原理
运行时生成 一个类的示例。名字为：$Proxy0.(不同接口，数字递增)；
继承Proxy类。实现给定的接口；
下面是反编译的class：
-
public final class $Proxy0 extends Proxy implements TestInterface
完整反编译class 见下方附录；
①：生成的类和实例。只是运行时的，并不是持久化的。
可以通过下面的代理，打印：
Class $Proxy0 = Class.forName("com.sun.proxy.$Proxy0");
System.out.println("$Proxy0:" + $Proxy0);
②：可以通过ProxyGenerator类，把class写到文件
byte[] classFile = ProxyGenerator.generateProxyClass("$Proxy0", TestImpl.class.getInterfaces());
附录
代理类反编译
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
import bean.TestInterface;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;
public final class $Proxy0 extends Proxy implements TestInterface {
private static Method m1;
private static Method m2;
private static Method m3;
private static Method m4;
private static Method m0;
public $Proxy0(InvocationHandler var1) throws {
super(var1);
}
public final boolean equals(Object var1) throws {
try {
return (Boolean)super.h.invoke(this, m1, new Object[]{var1});
} catch (RuntimeException | Error var3) {
throw var3;
} catch (Throwable var4) {
throw new UndeclaredThrowableException(var4);
}
}
public final String toString() throws {
try {
return (String)super.h.invoke(this, m2, (Object[])null);
} catch (RuntimeException | Error var2) {
throw var2;
} catch (Throwable var3) {
throw new UndeclaredThrowableException(var3);
}
}
public final void hey(String var1) throws {
try {
super.h.invoke(this, m3, new Object[]{var1});
} catch (RuntimeException | Error var3) {
throw var3;
} catch (Throwable var4) {
throw new UndeclaredThrowableException(var4);
}
}
public final void say() throws {
try {
super.h.invoke(this, m4, (Object[])null);
} catch (RuntimeException | Error var2) {
throw var2;
} catch (Throwable var3) {
throw new UndeclaredThrowableException(var3);
}
}
public final int hashCode() throws {
try {
return (Integer)super.h.invoke(this, m0, (Object[])null);
} catch (RuntimeException | Error var2) {
throw var2;
} catch (Throwable var3) {
throw new UndeclaredThrowableException(var3);
}
}
static {
try {
m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
m2 = Class.forName("java.lang.Object").getMethod("toString");
m3 = Class.forName("bean.TestInterface").getMethod("hey", Class.forName("java.lang.String"));
m4 = Class.forName("bean.TestInterface").getMethod("say");
m0 = Class.forName("java.lang.Object").getMethod("hashCode");
} catch (NoSuchMethodException var2) {
throw new NoSuchMethodError(var2.getMessage());
} catch (ClassNotFoundException var3) {
throw new NoClassDefFoundError(var3.getMessage());
}
}
}
总结
局限性很大：
1.代理类必须有一个接口。 cglib 更为强大
