Java讀取Properties文件的六種方法

使用JavaSE API讀取Properties文件的六種方法

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

2。使用java.util.ResourceBundle類的getBundle()方法
示例： ResourceBundle rb = ResourceBundle.getBundle(name, Locale.getDefault());

3。使用java.util.PropertyResourceBundle類的構造函數
示例： InputStream in = new BufferedInputStream(new FileInputStream(name));
ResourceBundle rb = new PropertyResourceBundle(in);

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

5。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);

6。使用java.lang.ClassLoader類的getSystemResourceAsStream()靜態方法
示例： InputStream in = ClassLoader.getSystemResourceAsStream(name);
Properties p = new Properties();
p.load(in);

補充

Servlet中可以使用javax.servlet.ServletContext的getResourceAsStream()方法
示例：InputStream in = context.getResourceAsStream(path);
Properties p = new Properties();
p.load(in);

public class PropertyUtils extends PropertyPlaceholderConfigurer {

    public static final String MD5_KEY = "md5_key";
   
    private Properties properties;
   
    public String getProperty(String key) throws Exception{
        if(properties == null){
            properties = mergeProperties();
        }
        return properties.getProperty(key);
    }
   
    private Map<String, String> sysProperties;
   
    public Map<String, String> getSysProperties(){
        return sysProperties;
    }
   
    public void setSysProperties(Map<String, String> sysProperties){
        Set<String> keySet = sysProperties.keySet();
        for(String key : keySet){
            String value = sysProperties.get(key);
            System.setProperty(key, value);
        }
    }
   
   
    public static void main(String args[]) throws Exception{
       
        /**
         *     <bean id="propertyConfigurer" class="com.grabweb.util.PropertyUtils">
         *    <property name="locations" value="web.properties" />
         *  </bean>
         *  md5_key = SBXT6XT2ZT9MNNC1WP7EDE86K1R6KNJDMWMRK5AOHS7CI7AALDHB9DGBF786WAIK
         */
        ApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"applicationContext.xml"});
        PropertyUtils pu = (PropertyUtils)context.getBean("propertyConfigurer");
        String result = pu.getProperty(PropertyUtils.MD5_KEY);
        System.out.println(result);
    }
   
}