Spring Boot makes it easy to create Spring-powered, production-grade applications and services with absolute minimum fuss. It takes an opinionated view of the Spring platform so that new and existing users can quickly get to the bits they need.
You can use Spring Boot to create stand-alone Java applications that can be started using
java -jar or more traditional WAR deployments. We also provide a command line tool
that runs spring scripts.
Our primary goals are:
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Provide a radically faster and widely accessible getting started experience for all Spring development
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Be opinionated out of the box, but get out of the way quickly as requirements start to diverge from the defaults
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Provide a range of non-functional features that are common to large classes of projects (e.g. embedded servers, security, metrics, health checks, externalized configuration)
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Absolutely no code generation and no requirement for XML configuration
The reference documentation includes detailed
installation
instructions as well as a comprehensive
getting started
guide.
Here is a quick teaser of a complete Spring Boot application in Java:
import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.*;
import org.springframework.web.bind.annotation.*;
@RestController
@SpringBootApplication
public class Example {
@RequestMapping("/")
String home() {
return "Hello World!";
}
public static void main(String[] args) {
SpringApplication.run(Example.class, args);
}
}Having trouble with Spring Boot? We’d like to help!
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Check the reference documentation, especially the How-to’s — they provide solutions to the most common questions.
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Learn the Spring basics — Spring Boot builds on many other Spring projects, check the spring.io web-site for a wealth of reference documentation. If you are just starting out with Spring, try one of the guides.
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If you are upgrading, read the release notes for upgrade instructions and "new and noteworthy" features.
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Ask a question - we monitor stackoverflow.com for questions tagged with
spring-boot. You can also chat with the community on Gitter. -
Report bugs with Spring Boot at github.com/spring-projects/spring-boot/issues.
Spring Boot uses GitHub’s integrated issue tracking system to record bugs and feature requests. If you want to raise an issue, please follow the recommendations below:
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Before you log a bug, please search the issue tracker to see if someone has already reported the problem.
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If the issue doesn’t already exist, create a new issue.
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Please provide as much information as possible with the issue report, we like to know the version of Spring Boot that you are using, as well as your Operating System and JVM version.
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If you need to paste code, or include a stack trace use Markdown ``` escapes before and after your text.
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If possible try to create a test-case or project that replicates the problem and attach it to the issue.
You don’t need to build from source to use Spring Boot (binaries in repo.spring.io), but if you want to try out the latest and greatest, Spring Boot can be easily built with the maven wrapper. You also need JDK 1.8.
$ ./mvnw clean install
If you want to build with the regular mvn command, you will need
Maven v3.5.0 or above.
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Note
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You may need to increase the amount of memory available to Maven by setting
a MAVEN_OPTS environment variable with the value -Xmx512m. Remember
to set the corresponding property in your IDE as well if you are building and running
tests there (e.g. in Eclipse go to Preferences→Java→Installed JREs and edit the
JRE definition so that all processes are launched with those arguments). This property
is automatically set if you use the maven wrapper.
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Also see CONTRIBUTING.adoc if you wish to submit pull requests, and in particular please fill out the Contributor’s Agreement before your first change, however trivial.
First of all, make sure you have built the project:
$ ./mvnw clean install
The reference documentation requires the documentation of the Maven plugin to be available so you need to build that first since it’s not generated by default.
$ ./mvnw clean install -pl spring-boot-project/spring-boot-tools/spring-boot-maven-plugin -Pdefault,full
The documentation also includes auto-generated information about the starters. You might have that in your local repository already (per the first step) but if you want to refresh it:
$ ./mvnw clean install -f spring-boot-project/spring-boot-starters
Once this is done, you can build the reference documentation with the command below:
$ ./mvnw clean prepare-package -pl spring-boot-project/spring-boot-docs -Pdefault,full
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Tip
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The generated documentation is available from spring-boot-project/spring-boot-docs/target/generated-docs/reference/html
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There are a number of modules in Spring Boot, here is a quick overview:
The main library providing features that support the other parts of Spring Boot, these include:
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The
SpringApplicationclass, providing static convenience methods that make it easy to write a stand-alone Spring Application. Its sole job is to create and refresh an appropriate SpringApplicationContext -
Embedded web applications with a choice of container (Tomcat, Jetty or Undertow)
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First class externalized configuration support
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Convenience
ApplicationContextinitializers, including support for sensible logging defaults
Spring Boot can configure large parts of common applications based on the content
of their classpath. A single @EnableAutoConfiguration annotation triggers
auto-configuration of the Spring context.
Auto-configuration attempts to deduce which beans a user might need. For example, if
HSQLDB is on the classpath, and the user has not configured any database connections,
then they probably want an in-memory database to be defined. Auto-configuration will
always back away as the user starts to define their own beans.
Starters are a set of convenient dependency descriptors that you can include in
your application. You get a one-stop-shop for all the Spring and related technology
that you need without having to hunt through sample code and copy paste loads of
dependency descriptors. For example, if you want to get started using Spring and JPA for
database access just include the spring-boot-starter-data-jpa dependency in your
project, and you are good to go.
The Spring command line application compiles and runs Groovy source, making it super easy to write the absolute minimum of code to get an application running. Spring CLI can also watch files, automatically recompiling and restarting when they change.
Actuator endpoints let you monitor and interact with your application.
Spring Boot Actuator provides the infrastructure required for actuator endpoints. It contains
annotation support for actuator endpoints. Out of the box, this module provides a number of endpoints
including the HealthEndpoint, EnvironmentEndpoint, BeansEndpoint and many more.
This provides auto-configuration for actuator endpoints based on the content of the classpath and a set of properties.
For instance, if Micrometer is on the classpath, it will auto-configure the MetricsEndpoint.
It contains configuration to expose endpoints over HTTP or JMX.
Just like Spring Boot AutoConfigure, this will back away as the user starts to define their own beans.
This module contains core items and annotations that can be helpful when testing your application.
Like other Spring Boot auto-configuration modules, spring-boot-test-autoconfigure, provides auto-configuration for tests based on the classpath. It includes a number of annotations that can be used to automatically configure a slice of your application that needs to be tested.
Groovy samples for use with the command line application are available in
spring-boot-cli/samples. To run the CLI samples type
spring run <sample>.groovy from samples directory.
The spring.io site contains several guides that show how to use Spring Boot step-by-step:
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Building an Application with Spring Boot is a very basic guide that shows you how to create a simple application, run it and add some management services.
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Building a RESTful Web Service with Spring Boot Actuator is a guide to creating a REST web service and also shows how the server can be configured.
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Converting a Spring Boot JAR Application to a WAR shows you how to run applications in a web server as a WAR file.
Spring Boot is Open Source software released under the Apache 2.0 license.