手写一个Spring Boot Starter - HelloWorld开发者社区

嗨~大家好，我是阿壮，一个后端程序员，今天和大家分享Spring Boot的自动装配原理，并手写一个Starter加深对Spring Boot的理解。

众所周知，Spring Boot为了简化开发，省去了Spring中很多的XML文件。为了理解Spring Boot中自动装配的原理，今天我们基于这个机制自己动手实现一个Starter组件。

项目结构

手写一个Spring Boot Starter

步骤

新建一个名为：redis-spring-boot-starter的Maven项目

添加Maven依赖

<dependencies>
     <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter</artifactId>
     </dependency>
     <dependency>
         <groupId>org.redisson</groupId>
         <artifactId>redisson</artifactId>
         <version>3.11.1</version>
     </dependency>
     <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-configuration-processor</artifactId>
         <optional>true</optional>
     </dependency>
 </dependencies>
 <dependencyManagement>
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-dependencies</artifactId>
             <version>2.3.2.RELEASE</version>
             <type>pom</type>
             <scope>import</scope>
         </dependency>
     </dependencies>
 </dependencyManagement>

定义属性，实现在applications.properties中的Redis的连接参数。

@ConfigurationProperties(prefix = "gp.redisson")
public class RedissonProperties {
 private String host = "localhost";
 private String password;
 private int port = 6379;
 private int timeout;
 private boolean ssl;

 public String getHost() {
     return host;
 }

 public void setHost(String host) {
     this.host = host;
 }

 public String getPassword() {
     return password;
 }

 public void setPassword(String password) {
     this.password = password;
 }

 public int getPort() {
     return port;
 }

 public void setPort(int port) {
     this.port = port;
 }

 public int getTimeout() {
     return timeout;
 }

 public void setTimeout(int timeout) {
     this.timeout = timeout;
 }

 public boolean isSsl() {
     return ssl;
 }

 public void setSsl(boolean ssl) {
     this.ssl = ssl;
 }
}

定义需要自动装配的配置类

@Configuration
@ConditionalOnClass(Redisson.class)
@EnableConfigurationProperties(RedissonProperties.class)
public class RedissonAutoConfiguration {
 @Bean
 RedissonClient redissonClient(RedissonProperties redissonProperties) {
     Config config = new Config();
     String prefix = "redis://";
     if (redissonProperties.isSsl()) {
         prefix = "rediss://";
     }
     SingleServerConfig singleServerConfig = config.useSingleServer()
             .setAddress(prefix + redissonProperties.getHost() + ":" + redissonProperties.getPort())
             .setConnectTimeout(redissonProperties.getTimeout());
     if (!StringUtils.hasText(redissonProperties.getPassword())) {
         singleServerConfig.setPassword(redissonProperties.getPassword());
     }
     return Redisson.create(config);
 }
}

在resource文件夹下新建META-INF/spring.fatories文件，使Spring Boot程序可以扫描文件完成自动装配
```
org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.jonssonyan.config.RedissonAutoConfiguration
```
打包成jar包

在其他项目引入当先依赖

     <dependency>
         <groupId>com.jonssonyan</groupId>
         <artifactId>redis-spring-boot-starter</artifactId>
         <version>1.0-SNAPSHOT</version>
     </dependency>