@ -4,19 +4,20 @@
[partintro]
--
If you are getting started with Spring Boot, or "Spring" in general, start by reading
this section. It answers the basic "`what?`", "`how?`" and "`why?`" questions. It includes
an introduction to Spring Boot, along with installation instructions.
We then walk you through building your first Spring Boot application, discussing some core
this section. It answers the basic "`what?`", "`how?`" and "`why?`" questions. It
includes an introduction to Spring Boot, along with installation instructions. We then
walk you through building your first Spring Boot application, discussing some core
principles as we go.
--
[[getting-started-introducing-spring-boot]]
== Introducing Spring Boot
Spring Boot makes it easy to create stand-alone, production-grade Spring based
Applications that you can run. We take an opinionated view of the Spring
platform and third-party libraries, so that you can get started with minimum fuss. Most
Spring Boot applications need very little Spring configuration.
Applications that you can run. We take an opinionated view of the Spring platform and
third-party libraries, so that you can get started with minimum fuss. Most Spring Boot
applications need very little Spring configuration.
You can use Spring Boot to create Java applications that can be started by using
`java -jar` or more traditional war deployments. We also provide a command line tool that
@ -38,8 +39,9 @@ configuration).
[[getting-started-system-requirements]]
== System Requirements
Spring Boot {spring-boot-version} requires http://www.java.com[Java 8] and Spring
Framework {spring-version} or above. Explicit build support is provided for Maven
3.2+, and Gradle 4.
Framework {spring-version} or above. Explicit build support is provided for Maven 3.2+
and Gradle 4.
[[getting-started-system-requirements-servlet-containers]]
@ -74,8 +76,8 @@ begin, you should check your current Java installation by using the following co
$ java -version
----
If you are new to Java development or if you want to experiment with Spring Boot,
you might want to try the <<getting-started-installing-the-cli, Spring Boot CLI>> (Command
If you are new to Java development or if you want to experiment with Spring Boot, you
might want to try the <<getting-started-installing-the-cli, Spring Boot CLI>> (Command
Line Interface) first, otherwise, read on for "`classic`" installation instructions.
@ -85,28 +87,28 @@ Line Interface) first, otherwise, read on for "`classic`" installation instructi
You can use Spring Boot in the same way as any standard Java library. To do so, include
the appropriate `+spring-boot-*.jar+` files on your classpath. Spring Boot does not
require any special tools integration, so you can use any IDE or text editor. Also, there
is nothing special about a Spring Boot application, so you can run and debug a Spring Boot
application as you would any other Java program.
is nothing special about a Spring Boot application, so you can run and debug a Spring
Boot application as you would any other Java program.
Although you _could_ copy Spring Boot jars, we generally recommend that you use a
build tool that supports dependency management (such as Maven or Gradle).
Although you _could_ copy Spring Boot jars, we generally recommend that you use a build
tool that supports dependency management (such as Maven or Gradle).
[[getting-started-maven-installation]]
==== Maven Installation
Spring Boot is compatible with Apache Maven 3.2 or above. If you do not already have Maven
installed, you can follow the instructions at http://maven.apache.org.
Spring Boot is compatible with Apache Maven 3.2 or above. If you do not already have
Maven installed, you can follow the instructions at http://maven.apache.org.
TIP: On many operating systems, Maven can be installed with a package manager. If you
use OSX Homebrew, try `brew install maven`. Ubuntu users can run
TIP: On many operating systems, Maven can be installed with a package manager. If you use
OSX Homebrew, try `brew install maven`. Ubuntu users can run
`sudo apt-get install maven`. Windows users with Chocolatey can run `choco install maven`
from an elevated (administrator) prompt.
Spring Boot dependencies use the `org.springframework.boot` `groupId`. Typically, your
Maven POM file inherits from the `spring-boot-starter-parent` project and declares
dependencies to one or more <<using-spring-boot.adoc#using-boot-starter,
"`Starters`">>. Spring Boot also provides an optional
dependencies to one or more <<using-spring-boot.adoc#using-boot-starter,"`Starters`">>.
Spring Boot also provides an optional
<<build-tool-plugins.adoc#build-tool-plugins-maven-plugin, Maven plugin>> to create
executable jars.
@ -176,9 +178,9 @@ endif::[]
</project>
----
TIP: The `spring-boot-starter-parent` is a great way to use Spring Boot, but it might
not be suitable all of the time. Sometimes you may need to inherit from a different
parent POM, or you might not like our default settings. In those cases, see
TIP: The `spring-boot-starter-parent` is a great way to use Spring Boot, but it might not
be suitable all of the time. Sometimes you may need to inherit from a different parent
POM, or you might not like our default settings. In those cases, see
<<using-boot-maven-without-a-parent>> for an alternative solution that uses an `import`
scope.
@ -199,11 +201,11 @@ jars.
.Gradle Wrapper
****
The Gradle Wrapper provides a nice way of "`obtaining`" Gradle when you need to build a
project. It is a small script and library that you commit alongside your code to bootstrap
the build process. See {gradle-user-guide}/gradle_wrapper.html for details.
project. It is a small script and library that you commit alongside your code to
bootstrap the build process. See {gradle-user-guide}/gradle_wrapper.html for details.
****
Here i s a typical `build.gradle` file:
The following example show s a typical `build.gradle` file:
[source,groovy,indent=0,subs="verbatim,attributes"]
----
@ -257,8 +259,8 @@ The Spring Boot CLI (Command Line Interface) is a command line tool that you can
quickly prototype with Spring. It lets you run http://groovy-lang.org/[Groovy] scripts,
which means that you have a familiar Java-like syntax without so much boilerplate code.
You do not need to use the CLI to work with Spring Boot, but it is definitely the quickest
way to get a Spring application off the ground.
You do not need to use the CLI to work with Spring Boot, but it is definitely the
quickest way to get a Spring application off the ground.
@ -269,10 +271,12 @@ You can download the Spring CLI distribution from the Spring software repository
* http://repo.spring.io/{spring-boot-repo}/org/springframework/boot/spring-boot-cli/{spring-boot-version}/spring-boot-cli-{spring-boot-version}-bin.zip[spring-boot-cli-{spring-boot-version}-bin.zip]
* http://repo.spring.io/{spring-boot-repo}/org/springframework/boot/spring-boot-cli/{spring-boot-version}/spring-boot-cli-{spring-boot-version}-bin.tar.gz[spring-boot-cli-{spring-boot-version}-bin.tar.gz]
Cutting edge http://repo.spring.io/snapshot/org/springframework/boot/spring-boot-cli/[snapshot
Cutting edge
http://repo.spring.io/snapshot/org/springframework/boot/spring-boot-cli/[snapshot
distributions] are also available.
Once downloaded, follow the {github-raw}/spring-boot-project/spring-boot-cli/src/main/content/INSTALL.txt[INSTALL.txt]
Once downloaded, follow the
{github-raw}/spring-boot-project/spring-boot-cli/src/main/content/INSTALL.txt[INSTALL.txt]
instructions from the unpacked archive. In summary, there is a `spring` script
(`spring.bat` for Windows) in a `bin/` directory in the `.zip` file. Alternatively, you
can use `java -jar` with the `.jar` file (the script helps you to be sure that the
@ -282,9 +286,10 @@ classpath is set correctly).
[[getting-started-sdkman-cli-installation]]
==== Installation with SDKMAN!
SDKMAN! (The Software Development Kit Manager) can be used for managing multiple versions of
various binary SDKs, including Groovy and the Spring Boot CLI.
Get SDKMAN! from http://sdkman.io and install Spring Boot by using the following commands:
SDKMAN! (The Software Development Kit Manager) can be used for managing multiple versions
of various binary SDKs, including Groovy and the Spring Boot CLI.
Get SDKMAN! from http://sdkman.io and install Spring Boot by using the following
commands:
[indent=0,subs="verbatim,quotes,attributes"]
----
@ -293,8 +298,8 @@ Get SDKMAN! from http://sdkman.io and install Spring Boot by using the following
Spring Boot v{spring-boot-version}
----
If you are developing features for the CLI and want easy access to the version you
built, use the following commands:
If you are developing features for the CLI and want easy access to the version you built,
use the following commands:
[indent=0,subs="verbatim,quotes,attributes"]
----
@ -304,9 +309,9 @@ built, use the following commands:
Spring CLI v{spring-boot-version}
----
The preceding instructions install a local instance of `spring` called the `dev` instance.
It points at your target build location, so every time you rebuild Spring
Boot, `spring` is up-to-date.
The preceding instructions install a local instance of `spring` called the `dev`
instance. It points at your target build location, so every time you rebuild Spring Boot,
`spring` is up-to-date.
You can see it by running the following command:
@ -331,8 +336,8 @@ You can see it by running the following command:
[[getting-started-homebrew-cli-installation]]
==== OSX Homebrew Installation
If you are on a Mac and use http://brew.sh/[Homebrew], you can install
the Spring Boot CLI by using the following commands:
If you are on a Mac and use http://brew.sh/[Homebrew], you can install the Spring Boot
CLI by using the following commands:
[indent=0]
----
@ -342,15 +347,15 @@ the Spring Boot CLI by using the following commands:
Homebrew installs `spring` to `/usr/local/bin`.
NOTE: If you do not see the formula, your installation of brew might be out-of-date.
In that case, run `brew update` and try again.
NOTE: If you do not see the formula, your installation of brew might be out-of-date. In
that case, run `brew update` and try again.
[[getting-started-macports-cli-installation]]
==== MacPorts Installation
If you are on a Mac and use http://www.macports.org/[MacPorts], you can
install the Spring Boot CLI by using the following command:
If you are on a Mac and use http://www.macports.org/[MacPorts], you can install the
Spring Boot CLI by using the following command:
[indent=0]
----
@ -361,8 +366,8 @@ install the Spring Boot CLI by using the following command:
[[getting-started-cli-command-line-completion]]
==== Command-line Completion
The Spring Boot CLI includes scripts that provide command completion for
the http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29[BASH] and
The Spring Boot CLI includes scripts that provide command completion for the
http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29[BASH] and
http://en.wikipedia.org/wiki/Zsh[zsh] shells. You can `source` the script (also named
`spring`) in any shell or put it in your personal or system-wide bash completion
initialization. On a Debian system, the system-wide scripts are in
@ -384,8 +389,8 @@ completion scripts are automatically registered with your shell.
[[getting-started-cli-example]]
==== Quick-start Spring CLI Example
You can use the following web application to test your installation. To start, create
a file called `app.groovy`, as follows:
You can use the following web application to test your installation. To start, create a
file called `app.groovy`, as follows:
[source,groovy,indent=0,subs="verbatim,quotes,attributes"]
----
@ -407,8 +412,8 @@ Then run it from a shell, as follows:
$ spring run app.groovy
----
NOTE: The first run of your application is slow, as dependencies are
downloaded. Subsequent runs are much quicker.
NOTE: The first run of your application is slow, as dependencies are downloaded.
Subsequent runs are much quicker.
Open http://localhost:8080 in your favorite web browser. You should see the following
output:
@ -423,13 +428,13 @@ output:
[[getting-started-upgrading-from-an-earlier-version]]
=== Upgrading from an Earlier Version of Spring Boot
If you are upgrading from an earlier release of Spring Boot check the "`release notes`"
hosted on the {github-wiki}[project wiki]. You'll find upgrade instructions along with
a list of "`new and noteworthy`" features for each release.
hosted on the {github-wiki}[project wiki]. You'll find upgrade instructions along with a
list of "`new and noteworthy`" features for each release.
To upgrade an existing CLI installation use the appropriate package manager command
(for example `brew upgrade`) or, if you manually installed the CLI, follow the
<<getting-started-manual-cli-installation, standard instructions>> remembering to
update your `PATH` environment variable to remove any older references.
To upgrade an existing CLI installation use the appropriate package manager command (for
example, `brew upgrade`) or, if you manually installed the CLI, follow the
<<getting-started-manual-cli-installation, standard instructions>> remembering to update
your `PATH` environment variable to remove any older references.
@ -441,14 +446,15 @@ most IDEs support it.
[TIP]
====
The http://spring.io[spring.io] web site contains many "`Getting Started`" http://spring.io/guides[guides]
that use Spring Boot. If you need to solve a specific problem, check there first.
The http://spring.io[spring.io] web site contains many "`Getting Started`"
http://spring.io/guides[guides] that use Spring Boot. If you need to solve a specific
problem, check there first.
You can shortcut the steps below by going to https://start.spring.io and choosing the
"Web" starter from the dependencies searcher. Doing so generates a new
project structure so that you can <<getting-started-first-application-code,start coding
right away>>. Check the https://github.com/spring-io/initializr[Spring Initializr
documentation] for more details.
"Web" starter from the dependencies searcher. Doing so generates a new project structure
so that you can <<getting-started-first-application-code,start coding right away>>. Check
the https://github.com/spring-io/initializr[Spring Initializr documentation] for more
details.
====
Before we begin, open a terminal and run the following commands to ensure that you have
@ -477,8 +483,8 @@ that you have created a suitable folder and that it is your "`current directory`
[[getting-started-first-application-pom]]
=== Creating the POM
We need to start by creating a Maven `pom.xml` file. The `pom.xml` is the recipe that
is used to build your project. Open your favorite text editor and add the following:
We need to start by creating a Maven `pom.xml` file. The `pom.xml` is the recipe that is
used to build your project. Open your favorite text editor and add the following:
[source,xml,indent=0,subs="verbatim,quotes,attributes"]
----
@ -526,29 +532,29 @@ endif::[]
</project>
----
The preceding listing should give you a working build. You can test it by running
`mvn package` (for now, you can ignore the "`jar will be empty - no content was marked for
The preceding listing should give you a working build. You can test it by running `mvn
package` (for now, you can ignore the "`jar will be empty - no content was marked for
inclusion!`" warning).
NOTE: At this point, you could import the project into an IDE (most modern Java IDEs
include built-in support for Maven). For simplicity, we continue to use a plain
text editor for this example.
include built-in support for Maven). For simplicity, we continue to use a plain text
editor for this example.
[[getting-started-first-application-dependencies]]
=== Adding Classpath Dependencies
Spring Boot provides a number of "`Starters`" that let you add jars to your
classpath. Our sample application has already used `spring-boot-starter-parent` in the
`parent` section of the POM. The `spring-boot-starter-parent` is a special starter
that provides useful Maven defaults. It also provides a
Spring Boot provides a number of "`Starters`" that let you add jars to your classpath.
Our sample application has already used `spring-boot-starter-parent` in the `parent`
section of the POM. The `spring-boot-starter-parent` is a special starter that provides
useful Maven defaults. It also provides a
<<using-spring-boot.adoc#using-boot-dependency-management,`dependency-management`>>
section so that you can omit `version` tags for "`blessed`" dependencies.
Other "`Starters`" provide dependencies that you are likely to need when
developing a specific type of application. Since we are developing a web application, we
add a `spring-boot-starter-web` dependency. Before that, we can look at what we
currently have by running the following command:
Other "`Starters`" provide dependencies that you are likely to need when developing a
specific type of application. Since we are developing a web application, we add a
`spring-boot-starter-web` dependency. Before that, we can look at what we currently have
by running the following command:
[indent=0]
----
@ -558,8 +564,8 @@ currently have by running the following command:
----
The `mvn dependency:tree` command prints a tree representation of your project
dependencies. You can see that `spring-boot-starter-parent` provides no
dependencies by itself. To add the necessary dependencies, edit your `pom.xml` and add the
dependencies. You can see that `spring-boot-starter-parent` provides no dependencies by
itself. To add the necessary dependencies, edit your `pom.xml` and add the
`spring-boot-starter-web` dependency immediately below the `parent` section:
[source,xml,indent=0,subs="verbatim,quotes,attributes"]
@ -572,8 +578,8 @@ dependencies by itself. To add the necessary dependencies, edit your `pom.xml` a
</dependencies>
----
If you run `mvn dependency:tree` again, you see that there are now a number of
additional dependencies, including the Tomcat web server and Spring Boot itself.
If you run `mvn dependency:tree` again, you see that there are now a number of additional
dependencies, including the Tomcat web server and Spring Boot itself.
@ -617,10 +623,10 @@ _stereotype_ annotation. It provides hints for people reading the code and for S
that the class plays a specific role. In this case, our class is a web `@Controller`, so
Spring considers it when handling incoming web requests.
The `@RequestMapping` annotation provides "`routing`" information. It tells Spring
that any HTTP request with the `/` path should be mapped to the `home` method. The
`@RestController` annotation tells Spring to render the resulting string directly
back to the caller.
The `@RequestMapping` annotation provides "`routing`" information. It tells Spring that
any HTTP request with the `/` path should be mapped to the `home` method. The
`@RestController` annotation tells Spring to render the resulting string directly back to
the caller.
TIP: The `@RestController` and `@RequestMapping` annotations are Spring MVC annotations.
(They are not specific to Spring Boot.) See the {spring-reference}web.html#mvc[MVC
@ -631,15 +637,15 @@ section] in the Spring Reference Documentation for more details.
[[getting-started-first-application-auto-configuration]]
==== The @EnableAutoConfiguration Annotation
The second class-level annotation is `@EnableAutoConfiguration`. This annotation tells
Spring Boot to "`guess`" how you want to configure Spring, based on the jar
dependencies that you have added. Since `spring-boot-starter-web` added Tomcat and
Spring MVC, the auto-configuration assumes that you are developing a web application
and sets up Spring accordingly.
Spring Boot to "`guess`" how you want to configure Spring, based on the jar dependencies
that you have added. Since `spring-boot-starter-web` added Tomcat and Spring MVC, the
auto-configuration assumes that you are developing a web application and sets up Spring
accordingly.
.Starters and Auto-Configuration
****
Auto-configuration is designed to work well with "`Starters`", but the two concepts
are not directly tied. You are free to pick-and- choose jar dependencies outside of the
Auto-configuration is designed to work well with "`Starters`", but the two concepts are
not directly tied. You are free to pick and choose jar dependencies outside of the
starters and Spring Boot still does its best to auto-configure your application.
****
@ -648,12 +654,12 @@ starters and Spring Boot still does its best to auto-configure your application.
[[getting-started-first-application-main-method]]
==== The "`main`" Method
The final part of our application is the `main` method. This is just a standard method
that follows the Java convention for an application entry point. Our main method delegates
to Spring Boot's `SpringApplication` class by calling `run`. `SpringApplication`
bootstraps our application, starting Spring, which, in turn, starts the auto-configured
Tomcat web server. We need to pass `Example.class` as an argument to the `run` method to
tell `SpringApplication` which is the primary Spring component. The `args` array is also
passed through to expose any command-line arguments.
that follows the Java convention for an application entry point. Our main method
delegates to Spring Boot's `SpringApplication` class by calling `run`.
`SpringApplication` bootstraps our application, starting Spring, which, in turn, starts
the auto-configured Tomcat web server. We need to pass `Example.class` as an argument to
the `run` method to tell `SpringApplication` which is the primary Spring component. The
`args` array is also passed through to expose any command-line arguments.
@ -705,10 +711,10 @@ Java does not provide a standard way to load nested jar files (jar files that ar
themselves contained within a jar). This can be problematic if you are looking to
distribute a self-contained application.
To solve this problem, many developers use "`uber`" jars. An uber jar packages
all the classes from all the application's dependencies into a single archive. The problem
with this approach is that it becomes hard to see which libraries are in your application.
It can also be problematic if the same filename is used (but with different content) in
To solve this problem, many developers use "`uber`" jars. An uber jar packages all the
classes from all the application's dependencies into a single archive. The problem with
this approach is that it becomes hard to see which libraries are in your application. It
can also be problematic if the same filename is used (but with different content) in
multiple jars.
Spring Boot takes a <<appendix-executable-jar-format.adoc#executable-jar, different
@ -730,9 +736,9 @@ To create an executable jar, we need to add the `spring-boot-maven-plugin` to ou
</build>
----
NOTE: The `spring-boot-starter-parent` POM includes `<executions>` configuration to
bind the `repackage` goal. If you do not use the parent POM, you need to declare
this configuration yourself. See the {spring-boot-maven-plugin-site}/usage.html[plugin
NOTE: The `spring-boot-starter-parent` POM includes `<executions>` configuration to bind
the `repackage` goal. If you do not use the parent POM, you need to declare this
configuration yourself. See the {spring-boot-maven-plugin-site}/usage.html[plugin
documentation] for details.
Save your `pom.xml` and run `mvn package` from the command line, as follows:
@ -757,16 +763,16 @@ Save your `pom.xml` and run `mvn package` from the command line, as follows:
----
If you look in the `target` directory, you should see `myproject-0.0.1-SNAPSHOT.jar`. The
file should be around 10 MB in size. If you want to peek inside, you can use `jar tvf`, as
follows:
file should be around 10 MB in size. If you want to peek inside, you can use `jar tvf`,
as follows:
[indent=0]
----
$ jar tvf target/myproject-0.0.1-SNAPSHOT.jar
----
You should also see a much smaller file named `myproject-0.0.1-SNAPSHOT.jar.original`
in the `target` directory. This is the original jar file that Maven created before it was
You should also see a much smaller file named `myproject-0.0.1-SNAPSHOT.jar.original` in
the `target` directory. This is the original jar file that Maven created before it was
repackaged by Spring Boot.
To run that application, use the `java -jar` command, as follows:
@ -794,17 +800,17 @@ As before, to exit the application, press `ctrl-c`.
[[getting-started-whats-next]]
== What to Read Next
Hopefully, this section provided some of the Spring Boot basics and got you
on your way to writing your own applications. If you are a task-oriented type of
developer, you might want to jump over to http://spring.io and check out some of the
http://spring.io/guides/[getting started] guides that solve specific
"`How do I do that with Spring?`" problems. We also have Spring Boot-specific
_<<howto.adoc#howto, How-to>>_ reference documentation.
Hopefully, this section provided some of the Spring Boot basics and got you on your way
to writing your own applications. If you are a task-oriented type of developer, you might
want to jump over to http://spring.io and check out some of the
http://spring.io/guides/[getting started] guides that solve specific "`How do I do that
with Spring?`" problems. We also have Spring Boot-specific
"`<<howto.adoc#howto, How-to>>`" reference documentation.
The http://github.com/{github-repo}[Spring Boot repository] also has a
{github-code}/spring-boot-samples[bunch of samples] you can run. The samples are
independent of the rest of the code (that is, you do not need to build the rest to run
or use the samples).
independent of the rest of the code (that is, you do not need to build the rest to run or
use the samples).
Otherwise, the next logical step is to read _<<using-spring-boot.adoc#using-boot>>_. If
you are really impatient, you could also jump ahead and read about
Jay Bryant
7 years ago
committed by
Phillip Webb