Java读写properties配置文件

package com.util;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.Properties;

/**
* 功能：读写配置文件
* @author Adam
*
*/
public class PropertyHelper {
static String profilepath = PropertyHelper.class.getClassLoader().
getResource("").getPath() + "config.properties";
private static Properties props = new Properties();
static {
try {
System.out.println("配置文件路径："+profilepath);
InputStream is = new BufferedInputStream (new FileInputStream(profilepath));
props.load(is);
is.close();
}catch (IOException e) {
e.printStackTrace();
}
}

/**
* 功能：根据key获得value
* @param key：key
* @return String：value
*/
public static String getValueByKey(String key) {
return props.getProperty(key);
}

/**
* 功能：根据属性文件路径和key读取value
* @param filePath：属性文件路径
* @param key：键名
*/
public static String readValue(String filePath, String key) {
Properties props = new Properties();
try {
InputStream in = new BufferedInputStream(new FileInputStream(filePath));
props.load(in);
return props.getProperty(key);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

/**
* 功能：写入properties文件的键值对，key存在，则修改，key不存在则添加
* @param keyname：key
* @param keyvalue：value
*/
public static void writeProperties(String keyname,String keyvalue) {
try {
props.load(new FileInputStream(profilepath));
OutputStream fos = new FileOutputStream(profilepath);
props.setProperty(keyname, keyvalue);
props.store(fos, "Update '" + keyname + "' value");
} catch (IOException e) {
System.err.println("属性文件写入异常");
}
}

/**
* 功能：读取properties的全部信息
* @param filePath：属性文件路径
*/
public static void readProperties(String filePath) {
Properties props = new Properties();
try {
InputStream is = new BufferedInputStream (new FileInputStream(filePath));
props.load(is);
Enumeration en = props.propertyNames();
while (en.hasMoreElements()) {
String key = (String) en.nextElement();
String Property = props.getProperty (key);
System.out.println(key + "=" + Property);
}
} catch (Exception e) {
e.printStackTrace();
}
}

public static void main(String[] args) {
System.out.println(PropertyHelper.getValueByKey("SYSTEM_SMTP"));
PropertyHelper.writeProperties("SYSTEM_SMTP","中文");
readProperties(profilepath);
}
}