Java 如何使用设计模式代替开关盒
我有枚举类Java 如何使用设计模式代替开关盒,java,design-patterns,enums,switch-statement,Java,Design Patterns,Enums,Switch Statement,我有枚举类 public enum TaskName { LOGIN,REGISTER,MESSAGE } 我将此枚举与开关大小写一起使用 public class TaskController { private UserDao userDaoJpaImpl; private FriendDao friendDaoJpaImpl; private GroupDao groupDaoJpaImpl; private MessageDao messa
public enum TaskName {
LOGIN,REGISTER,MESSAGE
}
我将此枚举与开关大小写一起使用
public class TaskController {
private UserDao userDaoJpaImpl;
private FriendDao friendDaoJpaImpl;
private GroupDao groupDaoJpaImpl;
private MessageDao messageDaoJpaImpl;
public TaskController() {
EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("Eclipselink_JPA");
userDaoJpaImpl = new UserDaoJpaImpl(emfactory);
friendDaoJpaImpl = new FriendDaoJpaImpl(emfactory);
groupDaoJpaImpl = new GroupDaoJpaImpl(emfactory);
messageDaoJpaImpl = new MessageDaoJpaImpl(emfactory);
}
public void doIt(String taskName)
{
switch (taskName) {
case LOGIN:
userDaoJpaImpl.create(/*Something*/);
//Implementation
break;
case REGISTER:
//Implementation
break;
case MESSAGE:
messageDaoJpaImpl.create(/*Something*/);
//Implementation
break;
}
}
}
我将TaskController的对象创建为
静态TaskController=new TaskController()
所以这个对象只创建了一次
现在我计划用命令模式代替开关盒
public class TaskController {
private UserDao userDaoJpaImpl;
private FriendDao friendDaoJpaImpl;
private GroupDao groupDaoJpaImpl;
private MessageDao messageDaoJpaImpl;
public TaskController() {
EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("Eclipselink_JPA");
userDaoJpaImpl = new UserDaoJpaImpl(emfactory);
friendDaoJpaImpl = new FriendDaoJpaImpl(emfactory);
groupDaoJpaImpl = new GroupDaoJpaImpl(emfactory);
messageDaoJpaImpl = new MessageDaoJpaImpl(emfactory);
}
public void doIt(String taskName)
{
switch (taskName) {
case LOGIN:
userDaoJpaImpl.create(/*Something*/);
//Implementation
break;
case REGISTER:
//Implementation
break;
case MESSAGE:
messageDaoJpaImpl.create(/*Something*/);
//Implementation
break;
}
}
}
但是我被困在了如何在命令类中使用我的UserDaoJpaImpl、friendaojpaimpl、GroupDaoJpaImpl、MessageDaoJpaImpl
编辑
命令类
public interface Command {
void setSession(Session session); //Session is websocket connection session not HttpSession
void setConnectedUser(Map<String, UserDTO> connectedUser);
void setData(String data);
JSONObject execute();
}
公共接口命令{
void setSession(会话会话);//会话是websocket连接会话而不是HttpSession
void setConnectedUser(映射connectedUser);
void setData(字符串数据);
JSONObject execute();
}
我想将整个逻辑从TaskController.doIt()移动到另一个将实现命令接口的命令类
我正在使用Websocket。我不想用弹簧来解决这个问题
提前感谢您正在寻找我对这个问题的解决方案 本质上
public enum TaskName {
LOGIN {
@Override
public void doIt(TaskController taskController) {
taskController.getUserDao().create(/*something*/);
//...
}
},
REGISTER {
@Override
public void doIt(TaskController taskController) {
//Implementation
}
},
MESSAGE {
@Override
public void doIt(TaskController taskController) {
taskController.getMessageDao().create(/*something*/);
//...
}
};
private TaskName() {
}
public abstract void doIt(TaskController taskController);
public static TaskName getByTaskName(String taskName) {
for(TaskName taskEnum : TaskName.values()) {
if(taskEnum.name().equalsIgnoreCase(taskName)) {
return taskEnum;
}
}
throw new IllegalArgumentException("The Task Name [" + taskName + "] is not a valid task name!");
}
}
public class TaskController {
private UserDao userDaoJpaImpl;
private FriendDao friendDaoJpaImpl;
private GroupDao groupDaoJpaImpl;
private MessageDao messageDaoJpaImpl;
public TaskController() {
EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("Eclipselink_JPA");
userDaoJpaImpl = new UserDaoJpaImpl(emfactory);
friendDaoJpaImpl = new FriendDaoJpaImpl(emfactory);
groupDaoJpaImpl = new GroupDaoJpaImpl(emfactory);
messageDaoJpaImpl = new MessageDaoJpaImpl(emfactory);
}
public void doIt(String taskName) {
TaskName.getByTaskName(taskName).doIt(this);
}
}
除非我完全误解了你的问题,因为你从来没有真正展示过你的命令
类
你也应该考虑使用一个框架来解决这个问题,比如<强> Spring框架
< p>你在寻找我的这个问题的解决方案。 本质上public enum TaskName {
LOGIN {
@Override
public void doIt(TaskController taskController) {
taskController.getUserDao().create(/*something*/);
//...
}
},
REGISTER {
@Override
public void doIt(TaskController taskController) {
//Implementation
}
},
MESSAGE {
@Override
public void doIt(TaskController taskController) {
taskController.getMessageDao().create(/*something*/);
//...
}
};
private TaskName() {
}
public abstract void doIt(TaskController taskController);
public static TaskName getByTaskName(String taskName) {
for(TaskName taskEnum : TaskName.values()) {
if(taskEnum.name().equalsIgnoreCase(taskName)) {
return taskEnum;
}
}
throw new IllegalArgumentException("The Task Name [" + taskName + "] is not a valid task name!");
}
}
public class TaskController {
private UserDao userDaoJpaImpl;
private FriendDao friendDaoJpaImpl;
private GroupDao groupDaoJpaImpl;
private MessageDao messageDaoJpaImpl;
public TaskController() {
EntityManagerFactory emfactory = Persistence.createEntityManagerFactory("Eclipselink_JPA");
userDaoJpaImpl = new UserDaoJpaImpl(emfactory);
friendDaoJpaImpl = new FriendDaoJpaImpl(emfactory);
groupDaoJpaImpl = new GroupDaoJpaImpl(emfactory);
messageDaoJpaImpl = new MessageDaoJpaImpl(emfactory);
}
public void doIt(String taskName) {
TaskName.getByTaskName(taskName).doIt(this);
}
}
除非我完全误解了你的问题,因为你从来没有真正展示过你的命令
类
你也应该考虑使用一个框架来解决这个问题,比如<强> Spring框架< /强> ./P> < P>保持这个问题有点模糊和主观给了我们想象的自由:这是我对结构的看法
public interface Command {
public void doIt(EntityManagerFactory emFactory);
}
class LoginCommand implements Command {
@Override public void doIt(EntityManagerFactory emFactory) {
UserDaoJpaImpl userDaoJpaImpl = new UserDaoJpaImpl(emFactory);
// Do something
}
}
class RegisterCommand implements Command {
@Override public void doIt(EntityManagerFactory emFactory) {
}
}
class MessageCommand implements Command {
@Override public void doIt(EntityManagerFactory emFactory) {
}
}
enum TaskName {
LOGIN(new LoginCommand()), REGISTER(new RegisterCommand()), MESSAGE(new MessageCommand());
private Command command;
TaskName(Command command) {
this.command = command;
}
public void doIt(EntityManagerFactory emFactory) {
command.doIt(emFactory);
}
}
public class TaskController {
private EntityManagerFactory emFactory = Persistence.createEntityManagerFactory("Eclipselink_JPA");
public void doIt(String taskName) {
TaskName task = TaskName.valueOf(taskName);
task.doIt(emFactory);
}
}
所有的方法都被称为
doIt
,当然它们也会改变。保持问题的模糊性和主观性让我们可以自由想象:)。这是我对结构的看法
public interface Command {
public void doIt(EntityManagerFactory emFactory);
}
class LoginCommand implements Command {
@Override public void doIt(EntityManagerFactory emFactory) {
UserDaoJpaImpl userDaoJpaImpl = new UserDaoJpaImpl(emFactory);
// Do something
}
}
class RegisterCommand implements Command {
@Override public void doIt(EntityManagerFactory emFactory) {
}
}
class MessageCommand implements Command {
@Override public void doIt(EntityManagerFactory emFactory) {
}
}
enum TaskName {
LOGIN(new LoginCommand()), REGISTER(new RegisterCommand()), MESSAGE(new MessageCommand());
private Command command;
TaskName(Command command) {
this.command = command;
}
public void doIt(EntityManagerFactory emFactory) {
command.doIt(emFactory);
}
}
public class TaskController {
private EntityManagerFactory emFactory = Persistence.createEntityManagerFactory("Eclipselink_JPA");
public void doIt(String taskName) {
TaskName task = TaskName.valueOf(taskName);
task.doIt(emFactory);
}
}
所有的方法都被称为
doIt
,当然它们也会改变。与@epicPandaForce的想法相同,但在Java8中,处理方法可能会有所不同。通过将lambda传递给构造函数
public enum TaskName {
LOGIN((taskController) -> {
taskController.getUserDao().create(/*something*/);
//...
}),
REGISTER((taskController) -> {
//Implementation
}),
MESSAGE((taskController) -> {
//...
});
private final Consumer<TaskController> doIt;
private TaskName(Consumer<TaskController> doIt) {
this.doIt = doIt;
}
public final void service(...) {
doIt(...);
}
公共枚举任务名{
登录((任务控制器)->{
taskController.getUserDao().create(/*something*/);
//...
}),
寄存器((任务控制器)->{
//实施
}),
消息((任务控制器)->{
//...
});
私人最终消费者doIt;
私有任务名(使用者doIt){
this.doIt=doIt;
}
公共最终作废服务(…){
doIt(…);
}
与@epicPandaForce的思想相同,但在java 8中,它的处理方式可能有点不同
public enum TaskName {
LOGIN((taskController) -> {
taskController.getUserDao().create(/*something*/);
//...
}),
REGISTER((taskController) -> {
//Implementation
}),
MESSAGE((taskController) -> {
//...
});
private final Consumer<TaskController> doIt;
private TaskName(Consumer<TaskController> doIt) {
this.doIt = doIt;
}
public final void service(...) {
doIt(...);
}
公共枚举任务名{
登录((任务控制器)->{
taskController.getUserDao().create(/*something*/);
//...
}),
寄存器((任务控制器)->{
//实施
}),
消息((任务控制器)->{
//...
});
私人最终消费者doIt;
私有任务名(使用者doIt){
this.doIt=doIt;
}
公共最终作废服务(…){
doIt(…);
}
公共接口命令{
公共无效执行();
}
公共类调用程序{
私有映射commandMap=newenummap(TaskName.class);
public void AddCommand(TaskName任务,Command命令){
commandMap.put(任务、命令);
}
public void HandleCommand(TaskName任务){
Command=commandMap.get(任务);
command.Execute();
}
}
公共类ConcreteMessageCommand实现该命令{
私有消息dao消息daojpaimpl;
公共消息命令(messagedaomd){
messageDaoJpaImpl=md;
}
@凌驾
public void Execute(){
//TODO自动生成的方法存根
messageDaoJpaImpl.create();
}
}
公共类ConcreteUserCommand实现该命令{
私有UserDao userDaoJpaImpl;
公共用户命令(userdaoud){
userDaoJpaImpl=ud;
}
@凌驾
public void Execute(){
userDaoJpaImpl.create();
}
}
公共类任务控制器{
调用者调用者;
公共任务控制器(){
EntityManagerFactory emfactory=Persistence.createEntityManagerFactory(“Eclipselink_JPA”);
invoker=newinvoker();
ConcreteUserCommand cuc=新ConcreteUserCommand(新用户DAOJPAIMPL(emfactory));
AddCommand(TaskName.LOGIN,cuc);
ConcreteMessageCommand cmc=new-ConcreteMessageCommand(new-MessageDaoJpaImpl(emfactory));
invoker.AddCommand(TaskName.MESSAGE,cmc);
}
public void doIt(TaskName TaskName)
{
invoker.HandleCommand(taskName);
}
}
公共班机{
公共静态void main(字符串[]args){
//TODO自动生成的方法存根
TaskController任务=新建TaskController();
task.doIt(TaskName.LOGIN);
}
}
您可以使用命令模式来消除这样的切换情况,GroupDaoJpaImpl-MessageDaoJpaImpl可以被视为接收方对象。您可以更改对象的创建位置以优化代码。公共接口命令{
公共无效执行();
}
公共类调用程序{
私有映射commandMap=newenummap(TaskName.class);
public void AddCommand(TaskName任务,Command命令){
commandMap.put(任务、命令);
}
public void HandleCommand(TaskName任务){
Command=commandMap.get(任务);
command.Execute();
}
}
公共类ConcreteMessageCommand实现该命令{
私有消息dao消息daojpaimpl;
公共消息命令(messagedaomd){
messageDaoJpaImpl=md;
}
@凌驾
public void Execute(){
//TODO自动生成的方法存根
messageDaoJpaImpl.create();
}
}
公共类ConcreteUserCommand实现该命令{
私有UserDao userDaoJpaImpl;
P