如何实现自定义类加载器_开发者不可以自定义类加载器

public class MyClassLoader extends ClassLoader {
/** * @param args * @throws ClassNotFoundException * @throws SecurityException * @throws NoSuchMethodException * @throws InvocationTargetException * @throws IllegalArgumentException * @throws IllegalAccessException */
public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException,SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
// TODO Auto-generated method stub
if (args.length == 0) {
System.out.println("没有类啊");
}
// 取出第一个参数，就是需要运行的类
String procressClass = args[0];
// 剩余参数为运行目标类的参数，将这些参数复制到一个新数组中
String[] procress = new String[args.length - 1];
System.arraycopy(args, 1, procress, 0, procress.length);
MyClassLoader myClassLoader = new MyClassLoader();
Class<?> class1 = myClassLoader.loadClass(procressClass);
Method main = class1.getMethod("main", (new 
String[0]).getClass());
Object argsArray[] = { procress };
main.invoke(null, argsArray);
}
/** * @TODO 读取文件内容 */
public byte[] getBytes(String fileName) {
File file = new File(fileName);
long len = file.length();
byte[] raw = new byte[(int) len];
try {
FileInputStream fileInputStream =
new FileInputStream(file);
try {
int r = fileInputStream.read(raw);
fileInputStream.close();
if (r != len)
throw new IOException("fail to read the file...");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return raw;
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
/** * @TODO 编译java文件 */
public boolean complie(String javaFile) {
System.out.println("正在编译...");
Process process = null;
try {
process = Runtime.getRuntime().exec("javac " + javaFile);
try {
process.waitFor();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
int result = process.exitValue();
return result == 0;
}
/** * @TODO 关键，重写findClass方法 */
@Override
protected Class<?> findClass(String arg0) throws ClassNotFoundException {
// TODO Auto-generated method stub
Class<?> class1 = null;
String filePath = arg0.replaceAll(".", "/");
String className = filePath + ".class";
String javaName = filePath + ".java";
File javaFile = new File(javaName);
File classFile = new File(className);
if (javaFile.exists()
&& (!classFile.exists() || javaFile.lastModified() > classFile .lastModified())) {
if (!complie(javaName) || !classFile.exists()) {
throw new ClassNotFoundException(javaName + " Class找不到");
}
}
if (classFile.exists()) {
byte[] raw = getBytes(className);
class1 = defineClass(arg0, raw, 0, raw.length);
}
if (class1 == null) {
throw new ClassNotFoundException(javaName + " 加载失败");
}
return class1;
}
}

public class ClassLoaderTest {
public static void main(String[] args) {
// TODO Auto-generated method stub
for (String arg : args) {
System.out.println("运行时的参数： " + arg);
}
}
}

java MyClassLoader ClassLoaderTest 自定义类加载器