Java操作properties文件

package com.hibernate.utils.util1;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

public final class PropertiesUtil {

    /**
     * 读取某个属性的值
     */
    public static String getProperty(String fileName, String propertyName) {
        Properties prop = new Properties();
        InputStream in = null;
        try {
            in = new FileInputStream(getFilePath() + fileName);
            prop.load(in);
            String propertyValue = prop.getProperty(propertyName);
            return propertyValue;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        } finally {
            try {
                in.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 增加或修改属性
     */
    public static void saveOrUpdateProperty(String fileName, String propertyName, String propertyValue) {
        Map<String, String> toSaveMap = getProperties(fileName);
        toSaveMap.put(propertyName, propertyValue);// 添加或更新属性
        Properties prop = new Properties();
        OutputStream out = null;
        try {
            out = new FileOutputStream(getFilePath() + fileName);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        prop.putAll(toSaveMap);
        try {
            prop.store(out, "come from add Or update action");// 更新properties文件
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 删除属性
     */
    public static void deleteProperty(String fileName, String propertyName) {
        Map<String, String> toSaveMap = getProperties(fileName);
        toSaveMap.remove(propertyName);// 移除属性
        Properties prop = new Properties();
        OutputStream out = null;
        try {
            out = new FileOutputStream(getFilePath() + fileName);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        prop.putAll(toSaveMap);
        try {
            prop.store(out, "");// 更新properties文件
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取类所在的绝对路径
     */
    public static String getFilePath() {
        return PropertiesUtil.class.getClass().getResource("/").getPath();
    }

    /**
     * 读取properties文件的所有属性
     */
    public static Map<String, String> getProperties(String fileName) {
        Properties prop = new Properties();
        try {
            InputStream in = new FileInputStream(getFilePath() + fileName);
            prop.load(in);// 加载属性值
        } catch (IOException e) {
            e.printStackTrace();
        }
        Map<String, String> toSaveMap = new HashMap<String, String>();
        Set<Object> keys = prop.keySet();
        Iterator<Object> it = keys.iterator();
        while (it.hasNext()) {
            String key = (String) it.next();
            String value = (String) prop.get(key);
            toSaveMap.put(key, value);
        }
        return toSaveMap;
    }

}