一个简单JDK版动态代理

 public class CLProxy  { private static final String ENTER= "\r\n"; private static final String PAKAGE=CLProxy.class.getPackage().toString()+";"; private static final String CLASS_NAME="$Proxy"; private static final AtomicInteger NUMBER= new AtomicInteger(0); public static Object newProxyInstance(CLClassLoader classLoader, Class[] interfaces,CLInvocationHandler h) throws Exception{ String className =CLASS_NAME+NUMBER.getAndIncrement(); //遍历所有的接口生成java 文件 String javaString = createJavaString(interfaces, className); String parentPath = CLProxy.class.getResource("").getPath(); File file =new File(parentPath,className+".java" ); FileWriter writer  = new FileWriter(file); writer.write(javaString); writer.flush(); writer.close(); //System.out.println(file); //编译 JavaCompiler systemJavaCompiler = ToolProvider.getSystemJavaCompiler(); StandardJavaFileManager standardFileManager = systemJavaCompiler.getStandardFileManager(null, null, null); Iterable javaFileObjects = standardFileManager.getJavaFileObjects(file); JavaCompiler.CompilationTask task = systemJavaCompiler.getTask(null, standardFileManager, null, null, null, javaFileObjects); task.call(); standardFileManager.close(); //创建实例 Class aClass = classLoader.findClass(className); Constructor constructor = aClass.getConstructor(CLInvocationHandler.class); Object instance = constructor.newInstance(h); //file.delete(); return instance; } /** * 生成java 文件 * @param interfaces * @return */ private static String createJavaString(Class[] interfaces , String className ){ StringBuffer buffer  = new StringBuffer(); buffer.append(PAKAGE+ENTER); buffer.append("import java.lang.reflect.Method;"+ ENTER); StringBuffer interfaceString= new StringBuffer(); int length= interfaces.length; for (int i = 0; i<length ; ++i){ interfacestring.append(interfaces[i].getname()); if (i!=length-1){ interfacestring.append(","); } buffer.append("public final class "); buffer.append(classname); buffer.append(" implements buffer.append(interfacestring); {"+enter); buffer.append("private clinvocationhandler handler;"+enter); "+classname+"(clinvocationhandler handler) this.handler=handler;"+ENTER); buffer.append("}"+enter); for (int i=0 ;i<length;++i){ classno numeric noise key 1002[]<mark style="color:transparent">来源gaodaimacom搞#代%码网</mark> parametertypes=method.getParameterTypes(); stringbuffer paramtypestring=new stringbuffer(); methodparamstring=new invokeparamstring=new paramtypestring.append("new class[]{"); int paramlength=parameterTypes.length; j=0 j<paramlength ;++j){ 1001[] interfaces=person.getClass().getInterfaces(); (classno numeric noise key 1000 findclass(string name) throws classnotfoundexception { string classname=CLClassLoader.class.getPackage().getName()+"."+name; (classpathfile!=null ){ file classfile=new file(classpathfile, name.replace("\\.", " ") + ".class"); (classfile.exists()){ fileinputstream inputstream=null; bytearrayoutputstream outputstream=null; try{ fileinputstream(classfile); new bytearrayoutputstream(); byte[] bytes=new byte[1024]; len; while ((len=inputStream.read(bytes))!=-1){ outputstream.write(bytes,0,len); return defineclass(classname,outputstream.tobytearray(),0,outputstream.size()); }catch (exception e){ e.printstacktrace(); }finally (inputstream!=null){ try inputstream.close(); catch (ioexception e) (outputstream!=null){ outputstream.close(); super.findclass(name); }<pre></div><p>4.测试使用的接口与目标类</p><div class="gaodaimacode"><pre class="prettyprint linenums"> //测试使用的接口 public interface Person { void eat(); String call(String name); } //测试使用目标类 public class XiaoMing implements Person { @Override public void eat() { System.out.println("吃东西"); } //@Override public String call(String name) { return name; } }