Overview of how IOC in spring and spring dependency injection works using annotations

1. Constructor Injection
2. Setter Injection
3. Field Injection - also covers @Qualifiers

In general, when using Annotations, for the default bean name, Spring uses the following rule.

If the annotation's value doesn't indicate a bean name, an appropriate name will be built based on the short name of the class (with the first letter lower-cased).

For example:

AccountInterest --> accountInterest 

However, for the special case of when BOTH the first and second characters of the class name are upper case, then the name is NOT converted.

For the case of ACCOUNTInterest

ACCOUNTInterest --> ACCOUNTInterest 

No conversion since the first two characters are upper case. Behind the scenes, Spring uses the Java Beans Introspector to generate the default bean name. Also, here's a link to the documentation.

• https://docs.oracle.com/javase/8/docs/api/java/beans/Introspector.html#decapitalize(java.lang.String)

As always, you can give explicity names to your beans.

@Component("foo") 

1. Create a properties file to hold your properties. It will be a name value pair.
   New text file: src/bank.properties

foo.name=HSBC foo.branch=East London 

2. Load the properties file in the XML config file. File: applicationContext.xml Add the following lines:

<context:property-placeholder location="classpath:bank.properties"/> 

This should appear just after the <context:component-scan .../> line

3. Inject the properties values into your class

@Value("${foo.name}") private String name; @Value("${foo.branch}") private String branch; 

https://repo.spring.io/release/org/springframework/spring/

1. Choose the latest stable release "*-dist.zip".
2. Copy all the jar files under lib folder from the downloaded zip.
3. Create a new folder name lib under your working directory.
4. Paste those jar files under lib folder.
5. Add classpath to your eclipse project.
6. Right click on your "Project" >> "Properties" >> "Java Build Path" >> "Libraries" tab >> Click "Add JARs" >> "Select all the JAR files from you lib folder" >> "Apply and Close".
7. Now there will be a "Referenced Libraries" folder which will have your all spring JAR files.
8. Done

Right click on your project >> Run As >> Java Application