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本篇內容主要講解“怎么使用自定義類加載器防止代碼被反編譯破解”，感興趣的朋友不妨來看看。本文介紹的方法操作簡單快捷，實用性強。下面就讓小編來帶大家學習“怎么使用自定義類加載器防止代碼被反編譯破解”吧!
@Slf4j
public class EncryptUtils {
private static String secretKey = "test123456lyb-geek"+System.currentTimeMillis();
private EncryptUtils(){}
public static void encrypt(String classFileSrcPath,String classFileDestPath) {
System.out.println(secretKey);
FileInputStream fis = null;
FileOutputStream fos = null;
try {
fis = new FileInputStream(classFileSrcPath);
fos = new FileOutputStream(classFileDestPath);
int len;
String[] arrs = secretKey.split("lyb-geek");
long key = Long.valueOf(arrs[1]);
System.out.println("key:"+key);
while((len = fis.read())!=-1){
byte data = (byte)(len + key + secretKey.length());
fos.write(data);
}
} catch (Exception e) {
log.error("encrypt fail:"+e.getMessage(),e);
}finally {
if(fis != null){
try {
fis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(fos != null){
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
} public static void main(String[] args) {
String classFileSrcPath = classFileSrcPath("UserServiceImpl");
System.out.println("classFileSrcPath:--->"+classFileSrcPath);
String classFileDestDir = ServiceGenerate.class.getClassLoader().getResource("META-INF/services/").getPath();
System.out.println("classFileDestDir:--->"+classFileDestDir);
String classFileDestPath = classFileDestDir + "com.github.lybgeek.user.service.impl.UserServiceImpl.lyb";
EncryptUtils.encrypt(classFileSrcPath,classFileDestPath);
}打開反編譯工具jd-gui，把加密的代碼拖入jd-gui
打不開，至少說明不能用jd-gui來反編譯加密過的代碼。
我們打開正常的編譯的class文件，其內容形如下 
從內容我們大概還是能看出一些東西，比如包名啥的。而打開加密后的文件，其內容如下 
內容宛若天書
答案：既然有加密，自然可以通過解密來使用。那這個解密得存放在什么地方進行解密？
如果對類加載有一定了解的朋友，就會知道java的class文件是通過類加載器把class加載入jvm內存中，因此我們可以考慮把解密放在類加載器中。常用的類加載有啟動類加載器、擴展類加載器、系統類加載。我們正常classpath路徑下的類都是通過系統類加載器進行加載。而不巧這三個jdk提供的加載器沒法滿足我們的需求。因此我們只能自己實現我們的類加載器。其自定義加載器代碼如下
@Slf4j
public class CustomClassLoader extends ClassLoader{
/**
* 授權碼
*/
private String secretKey;
private String SECRETKEY_PREFIX = "lyb-geek";
/**
* class文件的根目錄
*/
private String classRootDir = "META-INF/services/";
public CustomClassLoader(String secretKey) {
this.secretKey = secretKey;
}
public String getClassRootDir() {
return classRootDir;
}
public void setClassRootDir(String classRootDir) {
this.classRootDir = classRootDir;
}
@Override
protected Class<?> findClass(String name) throws ClassNotFoundException {
Class<?> clz = findLoadedClass(name);
//先查詢有沒有加載過這個類。如果已經加載，則直接返回加載好的類。如果沒有，則加載新的類。
if(clz != null){
return clz;
}else{
ClassLoader parent = this.getParent();
clz = getaClass(name, clz, parent);
if(clz != null){
return clz;
}else{
clz = getaClass(name);
}
}
return clz;
}
private Class<?> getaClass(String name) throws ClassNotFoundException {
Class<?> clz;
byte[] classData = getClassData(name);
if(classData == null){
throw new ClassNotFoundException();
}else{
clz = defineClass(name, classData, 0,classData.length);
}
return clz;
}
private Class<?> getaClass(String name, Class<?> clz, ClassLoader parent) {
try {
//委派給父類加載
clz = parent.loadClass(name);
} catch (Exception e) {
//log.warn("parent load class fail："+ e.getMessage(),e);
}
return clz;
}
private byte[] getClassData(String classname){
if(StringUtils.isEmpty(secretKey) || !secretKey.contains(SECRETKEY_PREFIX) || secretKey.split(SECRETKEY_PREFIX).length != 2){
throw new RuntimeException("secretKey is illegal");
}
String path = CustomClassLoader.class.getClassLoader().getResource("META-INF/services/").getPath() +"/"+ classname+".lyb";
InputStream is = null;
ByteArrayOutputStream bas = null;
try{
is = new FileInputStream(path);
bas = new ByteArrayOutputStream();
int len;
//解密
String[] arrs = secretKey.split(SECRETKEY_PREFIX);
long key = Long.valueOf(arrs[1]);
// System.out.println("key:"+key);
while((len = is.read())!=-1){
byte data = (byte)(len - key - secretKey.length());
bas.write(data);
}
return bas.toByteArray();
}catch(Exception e){
e.printStackTrace();
return null;
}finally{
try {
if(is!=null){
is.close();
}
} catch (IOException e) {
log.error("encrypt fail:"+e.getMessage(),e);
}
try {
if(bas!=null){
bas.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}通過如下方式進行調用
public static void main(String[] args) throws Exception{
CustomClassLoader customClassLoader = new CustomClassLoader("test123456lyb-geek1603895713759");
Class clz = customClassLoader.loadClass("com.github.lybgeek.user.service.impl.UserServiceImpl");
if(clz != null){
Method method = clz.getMethod("list", User.class);
method.invoke(clz.newInstance(),new User());
}
}答案： 通過spring提供的擴展點進行ioc容器注入
1、編寫bean定義，并注冊注冊bean定義
@Component
public class ServiceBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
Object secretKey = YmlUtils.getValue("lyb-geek.secretKey");
if(ObjectUtils.isEmpty(secretKey)){
throw new RuntimeException("secretKey can not be null,you maybe need to config in application.yml with key lyb-geek.secretKey");
}
registerBean(beanFactory,secretKey.toString());
// setClassLoader(beanFactory,secretKey.toString());
}
/**
* 如果項目中引入了>spring-boot-devtools，則默認加載器為org.springframework.boot.devtools.restart.classloader.RestartClassLoader
* 此時如果使用自定加載器，則需把bean的類加載器變更為AppClassLoader
* @param beanFactory
*/
private void setClassLoader(ConfigurableListableBeanFactory beanFactory,String secretKey) {
CustomClassLoader customClassLoader = new CustomClassLoader(secretKey);
beanFactory.setBeanClassLoader(customClassLoader.getParent());
}
private void registerBean(ConfigurableListableBeanFactory beanFactory,String secretKey){
DefaultListableBeanFactory defaultListableBeanFactory = (DefaultListableBeanFactory) beanFactory;
BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(UserService.class);
GenericBeanDefinition definition = (GenericBeanDefinition) builder.getRawBeanDefinition();
definition.getPropertyValues().add("serviceClz",UserService.class);
definition.getPropertyValues().add("serviceImplClzName", "com.github.lybgeek.user.service.impl.UserServiceImpl");
definition.getPropertyValues().add("secretKey", secretKey);
definition.setBeanClass(ServiceFactoryBean.class);
definition.setAutowireMode(GenericBeanDefinition.AUTOWIRE_BY_TYPE);
String beanId = StringUtils.uncapitalize(UserService.class.getSimpleName());
defaultListableBeanFactory.registerBeanDefinition(beanId, definition);
}
}2、如果是接口注入，還需通過FactoryBean進行貍貓換太子
@Data
@AllArgsConstructor
@NoArgsConstructor
public class ServiceFactoryBean <T> implements FactoryBean<T> , ApplicationContextAware, InitializingBean {
private ApplicationContext applicationContext;
private Class<T> serviceClz;
private String serviceImplClzName;
private String secretKey;
private Object targetObj;
@Override
public T getObject() throws Exception {
return (T) targetObj;
}
@Override
public Class<?> getObjectType() {
return serviceClz;
}
@Override
public void afterPropertiesSet() throws Exception {
targetObj = ServiceFactory.create(secretKey,serviceImplClzName,applicationContext);
}
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
}3、驗證是否整合成功
驗證示例代碼
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserService userService;
@PostMapping(value = "/save")
public User save(User user){
User newUser = userService.save(user);
return newUser;
}
}
能夠正常輸出，說明整合成功
到此，相信大家對“怎么使用自定義類加載器防止代碼被反編譯破解”有了更深的了解，不妨來實際操作一番吧！這里是億速云網站，更多相關內容可以進入相關頻道進行查詢，關注我們，繼續學習！
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