Java spi profile generated automatically using google autoservice

spi is a standard service discovery, for the development, we usually need to write META-INF/servicesa file folder defined in the class.
google auto in autoservice can help us generate the corresponding configuration, it is convenient

Preparing the Environment

• Project structure

 

├── pom. xml

└── src

    ├── main

    │ ├── java

    │ │ └── with

    │ │ └── dalong

    │ │ ├── sleeps

    │ │ │ └── TranslationService.java

    │ │ └── spimpl

    │ │ ├── BingTranslationServiceProvider.java

    │ │ └── GoogleTranslationServiceProvider.java

    │ └── resources

    └── test

        └── java

            └── with

                └── dalong

                    └── SPITestClass.java

• Code Description
  conventions:
  SPI interfaces defined in TranslationService.java
  BingTranslationServiceProvider.java to implement the interface and GoogleTranslationServiceProvider.java
  pom.xml file

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <properties>

        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

        <encoding>UTF-8</encoding>

        <java.version>1.8</java.version>

        <maven.compiler.source>1.8</maven.compiler.source>

        <maven.compiler.target>1.8</maven.compiler.target>

        <auto-service.version>1.0-rc6</auto-service.version>

    </properties>

    <groupId>com.dalong.appdemo</groupId>

    <artifactId>first</artifactId>

    <version>1.0-SNAPSHOT</version>

​

<dependencies>

    <dependency>

        <groupId>com.google.auto.service</groupId>

        <artifactId>auto-service-annotations</artifactId>

        <version>${auto-service.version}</version>

        <optional>true</optional>

        <scope>compile</scope>

    </dependency>

        <dependency>

            <groupId>com.google.auto.service</groupId>

            <artifactId>auto-service</artifactId>

            <version>${auto-service.version}</version>

            <optional>true</optional>

            <scope>compile</scope>

        </dependency>

    <dependency>

        <groupId>junit</groupId>

        <artifactId>junit</artifactId>

        <version>4.8</version>

        <scope>test</scope>

    </dependency>

​

</dependencies>

    <build>

        <plugins>

            <plugin>

                <groupId>org.apache.maven.plugins</groupId>

                <artifactId>maven-site-plugin</artifactId>

                <version>3.7</version>

                <dependencies>

                    <dependency>

                        <groupId>org.apache.maven.doxia</groupId>

                        <artifactId>doxia-site-renderer</artifactId>

                        <version>1.8</version>

                    </dependency>

                </dependencies>

            </plugin>

            <plugin>

                <groupId>org.apache.maven.plugins</groupId>

                <artifactId>maven-compiler-plugin</artifactId>

                <version>3.8.1</version>

                <configuration>

                    <annotationProcessorPaths>

                        <path>

                            <groupId>com.google.auto.service</groupId>

                            <artifactId>auto-service</artifactId>

                            <version>${auto-service.version}</version>

                        </path>

                    </annotationProcessorPaths>

                </configuration>

            </plugin>

        </plugins>

    </build>

</project>

 

Interface Definition:
TranslationService.java

 

package com.dalong.spi;

​

import java. useful. local;

​

public interface TranslationService {

    String translate(String message, Locale from, Locale to);

}

 

Realization:
BingTranslationServiceProvider.java and GoogleTranslationServiceProvider.java

 

package com.dalong.spimpl;

​

import com.dalong.spi.TranslationService;

import com.google.auto.service.AutoService;

​

import java. useful. local;

@AutoService(TranslationService.class)

public class BingTranslationServiceProvider implements TranslationService {

    @Override

    public String translate(String message, Locale from, Locale to) {

        return "bing";

    }

}

​package com.dalong.spimpl;

​

import com.dalong.spi.TranslationService;

import com.google.auto.service.AutoService;

​

import java. useful. local;

@AutoService(TranslationService.class)

public class GoogleTranslationServiceProvider implements TranslationService {

    @Override

    public String translate(String message, Locale from, Locale to) {

        return "google";

    }

}

​

 

 

Construction of packing

mvn  clean  package

effect

 

 

 

test

• Code

package com.dalong;

​

import com.dalong.spi.TranslationService;

import com.sun.prism.shader.AlphaOne_Color_AlphaTest_Loader;

import org.junit.Test;

​

import java. useful. local;

import java.util.ServiceLoader;

import java.util.function.Consumer;

import java.util.stream.StreamSupport;

​

import static org.junit.Assert.assertEquals;

​

public class SPITestClass {

    @Test

    public void myTestForSPI(){

        ServiceLoader<TranslationService> loader = ServiceLoader.load(TranslationService.class);

        long count = StreamSupport.stream(loader.spliterator(), false).count();

​

        loader.forEach(new Consumer<TranslationService>() {

            @Override

            public void accept(TranslationService translationService) {

                Locale localeFrom = new Locale("en");

                Locale localeFo = new Locale("zh");

                String message = translationService.translate("app", localeFrom,localeFo);

                System.out.println(message);

            }

        });

        assertEquals(2, count);

    }

}

 

Explanation

Based on spi we can develop more flexible modular system, and can be easily inserted and removed processing module

Reference material

https://github.com/google/auto/tree/master/service
https://www.jianshu.com/p/46b42f7f593c