通过PropertyPlaceholderConfigurer暴露properties到自定义类的属性中以供使用备忘

classpath:jdbc.properties

PropertyConfigurer类如下：
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;

import java.util.Properties;

/**
* properties配置文件读取类
*/
public class PropertyConfigurer extends PropertyPlaceholderConfigurer {

private Properties props;   

@Override
protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props)
                        throws BeansException {
    super.processProperties(beanFactoryToProcess, props);
    this.props = props;
}

public String getProperty(String key){
    return this.props.getProperty(key);
}

public String getProperty(String key, String defaultValue) {
    return this.props.getProperty(key, defaultValue);
}

public Object setProperty(String key, String value) {
    return this.props.setProperty(key, value);
}

}

public interface PropertiesService {
/**
* 获取properties文件中指定key的value
*/
String getPropery(String key);
}

serviceimpl如下
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

/**
* 获取properties文件内容的service的实现类
*/
@Service
public class PropertiesServiceImpl implements PropertiesService {
@Autowired
private PropertyConfigurer pc;

@Override
public String getPropery(String key) {
    return pc.getProperty(key);
}

}

@Controller
@RequestMapping(“/prop”)
public class PropertyController {
@Autowired
private PropertiesService ps;
return ps.getProperyByFourthWay(key, “defaultValue”);
}