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 {

 

 //根据key读取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;

        }

 }

 

 //读取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();

        }

    }

    //写入properties信息

    public static void writeProperties(String filePath,String parameterName,String parameterValue) {

     Properties prop = new Properties();

     try {

      InputStream fis = new FileInputStream(filePath);

            //从输入流中读取属性列表（键和元素对）

            prop.load(fis);

            //调用 Hashtable 的方法 put。使用 getProperty 方法提供并行性。

            //强制要求为属性的键和值使用字符串。返回值是 Hashtable 调用 put 的结果。

            OutputStream fos = new FileOutputStream(filePath);

            prop.setProperty(parameterName, parameterValue);

            //以适合使用 load 方法加载到 Properties 表中的格式，

            //将此 Properties 表中的属性列表（键和元素对）写入输出流

            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");

    }

}