content: package com.ctrip.framework.apollo.core.utils;
  
  import java.net.URL;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.FileNotFoundException;
  import java.nio.file.Paths;
  import java.util.Properties;
  
  public class ResourceUtils {
  
    private static final Logger logger = LoggerFactory.getLogger(ResourceUtils.class);
    private static final String[] DEFAULT_FILE_SEARCH_LOCATIONS = new String[]{"./config/", "./"};
  
    @SuppressWarnings("unchecked")
    public static Properties readConfigFile(String configPath, Properties defaults) {
      Properties props = new Properties();
      if (defaults != null) {
        props.putAll(defaults);
      }
  
      InputStream in = loadConfigFileFromDefaultSearchLocations(configPath);
  
      try {
        if (in != null) {
          props.load(in);
        }
      } catch (IOException ex) {
        logger.warn("Reading config failed: {}", ex.getMessage());
      } finally {
        if (in != null) {
          try {
            in.close();
          } catch (IOException ex) {
            logger.warn("Close config failed: {}", ex.getMessage());
          }
        }
      }
  
      if (logger.isDebugEnabled()) {
        StringBuilder sb = new StringBuilder();
        for (String propertyName : props.stringPropertyNames()) {
          sb.append(propertyName).append('=').append(props.getProperty(propertyName)).append('\n');
  
        }
        if (sb.length() > 0) {
          logger.debug("Reading properties: \n" + sb.toString());
        } else {
          logger.warn("No available properties");
        }
      }
      return props;
    }
  
    private static InputStream loadConfigFileFromDefaultSearchLocations(String configPath) {
      try {
        // load from default search locations
        for (String searchLocation : DEFAULT_FILE_SEARCH_LOCATIONS) {
          File candidate = Paths.get(searchLocation, configPath).toFile();
          if (candidate.exists() && candidate.isFile() && candidate.canRead()) {
            logger.debug("Reading config from resource {}", candidate.getAbsolutePath());
            return new FileInputStream(candidate);
          }
        }
  
        // load from classpath
        URL url = ClassLoaderUtil.getLoader().getResource(configPath);
  
        if (url != null) {
          InputStream in = getResourceAsStream(url);
  
          if (in != null) {
            logger.debug("Reading config from resource {}", url.getPath());
            return in;
          }
        }
  
        // load outside resource under current user path
        File candidate = new File(System.getProperty("user.dir"), configPath);
        if (candidate.exists() && candidate.isFile() && candidate.canRead()) {
          logger.debug("Reading config from resource {}", candidate.getAbsolutePath());
          return new FileInputStream(candidate);
        }
      } catch (FileNotFoundException e) {
        //ignore
      }
      return null;
    }
  
    private static InputStream getResourceAsStream(URL url) {
      try {
        return url != null ? url.openStream() : null;
      } catch (IOException e) {
        return null;
      }
    }
  }
  