package utils.properties;

import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * Created by weishuai on 2018/11/2.
 */
public class PropertiesUtil {
    private static ResourceLoader loader = ResourceLoader.getInstance();
    private static ConcurrentMap<String, String> configMap = new ConcurrentHashMap<String, String>();
    private static final String DEFAULT_CONFIG_FILE = "database.properties";

    private static Properties prop = null;

    public static String getStringByKey(String key, String propName) {
        try {
            prop = loader.getPropFromProperties(propName);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        key = key.trim();
        if (!configMap.containsKey(key)) {
            if (prop.getProperty(key) != null) {
                configMap.put(key, prop.getProperty(key));
            }
        }
        return configMap.get(key);
    }

    public static String getStringByKey(String key) {
        return getStringByKey(key, DEFAULT_CONFIG_FILE);
    }

    public static Properties getProperties() {
        try {
            return loader.getPropFromProperties(DEFAULT_CONFIG_FILE);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    public static void main(String[] args) {
         String TEST = PropertiesUtil.getStringByKey("user", "database.properties");
        System.out.println(TEST);
    }
}
 

package utils.properties;

import java.io.File;
import java.io.FileInputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

/**
 * Created by weishuai on 2018/11/2.
 */
public class ResourceLoader {
    private static ResourceLoader loader = new ResourceLoader();
    private static Map<String, Properties> loaderMap = new HashMap<String, Properties>();

    private ResourceLoader() {
    }

    public static ResourceLoader getInstance() {
        return loader;
    }

    public Properties getPropFromProperties(String fileName) throws Exception {

        Properties prop = loaderMap.get(fileName);
        if (prop != null) {
            return prop;
        }
        String filePath = null;
        String configPath = System.getProperty("configurePath");

        if (configPath == null) {
            filePath = this.getClass().getClassLoader().getResource(fileName).getPath();
        } else {
            filePath = configPath + "/" + fileName;
        }
        prop = new Properties();
        prop.load(new FileInputStream(new File(filePath)));

        loaderMap.put(fileName, prop);
        return prop;
    }
}