Java SPI Mechanism Usage Demo

① Building a MAVEN project

Contains the following directory structure:

Src/main/java

Src/main/resources

Src/test/java

Src/test/resources

② creating a new Meta-inf/services directory under the Src/main/resources directory

③ Create a new package in Src/main/java, and then create a new interface

For example

Package Com.liu.spi;public interface IA {void print ();}

④ several new implementation classes

For example:

Aiaimpl.java

Package Com.liu.spi;public class Aiaimpl implements IA {public void print () {System.out.println ("AIA");}}

Biaimpl.java

Package Com.liu.spi;public class Biaimpl implements ia{public void print () {System.out.println ("BIA");}}

Ciaimpl.java

Package Com.liu.spi;public class Ciaimpl implements IA {public void print () {System.out.println ("CIA");}}

⑤ Create a new file in the Src/main/resources/meta-inf/services directory named Com.liu.spi.IA (the full class name of the interface)

The file content is: The full class name of the interface implementation class (Must wrap)

Com.liu.spi.AIAImpl
Com.liu.spi.BIAImpl
Com.liu.spi.CIAImpl

Note: For comments, use "#" before the full class name

⑥ Writing test class Iatest.java

The code is as follows:

Package Com.liu.spi;import Java.util.iterator;import Java.util.serviceloader;public class Iatest {public static void Main (string[] args) {serviceloader<ia> Spiloader = Serviceloader.load (ia.class);          iterator<ia> iaiterator = Spiloader.iterator ();          while (Iaiterator.hasnext ()) {              iaiterator.next (). print ();}}  

⑦ printing results are as follows:

Java SPI Mechanism Usage Demo