通用Propterties工具类，兼容读jar同级目录的文件。

1.前言。
  properties文件的写方法比较不好用，折中写了个通用类。
2.例子。

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

/**
 * 读取Properties综合类
 * 
 * @author lijn 2014-02-25
 */
public class PropertiesUtil {
	/**
	 * 得到某一个类的路径
	 * 
	 * @param name
	 * @return
	 */
	public static String getPath(Class name) {
		String strResult = null;
		if (System.getProperty("os.name").toLowerCase().indexOf("window") > -1) {
			strResult = name.getResource("/").toString().replace("file:/", "")
					.replace("%20", " ");
		} else {
			strResult = name.getResource("/").toString().replace("file:", "")
					.replace("%20", " ");
		}
		return strResult;
	}

	/**
	 * 读取所有的property
	 * 
	 * @param filename
	 *            properties文件路径
	 * @return 所有的property的集合(map形式)
	 */
	@SuppressWarnings("unchecked")
	public static Map<String, String> getPropties(String filename) {
		if (null == filename) {
			return null;
		}
		String filePath = getPath(PropertiesUtil.class) + filename;
		Properties props = new Properties();
		InputStream in = null;
		try {
			in = new BufferedInputStream(new FileInputStream(filePath));
			props.load(in);
			Map<String, String> map = new HashMap<String, String>();
			Enumeration en = props.propertyNames();
			while (en.hasMoreElements()) {
				String key = (String) en.nextElement();
				String Property = props.getProperty(key);
				map.put(key, Property);
			}
			return map;
			// 关闭资源
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				in.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return null;
	}

	/**
	 * 获取某个property的值
	 * 
	 * @param filename
	 *            文件名
	 * @param key
	 *            property的key
	 * @return property的value
	 */
	public static String setProp(String filename, String key, String value) {
		if (null == filename || null == key) {
			return null;
		}
		String filePath = getPath(PropertiesUtil.class) + filename;
		Properties props = new Properties();
		FileOutputStream out = null;
		InputStream in = null;
		try {
			in = new BufferedInputStream(new FileInputStream(filePath));
			props.load(in);
			out = new FileOutputStream(new File(filePath));
			props.setProperty(key, value);
			props.store(out, "update");
			// 关闭资源
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				out.close();
				in.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return null;
	}

	/**
	 * 获取某个property的值
	 * 
	 * @param filename
	 *            文件名
	 * @param key
	 *            property的key
	 * @return property的value
	 */
	public static String getProp(String filename, String key) {
		if (null == filename || null == key) {
			return null;
		}
		String filePath = getPath(PropertiesUtil.class) + filename;
		Properties props = new Properties();
		InputStream in = null;
		try {
			in = new BufferedInputStream(new FileInputStream(filePath));
			props.load(in);
			return props.getProperty(key);
			// 关闭资源
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				in.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return null;
	}

	/**
	 * 需要将config.properies文件放到和本类同级目录下面
	 * 
	 * @param filename
	 * @param key
	 * @param value
	 * @return
	 */
	public static String setJarProp(String filename, String key, String value) {
		if (null == filename || null == key) {
			return null;
		}
		String filePath = getPath(PropertiesUtil.class) + filename;
		Properties props = new Properties();
		FileOutputStream out = null;
		InputStream in = null;
		try {
			in = PropertiesUtil.class.getResourceAsStream("config.properties");
			// System.out.println(PropertiesUtil.class.getClassLoader().getResource("config.properties"));
			BufferedInputStream b2 = new BufferedInputStream(in);
			props.load(b2);

			out = new FileOutputStream(filePath);
			props.setProperty(key, value);
			props.store(out, "update");
			// 关闭资源
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				out.close();
				in.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return null;
	}

	/**
	 * 读写jar外的properties文件
	 * 
	 * @param filename
	 * @param key
	 * @param value
	 */
	public static void setExtralProperty(String filename, String key,
			String value) {
		if (null == filename || null == key) {
			return;
		}
		String outPathString = System.getProperty("java.class.path");
		outPathString = outPathString.substring(0, outPathString
				.lastIndexOf("\\") + 1);

		String filePath = outPathString + filename;
		Properties props = new Properties();
		FileOutputStream out = null;
		BufferedInputStream b2 = null;
		try {
			b2 = new BufferedInputStream(new FileInputStream(filePath));
			props.load(b2);

			out = new FileOutputStream(new File(filePath));
			props.setProperty(key, value);
			props.store(out, "update");
			// 关闭资源
		} catch (FileNotFoundException e) {
			setProp(filename,key,value);
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				if(null!=out){
				 out.close();
				}
				if(null!=b2){
				b2.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

	}
	/**
	 * 以行的形式写ja内的文件
	 * 
	 * @param filename
	 * @param key
	 * @param value
	 */
	public static void writeLineInerFile(String filename, String content) {
		if (null == filename || null == content) {
			return;
		}
		String filePath = getPath(PropertiesUtil.class) + filename;
	
		FileOutputStream out = null;
		BufferedInputStream b2 = null;
		byte[] cont=new byte[4];
		String contentResult="";
		try {
			//先读取源文件的内容，再追加内容
			b2 = new BufferedInputStream(new FileInputStream(filePath));
			int res=b2.read(cont);
			while(res!=-1){
				contentResult=contentResult+new String(cont);
				res=b2.read(cont);
			}
			//追加
			contentResult+=content;
			out = new FileOutputStream(new File(filePath));
			out.write(contentResult.getBytes());
			// 关闭资源
		} catch (FileNotFoundException e) {
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				if(null!=out){
				 out.close();
				}
				if(null!=b2){
				b2.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}


	}
	/**
	 * 以行的形式写jar外的文件
	 * 
	 * @param filename
	 * @param key
	 * @param value
	 */
	public static void writeLineExtralFile(String filename, String content) {
		if (null == filename || null == content) {
			return;
		}
		String outPathString = System.getProperty("java.class.path");
		outPathString = outPathString.substring(0, outPathString
				.lastIndexOf("\\") + 1);

		String filePath = outPathString + filename;
		FileOutputStream out = null;
		BufferedInputStream b2 = null;
		byte[] cont=new byte[1024];
		String contentResult="";
		try {
			//先读取源文件的内容，再追加内容
			b2 = new BufferedInputStream(new FileInputStream(filePath));
			int res=b2.read(cont);
			while(res!=-1){
				contentResult=contentResult+new String(cont);
				res=b2.read(cont);
			}
			//追加
			contentResult+=content;
			out = new FileOutputStream(filePath);
			out.write(contentResult.getBytes());
			// 关闭资源
		} catch (FileNotFoundException e) {
			writeLineInerFile(filename,content);
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				if(null!=out){
				 out.close();
				}
				if(null!=b2){
				b2.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

	}
	/**
	 * 读jar外的properties文件的属性
	 * 
	 * @param filename
	 * @param key
	 * @param value
	 */
	public static String getExtralProperty(String filename, String key) {
		if (null == filename || null == key) {
			return null;
		}
		String outPathString = System.getProperty("java.class.path");
		outPathString = outPathString.substring(0, outPathString
				.lastIndexOf("\\") + 1);

		String filePath = outPathString + filename;
		Properties props = new Properties();
		BufferedInputStream b2=null;
		try {
			 b2 = new BufferedInputStream(new FileInputStream(filePath));
			props.load(b2);
			return props.getProperty(key);
			// 关闭资源
		} catch (FileNotFoundException e) {
		  return getProp(filename,key);
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				if(null!=b2){
					b2.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		return null;

	}

	public static void main(String[] args) throws IOException {
		writeLineExtralFile("error.txt","fiowe");

	}
}

3.后记。
   如果是要读jar里面的src直属的properties,直接用ResourseBundle就可以了。

ResourceBundle resourceBundle = ResourceBundle.getBundle(filename
				.replace(".properties", ""));
		String temp = resourceBundle.getString(key);