java读取properties文件的方法

盗亦有道：

http://blog.csdn.net/lwzcjd/article/details/3116298

http://hi.baidu.com/hgd0324/item/1d5e923973b77c4d033edcaf

这里介绍两种技术：利用spring读取properties 文件和利用java.util.Properties读取
(一)利用spring读取properties 文件
利用org.springframework.beans.factory.support.PropertiesBeanDefinitionReader来读取属性文件

构造如下config.properties文件properties代码

userDao.class=com.spring.dao.UserDao 

属性文件中的"userDao"名称即是Bean的别名设定，.class用于指定类来源。

然后利用org.springframework.beans.factory.support.PropertiesBeanDefinitionReader来读取属性文件
   BeanDefinitionRegistry reg = new DefaultListableBeanFactory();
   PropertiesBeanDefinitionReader reader = new PropertiesBeanDefinitionReader(reg);
   reader.loadBeanDefinitions(new ClassPathResource("config.properties"));
   BeanFactory factory = (BeanFactory)reg;
   UserDao userDao = (UserDao)factory.getBean("userDao");
(二)利用java.util.Properties读取属性文件
1.    String str=File.separator;
        InputStream path=this.getServletContext().getResourceAsStream(str+"WEB-INF"+str+"classes"+str+"password.properties");

        //InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("password.properties");

    /*File filepath=new File(this.getServletContext().getRealPath(str+"WEB-INF"+str+"classes")+str+"password.properties");

        InputStream path=new FileInputStream(filepath);*/
        Properties pros = new Properties();
        try {
            pros.load(path);
        } catch (IOException ex) {
            //System.out.println("file is not exist");
            errorMessage="资源文件不存在";
        }
        System.out.println("username:"+p.getProperty("username")+",password:"+p.getProperty("password"));

2.    import org.springframework.core.io.ClassPathResource;

        ClassPathResource cr = new ClassPathResource("password.properties");//会重新加载spring框架
        Properties pros = new Properties();
        try {
            pros.load(cr.getInputStream());
        } catch (IOException ex) {
            //System.out.println("file is not exist");
            errorMessage="资源文件不存在";
        }

3.使用java.util.Properties类的load()方法
示例： InputStream in = lnew BufferedInputStream(new FileInputStream(name));
Properties p = new Properties();
p.load(in);

4.使用java.util.ResourceBundle类的getBundle()方法
示例： ResourceBundle rb = ResourceBundle.getBundle(name, Locale.getDefault());

5.使用java.util.PropertyResourceBundle类的构造函数
示例： InputStream in = new BufferedInputStream(new FileInputStream(name));
ResourceBundle rb = new PropertyResourceBundle(in);

6.使用class变量的getResourceAsStream()方法
示例： InputStream in = JProperties.class.getResourceAsStream(name);
Properties p = new Properties();
p.load(in);

7.使用class.getClassLoader()所得到的java.lang.ClassLoader的getResourceAsStream()方法
示例： InputStream in = JProperties.class.getClassLoader().getResourceAsStream(name);
Properties p = new Properties();
p.load(in);

8.使用java.lang.ClassLoader类的getSystemResourceAsStream()静态方法
示例： InputStream in = ClassLoader.getSystemResourceAsStream(name);
Properties p = new Properties();
p.load(in);