使用 Spring Boot 启动器的更好方法

Question

I found two way of adding dependencies for spring boot rest service application.

Method 1 :

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
    </dependency>

Method 2:

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

Both method given above does the same job? Any difference in performance?

Thanks in advance

Answer 1

The difference between these methods is that spring-boot-starter-web contains more dependencies than just spring-boot-starter and spring-web .

For the version 1.5.8.RELEASE it will be:

• spring-boot-starter
• spring-boot-starter-tomcat
• hibernate-validator
• jackson-databind
• spring-web
• spring-webmvc

All other stuff depends on your requirements. For instance, if you're developing commercial product you must check all included transitive dependencies for their licenses.

The general advice is to use only features you need. Don't forget that you still can depend on top level artifact excluding not required parts using Maven feature.

At for the performance boost, basically it should not be that much. The difference is only if the Spring (with top-level artifact dependency) will load and auto configure some features which are not practically used in your code (during the classpath scanning). The startup time could be slightly increased by the same reason.

Hope it helps!

Answer 2

Obviously second approach is better ie using springboot starter pom.

Reasons I say that for are as follows:-

1. It allows zero configuration or auto configuration ie most of the web related settings would be given to you by default. eg by default tomcat server would be integrated, springboot dependencies would be added for you, automatic registration of converter and other web related dependencies etc. See this link.

2. You could take advantage of easy override ie if tomorrow you want to use jetty in place of tomcat just add the jetty dependency and it's configurations and now you could use jetty.

3. Your pom.xml would be neater and more readable as less no. of dependencies are put inside it and picked from starter poms.

4. Easy compatibility management. By default spring-boot picks up the version of starter parent . Hence, you could rest assured that all compatible dependencies would be downloaded as part of mvn dependencies and if you specifically want to upgrade any of those you could. But this gives advantage of upgrading to compatible dependencies by just changing the version of springboot starter parent(Note: You could use dependency management as well in place of starter parent pom. See this link).

Performance wise there would be a trade-off as springboot by default downloads more dependencies than minimum required initially. But over the time as application starts becoming mature most of these dependencies are used anyways.