定义一个加密解密工具类：

import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;

import java.util.Base64;
import java.util.Base64.Decoder;
import java.util.Base64.Encoder;

public class DesUtil {
	private static Key key;
	private static String KEY_STR="miyao";
	private static String CHARSETNAME="UTF-8";
	private static String ALGORTHM="DES";
	
	static {
		try {
			//生成DES算法对象
			KeyGenerator generator=KeyGenerator.getInstance(ALGORTHM);
			//运用SHA1安全策略
			SecureRandom secureRandom=SecureRandom.getInstance("SHA1PRNG");
			//设置秘钥种子
			secureRandom.setSeed(KEY_STR.getBytes());
			//初始化基于SHAI的算法对象
			generator.init(secureRandom);
			//生成秘钥对象
			key=generator.generateKey();
			generator=null;
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
	}
	/**
	 * 获取加密后的信息
	 * @param str
	 * @return
	 */
	public static String getEncryptString(String str) {
		//基于base64编码
		Encoder encoder=Base64.getEncoder();
		try {
			//按utf-8编码
			byte[] bytes=str.getBytes(CHARSETNAME);
			//获取加密对象
			Cipher cipher=Cipher.getInstance(ALGORTHM);
			//初始化密码信息
			cipher.init(Cipher.ENCRYPT_MODE, key);
			//加密
			byte[] doFimal=cipher.doFinal(bytes);
			//byte[]to encode好的String并返回
			return encoder.encodeToString(doFimal);
		}catch(Exception e) {
			throw new RuntimeException(e);
		}
	}
	/**
	 * 获取解密后的信息
	 * @param str
	 * @return
	 */
	public static String getDecryptString(String str) {
		Decoder decoder=Base64.getDecoder();
		try {
			byte[] bytes=decoder.decode(str);
			//获取解密对象
			Cipher cipher=Cipher.getInstance(ALGORTHM);
			//初始化解密信息
			cipher.init(Cipher.DECRYPT_MODE, key);
			//解密
			byte[] doFinal=cipher.doFinal(bytes);
			//返回解密之后的信息
			return new String(doFinal,CHARSETNAME);
		}catch(Exception e) {
			throw new RuntimeException(e);
		}
	}
}

示例：数据库的用户名和密码

jdbc.properties：关键属性使用加密后的

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/o2o?useUnicode=true&characterEncoding=utf8
jdbc.username=ggbPQcbwMcGf1UPGEUj6qq==
jdbc.password=QPGTeS3Pmnn=

spring配置文件：

<bean class="包.EncryptPropertyPlaceholderConfig">
	    <property name="locations">
		    <list>
		    <value>classpath:jdbc.properties</value>
		    <value>xxxx.properties</value>
		    </list>
	    </property>
    	<property name="fileEncoding" value="UTF-8"></property>
    </bean>

属性被拦截解码重新赋值使用：

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

public class EncryptPropertyPlaceholderConfig extends PropertyPlaceholderConfigurer {
	//需要加密的字段数组
	private String[] encryptPropNames= {"jdbc.username","jdbc.password"};
	
	/**
	 * 对关键属性进行转换
	 */
	@Override
	protected String convertProperty(String propertyName, String propertyValue) {
		if(isEncryptProp(propertyName)) {
			String decryptValue = DesUtil.getDecryptString(propertyValue);
			return decryptValue;
		} else {
			return propertyValue;
		}
	}
	
	private boolean isEncryptProp(String propertyName) {
		for (String encryptpropertyName : encryptPropNames) {
			if (encryptpropertyName.equals(propertyName)) {
				return true;
			}
		}
		return false;
	}
}