代理模式和装饰器模式比较相似，都是对原有对象进行额外的操作，不同的是装饰器是对原有对象的修饰，而代理模式是接手原对象的功能，并决定原功能的执行情况
先来看静态代理的例子，用户管理
package constructional.pattern.proxy.staticproxy; /*** * 用户控制接口 * @author Administrator * */ public interface UserManager { public void addUser(String userId,String userName); public void modifyUser(String userId,String userName); public void delUser(String userId); public String findUser(String userId); } package constructional.pattern.proxy.staticproxy; /**** * 用户管理真正的实现类 * @author Administrator * */ public class UserManagerImpl implements UserManager { /***** * 添加用户 */ public void addUser(String userId, String userName) { System.out.println("正在添加用户,用户为："+userId+userName+"……"); } /***** * 删除用户 */ public void delUser(String userId) { System.out.println("delUser,userId="+userId); } /*** * 查找用户 */ public String findUser(String userId) { System.out.println("findUser,userId="+userId); return userId; } public void modifyUser(String userId, String userName) { System.out.println("modifyUser,userId="+userId); } } package constructional.pattern.proxy.staticproxy; /*** * 代理类，提供用户实现类的访问控制 * @author Administrator * */ public class Proxy implements UserManager{ private UserManager userManager; public Proxy(UserManagerImpl ul) { userManager=ul; } public void addUser(String userId, String userName) { System.out.println("正在进行添加用户前的准备工作,用户id为："+userId+"……"); try { userManager.addUser(userId, userName); System.out.println("成功添加用户"+userId+"，正在进行确认处理……"); } catch (Exception e) { System.out.println("添加,userId="+userId+"失败！"); } } public void delUser(String userId) { // TODO Auto-generated method stub } public String findUser(String userId) { // TODO Auto-generated method stub return null; } public void modifyUser(String userId, String userName) { // TODO Auto-generated method stub } }测试代码
package constructional.pattern.proxy.staticproxy; /**** * 客户端 * @author Administrator * */ public class Client { public static void main(String []args) { UserManager userManager=new Proxy( new UserManagerImpl()); userManager.addUser("0001", "张三"); } }运行结果
看完了静态代理，再来看看动态代理，正常的动态代理
package constructional.pattern.proxy.dynamicproxy; import java.lang.reflect.InvocationHandler; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; public class LoginHandler2 implements InvocationHandler { private Object target; public LoginHandler2(Object target) { super(); this.target = target; } @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { System.out.println("登录成功"); try { method.invoke(target, null); } catch (IllegalArgumentException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalAccessException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InvocationTargetException e) { // TODO Auto-generated catch block e.printStackTrace(); } return null; } }package constructional.pattern.proxy.dynamicproxy; public class User implements UserMgr{ @Override public void addUser() { System.out.println("添加用户"); } } package constructional.pattern.proxy.dynamicproxy; public interface UserMgr { public void addUser(); }
测试代码
package constructional.pattern.proxy.dynamicproxy; import java.lang.reflect.Proxy; public class JdkTest2 { public static void main(String args[]){ User u = new User(); LoginHandler2 l = new LoginHandler2(u); ClassLoader c = ClassLoader.getSystemClassLoader(); try { UserMgr ur = (UserMgr)Proxy.newProxyInstance(c,new Class[]{UserMgr.class}, l); ur.addUser(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }运行结果
下面是手动编译代理类的代码
package constructional.pattern.proxy.dynamicproxy; import java.lang.reflect.Method; public interface InvocationHandler { public void invoke(Object o,Method m); } package constructional.pattern.proxy.dynamicproxy; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; public class LoginHandler implements InvocationHandler{ private Object target; public LoginHandler(Object target) { super(); this.target = target; } @Override public void invoke(Object o, Method m) { System.out.println("登录成功"); try { m.invoke(target, null); } catch (IllegalArgumentException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalAccessException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InvocationTargetException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } package constructional.pattern.proxy.dynamicproxy; public interface UserMgr { public void addUser(); } package constructional.pattern.proxy.dynamicproxy; public class User implements UserMgr{ @Override public void addUser() { System.out.println("添加用户"); } } package constructional.pattern.proxy.dynamicproxy; import java.io.FileWriter; import java.lang.reflect.Constructor; import java.lang.reflect.Method; import java.net.URL; import java.net.URLClassLoader; import java.util.Random; import javax.tools.JavaCompiler; import javax.tools.JavaCompiler.CompilationTask; import javax.tools.StandardJavaFileManager; import javax.tools.ToolProvider; public class Proxy { public static Object getProxyInstance(Class inface,InvocationHandler h) throws Exception{ String rt ="\r\t"; byte[] bytes = new byte[1]; bytes[0] = 1; String className = "P" + Math.abs(new Random().nextLong()); String methodStr = ""; // for(Method m:inface.getMethods()){ // methodStr+=" @Override" + rt+ // " public void " + m.getName() + "(){" + rt + // " long startTime = System.currentTimeMillis();"+ rt + // " System.out.println(\"startTime:\"+startTime);"+ rt + // " t." + m.getName() + "()" + ";"+ rt + // " long endTime = System.currentTimeMillis();"+ rt + // " System.out.println(\"Time:\"+(endTime-startTime));"+ rt + // // " }" + rt; // // } for(Method m : inface.getMethods()) { methodStr += "@Override" + rt + "public void " + m.getName() + "() {" + rt + " try {" + rt + " Method md = " + inface.getName() + ".class.getMethod(\"" + m.getName() + "\");" + rt + " h.invoke(this, md);" + rt + " }catch(Exception e) {e.printStackTrace();}" + rt + "}"; } String str = "package constructional.pattern.proxy.dynamicproxy;"+ rt + "import java.lang.reflect.Method;" + rt + "public class " + className + "Proxy implements " +inface.getName()+ "{"+ rt + " constructional.pattern.proxy.dynamicproxy.InvocationHandler h;" + rt + " public " + className + "Proxy(InvocationHandler h) {"+ rt + " super();"+ rt + " this.h = h;"+ rt + "}"+ rt + methodStr+ "}"; String fileName =System.getProperty("user.dir")+"/src/constructional/pattern/proxy/dynamicproxy/" + className + "Proxy.java"; FileWriter fw = new FileWriter(fileName); fw.write(str); fw.flush(); fw.close(); //compile JavaCompiler compiler = ToolProvider.getSystemJavaCompiler(); StandardJavaFileManager fileMgr = compiler.getStandardFileManager(null, null, null); Iterable units = fileMgr.getJavaFileObjects(fileName); CompilationTask t = compiler.getTask(null, fileMgr, null, null, null, units); t.call(); fileMgr.close(); //load into memory and create an instance URL[] urls = new URL[]{(new URL("file:/"+System.getProperty("user.dir")+"/src/"))}; URLClassLoader ul = new URLClassLoader(urls); Class c = ul.loadClass("constructional.pattern.proxy.dynamicproxy." + className +"Proxy"); System.out.println(c); Constructor ctr = c.getConstructor(InvocationHandler.class); Object m = (Object)ctr.newInstance(h); return m; } }测试类
package constructional.pattern.proxy.dynamicproxy; public class Test2 { public static void main(String args[]){ User u = new User(); LoginHandler l = new LoginHandler(u); try { UserMgr ur = (UserMgr)Proxy.getProxyInstance(UserMgr.class, l); ur.addUser(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }运行结果
转载于:https://www.cnblogs.com/liunianfeiyu/p/10116890.html
