package control;   
  
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 {   
    
 //根據key讀取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;   
        }   
 }   
    
 //讀取properties的全部信息   
    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();   
        }   
    }   
  
    //寫入properties信息   
    public static void writeProperties(String filePath,String parameterName,String parameterValue) {   
     Properties prop = new Properties();   
     try {   
      InputStream fis = new FileInputStream(filePath);   
            //從輸入流中讀取屬性列表（鍵和元素對）   
            prop.load(fis);   
            //調用 Hashtable 的方法 put。使用 getProperty 方法提供并行性。   
            //強制要求為屬性的鍵和值使用字符串。返回值是 Hashtable 調用 put 的結果。   
            OutputStream fos = new FileOutputStream(filePath);   
            prop.setProperty(parameterName, parameterValue);   
            //以適合使用 load 方法加載到 Properties 表中的格式，   
            //將此 Properties 表中的屬性列表（鍵和元素對）寫入輸出流   
            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");   
    }   
}