我听说了很多关于Spring的事情,人们在网上说Spring是一个很好的web开发框架。简而言之,Spring框架到底是用来干什么的?为什么我要用它而不是纯Java。
当前回答
我认为这有两部分:
"What exactly is Spring for" -> see the accepted answer by victor hugo. "[...] Spring is [a] good framework for web development" -> people saying this are talking about Spring MVC. Spring MVC is one of the many parts of Spring, and is a web framework making use of the general features of Spring, like dependency injection. It's a pretty generic framework in that it is very configurable: you can use different db layers (Hibernate, iBatis, plain JDBC), different view layers (JSP, Velocity, Freemarker...)
注意,不使用Spring MVC,你也可以在web应用程序中很好地使用Spring。我想说,大多数Java web应用程序都这样做,同时使用其他web框架,如Wicket, Struts, Seam,…
其他回答
Spring非常适合将类实例粘合在一起。你知道你的Hibernate类总是需要一个数据源,Spring将它们连接在一起(也有一个数据源的实现)。
数据访问对象总是需要Hibernate访问,Spring将Hibernate类连接到dao中。
此外,Spring基本上为您提供了一系列库的可靠配置,并指导您应该使用哪些库。
Spring真的是一个很棒的工具。(我说的不是Spring MVC,只是基本框架)。
春天有三样东西。
Spring handles Dependency Injection and I recommend you read Martin Fowler's excellent introduction on dependency injection. The second thing Spring does is wrap excellent Java libraries in a very elegant way to use in your applications. For a good example see how Spring wraps Task Executors and Quartz Scheduler. Thirdly Spring provides a bunch of implementations of web stuff like REST, an MVC web framework and more. They figure since you are using Spring for the first two, maybe you can just use it for everything your web app needs.
The problem is that Spring DI is really well thought out, the wrappers around other things are really well thought out in that the other things thought everything out and Spring just nicely wraps it. The Spring implementations of MVC and REST and all the other stuff is not as well done (YMMV, IMHO) but there are exceptions (Spring Security is da bomb). So I tend to use Spring for DI, and its cool wrappers but prefer other stuff for Web (I like Tapestry a lot), REST (Jersey is really robust), etc.
我认为这有两部分:
"What exactly is Spring for" -> see the accepted answer by victor hugo. "[...] Spring is [a] good framework for web development" -> people saying this are talking about Spring MVC. Spring MVC is one of the many parts of Spring, and is a web framework making use of the general features of Spring, like dependency injection. It's a pretty generic framework in that it is very configurable: you can use different db layers (Hibernate, iBatis, plain JDBC), different view layers (JSP, Velocity, Freemarker...)
注意,不使用Spring MVC,你也可以在web应用程序中很好地使用Spring。我想说,大多数Java web应用程序都这样做,同时使用其他web框架,如Wicket, Struts, Seam,…
简而言之,我认为Spring是应用程序中的“粘合剂”。它用于集成不同的框架和您自己的代码。
公认的答案不涉及注释的使用,因为Spring为配置引入了对各种注释的支持。
Spring注释方法(依赖注入)
还有另一种使用XML文件连接类的方法:注释。让我们使用接受的答案中的示例,并使用@Component、@Service、@Repository或@Configuration注释之一直接在类上注册bean:
@Component
public class UserListerDB implements UserLister {
public List<User> getUsers() {
// DB access code here
}
}
这样,当视图创建时,它将神奇地有一个UserLister准备工作。
上面的语句是有效的,它不需要使用任何XML文件,并使用另一个注释@Autowired来查找相关的实现并将其注入其中。
@Autowired
private UserLister userLister;
在用于获取要注入的bean实现的方法上使用@Bean注释。
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