Javaアクションpropertiesファイル

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.Properties;

public class TestMain {
 
 //  key  value
 public static String readValue(String filePath,String key) {
  Properties props = new Properties();
        try {
         InputStream in = new BufferedInputStream (new FileInputStream(filePath));
         props.load(in);
         String value = props.getProperty (key);
            System.out.println(key+value);
            return value;
        } catch (Exception e) {
         e.printStackTrace();
         return null;
        }
 }
 
 //  properties     
    public static void readProperties(String filePath) {
     Properties props = new Properties();
        try {
         InputStream in = new BufferedInputStream (new FileInputStream(filePath));
         props.load(in);
            Enumeration en = props.propertyNames();
             while (en.hasMoreElements()) {
              String key = (String) en.nextElement();
                    String Property = props.getProperty (key);
                    System.out.println(key+Property);
                }
        } catch (Exception e) {
         e.printStackTrace();
        }
    }


    //  properties  
    public static void writeProperties(String filePath,String parameterName,String parameterValue) {
     Properties prop = new Properties();
     try {
      InputStream fis = new FileInputStream(filePath);
            //           （     ）
            prop.load(fis);
            //   Hashtable     put。   getProperty        。
            //                。     Hashtable    put    。
            OutputStream fos = new FileOutputStream(filePath);
            prop.setProperty(parameterName, parameterValue);
            //      load       Properties      ，
            //   Properties        （     ）     
            prop.store(fos, "Update '" + parameterName + "' value");
        } catch (IOException e) {
         System.err.println("Visit "+filePath+" for updating "+parameterName+" value error");
        }
    }


    public static void main(String[] args) {
     readValue("info.properties","url");
        writeProperties("info.properties","age","21");
        readProperties("info.properties" );
        System.out.println("OK");
    }
}