properties文件配置數據

在代碼中有些項目是要變的，最好配置在config.properties文件中，方便修改的同時不影響程序。
在WEB-INF下建立config.properties文件，他是以鍵值對的形式存在的

UserName=name
Password=123

然後就是在java文件中讀取到配置文件中的值
比如我們有一個ParameterUtil文件

public class ParameterUtil{

	public static String getPara(String para) {
		String path = ParameterUtil.class.getResource("/").getPath(); 
		path = path.substring(1, path.indexOf("classes"));
		path = path + "config.properties";

		Properties property = PropertyUtil.getProperties(path);

		return property.getProperty(para);
	}
}

[b]注意[/b]：以上生成的路徑不能有空格space，所以文件路徑要去掉空格，比如：tomcat 6就不行，中間的空格要去掉。
PropertyUtil如下：

public class PropertyUtil {
	public static String readData(String path, String key) {
		Properties props = new Properties();
		InputStream in = null;
		FileInputStream fis = null;
		try {
			fis = new FileInputStream(path);
			in = new BufferedInputStream(fis);
			props.load(in);
			fis.close();
			in.close();
			String value = props.getProperty(key);
			props =null;
			System.gc();
			return value;
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	public static void writeData(String path, String key, String value) {
		Properties prop = new Properties();
		try {
			File file = new File(path);
			if (!file.exists())
				file.createNewFile();
			InputStream fis = new FileInputStream(file);
			prop.load(fis);
			fis.close();
			OutputStream fos = new FileOutputStream(path);
			prop.setProperty(key, value);
			prop.store(fos, "Update '" + key + "' value");
			fos.close();
			prop = null;
			System.gc();
		} catch (IOException e) {
			System.err.println("Visit " + path + " for updating " + value
					+ " value error");
		}
	}

	public static Map<String, String> getMap(String path) {
		Properties props = new Properties();
		InputStream in = null;
		FileInputStream fis = null;
		Map<String, String> map = null;
		try {
			fis = new FileInputStream(path);
			in = new BufferedInputStream(fis);
			props.load(in);
			fis.close();
			in.close();
			Set<Object> set = props.keySet();
			map = new HashMap<String, String>();
			for (Object o : set) {
				String tempKey = o.toString();
				String value = props.getProperty(tempKey);
				map.put(tempKey, value);
			}
			props = null;
			System.gc();
			return map;
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	public static Properties getProperties(String path) {
		Properties props = new Properties();
		InputStream in = null;
		FileInputStream fis = null;
		try {
			fis = new FileInputStream(path);
			in = new BufferedInputStream(fis);
			props.load(in);
			fis.close();
			in.close();
			System.gc();
			return props;
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}
}

調用方式如下：ParameterUtil.getPara("UserName")
這樣就完成了參數配置，改起來方便。