sys: 
  qq_back: http://www.123.club/indexes
  qq_appid: 1018
  qq_appkey: 025bf1d0

public class SystemStaticConstant {

	private static String qq_back;
	
	private static String qq_appid;
	
	private static String qq_appkey;
	
	public static String getQq_back() {
		return qq_back;
	}
	public static String getQq_appid() {
		return qq_appid;
	}
	public static String getQq_appkey() {
		return qq_appkey;
	}
}

项目启动中执行，完成注入。

import java.io.File;
import java.lang.reflect.Field;
import java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.context.properties.bind.Bindable;
import org.springframework.boot.context.properties.bind.Binder;
import org.springframework.boot.context.properties.source.ConfigurationPropertyName;
import org.springframework.core.annotation.Order;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.stereotype.Component;

import com.baidu.aip.util.PhotoCheckUpService;

@Component
@Order(value=1)
public class SystemAttributeConfig implements CommandLineRunner {
	
	@Autowired
	private ConfigurableEnvironment environment;
	
    private static Map<String, String> attributeMap = new ConcurrentHashMap<>();

    /**
     * 指定需要自动注入的范围
     */
    private static final ConfigurationPropertyName attributes = ConfigurationPropertyName.of("sys");
    private static final Bindable<Map<String, String>> STRING_STRING_MAP = Bindable.mapOf(String.class, String.class);
	

    @Override
    public void run(String... var1) throws Exception {
    	/**
    	 * 	在SystemStaticConstant类中配置常量
    	 */
    	Binder binder = Binder.get(environment);
    	attributeMap = binder.bind(attributes, STRING_STRING_MAP).orElseGet(Collections::emptyMap);
        System.out.println(attributeMap);
        
    	Class<SystemStaticConstant> c = SystemStaticConstant.class;
    	Field[] fs = c.getDeclaredFields();
    	for(Field f : fs) {
			try {
				f.setAccessible(true);
				if(attributeMap.containsKey(f.getName())) {
					if(f.getType()==String.class) {
						f.set(c,attributeMap.get(f.getName()));
					}else if(f.getType()==Integer.class||f.getType()==int.class) {
						f.set(c,new Integer(attributeMap.get(f.getName())));
					}else if(f.getType()==Long.class||f.getType()==long.class) {
						f.set(c,new Long(attributeMap.get(f.getName())));
					}else if(f.getType()==Double.class||f.getType()==double.class) {
						f.set(c,new Double(attributeMap.get(f.getName())));
					}else if(f.getType()==Short.class||f.getType()==short.class) {
						f.set(c,new Short(attributeMap.get(f.getName())));
					}else if(f.getType()==Float.class||f.getType()==float.class) {
						f.set(c,new Float(attributeMap.get(f.getName())));
					}else if(f.getType()==Boolean.class||f.getType()==boolean.class) {
						f.set(c,new Boolean(attributeMap.get(f.getName())));
					}
				}
			} catch (Exception e) {
				throw new Exception(e.getMessage()+"----配置文件类型转换异常--->"+f.getName());
			}
    	}
    }
}