Java code to read properties file

When developing the Spring project, I wanted to do an operation to read the properties file in the java code. After checking it, most of them are read in the following two ways.

method one:

<bean id="propertyConfigurer"  
     class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">  
      <property name="location">  
          <value>/WEB-INF/configs/aa.properties</value>  
      </property>  
</bean>  

Method Two:

<bean id="prop" class="org.springframework.beans.factory.config.PropertiesFactoryBean">  
   <property name="locations"><!-- 这里是PropertiesFactoryBean类，它也有个locations属性，也是接收一个数组，跟上面一样  
        <array>  
            <value>classpath:public.properties</value>  
        </array>  
    </property>  
</bean>  

However, neither of these methods meet the requirements.

The value in the properties of method 1 can only be retrieved in the xml configuration file through the ${key} method, while the value in method 2 can only be retrieved through the annotation @Value(“#{key}”).

---

And my requirement is to read the key value through java code. So, I wrote the following code to read the properties file and get the value through getData.

@Component
public class PropertiesRead {
    private String Tag = "PropertiesRead";
    @Resource
    private BusinessLogger Log;
    private Properties props;
    public Properties getInstance() throws IOException{
        if(props==null){//判断是否读取过，只读一次
            loadProps();//读取文件
        }
        return props;
    }

    private void loadProps() {
        Log.log(Tag, "开始读取properties文件内容");
        InputStream in = null;
        // 根目录是编译的class的目录
       in = PropertiesRead.class.getResourceAsStream("/msgpackage.properties");
       props = new Properties();
        try {
            props.load(in);
        } catch (IOException e) {
            e.printStackTrace();
        }
       Log.log(Tag, "加载properties文件内容结束");

    }
    public String getData(String key) throws IOException{
       return getInstance().getProperty(key);
    }
}

The code of the calling class is as follows:

@RestController
public class BusinessCommonController {
    ...
    @Resource
    private PropertiesRead pr ;
    ...
    public Object getform(HttpSession session,@RequestParam("functionId") String functionId) throws Exception {
        String trancode = pr.getData("trancode");//取值
        Log.log(TAG, trancode);
        ...
        ...
        return formReturn;
    }
}

msgpackage.properties

trancode=5389

The log is as follows, the properties file will be read for the first access, and the memory will be directly fetched when accessed again.

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