使用SSM框架開發WEB專案時，資料庫的賬號密碼一般會寫在dbconfig.properties裡，為了做到保護版權等效果，要對資料庫賬號密碼進行加密，一共有分為三步。

一、建立DESUtil類

提供自定義金鑰，加密解密的方法。

package com.hzdy.DCAD.common.util;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import java.security.Key;
import
 
 java.security.SecureRandom;

/**
 * Created by Wongy on 2017/10/30.
 */
public class DESUtil {
    private static Key key;
    //自己的金鑰
    private static String KEY_STR = "mykey";

    static {
        try {
            KeyGenerator generator = KeyGenerator.getInstance("DES");
            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);
        }
    }

    /**
     * 對字串進行加密，返回BASE64的加密字串
     *
     * @param
 
 str
     * @return
     * @see [類、類#方法、類#成員]
     */
    public static String getEncryptString(String str) {
        BASE64Encoder base64Encoder = new BASE64Encoder();
        try {
            byte[] strBytes = str.getBytes("UTF-8");
            Cipher cipher = Cipher.getInstance("DES");
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] encryptStrBytes = cipher.doFinal(strBytes);
            return base64Encoder.encode(encryptStrBytes);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }

    }

    /**
     * 對BASE64加密字串進行解密
     *
     */
    public static String getDecryptString(String str) {
        BASE64Decoder base64Decoder = new BASE64Decoder();
        try {
            byte[] strBytes = base64Decoder.decodeBuffer(str);
            Cipher cipher = Cipher.getInstance("DES");
            cipher.init(Cipher.DECRYPT_MODE, key);
            byte[] encryptStrBytes = cipher.doFinal(strBytes);
            return new String(encryptStrBytes, "UTF-8");
        } catch (Exception e) {
            throw new RuntimeException(e);
        }

    }


    public static void main(String[] args) {
        String name = "root";
        String password = "hzdy2016";
        String encryname = getEncryptString(name);
        String encrypassword = getEncryptString(password);
        System.out.println("encryname : " + encryname);
        System.out.println("encrypassword : " + encrypassword);

        System.out.println("name : " + getDecryptString(encryname));
        System.out.println("password : " + getDecryptString(encrypassword));
    }
}

二、 建立EncryptPropertyPlaceholderConfigurer類

建立與配置檔案的關聯。

package com.hzdy.DCAD.common.util;

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

public class EncryptPropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {
    //屬性需與配置檔案的KEY保持一直
    private String[] encryptPropNames = {"jdbc.username", "jdbc.password"};

    @Override
    protected String convertProperty(String propertyName, String propertyValue) {

        //如果在加密屬性名單中發現該屬性  
        if (isEncryptProp(propertyName)) {
            String decryptValue = DESUtil.getDecryptString(propertyValue);
            System.out.println(decryptValue);
            return decryptValue;
        } else {
            return propertyValue;
        }

    }

    private boolean isEncryptProp(String propertyName) {
        for (String encryptName : encryptPropNames) {
            if (encryptName.equals(propertyName)) {
                return true;
            }
        }
        return false;
    }
} 

修改配置檔案

將spring-context中的
<context:property-placeholder location="classpath:.properties" />
修改為
<bean class="com.hzdy.DCAD.common.util.EncryptPropertyPlaceholderConfigurer"p:locations="classpath:*.properties"/>
//注意只能存在一個讀取配置檔案的bean，否則系統只會讀取最前面的

這個時候就能實現，在配置檔案中寫密文，系統讀取時自動變成明文的效果。