在java中通常会有变量，但是如果想改变变量的值，老是在程序里面改很麻烦，最方便的就是在配置文件里面改。程序直接引用就可以了。下面我就来分享一下。。。。

先在常量类里面定义

SystemParams.java

public static String COLLECTION_MUSIC_HOUR="collection_music_hour";

配置文件

config.properties

collection_music_hour=14:40

下面就是如何把变量从配置文件里面取值

MyEncryptablePropertyPlaceholderConfigurer.java

package com.chinaGPS.song.util;

import java.util.Map;

import java.util.Properties;

import org.apache.commons.lang.StringUtils;

import org.jasypt.commons.CommonUtils;

import org.jasypt.encryption.StringEncryptor;

import org.jasypt.properties.PropertyValueEncryptionUtils;

import org.jasypt.util.text.TextEncryptor;

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.BeanInitializationException;

import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;

import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;

import com.chinaGPS.song.util.constant.SystemParams;

public final class MyEncryptablePropertyPlaceholderConfigurer

private final StringEncryptor stringEncryptor;

private final TextEncryptor textEncryptor;

private Map resolvedProps;//将属性保存起来

public MyEncryptablePropertyPlaceholderConfigurer(

final StringEncryptor stringEncryptor) {

super();

CommonUtils.validateNotNull(stringEncryptor, "Encryptor cannot be null");

this.stringEncryptor = stringEncryptor;

this.textEncryptor = null;

}

public MyEncryptablePropertyPlaceholderConfigurer(final TextEncryptor textEncryptor) {

super();

CommonUtils.validateNotNull(textEncryptor, "Encryptor cannot be null");

this.stringEncryptor = null;

this.textEncryptor = textEncryptor;

}

@Override

protected String convertPropertyValue(final String originalValue) {

if (!PropertyValueEncryptionUtils.isEncryptedValue(originalValue)) {

return originalValue;

}

if (this.stringEncryptor != null) {

return PropertyValueEncryptionUtils.decrypt(originalValue,

this.stringEncryptor);

}

return PropertyValueEncryptionUtils.decrypt(originalValue, this.textEncryptor);

}

@Override

protected String resolveSystemProperty(final String key) {

return convertPropertyValue(super.resolveSystemProperty(key));

}

@Override

protected void processProperties(

ConfigurableListableBeanFactory beanFactoryToProcess,

Properties props) throws BeansException {

super.processProperties(beanFactoryToProcess, props);

tmp=resolvePlaceholder(SystemParams.COLLECTION_MUSIC_HOUR, props);

if(StringUtils.isBlank(tmp)) {

logger.error(SystemParams.COLLECTION_MUSIC_HOUR+"解析出错");

throw new BeanInitializationException(SystemParams.COLLECTION_MUSIC_HOUR+"属性为空");

}

SystemParams.COLLECTION_MUSIC_HOUR  = tmp;

}

最后就是通过spring的注入

class="com.chinaGPS.song.util.MyEncryptablePropertyPlaceholderConfigurer">

///WEB-INF/jdbc/mysql.properties

/WEB-INF/jdbc/config.properties