SpringBoot中的配置类(@Configuration)

<!--druid 数据连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.12</version>
        </dependency>

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/order?characterEncoding=utf-8
name=root
pass=root
initialSize=1
minIdle=1
maxActive=20
maxWait=3

package cn.boke.config;
import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import javax.sql.DataSource;
@Configuration  //声明配置类
@PropertySource("classpath:druid.properties")   //导入配置文件
public class JdbcConfig {
    //将配置文件内的 信息 放入变量中
    @Value("${driverClassName}")
    private  String driverClassName;  //JDBC驱动
    @Value("${url}")
    private String url;  //连接地址
    @Value("${name}")
    private  String name;  //数据库用户
    @Value("${pass}")
    private String pass;  //数据库密码
    @Value("${initialSize}")
    private int initialSize;   //初始化连接数量
    @Value("${minIdle}")
    private int minIdle;  //最小连接数量
    @Value("${maxActive}")
    private int maxActive;  //最大连接数量
    @Value("${maxWait}")
    private int maxWait;  //最大等待时间
    @Bean("dataSource")  //将配置信息 存入Spring 容器中 名称为 dataSource
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setUrl(url);
        dataSource.setDriverClassName(driverClassName);
        dataSource.setUsername( name);
        dataSource.setPassword(pass);
        dataSource.setInitialSize(initialSize);
        dataSource.setMaxActive(maxActive);
        dataSource.setMaxWait(maxWait);
        return dataSource;
    }
}

@Component //将该Bean放入spring容器中
@ConfigurationProperties(prefix = "com.example")//指定该类为配置获取类，并指定前缀
public class MyConfig {
    private String name;
    private Integer age;
    //必须设置get set方法
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
}

com.example.age=20
com.example.name=xxx

@RestController
public class DemoController {
    @Autowired
    private MyConfig config;
    @GetMapping("/demo2")
    public String m2(){
        return config.getName();
    }
}

@ConfigurationProperties(prefix = "com.example")//指定该类为配置获取类，并指定前缀
public class MyConfig {
    private String name;
    private Integer age;
    //必须设置get set方法
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
}

@SpringBootApplication
@EnableConfigurationProperties(MyConfig.class) //引入自定义配置类
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class,args);
    }
}