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Updated on 2025-04-12

Spring Boot: How to implement custom configuration when the convention is greater than the configuration

Spring Boot Convention is greater than configuration: Implement custom configuration

introduction

Spring Boot is a fast development framework based on the Spring framework. One of its core concepts is"Agreement is greater than configuration". This means that Spring Boot provides many default configurations, and developers only need to focus on their own business logic without manually configuring a lot of details. However, in some cases, we may need to customize the configuration to meet specific needs. This article will explain how to implement custom configuration in Spring Boot, through implementation of interfaces and additions@ConfigurationAnnotation to complete this process.

1. Spring Boot's conventions are greater than configuration

Spring Boot's concept of "conventions are greater than configuration" is reflected in the following aspects:

  • Automatic configuration: Spring Boot automatically configures applications based on project dependencies. For example, if the project has been introducedspring-boot-starter-web, Spring Boot will automatically configure Tomcat and Spring MVC.
  • Default configuration: Spring Boot provides many default configurations, such as the default port number is8080The default static resource path isclasspath:/staticwait.
  • Simplify configuration:passorFiles, developers can easily override the default configuration.

This design greatly reduces the configuration workload of developers, allowing developers to focus more on the implementation of business logic.

2. Requirements for custom configuration

Although Spring Boot provides many default configurations, in actual development we may need to customize some configurations. For example:

  • Customize the loading order of the beans.
  • Customize the initialization logic for certain components.
  • Dynamically load the configuration according to environment variables.

To achieve these requirements, Spring Boot provides flexible extension mechanisms that allow developers to customize configurations by implementing interfaces and adding annotations.

3. Steps to implement custom configuration

In Spring Boot, implementing custom configuration usually requires the following steps:

  • accomplishWebMvcConfigurerOr other related interfaces: Choose the appropriate interface according to your needs.
  • Add to@ConfigurationNote: Mark the custom configuration class as a Spring configuration class.
  • Rewrite interface method: Rewrite interface methods in configuration class to implement custom logic.

The following is a specific example to demonstrate how to implement custom configuration.

4. Example: Custom Spring MVC configuration

Suppose we need to customize the configuration of Spring MVC, such as adding an interceptor or modifying the static resource path. It can be achieved through the following steps:

4.1 Create a custom configuration class

First, create a class and implement itWebMvcConfigurerinterface.WebMvcConfigurerIs an interface provided by Spring MVC for customizing MVC configuration.

import ;
import ;
import ;
@Configuration // Mark as configuration classpublic class CustomWebMvcConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // Add a custom interceptor        (new CustomInterceptor())
                .addPathPatterns("/**"); // Intercept all requests    }
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        // Customize static resource path        ("/static/**")
                .addResourceLocations("classpath:/custom-static/");
    }
}

4.2 Create a custom interceptor

In the configuration class above, we have added a custom interceptor. The interceptor is implemented as follows:

import ;
import ;
import ;
import ;
@Component
public class CustomInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        ("CustomInterceptor: The request is intercepted");
        return true; // Continue to execute subsequent logic    }
}

4.3 Test custom configuration

After starting the Spring Boot application, access any path and the console will output itCustomInterceptor: The request is intercepted, indicating that the interceptor has taken effect. At the same time, the static resource path will also be mapped toclasspath:/custom-static/。

5. Other custom configuration scenarios

In addition to customizing Spring MVC configurations, Spring Boot supports many other custom configuration scenarios. Here are some common examples:

5.1 Customize data source configuration

By implementingDataSourceInitializerInterface, which can customize the initialization logic of the data source.

import ;
import ;
@Configuration
public class CustomDataSourceConfig {
    @Bean
    public DataSource dataSource() {
        // Customize data source configuration        return new HikariDataSource();
    }
}

5.2 Customize Spring Security Configuration

Through inheritanceWebSecurityConfigurerAdapterClass, you can customize Spring Security configuration.

import ;
import ;
import ;
@Configuration
@EnableWebSecurity
public class CustomSecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        ()
            .antMatchers("/public/**").permitAll()
            .anyRequest().authenticated();
    }
}

6. Summary

Spring Boot's concept of "conventions greater than configuration" greatly simplifies the development process, but in actual projects, we still need to customize the configuration according to our needs. By implementing relevant interfaces (e.g.WebMvcConfigurer) and add@ConfigurationAnnotation, developers can flexibly extend and customize Spring Boot's default behavior.

The core steps of custom configuration are as follows:

  • Select the right interface (such asWebMvcConfigurer）。
  • Create a configuration class and add@ConfigurationAnnotation.
  • Rewrite the interface method to implement custom logic.

I hope this article can help you better understand Spring Boot’s custom configuration mechanism and flexibly apply it in actual projects!

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