Spring Boot: Tutorials

Online resources for learning Spring Boot

`Baeldung.com`

The site Baeldung.com has many tutorials related to Spring and Spring Boot.

Many of these have their source code in one giant repo that can be found here:

https://github.com/eugenp/tutorials

However, beware! There are a few things you should know about that repo.

It may appear that each of the subdirectories has stand-alone code for a single tutorial. That’s not strictly true. There are some things that the code in each of those subdirectories depends on that are in the giant mega-repo.

So, it isn’t as simple as just copying that one directory into another and expecting the code to work.

So, what do you need?

In addition to the subdirectory, e.g. spring-boot-crud for example, you need these files:

The pom.xml from the top level directory. This contains a <parent> that is referred to by many of the other pom.xml files
You may need a directory such as parent-boot-2, in its entirety, if that pom.xml of the subdirectory that you are using (e.g. spring-boot-crud) refers to a <parent> element in that directory.

For example, the pom.xml in spring-boot-crud has this <parent> element:
```
 <parent>
      <artifactId>parent-boot-2</artifactId>
      <groupId>com.baeldung</groupId>
      <version>0.0.1-SNAPSHOT</version>
      <relativePath>../parent-boot-2</relativePath>
  </parent>
```
That refers to ../parent-boot-2, so you need that entire subdirectory inside your repo, as a sibling of spring-boot-crud.

But wait, there’s more…
You may find that the pom.xml in, for example, ../parent-boot-2, refers to a <parent> element such as this one:
```
  <parent>
      <groupId>com.baeldung</groupId>
      <artifactId>parent-modules</artifactId>
      <version>1.0.0-SNAPSHOT</version>
  </parent>
```
That one happens to be defined in the pom.xml at the top level of the repo. So you need that pom.xml, plus the two subdirectories: the tutorial you are interested in, and the one that defines it’s parent.

But there is still more!
You may need some other files. I found that I needed these for spring-boot-crud
- The entire custom-pmd subdirectory
- The file custom-pmd-0.0.1.jar (this one you may have to commit with git add -f since .jar is in the .gitignore or should be.)
- baeldung-pmd-rules.xml.
What is this pmd stuff? Glad you asked. It appears to be a source code analyzer, as explained in this article on PMD. As explained there, “PMD is a source code analyzer to find common programming flaws like unused variables, empty catch blocks, unnecessary object creation, and so forth.” My guess is that the custom-pmd-0.0.1.jar is enforcing some custom source control rules that Baeldung.com has for their organization’s code.

mkyong

There is another giant repo of spring boot tutorials here:

https://github.com/mkyong/spring-boot.git

It has the same property as the baedlung.com tutorials, that all of them are in one giant repo.

I was successful at running the spring-data-jpa-postgres tutorial described here on a Mac running Postgres by making this change in application.properties:

Comment out:

#spring.datasource.url=jdbc:postgresql://192.168.1.4:5432/postgres

Add:

spring.datasource.url=jdbc:postgresql://localhost:5432/postgres