[Java知识库]springboot手写自定义配置

阅读之前建议先看springboot自定义配置应用详解

1. demo

@ConfigurationProperties(
        prefix = "xulehuang.redis" //yml或者properties文件里面属性的前缀，前缀加具体属性名就对应RabbitProperties 的属性名，值自然而然也会取到
)
@Configuration
@Data
public class MyRedisProperties {
    private String hostName;
    private String port;
    private String password;
    private String database;


}

@Configuration
@EnableConfigurationProperties({MyRedisProperties.class})
public class MyRedisConfig {

    @Bean
    public RedisTemplate<Object, Object> redisTemplate(MyRedisProperties myRedisProperties ,RedisConnectionFactory redisConnectionFactory) {
        RedisTemplate<Object, Object> template = new RedisTemplate();
        template.setConnectionFactory(redisConnectionFactory);
        template.setKeySerializer(jackson2JsonRedisSerializer());
        template.setValueSerializer(jackson2JsonRedisSerializer());
        template.setHashKeySerializer(new StringRedisSerializer());
        template.setHashValueSerializer(jackson2JsonRedisSerializer());
        template.afterPropertiesSet();
        logger().info("加载Redis模板方法:{}", template.getClass());
        return template;
    }

    @Bean
    public RedisSerializer<Object> jackson2JsonRedisSerializer() {        //使用Jackson2JsonRedisSerializer来序列化和反序列化redis的value值
        Jackson2JsonRedisSerializer serializer = new Jackson2JsonRedisSerializer(Object.class);

        ObjectMapper mapper = new ObjectMapper();
        mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        serializer.setObjectMapper(mapper);
        logger().info("加载Redis序列化方法:{}", serializer.getClass());
        return serializer;
    }

    @Bean
    public Logger logger() {
        return  LoggerFactory.getLogger(MyRedisConfig.class);
    }

    @Bean
    public RedisStandaloneConfiguration redisStandaloneConfiguration( MyRedisProperties myRedisProperties) {
        RedisStandaloneConfiguration redisStandaloneConfiguration = new RedisStandaloneConfiguration(myRedisProperties.getHostName(), Integer.valueOf(myRedisProperties.getPort()));
        redisStandaloneConfiguration.setPassword(myRedisProperties.getPassword());
        redisStandaloneConfiguration.setDatabase(Integer.valueOf(myRedisProperties.getDatabase()));
        return redisStandaloneConfiguration;
    }
}

```yml
xulehuang.redis.hostName = ip
xulehuang.redis.port =  自定义
xulehuang.redis.database =  自定义
xulehuang.redis.password =  自己的密码

2. 难点剖析

关键在于如何找到有host、name和password的类，然后去注册为bean就可以了。我是从public RedisTemplate<Object, Object> redisTemplate(MyRedisProperties myRedisProperties ,RedisConnectionFactory redisConnectionFactory)中的setConnectionFactory debug出来的，发现configuration属性是RedisStandaloneConfiguration类的，而且有默认实现，所以就new了一个，然后配合我的MyRedisProperties 类去自定义它。同时，默认是LettuceConnectionFactory实现RedisConnectionFactory 。

3. debug三个构造方法，确定调用关系
   不难发现configuration = standaloneConfig ，而standaloneConfig 正是有我们想要的属性，同时默认实现符合预期，所以我们就自定义一个再去注册它。

private LettuceConnectionFactory(LettuceClientConfiguration clientConfig) {
        this.log = LogFactory.getLog(this.getClass());
        this.validateConnection = false;
        this.shareNativeConnection = true;
        this.eagerInitialization = false;
        this.connectionMonitor = new Object();
        this.convertPipelineAndTxResults = true;
        this.standaloneConfig = new RedisStandaloneConfiguration("localhost", 6379);
        this.pipeliningFlushPolicy = PipeliningFlushPolicy.flushEachCommand();
        Assert.notNull(clientConfig, "LettuceClientConfiguration must not be null!");
        this.clientConfiguration = clientConfig;
        this.configuration = this.standaloneConfig;
    }

4. 为什么debug的时候 this.standaloneConfig有值？

这就是spring ioc的问题了，configuration 是这个类的属性，实例化的时候就会去找对应的实现实例化

5. 使用@ConfigurationProperties要加入

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-configuration-processor</artifactId>
			<optional>true</optional>
		</dependency>

6. 在原有的redis依赖上做的修改，要加入

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-redis</artifactId>
		</dependency>

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