希望使用函数式编程来解决重复代码

Question

我有一些代码经常以相同的模式重复，我将其作为伪代码包含在下面。

我有许多方法具有相同的事务代码（见 A.），然后是 DB 代码，每种方法总是不同的（见 B.）。B处的代码需要在匿名类中执行。

public static Foo doMyDatabaseStuff(ApplicationContext context, WebSite webSite) {

    //A. Do a bunch of boilerplate Transaction stuff

    TransactionUtils transactionUtils = getTransactionUtils(context);

    Foo foo = (Foo) transactionUtils.execute(new TransactionCallback() {

        public Object doInTransaction(TransactionStatus ts) {

            //B. Do a bunch of use case specific DB stuff

            FooDao fooDao = (FooDao) context.getBean("FooDao");

            Foo foo = fooDao.create(webSite);

            {

                foo.setName("Administratoren");

                foo.setSite(webSite);

                //call a bunch of other setters

                fooDao.update(foo);

                return foo;

            }

        }

    });

    return foo;

}

我觉得这是函数式编程的完美候选者。我有一堆要执行的代码，但我想将它包装在其他一些函数中（即使用高阶函数）。

我天真地尝试使用 Function 接口产生了这个：

public Foo doMyDatabaseStuff(ApplicationContext context, WebSite webSite) {

    Function<ApplicationContext, Foo> func = new Function<ApplicationContext, Foo>() {

        public Foo apply(ApplicationContext context) {

            FooDao fooDao = (FooDao) context.getBean("FooDao");

            Foo foo = fooDao.create(webSite);

            {

                foo.setName("Administratoren");

                foo.setSite(webSite);

                //call a bunch of other setters

                fooDao.update(foo);

                return foo;

            }

        }

    };

    return DefaultContents.executeTransaciton(context, func);

}

我觉得这走错了路，因为

'executeTransaciton' 方法被锁定为使用 'Foo' 对象。我猜它应该返回Object。

函数泛型有点奇怪。我想从 doMyDatabaseStuff 方法（即封闭方法范围）的参数中传入我的所有变量，而不是通过apply(param)方法传入。

看起来我在样板代码中并没有节省那么多，我仍然需要将这个庞大的“函数”匿名类代码添加到每个方法中。

我在这里是在正确的轨道上吗？......还是完全偏离了？

Answer 1

如果所有不同的是您在 中所做的TransactionCallback，只需将TransactionCallback作为参数传递给执行“样板事务”的方法，然后执行TransactionUtils：private static Foo doMyDatabaseStuff(ApplicationContext context, WebSite webSite, TransactionCallback cb) {&nbsp; &nbsp; //A. Do a bunch of boilerplate Transaction stuff&nbsp; &nbsp; TransactionUtils transactionUtils = getTransactionUtils(context);&nbsp; &nbsp; return (Foo) transactionUtils.execute(cb);}并从您现有的方法调用此方法：public static Foo doMyDatabaseStuff(ApplicationContext context, WebSite webSite) {&nbsp; &nbsp; return doMyDatabaseStuff(context, webSite, new TransactionCallback() {&nbsp; &nbsp; &nbsp; &nbsp; public Object doInTransaction(TransactionStatus ts) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //B. Do a bunch of use case specific DB stuff&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; FooDao fooDao = (FooDao) context.getBean("FooDao");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Foo foo = fooDao.create(webSite);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foo.setName("Administratoren");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; foo.setSite(webSite);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //call a bunch of other setters&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; fooDao.update(foo);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return foo;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; });}