在我们日常的开发中，必须要连接数据库，但是数据库的账户和密码有么有加密呢？在这里我们使用DES对称加密算法

步骤

1. 编写一个DESUtil，我从网上搞了一个过来，贴在这里

   import java.security.Key;
   import java.security.SecureRandom;
   import javax.crypto.Cipher;
   import javax.crypto.KeyGenerator;
   import sun.misc.BASE64Decoder;
   import sun.misc.BASE64Encoder;
   
   @SuppressWarnings("restriction")
   public class DESUtils {
   
       private static Key key;
       private static String KEY_STR = "myKey";
       private static String CHARSETNAME = "UTF-8";
       private static String ALGORITHM = "DES";
   
       static {
           try {
               KeyGenerator generator = KeyGenerator.getInstance(ALGORITHM);
               SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
               secureRandom.setSeed(KEY_STR.getBytes());
               generator.init(secureRandom);
               key = generator.generateKey();
               generator = null;
           } catch (Exception e) {
               throw new RuntimeException(e);
           }
       }
   
       public static String encrypt(String str) {
           BASE64Encoder base64encoder = new BASE64Encoder();
           try {
               byte[] bytes = str.getBytes(CHARSETNAME);
               Cipher cipher = Cipher.getInstance(ALGORITHM);
               cipher.init(Cipher.ENCRYPT_MODE, key);
               byte[] doFinal = cipher.doFinal(bytes);
               return base64encoder.encode(doFinal);
           } catch (Exception e) {
               throw new RuntimeException(e);
           }
       }
   
       public static String decrypt(String str) {
           BASE64Decoder base64decoder = new BASE64Decoder();
           try {
               byte[] bytes = base64decoder.decodeBuffer(str);
               Cipher cipher = Cipher.getInstance(ALGORITHM);
               cipher.init(Cipher.DECRYPT_MODE, key);
               byte[] doFinal = cipher.doFinal(bytes);
               return new String(doFinal, CHARSETNAME);
           } catch (Exception e) {
               throw new RuntimeException(e);
           }
       }
   
   }
   

2. 使用上面的类加密自己的账户和密码，并把结果填写到配置文件中
3. 编写配置类

   import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
   
   public class EncryptPropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {
       
       private String[] encryptPropNames = { "jdbc.username", "jdbc.password" };
   
       @Override
       protected String convertProperty(String propertyName, String propertyValue) {
           if (isEncrypted(propertyName)) {
               String decryptValue = DESUtil.decrypt(propertyValue);
               return decryptValue;
           } else {
               return propertyValue;
           }
       }
   
       private boolean isEncrypted(String propertyName) {
           for (String encryptpropertyName : encryptPropNames) {
               if (encryptpropertyName.equals(propertyName)) {
                   return true;
               }
           }
           return false;
       }
       
   }
   

4. 使用上面编写的类替换context:property-placeholder

   <bean class="org.sherekr.dfo.core.util.EncryptPropertyPlaceholderConfigurer">
       <property name="locations">
           <list>
               <value>classpath:jdbc.properties</value>
           </list>
       </property>
       <property name="fileEncoding" value="UTF-8" />
   </bean>
   

5. 完成编写，启动测试