java.util.Properties 的常见使用方法

Properties 文件通常被用来当做 java 的配置文件使用，通过键值对来操作数据, 在实际的使用过程中，经常会有如下一些用法.
1. 从文件中得到 properties 的各种键值对。
2. 将Properties 对象保存到文件中.
3. 获取Properties 对象某个具体key的值, 如果没有给默认值的情况。
在项目中经常使用的几个处理Properties 的公用类

package com.yihaomen.util;

/**
 * 实现任意properties文件读写,支持各种字符集
 */
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Arrays;


public class PropertiesUtil extends ArrayList {
	private static final long serialVersionUID = 6853092427667171450L;

	// 设置字符集
	private String encoding = "GBK";

	private String fileName;

	@SuppressWarnings("unchecked")
	public PropertiesUtil(String fileName) {
		try {
			this.fileName = fileName;
			if (!isFileExist(fileName))
				this.write("");
			this.addAll(Arrays.asList(read(fileName, encoding).split("\n")));
		} catch (Exception ex) {
			throw new RuntimeException("解析[" + fileName + "]出现异常!", ex);
		}
	}

	@SuppressWarnings("unchecked")
	public PropertiesUtil(String fileName, String encoding) {
		try {
			this.fileName = fileName;
			this.setCharacterEncoding(encoding);
			if (!isFileExist(fileName))
				this.write("");
			this.addAll(Arrays.asList(read(fileName, encoding).split("\n")));
		} catch (Exception ex) {
			throw new RuntimeException("解析[" + fileName + "]出现异常!", ex);
		}
	}

	/**
	 * 设置字符集
	 * 
	 * @param encoding
	 * @throws UnsupportedEncodingException
	 */
	@SuppressWarnings("unused")
	private void setCharacterEncoding(String encoding)
			throws UnsupportedEncodingException {
		this.encoding = encoding;
	}

	private static boolean isFileExist(String fileName) {
		return new File(fileName).isFile();
	}

	/**
	 * read file as single strings
	 * 
	 * @return
	 * @throws IOException
	 */
	private static String read(String fileName, String encoding)
			throws IOException {
		StringBuffer sb = new StringBuffer();
		BufferedReader in = new BufferedReader(new FileReader(fileName));
		String s;
		while ((s = in.readLine()) != null) {
			sb.append(s);
			sb.append("\n");
		}
		in.close();
		return sb.toString();
	}

	/**
	 * write file as single strings
	 * 
	 * @param text
	 * @throws IOException
	 */
	private void write(String text) throws IOException {
		PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(
				fileName)));
		out.print(text);
		out.close();
	}

	/**
	 * save the content to file
	 * 
	 * @throws IOException
	 */
	public void save() throws IOException {
		PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(
				fileName)));
		String tmp;
		for (int i = 0; i < size(); i++) {
			tmp = get(i) + "";
			out.println(tmp);
		}
		out.close();
	}

	/**
	 * set properties file with a par key and value
	 * 
	 * @param key
	 * @param val
	 * @throws UnsupportedEncodingException
	 */
	@SuppressWarnings("unchecked")
	public void setProperties(String key, String val) {
		int ipos = findKey(key);
		if (ipos >= 0)
			this.set(ipos, key + "=" + val);
		else
			this.add(key + "=" + val);
	}

	/**
	 * 查找KEY的序号
	 * 
	 * @param key
	 * @return
	 */
	private int findKey(String key) {
		try {
			String tmp;
			for (int i = 0; i < size(); i++) {
				tmp = get(i) + "";
				tmp = new String(tmp.getBytes("GBK"), encoding);
				if (tmp.indexOf(key) == 0) {
					return i;
				}
			}
		} catch (Exception e) {
		}
		return -1;
	}

	/**
	 * 增加备注
	 * 
	 * @param memo
	 */
	@SuppressWarnings("unchecked")
	public void setMemo(String key, String memo) {
		if ("".equals(key)) {
			this.add("#" + memo);
			return;
		}
		String tmp;
		int ret = findKey(key);
		if (ret == -1) {
			this.add("#" + memo);
			this.add(key + "=");
		} else {
			int ipos = ret - 1;
			if (ipos < 0)
				this.add(ipos, "#" + memo);
			else {
				tmp = this.get(ipos) + "";
				if ("#".equals(tmp.substring(0, 1)))
					this.set(ipos, "#" + memo);
				else
					this.add(ipos + 1, "#" + memo);
			}
		}
	}

	/**
	 * get the value of a key
	 * 
	 * @param key
	 * @return
	 */
	public String getProperties(String key) {
		return getProperties(key, "");
	}

	public String getProperties(String key, String defaultStr) {
		if (key == null) {
			return defaultStr;
		}
		String tmp, ret;
		try {
			for (int i = 0; i < size(); i++) {
				tmp = get(i) + "";
				tmp = new String(tmp.getBytes("GBK"), encoding);
				if (tmp.indexOf(key) == 0) {
					ret = tmp.substring(key.length() + 1);
					return ret;
				}
			}
		} catch (Exception ex) {
			throw new RuntimeException("获取[" + fileName + "]中属性[" + key
					+ "]的值出现异常!", ex);
		}
		return defaultStr;
	}

	// Simple test:
	public static void main(String[] args) throws Exception {
		String path = "E:\\PropetiesUtil\\test.properties";
		PropertiesUtil pro = new PropertiesUtil(path);
		pro.setProperties("test", "测试测试");
		pro.setProperties("must", "1");
		pro.setProperties("hehe", "it's so simple");
		pro.save();
		System.out.println(pro.getProperties("test"));
		pro = null;
	}
}

一个处理多语言自定义国际化的类, 也用来处理 porperties 文件
如果自己写一个多语言的应用程序，自己在应用程序总定义了如下几个国际化的文件：
1.application_zh_CN.properties
2.application_cn.properties

要的到文件里面国际化的内容也有通用的方法，当然，你可以采用上面的方法，一个更简单的方法如下:

package com.yihaomen.util;

import java.text.MessageFormat;
import java.util.Locale;
import java.util.ResourceBundle;


public class ResourcesUtil {

	/**
	 * 通过Key获取对应的统一资源文件中的描述信息
	 * 
	 * @param args
	 *            参数输入顺序：第一个参数为key，从第二个往后对应为Resource文件中的{0}、{1}、{2}
	 * @return String
	 */
	public static String getText(Object... args) {
		if (args == null || args.length == 0) {
			throw new RuntimeException(
					"bad parameters of ResourceUtil.getText.");
		}
		String key = args[0].toString();

		Locale locale = null;
		String bundleName = null;
		//国际化的文件放在这个package 下面.
		bundleName = "com.yihaomen.ApplicationResources";
		locale = Locale.SIMPLIFIED_CHINESE;
		
		ResourceBundle rb = ResourceBundle.getBundle(bundleName, locale);
		String msg = rb.getString(key);
		if (msg == null) {
			throw new RuntimeException("bundle key not found:" + key);
		}
		Object[] fmargs = new Object[args.length - 1];
		if (fmargs.length == 0) {
			return msg;
		}
		for (int i = 0; i < fmargs.length; i++) {
			fmargs[i] = args[i + 1];
		}
		return MessageFormat.format(msg, fmargs);
	}
}

这是常用来处理properties 文件的两个工具类，可以直接在项目中使用，也还有别的方法，与 properties 相关的操作方法，还可以参考这里:
Propeties文件与stream 之间的转换

From：一号门