Java Tutorial/Spring/Decouple

Closed Coupled

File: Main.java

   <source lang="java">

import java.io.PrintStream; public class Main {

 public static void main(String[] a) {
   MessageData source = new MessageData("Hello, world");
   MessageReporter destination = new MessageReporter();
   destination.write(System.out, source.getMessage());
 }

} final class MessageData {

 private final String message;
 public MessageData(String message) {
   this.message = message;
 }
 public String getMessage() {
   return message;
 }

} class MessageReporter {

 public void write(PrintStream out, String message) {
   out.println(message);
 }

}</source>

Decouple With Interface

File: Main.java

   <source lang="java">

public class Main {

 public static void main(String[] a) {
   MessageData source = new SimpleMessageData("Hello, world");
   MessageReporter destination = new StdoutMessageReporter();
   destination.write(source.getMessage());
 }

} interface MessageReporter {

 void write(String message);

} interface MessageData {

 String getMessage();

} class StdoutMessageReporter implements MessageReporter {

 public void write(String message) {
   System.out.println(message);
 }

} class SimpleMessageData implements MessageData {

 private final String message;
 public SimpleMessageData() {
   this("Hello, world");
 }
 public SimpleMessageData(String message) {
   this.message = message;
 }
 public String getMessage() {
   return this.message;
 }

}</source>

Spring Style Decouple

File: helloworld-context.properties

   <source lang="java">

source.(class)=SimpleMessageData destination.(class)=StdoutMessageReporter</source>