过去，我从纯技术的角度考虑Spring框架。

根据一些团队工作和开发企业web应用程序的经验，我会说Spring通过解耦各个元素(bean)来实现更快的应用程序(web应用程序)开发。更快的发展使它如此受欢迎。Spring允许将构建(连接)应用程序的责任转移到Spring框架上。Spring框架的依赖注入负责将单个bean连接/连接到工作应用程序中。

这样，一旦定义了bean之间的接口，开发人员就可以更专注于单个组件(bean)的开发。

测试这样的应用程序很容易——主要的关注点是单个bean。它们可以很容易地解耦和模拟，因此单元测试是快速和有效的。

Spring框架定义了多个专门的bean，如@Controller (@Restcontroller)、@Repository、@Component来服务于web目的。Spring和Maven一起提供了一个对开发人员来说很直观的结构。 团队工作简单快捷，因为单独的元素是分开的，可以重复使用。

Spring一开始是依赖注入，然后为几乎所有的东西添加了包装之王(JPA实现的包装等)。

说来话长……Spring的大多数部分更倾向于XML解决方案(XML脚本引擎…brrrr)，所以对于DI，我使用Guice

很好的库，但是随着依赖性的增长，例如Spring JDBC(可能是一个具有实名参数的Java JDBC解决方案)将从maven 4-5继承。

使用Spring MVC(“big Spring”的一部分)进行web开发…它是“基于请求的”框架，有“请求vs组件”的圣战…由你决定

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。

Spring是Enterprise JavaBeans (EJB)技术的一个很好的替代方案。它还具有web框架和web服务框架组件。

其优点是依赖注入(DI)。这意味着将对象创建任务外包出去。让我用一个例子来解释。

public interface Lunch
{
   public void eat();
}

public class Buffet implements Lunch
{
   public void eat()
   {
      // Eat as much as you can 
   }
}

public class Plated implements Lunch
{
   public void eat()
   {
      // Eat a limited portion
   }
}

现在在我的代码中，我有一个类LunchDecide，如下所示:

public class LunchDecide {
    private Lunch todaysLunch;
    public LunchDecide(){
        this.todaysLunch = new Buffet(); // choose Buffet -> eat as much as you want
        //this.todaysLunch = new Plated(); // choose Plated -> eat a limited portion 
    }
}

在上面的类中，根据心情选择Buffet()或Plated()。但是这个系统是紧密耦合的。每次需要不同类型的对象时，我们都需要更改代码。在本例中，注释掉一行!假设有50个不同的人使用50个不同的类。那会是一团乱麻。在这种情况下，我们需要解耦系统。让我们重写LunchDecide类。

public class LunchDecide {
    private Lunch todaysLunch;
    public LunchDecide(Lunch todaysLunch){
        this.todaysLunch = todaysLunch
        }
    }

Notice that instead of creating an object using new keyword we passed the reference to an object of Lunch Type as a parameter to our constructor. Here, object creation is outsourced. This code can be wired either using Xml config file (legacy) or Java Annotations (modern). Either way, the decision on which Type of object would be created would be done there during runtime. An object would be injected by Xml into our code - Our Code is dependent on Xml for that job. Hence, Dependency Injection (DI). DI not only helps in making our system loosely coupled, it simplifies writing of Unit tests since it allows dependencies to be mocked. Last but not the least, DI streamlines Aspect Oriented Programming (AOP) which leads to further decoupling and increase of modularity. Also note that above DI is Constructor Injection. DI can be done by Setter Injection as well - same plain old setter method from encapsulation.

你可能想在一个web应用程序中使用Spring -

Spring MVC, which with 2.5+ allows you to use POJOs as Controller classes, meaning you don't have to extend from any particular framework (as in Struts or Spring pre-2.5). Controller classes are also dead simple to test thanks in part to dependency injection Spring integration with Hibernate, which does a good job of simplifying work with that ORM solution (for most cases) Using Spring for a web app enables you to use your Domain Objects at all levels of the application - the same classes that are mapped using Hibernate are the classes you use as "form beans." By nature, this will lead to a more robust domain model, in part because it's going to cut down on the number of classes. Spring form tags make it easier to create forms without much hassle.

此外，Spring是巨大的——所以在web应用程序中使用很多其他的东西你可能会感兴趣，比如Spring AOP或Spring Security。但上面列出的四件事描述了Spring在web应用程序中使用的常见组件。