本文将介绍android studio利用gradle进行raw资源文件加密的一种方式（所有代码均写在build.gradle中）：
第一步：首先要需要了解的是gradle打包监听器BuildListener的两个方法：
- projectsEvaluated（）方法执行在生成apk前： 所以在projectsEvaluated方法进行apk资源文件copy工作和加密工作。
- buildFinished（）方法执行在apk生成之后： 在buildFinished方法中进行加密资源文件的恢复和临时文件的删除工作（临时文件用于未加密代码的临时存储，打包结束后需要放会raw文件夹中）
- 需copy如下代码：
gradle.addBuildListener(new BuildListener() { @Override void buildStarted(Gradle gradle) { println "buildStarted" } @Override void settingsEvaluated(Settings settings) { println "settingsEvaluated" } @Override void projectsLoaded(Gradle gradle) { println "projectsLoaded" } @Override void projectsEvaluated(Gradle gradle) { println "projectsEvaluated" copyFolder(rawDir,tempDir) encodeDir(rawDir,aesKeyCommen) } @Override void buildFinished(BuildResult buildResult) { copyFolder(tempDir,rawDir); deleteAllFilesOfDir(tempDir); } })
第二步：在build.gradle中实现上步骤的方法copyFolder，encodeDir，deleteAllFileofDir
gradle打包兼容java代码，下面贴出这些方法的实现：
//加密的资源文件路径
def rawDir ='./app/src/main/res/raw/'
//资源文件临时存储文件夹名称
def tempDir ='./tempDir'
//加密的key
def aesKey = "\"abcdefgabcdefg12\""
def aesKeyCommen = "abcdefgabcdefg12"
//拷贝文件夹
void copyFolder(String oldPath, String newPath) {
try {
(new File(newPath)).mkdirs(); //如果文件夹不存在 则建立新文件夹
File a = new File(oldPath);
String[] file = a.list();
File temp = null;
for (int i = 0; i < file.length; i++) {
if (oldPath.endsWith(File.separator)) {
temp = new File(oldPath + file[i]);
} else {
temp = new File(oldPath + File.separator + file[i]);
}
if (temp.isFile()) {
FileInputStream input = new FileInputStream(temp);
FileOutputStream output = new FileOutputStream(newPath + "/" +
(temp.getName()).toString());
byte[] b = new byte[1024 * 5];
int len;
while ((len = input.read(b)) != -1) {
output.write(b, 0, len);
}
output.flush();
output.close();
input.close();
}
if (temp.isDirectory()) {//如果是子文件夹
copyFolder(oldPath + "/" + file[i], newPath + "/" + file[i]);
}
}
}
catch (Exception e) {
println("复制整个文件夹内容操作出错");
e.printStackTrace();
}
}
//删除文件夹
void deleteAllFilesOfDir(String path) {
File file=new File(path);
if (!file.exists())
return;
if (file.isFile()) {
file.delete();
return;
}
File[] files = file.listFiles();
for (int i = 0; i < files.length; i++) {
deleteAllFilesOfDir(files[i].getAbsolutePath());
}
file.delete();
}
//读取文件到string
static String file2String(File file, String encoding) {
InputStreamReader reader = null;
StringWriter writer = new StringWriter();
try {
if (encoding == null || "".equals(encoding.trim())) {
reader = new InputStreamReader(new FileInputStream(file), encoding);
} else {
reader = new InputStreamReader(new FileInputStream(file));
}
//将输入流写入输出流
char[] buffer = new char[1024];
int n = 0;
while (-1 != (n = reader.read(buffer))) {
writer.write(buffer, 0, n);
}
} catch (Exception e) {
e.printStackTrace();
return null;
} finally {
if (reader != null)
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
//返回转换结果
if (writer != null)
return writer.toString();
else return null;
}
//加密算法
private static byte[] encrypt(String content, String password) {
try {
byte[] keyStr = getKey(password);
SecretKeySpec key = new SecretKeySpec(keyStr, "AES");
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");//algorithmStr
byte[] byteContent = content.getBytes("utf-8");
cipher.init(Cipher.ENCRYPT_MODE, key);// ʼ
byte[] result = cipher.doFinal(byteContent);
return result; //
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
}
return null;
}
//解密算法
private static byte[] decrypt(byte[] content, String password) {
try {
byte[] keyStr = getKey(password);
SecretKeySpec key = new SecretKeySpec(keyStr, "AES");
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");//algorithmStr
cipher.init(Cipher.DECRYPT_MODE, key);// ʼ
byte[] result = cipher.doFinal(content);
return result; //
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
}
return null;
}
private static byte[] getKey(String password) {
byte[] rByte = null;
if (password!=null) {
rByte = password.getBytes();
}else{
rByte = new byte[24];
}
return rByte;
}
//二进制转16进制
static String parseByte2HexStr(byte[] buf) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i < buf.length; i++) {
String hex = Integer.toHexString(buf[i] & 0xFF);
if (hex.length() == 1) {
hex = '0' + hex;
}
sb.append(hex.toUpperCase());
}
return sb.toString();
}
static byte[] parseHexStr2Byte(String hexStr) {
if (hexStr.length() < 1)
return null;
byte[] result = new byte[hexStr.length() / 2];
for (int i = 0; i < hexStr.length() / 2; i++) {
int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2),
16);
result[i] = (byte) (high * 16 + low);
}
return result;
}
//加密方法
static String encodeContent(String content, String keyBytes){
//加密之后的字节数组,转成16进制的字符串形式输出
return parseByte2HexStr(encrypt(content, keyBytes));
}
//解密方法
static String decodeContent(String content, String keyBytes){
//解密之前,先将输入的字符串按照16进制转成二进制的字节数组,作为待解密的内容输入
byte[] b = decrypt(parseHexStr2Byte(content), keyBytes);
return new String(b);
}
//projectsEvaluated里调用的方法 aesKey： key rawDir：加密的文件夹
void encodeDir(String rawDir, String aesKey){
println "do 加密代码"
File searchPlug = new File(rawDir);
if (searchPlug.exists() && searchPlug.isDirectory()) {
print "文件夹存在"
File[] files = searchPlug.listFiles()
for (File file : files) {
if(!file.name.endsWith(".glsl")){
continue
}
String str=file2String(file,"utf-8")
def content = encodeContent(str, aesKey)
// def result = decodeContent(content, aesKey)
// println(" 原始文件:content"+str)
// println(" 加密后文件:content"+content)
// println(" 解密后文件:content"+result)
def stream = file.newOutputStream()
stream.write(content.bytes)
stream.flush()
}
}
}
第三步：在gradle和android程序中实现加密key的共享
- 在gradle文件中增加代码
defaultConfig {
buildConfigField "String", "AES_KEY",aesKey
}
- 在android代码中利用BuildConfig.AES_KEY获取build.gradle文件中配置的key。
- 注：在gradle文件中使用的key用def aesKeyCommen = "abcdefgabcdefg12"
在 buildConfigField 里需要传入的String为： ""abcdefgabcdefg12""
因为gradle生成java类时会默认省掉“”。
第四步：android程序里解密
1 . 新建工具类：
public class AESUtils {
private static byte[] encrypt(String content, String password) {
try {
byte[] keyStr = getKey(password);
SecretKeySpec key = new SecretKeySpec(keyStr, "AES");
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");//algorithmStr
byte[] byteContent = content.getBytes("utf-8");
cipher.init(Cipher.ENCRYPT_MODE, key);// ʼ
byte[] result = cipher.doFinal(byteContent);
return result; //
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
}
return null;
}
private static byte[] decrypt(byte[] content, String password) {
try {
byte[] keyStr = getKey(password);
SecretKeySpec key = new SecretKeySpec(keyStr, "AES");
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");//algorithmStr
cipher.init(Cipher.DECRYPT_MODE, key);// ʼ
byte[] result = cipher.doFinal(content);
return result; //
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
}
return null;
}
private static byte[] getKey(String password) {
byte[] rByte = null;
if (password!=null) {
rByte = password.getBytes();
}else{
rByte = new byte[24];
}
return rByte;
}
/**
* 将二进制转换成16进制
* @param buf
* @return
*/
public static String parseByte2HexStr(byte buf[]) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i < buf.length; i++) {
String hex = Integer.toHexString(buf[i] & 0xFF);
if (hex.length() == 1) {
hex = '0' + hex;
}
sb.append(hex.toUpperCase());
}
return sb.toString();
}
/**
* 将16进制转换为二进制
* @param hexStr
* @return
*/
public static byte[] parseHexStr2Byte(String hexStr) {
if (hexStr.length() < 1)
return null;
byte[] result = new byte[hexStr.length() / 2];
for (int i = 0; i < hexStr.length() / 2; i++) {
int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2),
16);
result[i] = (byte) (high * 16 + low);
}
return result;
}
/**
*加密
*/
public static String encode(String content,String keyBytes){
//加密之后的字节数组,转成16进制的字符串形式输出
return parseByte2HexStr(encrypt(content, keyBytes));
}
/**
*解密
*/
public static String decode(String content,String keyBytes){
//解密之前,先将输入的字符串按照16进制转成二进制的字节数组,作为待解密的内容输入
byte[] b = decrypt(parseHexStr2Byte(content), keyBytes);
return new String(b);
}
}
2 . 读取raw资源文件，并进行解密
public static String readShaderFromRawResource(final int resourceId) {
final InputStream inputStream = CameraApplication.getInstance().getResources().openRawResource(
resourceId);
final InputStreamReader inputStreamReader;
try {
inputStreamReader = new InputStreamReader(inputStream, "utf-8");
final BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String nextLine;
final StringBuilder body = new StringBuilder();
try {
while ((nextLine = bufferedReader.readLine()) != null) {
body.append(nextLine);
body.append('\n');
}
} catch (IOException e) {
return null;
}
//AESUtils.decode是解密方法，BuildConfig.AES_KEY，为gradle中配置的key
String decrypt = AESUtils.decode(body.toString(), BuildConfig.AES_KEY);
return decrypt;
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return "";
}
第五步：大功告成，解压生成的apk，然后查看raw资源文件
可看到文件内容为3134141425425 的十六进制构成，而代码中的raw文件还是原来的代码，没有发生任何变化
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