Java 文件加密

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好记忆不如烂笔头，有些东西，可能简单，但是用到的时候却不一定能立马想起来，所以即便是再简单的知识，写出来，记忆一下还是很好的！

文件加密，可以很好的来判断两个文件是否相等。

废话不说了，直接上代码来看吧，详细的描述都在文件中描述了！

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.security.MessageDigest;

/**

* 文件加密

public class EncryptFile {

public static void main(String[] args) {

File file1 =new File("2.jar");

String aString = EncryptFile.getMD5(file1);

System.out.println(aString);

File file2 =new File("1.jar");

String bString = EncryptFile.getMD5(file2);

System.out.println(bString);

}

staticcharhexdigits[] = {'0','1', '2','3','4', '5','6','7', '8','9','a', 'b','c','d', 'e','f' };

public static String getMD5(Filefile) {

FileInputStream fis = null;

try {

MessageDigest md = MessageDigest.getInstance("MD5");

fis = new FileInputStream(file);

byte[] buffer =newbyte[2048];

int length = -1;

long s = System.currentTimeMillis();

while ((length =fis.read(buffer)) != -1) {

md.update(buffer, 0,length);

}

byte[] b =md.digest();

return byteToHexString(b);

}

catch (Exception ex) {

ex.printStackTrace();

return null;

}

finally {

try {

fis.close();

}

catch (IOException ex) {

ex.printStackTrace();

}

private static String byteToHexString(byte[]tmp) {

String s;

// 用字节表示就是 16 个字节

charstr[] =newchar[16 * 2];// 每个字节用 16 进制表示的话，使用两个字符，

// 所以表示成 16 进制需要 32 个字符

intk = 0;// 表示转换结果中对应的字符位置

for (int i = 0; i < 16; i++) { // 从第一个字节开始，对 MD5 的每一个字节

// 转换成 16 进制字符的转换

byte byte0 =tmp[i];// 取第 i 个字节

str[k++] =hexdigits[byte0 >>> 4 & 0xf];// 取字节中高 4 位的数字转换,

// >>> 为逻辑右移，将符号位一起右移

str[k++] =hexdigits[byte0 & 0xf];// 取字节中低 4 位的数字转换

}

s = new String(str);// 换后的结果转换为字符串

return s;

}

在上来一个用jdk自带的加密方式实现：

spring 加载实现.

public class DecryptPropertyPlaceholderConfigurerextends PropertyPlaceholderConfigurer {

private String keyPath;

private String[]encryptPropNames;

@Override

protected void processProperties(ConfigurableListableBeanFactorybeanFactoryToProcess, Properties props)throws BeansException {

if (encryptPropNames !=null && encryptPropNames.length > 0 &&props.size() > 0) {

for (String propName :encryptPropNames) {

String value = props.getProperty(propName);

System.out.println( DESEncryptUtil.doEncrypt(value,keyPath));

props.setProperty(propName, DESEncryptUtil.doEncrypt(value,keyPath));

}

super.processProperties(beanFactoryToProcess,props);

}

public void setEncryptPropNames(String[]encryptPropNames) {

this.encryptPropNames =encryptPropNames;

}

public void setKeyPath(StringkeyPath) {

this.keyPath =keyPath;

}

加密工具

@SuppressWarnings("restriction")

public class DESEncryptUtil {

/**

* 数据解密

* @param data

* @return

static String doEncrypt(String data,String keyPath) {

String decryptedData = null;

try {

// DES算法要求有一个可信任的随机数源

SecureRandom sr = new SecureRandom();

DESKeySpec deskey = new DESKeySpec(ReadFileHandle.readFileByChars(keyPath).getBytes());

SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");

SecretKey key = keyFactory.generateSecret(deskey);

// 解密对象

Cipher cipher = Cipher.getInstance("DES");

cipher.init(Cipher.DECRYPT_MODE,key, sr);

// 把字符串解码为字节数组，并解密

decryptedData = new String(cipher.doFinal(new BASE64Decoder().decodeBuffer(data)));

} catch (Exception e) {

throw new RuntimeException("解密错误，错误信息：",e);

}

returndecryptedData;

}

/**

* 数据加密

* @param data

* @return

public static String doDecrypt(Stringdata,String keyPath) {

String encryptedData = null;

try {

// DES算法要求有一个可信任的随机数源

SecureRandom sr = new SecureRandom();

DESKeySpec deskey = new DESKeySpec(ReadFileHandle.readFileByChars(keyPath).getBytes());

SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");

SecretKey key = keyFactory.generateSecret(deskey);

// 加密对象

Cipher cipher = Cipher.getInstance("DES");

cipher.init(Cipher.ENCRYPT_MODE,key, sr);

encryptedData = new BASE64Encoder().encode(cipher.doFinal(data.getBytes()));

} catch (Exception e) {

throw new RuntimeException("加密错误，错误信息：",e);

}

returnencryptedData;

}

读取 key 信息

public class ReadFileHandle {

protected staticfinal Log logger = LogFactory.getLog(ReadFileHandle.class);

/**

* 读取文本

* @param fileName

public static String readFileByChars(StringfileName) {

File file = new File(fileName);

InputStreamReader inputReader = null;

BufferedReader bufferReader = null;

OutputStream outputStream = null;

try {

InputStream inputStream = new FileInputStream(file);

inputReader = new InputStreamReader(inputStream);

bufferReader = new BufferedReader(inputReader);

String line = bufferReader.readLine();

return line;

} catch (IOException e) {

logger.error("文件读取异常!===========================");

e.printStackTrace();

} finally {

if (outputStream !=null) {

try {

outputStream.flush();

outputStream.close();

} catch (IOException e) {

e.printStackTrace();

}

if (inputReader !=null) {

try {

inputReader.close();

} catch (IOException e) {

e.printStackTrace();

}

if (bufferReader !=null) {

try {

bufferReader.close();

} catch (IOException e) {

e.printStackTrace();

}

return null;

}

其他用到的地方，后期会进一步补充。。。

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