Properties类（一）

Java中读写资源文件最重要的类是Properties,功能大致如下：

1. 读写Properties文件

2. 读写XML文件

3. 不仅可以读写上述两类文件，还可以读写其它格式文件如txt等，只要符合key=value格式即可.

注意：资源文件中含有中文时的处理方法 

1. 将中文字符通过工作转成utf8编码，可以通过Java自带的nativetoascii或Eclipse中的属性编辑器。

2. 直接调用 new String(youChineseString.getBytes("ISO-8859-1"), "GBK");

附：WEB程序中加载资源文件的方法

Properties prop = null; 

1. prop = Thread.currentThread().getContextClassLoader().getResourceAsStream("filename");

2. prop = this.getClass().getClassLoader().getResourceAsStream("filename");

Properties能读取以key,value存储的任何格式文件，究竟有什么神奇，猫一眼类结构，

原来它继承了Hashtable并实现了Map接口,这样大家放心了吧。

package apistudy;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.Properties;

public class PropertiesTest
{

    public static void main(String[] args)
    {

        String readfile = "d:" + File.separator + "readfile.properties";
        String writefile = "d:" + File.separator + "writefile.properties";
        String readxmlfile = "d:" + File.separator + "readxmlfile.xml";
        String writexmlfile = "d:" + File.separator + "writexmlfile.xml";
        String readtxtfile = "d:" + File.separator + "readtxtfile.txt";
        String writetxtfile = "d:" + File.separator + "writetxtfile.txt";

        readPropertiesFile(readfile); //读取properties文件
        writePropertiesFile(writefile); //写properties文件
        readPropertiesFileFromXML(readxmlfile); //读取XML文件
        writePropertiesFileToXML(writexmlfile); //写XML文件
        readPropertiesFile(readtxtfile); //读取txt文件
        writePropertiesFile(writetxtfile); //写txt文件
    }

    //读取资源文件,并处理中文乱码
    public static void readPropertiesFile(String filename)
    {
        Properties properties = new Properties();
        try
        {
            InputStream inputStream = new FileInputStream(filename);
            properties.load(inputStream);
            inputStream.close(); //关闭流
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        String username = properties.getProperty("username");
        String passsword = properties.getProperty("password");
        String chinese = properties.getProperty("chinese");
        try
        {
            chinese = new String(chinese.getBytes("ISO-8859-1"), "GBK"); // 处理中文乱码
        }
        catch (UnsupportedEncodingException e)
        {
            e.printStackTrace();
        }
        System.out.println(username);
        System.out.println(passsword);
        System.out.println(chinese);
    }

    //读取XML文件,并处理中文乱码
    public static void readPropertiesFileFromXML(String filename)
    {
        Properties properties = new Properties();
        try
        {
            InputStream inputStream = new FileInputStream(filename);
            properties.loadFromXML(inputStream);
            inputStream.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        String username = properties.getProperty("username");
        String passsword = properties.getProperty("password");
        String chinese = properties.getProperty("chinese"); //XML中的中文不用处理乱码，正常显示
        System.out.println(username);
        System.out.println(passsword);
        System.out.println(chinese);
    }

    //写资源文件，含中文
    public static void writePropertiesFile(String filename)
    {
        Properties properties = new Properties();
        try
        {
            OutputStream outputStream = new FileOutputStream(filename);
            properties.setProperty("username", "myname");
            properties.setProperty("password", "mypassword");
            properties.setProperty("chinese", "中文");
            properties.store(outputStream, "author: shixing_11@sina.com");
            outputStream.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

    //写资源文件到XML文件，含中文
    public static void writePropertiesFileToXML(String filename)
    {
        Properties properties = new Properties();
        try
        {
            OutputStream outputStream = new FileOutputStream(filename);
            properties.setProperty("username", "myname");
            properties.setProperty("password", "mypassword");
            properties.setProperty("chinese", "中文");
            properties.storeToXML(outputStream, "author: shixing_11@sina.com");
            outputStream.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

}

运行本程序所需的资源文件，我是放在D盘根目录，如D:/readfile.properties

1. readfile.properties

username=myname

password=mypassword

chinese=中文

2. writefile.properties

#author: shixing_11@sina.com

#Fri May 28 22:19:44 CST 2010

password=mypassword

chinese=/u4E2D/u6587

username=myname

    3. readxmlfile.xml
         <?xml version="1.0" encoding="UTF-8" standalone="no"?>

<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">

<properties>

<entry key="password">mypassword</entry>

<entry key="chinese">中文</entry>

<entry key="username">myname</entry>

</properties>

    4. writexmlfile.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">

<properties>

<comment>author: shixing_11@sina.com</comment>

<entry key="password">mypassword</entry>

<entry key="chinese">中文</entry>

<entry key="username">myname</entry>

</properties>

    5. readtxtfile.txt    

           username=myname

           password=mypassword

           chinese=中文

    6. writetxtfile.txt

#author: shixing_11@sina.com

#Fri May 28 22:25:16 CST 2010

password=mypassword

chinese=/u4E2D/u6587

username=myname