Spring boot将配置属性注入到bean类中

一、@ConfigurationProperties注解的使用

看配置文件，我的是yaml格式的配置：

// file application.yml
my:
  servers:
    - dev.bar.com
    - foo.bar.com
    - jiaobuchong.com

下面我要将上面的配置属性注入到一个Java Bean类中，看码：

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;

/**
 * file: MyConfig.java
 * Created by jiaobuchong on 12/29/15.
 */
@Component      //不加这个注解的话, 使用@Autowired 就不能注入进去了
@ConfigurationProperties(prefix = "my")  // 配置文件中的前缀
public class MyConfig {
    private List<String> servers = new ArrayList<String>();
    public List<String> getServers() { return this.servers;
    }
}

下面写一个Controller来测试一下：

/**
 * file： HelloController
 * Created by jiaobuchong on 2015/12/4.
 */
@RequestMapping("/test")
@RestController
public class HelloController {
    @Autowired
    private MyConfig myConfig;

    @RequestMapping("/config")
    public Object getConfig() {
        return myConfig.getServers();
    }
}

下面运行Application.java的main方法跑一下看看：

@Configuration   //标注一个类是配置类，spring boot在扫到这个注解时自动加载这个类相关的功能，比如前面的文章中介绍的配置AOP和拦截器时加在类上的Configuration
@EnableAutoConfiguration  //启用自动配置 该框架就能够进行行为的配置，以引导应用程序的启动与运行, 根据导入的starter-pom 自动加载配置
@ComponentScan  //扫描组件 @ComponentScan(value = "com.spriboot.controller") 配置扫描组件的路径
public class Application {
    public static void main(String[] args) {
        // 启动Spring Boot项目的唯一入口
        SpringApplication app = new SpringApplication(Application.class);
        app.setBannerMode(Banner.Mode.OFF);
        app.run(args);
    }

在浏览器的地址栏里输入： 
localhost:8080/test/config 得到： 
[“dev.bar.com”,”foo.bar.com”,”jiaobuchong.com”] 

二、@ConfigurationProperties和@EnableConfigurationProperties注解结合使用

在spring boot中使用yaml进行配置的一般步骤是， 
1、yaml配置文件，这里假设： 

my:
  webserver:
    #HTTP 监听端口
    port: 80
    #嵌入Web服务器的线程池配置
    threadPool:
      maxThreads: 100
      minThreads: 8
      idleTimeout: 60000

2、

//file MyWebServerConfigurationProperties.java
import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "my.webserver")
public class MyWebServerConfigurationProperties {
    private int port;
    private ThreadPool threadPool;

    public int getPort() {
        return port;
    }

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

    public ThreadPool getThreadPool() {
        return threadPool;
    }

    public void setThreadPool(ThreadPool threadPool) {
        this.threadPool = threadPool;
    }

    public static class ThreadPool {
        private int maxThreads;
        private int minThreads;
        private int idleTimeout;

        public int getIdleTimeout() {
            return idleTimeout;
        }

        public void setIdleTimeout(int idleTimeout) {
            this.idleTimeout = idleTimeout;
        }

        public int getMaxThreads() {
            return maxThreads;
        }

        public void setMaxThreads(int maxThreads) {
            this.maxThreads = maxThreads;
        }

        public int getMinThreads() {
            return minThreads;
        }

        public void setMinThreads(int minThreads) {
            this.minThreads = minThreads;
        }
    }
}

3、

// file: MyWebServerConfiguration.java
import org.springframework.context.annotation.Configuration;
import org.springframework.boot.context.properties.EnableConfigurationProperties;

@Configuration
@EnableConfigurationProperties(MyWebServerConfigurationProperties.class)
public class MyWebServerConfiguration {
    @Autowired
    private MyWebServerConfigurationProperties properties;
    /**
     *下面就可以引用MyWebServerConfigurationProperties类       里的配置了
    */
   public void setMyconfig() {
       String port = properties.getPort();
       // ...........
   }   
}

The @EnableConfigurationProperties annotation is automatically applied to your project so that any beans annotated with @ConfigurationProperties will be configured from the Environment properties. This style of configuration works particularly well with the SpringApplication external YAML configuration.(引自spring boot官方手册) 

三、@Bean配置第三方组件(Third-party configuration)

创建一个bean类：

// file ThreadPoolBean.java
/**
 * Created by jiaobuchong on 1/4/16.
 */
public class ThreadPoolBean {
    private int maxThreads;
    private int minThreads;
    private int idleTimeout;

    public int getMaxThreads() {
        return maxThreads;
    }

    public void setMaxThreads(int maxThreads) {
        this.maxThreads = maxThreads;
    }

    public int getMinThreads() {
        return minThreads;
    }

    public void setMinThreads(int minThreads) {
        this.minThreads = minThreads;
    }

    public int getIdleTimeout() {
        return idleTimeout;
    }

    public void setIdleTimeout(int idleTimeout) {
        this.idleTimeout = idleTimeout;
    }
}

引用前面第二部分写的配置类：MyWebServerConfiguration.java和MyWebServerConfigurationProperties.java以及yaml配置文件,现在修改MyWebServerConfiguration.java类：

import com.jiaobuchong.springboot.domain.ThreadPoolBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * Created by jiaobuchong on 1/4/16.
 */
@Configuration  //这是一个配置类，与@Service、@Component的效果类似。spring会扫描到这个类，@Bean才会生效，将ThreadPoolBean这个返回值类注册到spring上下文环境中
@EnableConfigurationProperties(MyWebServerConfigurationProperties.class) //通过这个注解, 将MyWebServerConfigurationProperties这个类的配置到上下文环境中,本类中使用的@Autowired注解注入才能生效
public class MyWebServerConfiguration {
    @SuppressWarnings("SpringJavaAutowiringInspection") //加这个注解让IDE 不报: Could not autowire
    @Autowired
    private MyWebServerConfigurationProperties properties;

    @Bean //@Bean注解在方法上,返回值是一个类的实例,并声明这个返回值(返回一个对象)是spring上下文环境中的一个bean
    public ThreadPoolBean getThreadBean() {
        MyWebServerConfigurationProperties.ThreadPool threadPool = properties.getThreadPool();
        ThreadPoolBean threadPoolBean = new ThreadPoolBean();
        threadPoolBean.setIdleTimeout(threadPool.getIdleTimeout());
        threadPoolBean.setMaxThreads(threadPool.getMaxThreads());
        threadPoolBean.setMinThreads(threadPool.getMinThreads());
        return threadPoolBean;
    }
}

被@Configuration注解标识的类，通常作为一个配置类，这就类似于一个xml文件，表示在该类中将配置Bean元数据，其作用类似于Spring里面application-context.xml的配置文件，而@Bean标签，则类似于该xml文件中，声明的一个bean实例。 
写一个controller测试一下：

import com.jiaobuchong.springboot.domain.ThreadPoolBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Created by jiaobuchong on 2015/12/4.
 */
@RequestMapping("/first")
@RestController
public class HelloController {
    @Autowired
    private ThreadPoolBean threadPoolBean;
    @RequestMapping("/testbean")
    public Object getThreadBean() {
        return threadPoolBean;
    }

}

运行Application.java的main方法， 
在浏览器里输入：http://localhost:8080/first/testbean 
得到的返回值是： 
{“maxThreads”:100,”minThreads”:8,”idleTimeout”:60000} 

ok，fucking nice