jdbc工具类

 jdbc抽取到工具类中：

public class CopyUtils {
    private      Properties properties;
     private  static  CopyUtils copyUtils;
    private CopyUtils(){
        //通过构造方法来执行加载properites文件
        try {
            FileInputStream fis = new FileInputStream("database.properties" );
            properties =new Properties();
            properties.load(fis);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static synchronized CopyUtils getCopyUtils(){
        if(copyUtils==null){
            synchronized (CopyUtils.class){
                copyUtils =new CopyUtils();
            }
        }
        return  copyUtils;
    }
    public String getValue(String key){
       return properties.getProperty(key);
    }
}