SpringBoot+SPI機(jī)制實(shí)現(xiàn)可插拔組件

更新時(shí)間：2026年01月28日 09:25:01 作者：Java編程愛好者

本文主要介紹了SpringBoot+SPI機(jī)制實(shí)現(xiàn)可插拔組件,文中通過示例代碼介紹的非常詳細(xì),對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值,需要的朋友們下面隨著小編來一起學(xué)習(xí)學(xué)習(xí)吧

什么是Java的SPI

Java SPI（‌Service Provider Interface）‌是一種服務(wù)提供界面，‌它是Java提供的一種服務(wù)發(fā)現(xiàn)和加載機(jī)制，‌允許開發(fā)者為接口定義多種實(shí)現(xiàn)，‌并在運(yùn)行時(shí)動(dòng)態(tài)地發(fā)現(xiàn)和加載這些實(shí)現(xiàn)。‌

Java SPI機(jī)制的核心在于它提供了一種方式，‌使得服務(wù)提供者可以根據(jù)SPI的約定，‌為某個(gè)接口提供具體的實(shí)現(xiàn)類。‌這些實(shí)現(xiàn)類被放置在特定的位置，‌如META-INF/services目錄下，‌并通過配置文件指定。‌當(dāng)需要使用這些服務(wù)時(shí)，‌Java運(yùn)行時(shí)環(huán)境能夠自動(dòng)掃描這些目錄，‌找到并加載相應(yīng)的實(shí)現(xiàn)類，‌從而實(shí)現(xiàn)服務(wù)的動(dòng)態(tài)發(fā)現(xiàn)和加載。‌

Java SPI的主要用途包括：‌

服務(wù)提供者可以在不修改業(yè)務(wù)代碼的情況下，‌為框架或庫提供擴(kuò)展點(diǎn)。‌
允許在運(yùn)行時(shí)動(dòng)態(tài)地插入或更換組件實(shí)現(xiàn)，‌鼓勵(lì)松耦合的設(shè)計(jì)原則。‌
允許第三方擴(kuò)展和替換核心庫中的組件，‌豐富了Java生態(tài)，‌為開發(fā)者提供了極大的靈活性。‌

在Java中，‌SPI被廣泛應(yīng)用于各種框架和庫的擴(kuò)展，‌如Servlet容器初始化、‌類型轉(zhuǎn)換、‌日志記錄等場景。‌通過SPI機(jī)制，‌Java應(yīng)用程序可以在不修改業(yè)務(wù)代碼的情況下，‌輕松地集成和使用第三方提供的服務(wù)實(shí)現(xiàn)，‌從而提高了軟件的可擴(kuò)展性和可維護(hù)性

SPI和API的區(qū)別

SPI和API的主要區(qū)別在于它們的定義方式、‌調(diào)用方式、‌靈活性、‌依賴關(guān)系以及用途。‌

定義方式：‌ API是由開發(fā)者主動(dòng)編寫并公開給其他開發(fā)者使用的，‌而SPI是由框架或庫提供方定義的接口，‌供第三方開發(fā)者實(shí)現(xiàn)。‌
調(diào)用方式：‌ API通過直接調(diào)用接口的方法來使用功能，‌而SPI是通過配置文件來指定具體的實(shí)現(xiàn)類，‌然后由框架或庫自動(dòng)加載和調(diào)用。‌
靈活性：‌ API的實(shí)現(xiàn)類必須在編譯時(shí)就確定，‌無法動(dòng)態(tài)替換；‌而SPI的實(shí)現(xiàn)類可以在運(yùn)行時(shí)根據(jù)配置文件的內(nèi)容進(jìn)行動(dòng)態(tài)加載和替換。‌
依賴關(guān)系：‌ API是被調(diào)用方依賴的，‌即應(yīng)用程序需要引入API所在的庫才能使用其功能；‌而SPI是調(diào)用方依賴的，‌即框架或庫需要引入第三方實(shí)現(xiàn)類的庫才能加載和調(diào)用。‌
用途：‌ API通常用于描述庫、‌框架、‌操作系統(tǒng)、‌服務(wù)等對外提供的編程接口，‌開發(fā)者通過API調(diào)用相應(yīng)的功能來實(shí)現(xiàn)自己的應(yīng)用程序。‌而SPI定義了一種插件式的架構(gòu)，‌允許開發(fā)者定義接口，‌并通過服務(wù)提供者來提供不同的實(shí)現(xiàn)，‌主要目的是允許系統(tǒng)在運(yùn)行時(shí)發(fā)現(xiàn)和加載具體的服務(wù)提供者，‌從而實(shí)現(xiàn)動(dòng)態(tài)擴(kuò)展和替換功能的能力。‌

綜上所述，‌API是一種規(guī)范，‌描述了如何與一個(gè)組件進(jìn)行交互；‌而SPI則是一種機(jī)制，‌用于動(dòng)態(tài)地發(fā)現(xiàn)和加載實(shí)現(xiàn)了特定接口的組件。‌

實(shí)現(xiàn)過程

0.目錄結(jié)構(gòu)

sa-auth 父工程
-- sa-auth-bus 業(yè)務(wù)工程
-- sa-auth-plugin 定義SPI接口的工程
-- sa-auth-plugin-ldap 模擬第三方庫的實(shí)現(xiàn)工程

1.idea創(chuàng)建名為sa-auth 的pom 項(xiàng)目，pom 如下

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.1.16.RELEASE</version>
        </parent>
    <groupId>com.vijay</groupId>
    <artifactId>cs-auth</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>cs-auth</name>
    <packaging>pom</packaging>
    <description>cs-auth</description>
    <properties>
        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
    </properties>
    <modules>
        <module>cs-auth-plugin</module>
        <module>cs-auth-bus</module>
        <module>cs-auth-plugin-ldap</module>
    </modules>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.18.20</version>
            </dependency>
            <dependency>
                <groupId>com.vijay</groupId>
                <artifactId>cs-auth-plugin</artifactId>
                <version>0.0.1-SNAPSHOT</version>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

2.然后創(chuàng)建sa-auth-plugin，pom 如下

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.vijay</groupId>
        <artifactId>cs-auth</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>../pom.xml</relativePath>
    </parent>
    <artifactId>cs-auth-plugin</artifactId>
    <name>cs-auth-plugin</name>
    <description>cs-auth-plugin</description>
</project>

3.sa-auth-bus，pom 如下

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.vijay</groupId>
        <artifactId>cs-auth</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>../pom.xml</relativePath>
    </parent>
    <artifactId>cs-auth-bus</artifactId>
    <name>cs-auth-bus</name>
    <description>cs-auth-bus</description>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.vijay</groupId>
            <artifactId>cs-auth-plugin</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
            </resource>
        </resources>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.1.1.RELEASE</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

4.sa-auth-plugin-ldap，pom如下

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.vijay</groupId>
        <artifactId>cs-auth</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>../pom.xml</relativePath>
    </parent>
    <artifactId>cs-auth-plugin-ldap</artifactId>
    <name>cs-auth-plugin</name>
    <description>cs-auth-plugin-ldap</description>
    <dependencies>
        <dependency>
            <groupId>com.vijay</groupId>
            <artifactId>cs-auth-plugin</artifactId>
        </dependency>
    </dependencies>
</project>

5.創(chuàng)建好的項(xiàng)目結(jié)構(gòu)如下

6.打開sa-auth-plugin，定義SPI接口

package com.vijay.csauthplugin.service;  

/**  
* 插件SPI接口  
*  
* @author vijay  
*/
publicinterface AuthPluginService {  

    /**  
    * 登錄認(rèn)證  
    *  
    * @param userName 用戶名  
    * @param password 密碼  
    * @return 認(rèn)證結(jié)果  
    */
    boolean login(String userName, String password);  

    /**  
    * AuthPluginService Name which for conveniently find AuthPluginService instance.  
    *  
    * @return AuthServiceName mark a AuthPluginService instance.  
    */
    String getAuthServiceName();  
}

7.cs-auth-plugin-ldap 中實(shí)現(xiàn)SPI的接口并且打成jar包，模擬外部提供的插件jar包

1.實(shí)現(xiàn)引入的cs-auth-plug包的SPI接口 package com.vijay.csauthplugin.ldap;

package com.vijay.csauthplugin.ldap;
import com.vijay.csauthplugin.service.AuthPluginService;  
/**  
* @author vijay  
*/
publicclass LdapProviderImpl implements AuthPluginService {  
    @Override
    public boolean login(String userName, String password) {  
        return"vijay".equals(userName) && "123456".equals(password);  
    }  

    @Override
    public String getAuthServiceName() {  
        return"LdapProvider";  
    }  
}

2.resources目錄下創(chuàng)建META-INF/services目錄，并在目錄下創(chuàng)建一個(gè)名為SPI接口類的全路徑限定名com.vijay.csauthplugin.service.AuthPluginService的文件，文件中寫入LdapProviderImpl 實(shí)現(xiàn)類的全路徑限定名com.vijay.csauthplugin.ldap.LdapProviderImpl

3.cs-auth-plugin-ldap打包成jar包

8.打開cs-auth-plugin-bus

1.項(xiàng)目下創(chuàng)建plugin包，添加一個(gè)插件的默認(rèn)實(shí)現(xiàn)DefaultProviderImpl

package com.vijay.bus.plugin;  

import com.vijay.csauthplugin.service.AuthPluginService;  

/**  
* 默認(rèn)插件實(shí)現(xiàn)  
*  
* @author vijay  
*/
publicclass DefaultProviderImpl implements AuthPluginService {  
    @Override
    public boolean login(String userName, String password) {  
        return"vijay".equals(userName) && "123456".equals(password);  
    }  

    @Override
    public String getAuthServiceName() {  
        return"DefaultProvider";  
    }  
}

2.resources目錄下創(chuàng)建META-INF/services目錄并在目錄下創(chuàng)建一個(gè)名為SPI接口類全路徑限定名的文件com.vijay.csauthplugin.service.AuthPluginService，文件內(nèi)容為DefaultProviderImpl全路徑限定名com.vijay.bus.plugin.DefaultProviderImpl.自定義類加載器

package com.vijay.bus.plugin;  

import java.net.URL;  
import java.net.URLClassLoader;  

/**  
* 自定義類加載器  
*  
* @author vijay  
*/
publicclass PluginClassLoader extends URLClassLoader {  

    public PluginClassLoader(URL[] urls) {  
        super(urls);  
    }  

    /**  
    * @param url 路徑  
    */
    public void addzURL(URL url) {  
        super.addURL(url);  
    }  

}

4.定義一個(gè)加載外部jar包的類

package com.vijay.bus.plugin;  

import java.io.File;  
import java.net.URL;  
import java.util.ArrayList;  
import java.util.List;  
import java.util.Objects;  

/**  
* 加載指定目錄jar包  
* @author vijay  
*/
publicclass ExternalJarLoader {  

    /**  
    * 加載外部jia包  
    *  
    * @param externalDirPath jar包目錄  
    */
    public static void loadExternalJars(String externalDirPath) {  
        File dir = new File(externalDirPath);  
        if (!dir.exists() || !dir.isDirectory()) {  
            thrownew IllegalArgumentException("Invalid directory path");  
        }  
        List<URL> urls = new ArrayList<>();  
        File[] listFiles = dir.listFiles();  
        if (Objects.nonNull(listFiles) && listFiles.length > 0) {  
            ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();  
            try {  
                for (File file : listFiles) {  
                    if (file.getName().endsWith(".jar")) {  
                        urls.add(file.toURI().toURL());  
                    }  
                }  
                PluginClassLoader customClassLoader = new PluginClassLoader(urls.toArray(new URL[0]));  
                Thread.currentThread().setContextClassLoader(customClassLoader);  
            } catch (Exception e) {  
                e.printStackTrace();  
                Thread.currentThread().setContextClassLoader(contextClassLoader);  
            }  
        }  
    }  
}

5.啟動(dòng)類中添加類加載器

package com.vijay.bus;  

import com.vijay.bus.plugin.ExternalJarLoader;  
import org.springframework.boot.SpringApplication;  
import org.springframework.boot.autoconfigure.SpringBootApplication;  

/**  
* @author vijay  
*/
@SpringBootApplication
publicclass CsAuthBusApplication {  
    public static void main(String[] args) {  
        String jarPath="/Users/vijay/Downloads/build/plugin";
        ExternalJarLoader.loadExternalJars(jarPath);  
        SpringApplication.run(CsAuthBusApplication.class, args);  
    }  
}

6.創(chuàng)建插件提供者類PluginProvider，提供實(shí)現(xiàn)類供springboot注入

package com.vijay.bus.plugin;  

import com.vijay.csauthplugin.service.AuthPluginService;  

import java.util.ServiceLoader;  

/**  
* 插件提供者  
*  
* @author vijay  
*/
publicclass PluginProvider {  

    /**  
    * 提供一個(gè)插件供注入(默認(rèn)返回外部目錄的插件,外部目錄沒有插件時(shí)返回默認(rèn)插件)  
    *  
    * @return 具體的插件實(shí)現(xiàn)  
    */
    public static AuthPluginService getAuthPluginService() {  
        ServiceLoader<AuthPluginService> defaultLoad = ServiceLoader.load(AuthPluginService.class);  
        AuthPluginService plugin = null;  
        for (AuthPluginService authPluginService : defaultLoad) {  
            if (authPluginService instanceof DefaultProviderImpl) {  
                plugin = authPluginService;  
            } else {  
                return authPluginService;  
            }  
        }  
        return plugin;  
    }  
}

7.項(xiàng)目下創(chuàng)建conf包，注入實(shí)現(xiàn)類到springboot

package com.vijay.bus.conf;  

import com.vijay.bus.plugin.PluginProvider;  
import com.vijay.csauthplugin.service.AuthPluginService;  
import org.springframework.context.annotation.Bean;  
import org.springframework.context.annotation.Configuration;  


/**  
* @author vijay  
*/
@Configuration
publicclass PluginConfig {  


    @Bean
    public AuthPluginService authPluginService() {  
        return PluginProvider.getAuthPluginService();  
    }  
}

8.項(xiàng)目下創(chuàng)建controller包，定義controller接口，調(diào)用測試

package com.vijay.bus.controller;  

import com.vijay.csauthplugin.service.AuthPluginService;  
import org.springframework.web.bind.annotation.GetMapping;  
import org.springframework.web.bind.annotation.RestController;  

import javax.annotation.Resource;  
import java.util.HashMap;  
import java.util.Map;  

/**  
* @author vijay  
*/
@RestController
publicclass TestController {  
    @Resource
    private AuthPluginService authPluginService;  
    @GetMapping("test")  
    public Object test() {  
        returnnew HashMap() {{  
            put("name", authPluginService.getAuthServiceName());  
            put("login", authPluginService.login("vijay", "123456"));  
        }};  
    }  
}

完整結(jié)構(gòu)