AOP 解决紧密耦合的难题-用静态横切的强大功能建立高度松散的系统

public class Foo{

public Foo() {
super();
}

}

public aspect FooBar {

void Foo.bar() {
System.out.println("in Foo.bar()");
}

}

public aspect FooNew {

public Foo.new(String parm1){
super();
System.out.println("in Foo(string parm1)");
}

}

public aspect FooRunnable {

declare parents: Fooimplements Runnable;

public void Foo.run() {
System.out.println("in Foo.run()");
}

}

public class Email implements Sendable{
private String body;
private String toAddress;
private String fromAddress;
private String subject;

public String getBody() {
return body;
}

public String getFromAddress() {
return fromAddress;
}

public String getSubject() {
return subject;
}

public String getToAddress() {
return toAddress;
}

public void setBody(String string) {
body = string;
}

public void setFromAddress(String string) {
fromAddress = string;
}

public void setSubject(String string) {
subject = string;
}

public void setToAddress(String string) {
toAddress = string;
}
}

public interface Sendable{
String getBody();
String getToAddress();
}

package com.acme.validate;

public interface Validatable {

boolean validateAddress();

}

import com.acme.validate.Validatable;

public aspect EmailValidateAspect {

declare parents: Email implements Validatable;

public boolean Email.validateAddress(){
if(this.getToAddress() != null){
return true;
}else{
return false;
}
}
}

import com.acme.validate.Validatable;

public class EmailTest extends TestCase {
private Email email;

protected void setUp() throws Exception {
//set up an email instance
this.email = new Email();
this.email.setBody("body");
this.email.setFromAddress("dev@dev.com");
this.email.setSubject("validate me");
this.email.setToAddress("ag@ag.com");
}

protected void tearDown() throws Exception {
this.email = null;
}

//EmailTest continued...
}

public void testEmailValidateInstanceof() throws Exception{

TestCase.assertEquals("Email object should be of type Validatable",
true, this.email instanceof Validatable);
}

public void testEmailAddressValidateNull() throws Exception{

//force a false
this.email.setToAddress(null);

Validatable validtr = (Validatable)this.email;

TestCase.assertEquals("validateAddress should return false",
false, validtr.validateAddress());
}

public void testEmailAddressValidateTrue() throws Exception{

Validatable validtr = (Validatable)this.email;

TestCase.assertEquals("validateAddress should return true",
true, validtr.validateAddress());
}

import com.acme.validate.Validatable;

public aspect SendableValidateAspect {

declare parents: Sendableextends Validatable;

public boolean Email.validateAddress(){

if(this.getToAddress() != null){
return true;
}else{
return false;
}
}

public boolean Fax.validateAddress(){

if(this.getToAddress() != null
&& this.getToAddress().length() >= 11){

return true;
}else{
return false;
}
}
}

Sendable

validateAddress()