Java hotswap demo

package hotswap; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.util.HashSet; class CustomCL extends ClassLoader { private String basedir; // 需要该类加载器直接加载的类文件的基目录 private HashSet dynaclazns; // 需要由该类加载器直接加载的类名 public CustomCL(String basedir, String[] clazns) { super(null); // 指定父类加载器为 null this.basedir = basedir; dynaclazns = new HashSet(); loadClassByMe(clazns); } private void loadClassByMe(String[] clazns) { for (int i = 0; i < clazns.length; i++) { loadDirectly(clazns[i]); dynaclazns.add(clazns[i]); } } private Class loadDirectly(String name) { Class cls = null; StringBuffer sb = new StringBuffer(basedir); String classname = name.replace('.', File.separatorChar) + ".class"; sb.append(File.separator + classname); File classF = new File(sb.toString()); System.out.println(classF.getPath() + classF.length()); try { cls = instantiateClass(name, new FileInputStream(classF), classF.length()); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } return cls; } private Class instantiateClass(String name, InputStream fin, long len) { byte[] raw = new byte[(int) len]; try { fin.read(raw); fin.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } return defineClass(name, raw, 0, raw.length); } protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException { Class cls = null; cls = findLoadedClass(name); if (!this.dynaclazns.contains(name) && cls == null) cls = getSystemClassLoader().loadClass(name); if (cls == null) throw new ClassNotFoundException(name); if (resolve) resolveClass(cls); return cls; } }