编写这个java代码最简洁/最好的方法是什么？

Question

我正在编写一个简单的分布式java rmi应用程序,我有一堆方法,每个方法都需要遍历客户端接口的映射,以便在这些接口上调用各种其他方法,如下所示:

public void methodX (arg1, arg2) {
  Iterator<String> itr = clients.keySet().iterator;
  while (itr.hasNext()) {
    String name = itr.next();
    if (!"mod".equals(name)) {
      try {
        clients.get(name).methodXX(arg1, arg2);
      } catch(RemoteException ex) {
        // do something
      }
    }
  }
}

public void methodY (arg1, arg2, arg3) {
  Iterator<String> itr = clients.keySet().iterator;
  while (itr.hasNext()) {
    String name = itr.next();
    if (!"mod".equals(name)) {
      try {
        clients.get(name).methodYY(arg1, arg2, arg3);
      } catch(RemoteException ex) {
        // do something
      }
    }
  }
}

现在我修改了这些,以便它们通过传递一个名为MESSAGE_TYPE的新参数来调用单个方法doAll,如下所示:

public void methodX (arg1, arg2) {
  doAll(MESSAGE_TYPE.METHODX, arg1, arg2, null);
}

public void methodY (arg1, arg2, arg3) {
  doAll(MESSAGE_TYPE_METHODY, arg1, arg2, arg3);
}

和doAll方法:

public void doAll(msg_type, arg1, arg2, arg3) {
 Iterator<String> itr = clients.keySet().iterator;
  while (itr.hasNext()) {
    String name = itr.next();
    if (!"mod".equals(name)) {
      try {
        switch(msg_type) {
          case METHODX:
            clients.get(name).methodXX(arg1, arg2);
            break;
          case METHODY:
            clients.get(name).methodYY(arg1, arg2, arg3);
            break;
        }
      } catch(RemoteException ex) {
        // do something
      }
    }
  }
}

现在有更多这样的方法,所以我的doAll方法需要一堆args,每个调用它的methodXX都会传递一堆空值.

我可以重写这个,这样更简洁吗？如果是这样,你能提供一个例子吗？

Answer 1

首先,我将使用增强的for循环,并按照条目中的建议迭代条目而不是键:

public void doAll(arg1, arg2, arg3) {
  for (Map.Entry<String,Client> entry : clients.entrySet()) {
    if (!"mod".equals(entry.getKey())) {
      try {
        switch(MESSAGE_TYPE) {
          case METHODX:
            entry.getValue().methodXX(arg1, arg2);
            break;
          case METHODY:
            entry.getValue().methodYY(arg1, arg2, arg3);
            break;
        }
      } catch(RemoteException ex) {
        // do something
      }
    }
  }
}

我想我会重构它以传递一个"动作"来调用每个客户端,并使用来自调用站点的匿名内部类:

public interface RemoteAction {
  public void execute(Client client) throws RemoteException;
}

public void doAll(RemoteAction action) {
  for (Map.Entry<String,Client> entry : clients.entrySet()) {
    if (!"mod".equals(entry.getKey())) {
      try {
        action.execute(entry.getValue());
      } catch(RemoteException ex) {
        // do something
      }
    }
  }
}

public void methodX (final arg1, final arg2) {
  doAll(new Action() {
    @Override public void execute(Client client) throws RemoteException {
      client.methodX(arg1, arg2);
    }
  });
}

public void methodY (final arg1, final arg2, final arg3) {
  doAll(new Action() {
    @Override public void execute(Client client) throws RemoteException {
      client.methodY(arg1, arg2, arg3);
    }
  });
}

它不像支持lambda表达式的语言那样好,但它比switch语句更好.