Spring Retrieve Beans by Interface and Type

Table of Contents

Spring: get all Beans of certain interface AND type

Introduction:

Spring is a powerful framework for building Java applications.

It provides the concept of Beans, which are managed objects that follow the Inversion of Control principle.

Overview:

In Spring, Beans can be defined in various ways, such as using XML configuration, Java configuration, or component scanning.

Sometimes, there is a need to retrieve all Beans that implement a certain interface and are of a specific type.

Problem:

The challenge is to get a collection of all Beans that implement a specific interface and are of a particular type without having to manually iterate through all Beans.

Solution:

One way to accomplish this in Spring is by using the ApplicationContext interface along with the getBeansOfType() method.

By providing the interface class and the desired type, you can retrieve all Beans that match the criteria.

Here is an example:


@Autowired
private ApplicationContext applicationContext;

Map<String, MyInterface> myBeans = applicationContext.getBeansOfType(MyInterface.class);

List<MyType> myTypeBeans = myBeans.values().stream()
        .filter(bean -> bean instanceof MyType)
        .map(bean -> (MyType) bean)
        .collect(Collectors.toList());

In this example, myBeans is a map containing all Beans that implement MyInterface.

Then, we filter the Beans to include only those that are of type MyType.

By using the ApplicationContext and getBeansOfType() method, you can easily retrieve all Beans of a specific interface and type in your Spring application.

Key points to address:

– Identify and retrieve all Beans that implement a specific interface in a Spring application
– Find and retrieve all Beans of a specific type in a Spring application

Explain the Core Concept:

In Spring, to get all beans of a certain interface and type, you can use the ApplicationContext to retrieve all beans that implement a specific interface and have a specific type.

This can be achieved by using the ApplicationContext’s `getBeansOfType` method and specifying the interface and type of the beans you want to retrieve.

This method will return a map of bean names and corresponding bean instances that match the specified interface and type.

Different Solutions with code samples:


// Using ApplicationContext to get all beans of a certain interface
Map<String, MyInterface> beans = context.getBeansOfType(MyInterface.class);

// Using Stream API to filter beans of a certain type
Map<String, Object> allBeans = context.getBeansOfType(Object.class);
Map<String, MyInterface> myInterfaceBeans = allBeans.entrySet().stream()
        .filter(e -> MyInterface.class.isAssignableFrom(e.getValue().getClass()))
        .collect(Collectors.toMap(Map.Entry::getKey, e -> (MyInterface) e.getValue()));