Java Read Properties configuration file

1.Properties class and properties configuration file

The properties class inherits from the Hashtable class and implements the map interface, using the form of a key-value pair to hold the property set. However, the properties ' keys and values are string types.

The main methods in 2.Properties

(1) Load (InputStream instream)
This method can load a property list into the Properties class object from the file input stream corresponding to the. Properties property file. Used to read the properties configuration file.

Properties prop = new properties ();     Read the properties file A.propertiesinputstream in = new Bufferedinputstream (New FileInputStream ("A.properties"));p rop.load (in); Load Property list iterator<string> it=prop.stringpropertynames (). iterator (); while (It.hasnext ()) {String Key=it.next (    ); System.out.println (key+ ":" +prop.getproperty (Key));} In.close ();

(2) Store (OutputStream out, String comments)
This method saves the property list of the Properties class object to the output stream. Used to write properties configuration files.

Properties prop = new properties (); Save property to B.properties file FileOutputStream ofile = new FileOutputStream ("B.properties", true);// True means append open prop.setproperty ("Phone", "10086");p Rop.store (ofile, "Comment");//If comments is not empty, the first row of the saved properties file is #comments , which represents the comment information, or no comment if it is empty. The comment information is followed by the current save time information for the property file. Ofile.close ();

(3) Getproperty/setproperty
The two methods are to get and set property information, respectively.

3. Example

The following is a tool class written by Huang Yong to get the properties file.

/** *  Properties File Tool class  */public final class PropsUtil {     Private static final logger logger = loggerfactory.getlogger (PropsUtil.class);     /**     *  Load Properties File      */     public static properties loadprops (String filename)  {         Properties props = null;         inputstream is = null;        try  {            is =  Thread.CurrentThread (). Getcontextclassloader (). getResourceAsStream (FileName);             if  (is == null)  {              &nBsp;  throw new filenotfoundexception (filename +  " file is not  found ");            }             props = new properties ();             props.load (IS);         } catch  (ioexception e)  {             logger.error ("Load properties file failure",  e);         } finally {             if  (is != null)  {                 try {                     is.close ();                 } catch  (ioexception e)  {                     logger.error ("Close  input stream failure ",  e);                 }            }         }        return  props;    }    /**     *  Get Character Type property (default is an empty string)      */    public static String  GetString (Properties props, string key)  {         Return getstring (PROPS, KEY,  "");     }    /**     *  Get character attributes (you can specify default values)       */    public static string getstring (Properties  props, string key, string defaultvalue)  {         string value = defaultvalue;        if   (Props.containskey (key))  {             Value = props.getproperty (Key);        }         return value;    }    /**      *  Get numeric properties (default =  0)      */     Public static int getint (Properties props, string key)  {         return getint (props, key, 0);    }    //  Gets the numeric property (can specify a default value)     public static int getint (properties props,  String key, int defaultvalue)  {        int  value = defaultvalue;        if  (Props.containsKey (key) )  {            value =  Castutil.castint (Props.getproperty (key));        }         return value;    }    /**      *  Get Boolean property (default =  false)      */     public static boolean getboolean (Properties props, string key)  {        &nbsP;return getboolean (props, key, false);     }    /**      *  Get Boolean properties (you can specify default values)      */     Public static boolean getboolean (Properties props, string key, boolean  defaultvalue)  {        boolean value =  defaultvalue;        if  (Props.containskey (key))  {             value = castutil.castboolean ( Props.getproperty (key));        }         return value;    }}

/** *  Transformation Operation Tool class  */public final class castutil {    /**      *  switch to  String  type      */     public static string caststring (object obj)  {         return castutil.caststring (obj,  "");    }     /**     *  to  String  (default value provided)      */     public static string caststring (object obj, string  DefaultValue)  {        return obj != null ?  string.valueof (obj)  : defaultValue;    }    /**      *  switch to  double  type      */     public static double Castdouble (object obj)  {        return  Castutil.castdouble (obj, 0);    }    /**      *  to  double  (default value provided)      */    public  Static double castdouble (Object obj, double defaultvalue)  {         double doubleValue = defaultValue;         if  (obj != null)  {             string strvalue = caststring (obj);             if  (Stringutil.isnotempty (strvalue))  {                 try {            &nbSp;        doublevalue = double.parsedouble (StrValue);                 } catch  ( Numberformatexception e)  {                     doubleValue = defaultValue;                 }             }        }         return doubleValue;    }    /**      *  switch to  long  type      */     Public static long castlong (object obj)  {         return castutiL.castlong (obj, 0);     }    /**     *   to  long  (default value provided)      */    public static  long castlong (Object obj, long defaultvalue)  {         long longValue = defaultValue;         if  (obj != null)  {             string strvalue = caststring (obj);             if  (Stringutil.isnotempty (strvalue))  {                 try {                     longValue =  Long.parselong (strvalue);                 } catch  ( Numberformatexception e)  {                     longValue = defaultValue;                 }             }        }         return longValue;    }    /**      *  switch to  int  type      */    public  static int castint (object obj)  {         Return castutil.castint (obj, 0);    }    /**      *  Switch to  INT  Type (provides default value)      */    public static int castint ( Object obj, int defaultvalue)  {        int  intvalue = defaultvalue;        if  (obj !=  NULL)  {            String strValue  = caststring (obj);            if  ( Stringutil.isnotempty (strvalue))  {                 try {                     intvalue = integer.parseint (StrValue);                 } catch  ( Numberformatexception e)  {                     intValue = defaultValue;                 }            }         }        return  intvalue;    }    /**     *  converted to   boolean  type      */    public static boolean  Castboolean (object obj)  {        return  Castutil.castboolean (Obj, false);    }    /**      *  to  boolean  (default value provided)      */    public  static boolean castbooleaN (object obj, boolean defaultvalue)  {         boolean booleanvalue = defaultvalue;        if  ( Obj != null)  {             Booleanvalue = boolean.parseboolean (caststring (obj));         }        return booleanvalue;    }}

/** *  string tool class  */public  final class stringutil {    /**     *  Determines whether the string is empty      */    public static boolean isempty ( STRING STR)  {        if  (str != null)  {             str = str.trim ();         }        return  Stringutils.isempty (str);     }    /**     *   Determine if the string is non-null      */    public static boolean  Isnotempty (STRING STR)  {        return !isempty (str);     }} 

This allows you to manipulate the properties configuration file directly using this tool class.
Action example (get the value of an int property and give a default value of 1):

Properties conf = propsutil.loadprops ("config.properties"); int value = Propsutil.getint (conf, "key", 1);

This makes the operation much more convenient.

Java Read Properties configuration file