INFO] Echo Server
    9. [INFO]
    10. [INFO] --------------------------------------------------------------------
    11. [INFO] Building Echo Client and Server 1.0-SNAPSHOT
    12. [INFO] --------------------------------------------------------------------
    13. [INFO]
    14. [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ echo-parent ---
    15. [INFO]
    16. [INFO] --------------------------------------------------------------------
    17. [INFO] Building Echo Client 1.0-SNAPSHOT
    18. [INFO] --------------------------------------------------------------------
    19. [INFO]
    20. [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ echo-client ---
    21. [INFO]
    22. [INFO] --- maven-compiler-plugin:3.1:compile (default-compile)
    23. @ echo-client ---
    24. [INFO] Changes detected - recompiling the module!
    25. [INFO] --------------------------------------------------------------------
    26. [INFO] Reactor Summary:
    27. [INFO]
    28. [INFO] Echo Client and Server ......................... SUCCESS [ 0.118 s]
    29. [INFO] Echo Client .................................... SUCCESS [ 1.219 s]
    30. [INFO] Echo Server .................................... SUCCESS [ 0.110 s]
    31. [INFO] --------------------------------------------------------------------
    32. [INFO] BUILD SUCCESS
    33. [INFO] --------------------------------------------------------------------
    34. [INFO] Total time: 1.561 s
    35. [INFO] Finished at: 2014-06-08T17:39:15-05:00
    36. [INFO] Final Memory: 14M/245M
    37. [INFO] --------------------------------------------------------------------

    注意事项：

    • Maven Reactor 构建顺序：先是 父 POM，然后是子项目
    • Netty artifact 没在用户的本地存储库中找到，所以 Maven 就会从互联网上下载
    • clean 和 compile 在构建生命周期的运行。事后 mavensurefire-plugin
      插件运行，但不会有测试类存在。最后 mavenjar-plugin 执行

    这段说明了项目已经成功编译。

    运行 Echo 服务器 和 客户端

    我们使用 exec-maven-plugin 来运行项目。

    在 chapter2/Server 目录，执行

    1. mvn exec:java

    输出如下：

    1. [INFO] Scanning for projects...
    2. [INFO]
    3. [INFO] --------------------------------------------------------------------
    4. [INFO] Building Echo Server 1.0-SNAPSHOT
    5. [INFO] --------------------------------------------------------------------
    6. [INFO]
    7. [INFO] >>> exec-maven-plugin:1.2.1:java (default-cli) @ echo-server >>>
    8. [INFO]
    9. [INFO] <<< exec-maven-plugin:1.2.1:java (default-cli) @ echo-server <<<
    10. [INFO]
    11. [INFO] --- exec-maven-plugin:1.2.1:java (default-cli) @ echo-server ---
    12. nettyinaction.echo.EchoServer started and listening for connections on
    13. /0:0:0:0:0:0:0:0:9999

    在 chapter2/Client 目录，执行

    1. mvn exec:java

    输出如下：

    1. [INFO] Scanning for projects...
    2. [INFO]
    3. [INFO] --------------------------------------------------------------------
    4. [INFO] Building Echo Client 1.0-SNAPSHOT
    5. [INFO] --------------------------------------------------------------------
    6. [INFO]
    7. [INFO] >>> exec-maven-plugin:1.2.1:java (default-cli) @ echo-client >>>
    8. [INFO]
    9. [INFO] <<< exec-maven-plugin:1.2.1:java (default-cli) @ echo-client <<<
    10. [INFO]
    11. [INFO] --- exec-maven-plugin:1.2.1:java (default-cli) @ echo-client ---
    12. Client received: Netty rocks!
    13. [INFO] --------------------------------------------------------------------
    14. [INFO] BUILD SUCCESS
    15. [INFO] --------------------------------------------------------------------
    16. [INFO] Total time: 3.907 s
    17. [INFO] Finished at: 2014-06-08T18:26:14-05:00
    18. [INFO] Final Memory: 8M/245M
    19. [INFO] --------------------------------------------------------------------

    在服务器的控制台输出：

    1. Server received: Netty rocks!

    发生了什么事：

    • 客户端连接后，它发送消息：“Netty rocks！”
    • 服务器输出接收到消息并将其返回给客户端
    • 客户输出接收到的消息并退出。

    每次运行客户端，你会看到在服务器的控制台输出：

    1. Server received: Netty rocks!

    现在，我们看下错误的情况。在控制台 输入 Ctrl-C 来关闭服务器。而后运行客户端，此时输出如下：

    1. [INFO] Scanning for projects...
    2. [INFO]
    3. [INFO] --------------------------------------------------------------------
    4. [INFO] Building Echo Client 1.0-SNAPSHOT
    5. [INFO] --------------------------------------------------------------------
    6. [INFO]
    7. [INFO] >>> exec-maven-plugin:1.2.1:java (default-cli) @ echo-client >>>
    8. [INFO]
    9. [INFO] <<< exec-maven-plugin:1.2.1:java (default-cli) @ echo-client <<<
    10. [INFO]
    11. [INFO] --- exec-maven-plugin:1.2.1:java (default-cli) @ echo-client ---
    12. [WARNING]
    13. java.lang.reflect.InvocationTargetException
    14.     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    15.     at sun.reflect.NativeMethodAccessorImpl.invoke
    16.     (NativeMethodAccessorImpl.java:57)
    17.     at sun.reflect.DelegatingMethodAccessorImpl.invoke
    18.     (DelegatingMethodAccessorImpl.java:43)
    19.     at java.lang.reflect.Method.invoke(Method.java:606)
    20.     at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:297)
    21.     at java.lang.Thread.run(Thread.java:744)
    22.     Caused by: java.net.ConnectException: Connection refused:
    23.     no further information: localhost/127.0.0.1:9999
    24.     at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    25.     at sun.nio.ch.SocketChannelImpl.finishConnect
    26.     (SocketChannelImpl.java:739)
    27.     at io.netty.channel.socket.nio.NioSocketChannel
    28.     .doFinishConnect(NioSocketChannel.java:191)
    29.     at io.netty.channel.nio.
    30.     AbstractNioChannel$AbstractNioUnsafe.finishConnect(
    31.     AbstractNioChannel.java:279)
    32.     at io.netty.channel.nio.NioEventLoop
    33.     .processSelectedKey(NioEventLoop.java:511)
    34.     at io.netty.channel.nio.NioEventLoop
    35.     .processSelectedKeysOptimized(NioEventLoop.java:461)
    36.     at io.netty.channel.nio.NioEventLoop
    37.     .processSelectedKeys(NioEventLoop.java:378)
    38.     at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:350)
    39.     at io.netty.util.concurrent
    40.     .SingleThreadEventExecutor$2.run
    41.     (SingleThreadEventExecutor.java:101)
    42.     ... 1 more
    43. [INFO] --------------------------------------------------------------------
    44. [INFO] BUILD FAILURE
    45. [INFO] --------------------------------------------------------------------
    46. [INFO] Total time: 3.728 s
    47. [INFO] Finished at: 2014-06-08T18:49:13-05:00
    48. [INFO] Final Memory: 8M/245M
    49. [INFO] --------------------------------------------------------------------
    50. [ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:java
    51.     (default-cli) on project echo-client: An exception occured while executing the
    52.     Java class. null: InvocationTargetException: Connection refused: no further
    53.     information:
    54.     localhost/127.0.0.1:9999 -> [Help 1]

    发生了啥？客户端尝试连接服务器，但服务器是关闭的，所以引发了一个 java.net.ConnectException ，这个异常被 EchoClientHandler 的 exceptionCaught() 触发，打印出异常信息，并关闭 channel