自定义类加载器中关于截取子串的疑问 - 黑马程序员技术交流社区

package com.itheima;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
public class MyClassLoader extends ClassLoader {
public static void main(String[] args) throws Exception {
String srcPath = args[0];
String destDir = args[1];
FileInputStream fis = new FileInputStream(srcPath);
String destFilename = srcPath.substring(srcPath.lastIndexOf('\\') + 1);// ?
String destPath = destDir + "\\" + destFilename;
FileOutputStream fos = new FileOutputStream(destPath);
cypher(fis, fos);
}
private static void cypher(InputStream ips, OutputStream ops)
throws Exception {
int b = -1;
while ((b = ips.read()) != -1) {
ops.write(b ^ 0xff);
}
ips.close();
ops.close();
}
private String classDir;
@Override
protected Class<?> findClass(String name) throws ClassNotFoundException {
// TODO Auto-generated method stub
// String classFileName = classDir + "\\" + name + ".class";
String classFileName = classDir + "\\" + name.substring(name.lastIndexOf('.')+1) + ".class";
try {
FileInputStream fis = new FileInputStream(classFileName);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
cypher(fis, bos);
fis.close();
System.out.println("aaaaaaa");
byte[] bytes = bos.toByteArray();
return defineClass(null, bytes, 0, bytes.length);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return super.findClass(name);
}
MyClassLoader() {
}
MyClassLoader(String classDir) {
this.classDir = classDir;
}
}

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