load and decrypt class file (#30)

merge

Author: dntam00

src/main/java/club/shengsheng/MyClassLoader.java

@@ -1,9 +1,52 @@
 package club.shengsheng;
 
 
+import java.io.ByteArrayOutputStream;
+import java.io.FileInputStream;
+import java.io.IOException;
+
 /**
  * @author gongxuanzhangmelt@gmail.com
  **/
 public class MyClassLoader extends ClassLoader {
 
+    private static final String classFile = "加密.class";
+
+    @Override
+    public Class<?> loadClass(String name) throws ClassNotFoundException {
+        if (name != null && name.startsWith("java.")) {
+            return super.loadClass(name);
+        }
+        return findClass(name);
+    }
+
+    @Override
+    protected Class<?> findClass(String name) throws ClassNotFoundException {
+        byte[] classData = null;
+        try {
+            classData = readClassFile();
+        } catch (IOException e) {
+            throw new ClassNotFoundException("Could not read class file: " + classFile);
+        }
+        return defineClass(name, classData, 0, classData.length);
+    }
+
+    private byte[] readClassFile() throws IOException {
+        try (FileInputStream fis = new FileInputStream(classFile);
+             ByteArrayOutputStream byteArrStream = new ByteArrayOutputStream()) {
+
+            byte[] buffer = new byte[1024];
+            int bytesRead;
+
+            while ((bytesRead = fis.read(buffer)) != -1) {
+                byteArrStream.write(buffer, 0, bytesRead);
+            }
+
+            byte[] byteArray = byteArrStream.toByteArray();
+            for (int i = 0; i < byteArray.length; i++) {
+                byteArray[i] = (byte)(byteArray[i] - 1);
+            }
+            return byteArray;
+        }
+    }
 }