将属性文件以key-value值形式输出的工具类

package com.lmb.util;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Properties;
import java.util.Set;

public class PropertyUtil {
private HashMap<String, String> map = null;

private HashMap<String, String> reverseMap = null;

private String fileDir = "";

/**
* 功能描述：获取fileDir文件的内容，将其以key-value的形式解析到一个map中
* @param fileDir 文件名
*/
public PropertyUtil(String fileDir) {
this.fileDir = fileDir;
map = new HashMap<String, String>();
try {
String key = "";
String value = "";
Properties props = new Properties();
//得到fileDir文件的输入流并将其load到我们生成的Properties对象中
props.load(PropertyUtil.class.getClassLoader()
.getResourceAsStream(fileDir));
//遍历这个Properties对象，将对象内容以key-value的形式解析到map中
Enumeration enumFile = props.keys();
for (int i = 0; i < props.size(); i++) {
key = (String) enumFile.nextElement();
value = props.getProperty(key);
map.put(key, value);
}
} catch (IOException e) {
System.out.println("I/O error occurs when reading the file");
e.printStackTrace();
}
}

/**
* 功能描述：获取fileDir文件的内容，将其以value-key的反转形式解析到一个map中
* @param fileDir 文件名
*/
public void reverse() {
reverseMap = new HashMap<String, String>();
try {
String key = "";
String value = "";
Properties props = new Properties();
props.load(PropertyUtil.class.getClassLoader()
.getResourceAsStream(fileDir));
Enumeration enumFile = props.keys();
for (int i = 0; i < props.size(); i++) {
key = (String) enumFile.nextElement();
value = props.getProperty(key);
reverseMap.put(value, key);//map.put(key, value)
}
} catch (IOException e) {
System.out.println("I/O error occurs when reading the file");
e.printStackTrace();
}
}

/**
* 功能描述：通过key获取到该key对应的value值
* @param key
* @return value
*/
public String getValueByKey(String key) {
return (String) map.get(key);
}

/**
* 功能描述：获取map集合的所有key值
* @return
*/
public ArrayList getKeyList() {
Set keySet = map.keySet();
Object[] keyArray = keySet.toArray();
ArrayList<String> keyList = new ArrayList<String>();
for (int i = 0; i < keyArray.length; i++) {
String tempKey = (String) keyArray[i];
keyList.add(tempKey);
}
return keyList;
}

/**
* 功能描述：获取反转map中key对应的value值（也就是正常情况下value对应的key）
* @param key
* @return
*/
public String getReverseValueByKey(String key) {
if (reverseMap==null){
reverse();
return (String) reverseMap.get(key);
}else{
return (String) reverseMap.get(key);
}
}

/**
* test
* @param args
*/
public static void main(String[] args) {
System.out.println("________test start!______");
PropertyUtil pu = new PropertyUtil("user.properties");
for (int i = 0; i < pu.getKeyList().size(); i++) {
System.out.println("   " + pu.getKeyList().get(i) + "="
+ pu.getValueByKey((String) pu.getKeyList().get(i)));
}
System.out.println(pu.getValueByKey("USERNAME").trim());
System.out.println("_________test end!_______");
}
}