The core idea of Spring Framework is elaborated to build elegant and concise Java applications
1. Introduction
Spring Framework is an open source Java development framework that provides a series of underlying architectures and patterns to help Java developers simplify the development process of enterprise-level applications.
Advantages of Spring Framework :
Spring Framework has a powerful implementation of core ideas such as inversion of control (IoC) and aspect-oriented programming (AOP). It provides a modular architecture that allows Java developers to more easily complete a series of general-purpose , Development of reusable components and services.
2. The core idea of Spring Framework
Inversion of Control (IoC)
Inversion of Control (IoC) is a design pattern implemented by handing over the creation and management of objects to the container. The advantage of this is that the application decouples the dependencies between modules and makes it easier to maintain and expand.
The concept of IoC
In traditional object-oriented programming, the dependencies between modules are usually directly created in the code itself, which will lead to a high degree of coupling of the code and make it difficult to maintain and expand. Inversion of Control (IoC) solves this problem by handing over the dependencies between modules to the container for management. The advantage of this is that the dependencies between modules are completely decoupled, making the code more concise, easy to maintain and expand.
The way IoC is implemented
There are two main ways for Spring Framework to implement IoC: Setter method injection and constructor injection.
Setter method injection
The Setter method is the get and set method of JavaBean. By defining the setter method for the property of the Bean, when the container instantiates the Bean, it will dynamically inject the dependent Bean into the place where it needs to be used through the Setter method.
public class MyClass {
private Dependency dependency;
// 定义Setter方法
public void setDependency(Dependency dependency) {
this.dependency = dependency;
}
...
}
constructor injection
Constructor injection is another IoC implementation, which completes the creation of dependencies by passing in the dependencies of Beans through the constructor.
public class MyClass {
private Dependency dependency;
// 定义构造方法
public MyClass(Dependency dependency) {
this.dependency = dependency;
}
...
}
Aspect Oriented Programming (AOP)
Aspect-Oriented Programming (AOP) is a programming paradigm that helps developers solve problems through horizontal aspects without interfering with existing code.
The concept of AOP
In traditional object-oriented programming, the functions of a software system are usually dispersed in many different objects, and the objects cooperate with each other, resulting in many "cross-cutting" concerns, such as logging, performance monitoring, or access control. Such concerns are not suitable for integration into the core logic of the object, and will also lead to code duplication and inefficiency. AOP realizes the hierarchical design and modular development of the system by abstracting these "cross-cutting" concerns into aspects (Aspect).
Application scenarios of AOP
AOP can achieve some general requirements, such as logging, performance monitoring, or permission control, by intercepting and enhancing methods without changing the existing functional code.
Annotation Driven
Annotation-driven is a programming method provided by Spring Framework, which provides a convenient way to describe the dependencies and roles of Beans and other components, so as to realize the core ideas such as IoC and AOP.
The concept of annotation
Annotation is an annotation mechanism that can provide additional information for the code, so that you can add the required business logic to your code through custom annotations.
Annotations in Spring Framework
Spring Framework provides a variety of annotations, such as @Controller, @Autowired, @Bean, etc., which are used to describe some basic information of Bean, and then realize the core ideas such as IoC and AOP.
3. Build elegant and concise Java applications
1. Dependency Injection
The concept of dependency injection
Dependency injection is an object creation method in which the dependencies required by the created object are passed through constructors, properties, or factory methods, rather than created by the created object. This process can be realized by Inversion of Control (IoC).
Advantages of Dependency Injection
Dependency injection has the following advantages:
- Easy to maintain: No hard-coded dependencies are required, reducing the complexity of creating objects and enhancing code readability.
- Ease of testing: Mock objects can be used instead of real dependencies for better test isolation and test scope control.
- More flexible: Dependencies can be dynamically modified and replaced, which enhances the flexibility of the code.
In addition, there is an elegant and clean code style, without writing a lot of repetitive code.
2. Spring MVC Framework
Introduction to Spring MVC framework
The Spring MVC framework is an MVC (Model-View-Controller)-based web framework that distributes requests to appropriate controllers (Controllers), models (Models) and views (Views) to achieve complex web applications. Maintainability and scalability.
Advantages of the Spring MVC framework
The Spring MVC framework has the following advantages:
- Clear layered structure: Web applications are divided into models, views, and controllers, and these layers have clear responsibilities and tasks, thereby reducing coupling and improving maintainability and scalability.
- Application of dependency injection: The Spring MVC framework uses dependency injection (Dependency Injection, DI) to achieve loose coupling between layers, improving the readability and testability of the code.
- Strong scalability: By using plug-ins and extensions, the Spring MVC framework can easily adapt to new business needs and can be integrated with other frameworks and technologies.
3. Spring Boot framework
Introduction to Spring Boot Framework
The Spring Boot framework is a quick way to build an elegant and concise Spring application. It can quickly build an application for production, and can achieve some common application requirements with minimal configuration and code costs, such as embedded Tomcat container, auto-configuration and more.
Advantages of the Spring Boot framework
The Spring Boot framework has the following advantages:
- Quick start: The Spring Boot framework starts very quickly, and you only need to write a minimum amount of configuration and code to build an out-of-the-box production application.
- Automatic configuration: The Spring Boot framework can automatically configure most application features, such as embedded Tomcat containers, persistence mechanisms, web frameworks, security frameworks, and more. Therefore, you only need to focus on the business logic.
- Application monitoring: The Spring Boot framework can automatically inject some common configurations, components, and plug-ins into the application, such as health checks, indicator monitoring, logging, and more.
4. Summary and review
1. Advantages of the core idea of Spring Framework
The advantages of the core ideas of the Spring Framework include:
- Loosely coupled: Use inversion of control (IoC) and dependency injection (DI) to decouple loosely coupled objects.
- More flexible: Through aspect-oriented programming (AOP), annotation-driven programming, etc., some programming requirements can be handled more flexibly.
- Rich support: Spring Framework provides a series of frameworks and class libraries, which can quickly realize efficient Java application development.
2. The actual application effect of Spring Framework in Java applications
As a modern Java framework, Spring Framework has a good application effect in actual application development and testing. For example, Spring Framework can play a higher value in the development of enterprise-level Java applications, Web applications, mobile applications, and cloud services.