Java 8 在java8中，如何仅使用自定义代码定义函数？

我想发送两种电子邮件，一些逻辑可以共享。e、 g

try {
    MimeMessage msg = javaMailService.createMimeMessage();
    MimeMessageHelper helper = new MimeMessageHelper(msg, true, DEFAULT_ENCODING);
    //custom code here ...
} catch (MessagingException e) {
    logger.error("build email fail", e);
} catch (Exception e) {
    logger.error("send email fail", e);
}

上面是通用代码（例如sendEmail（函数customCode）），下面是向foo发送电子邮件的自定义代码

logger.info("send count mail to {}", toFoo);
helper.setFrom(sender);
helper.setTo(toFoo);
helper.setSubject("Foo Subject");
String content = generateFooContent(foo); //use fooTemplate.ftl
helper.setText(content, true);
javaMailService.send(msg);

我想这样说,

Function fooFunc = ()->{logger.info("send count mail to {}", toFoo);
    helper.setFrom(sender);
    helper.setTo(toFoo);
    helper.setSubject("Foo");
    String content = generateFooContent(foo);
    helper.setText(content, true);
    javaMailService.send(msg);}

然后调用

sendmail

方法

sendEmail(fooFunc);

如果我想发送酒吧信息

Function barFunc = ()->{...} //cunstom code here
sendEmail(barFunc);

在java8中可以实现这一点吗？如果可以，如何实现？

您的“函数”有一个签名：

void doStuff(MimeMessageHelper helper)

我们已经有了其中一个——它被称为

消费者

因此：

---

请注意我的格式。

谢谢@Boris the Spider，它确实有效，请参见下文

private void sendFooHtmlMessage(List<Foo> body) {
    BiConsumer<MimeMessage,MimeMessageHelper> fooFunc = (msg,helper) -> {
        logger.info("send foo mail to {}", toFoo);
        try {
            helper.setTo(toFoo);
            helper.setSubject("Foo Subject");
            String content = generateFooContent(body);
            helper.setText(content, true);
            javaMailService.send(msg);
        } catch (Exception e) {
        }
    };
    sendMessage(fooFunc);
}

private void sendMessage(BiConsumer<MimeMessage,MimeMessageHelper> consumer) {
    try {
        final MimeMessage msg = javaMailService.createMimeMessage();
        final MimeMessageHelper helper = new MimeMessageHelper(msg, true, DEFAULT_ENCODING);
        helper.setFrom(sender);
        consumer.accept(msg, helper);
    } catch (MessagingException e) {
        logger.error("build email failed", e);
    } catch (Exception e) {
        logger.error("send email failed", e);
    }
}

public interface SendMessageAction {
    void action(MimeMessage msg, MimeMessageHelper helper) throws MessagingException;
}

private void sendMessage(SendMessageAction action) {
    //...
}

private void sendFooHtmlMessage(List<Foo> body) {
    SendMessageAction fooAction = (msg, helper) -> {
        logger.info("send foo mail to {}", toFoo);
        //...
    };
    sendMessage(fooAction);
}

---

谢谢但还有一个问题，请看我下面的帖子。首先，将你的答案改写为完整答案，而不是引用我答案的评论。第二，如果你打算使用你自己的功能界面；使用

@functioninterface

对其进行注释。第三，请参阅我的答案-在参数中不需要

消息

，只需在回调中填充消息，然后用公共代码发送消息。

private void sendFooHtmlMessage(List<Foo> body) {
    BiConsumer<MimeMessage,MimeMessageHelper> fooFunc = (msg,helper) -> {
        logger.info("send foo mail to {}", toFoo);
        try {
            helper.setTo(toFoo);
            helper.setSubject("Foo Subject");
            String content = generateFooContent(body);
            helper.setText(content, true);
            javaMailService.send(msg);
        } catch (Exception e) {
        }
    };
    sendMessage(fooFunc);
}

private void sendMessage(BiConsumer<MimeMessage,MimeMessageHelper> consumer) {
    try {
        final MimeMessage msg = javaMailService.createMimeMessage();
        final MimeMessageHelper helper = new MimeMessageHelper(msg, true, DEFAULT_ENCODING);
        helper.setFrom(sender);
        consumer.accept(msg, helper);
    } catch (MessagingException e) {
        logger.error("build email failed", e);
    } catch (Exception e) {
        logger.error("send email failed", e);
    }
}

public interface SendMessageAction {
    void action(MimeMessage msg, MimeMessageHelper helper) throws MessagingException;
}

private void sendMessage(SendMessageAction action) {
    //...
}

private void sendFooHtmlMessage(List<Foo> body) {
    SendMessageAction fooAction = (msg, helper) -> {
        logger.info("send foo mail to {}", toFoo);
        //...
    };
    sendMessage(fooAction);
}