fix: Add source code of Chapter 04 (#8)

.gitignore

@@ -0,0 +1,22 @@
+.DS_Store
+
+.idea
+*.iml
+
+.gradle
+
+# Ignore Gradle GUI config
+gradle-app.setting
+
+# Avoid ignoring Gradle wrapper jar file (.jar files are usually ignored)
+!gradle-wrapper.jar
+
+# Cache of project
+.gradletasknamecache
+
+build
+out
+bin
+.settings
+.classpath
+.project

Chapter_04/aop-aspectj/build.gradle

@@ -0,0 +1,20 @@
+plugins {
+    id 'java'
+    id "aspectj.gradle" version "0.1.6"
+    id 'application'
+}
+
+group 'com.whezh'
+version '1.0-SNAPSHOT'
+
+sourceCompatibility = 1.8
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    compile "org.springframework:spring-context:${springVersion}"
+}
+
+mainClassName = 'concert.Main'

Chapter_04/aop-aspectj/gradle.properties

@@ -0,0 +1,3 @@
+springVersion=4.0.7.RELEASE
+systemRulesVersion=1.5.0
+aspectjVersion=1.8.5

Chapter_04/aop-aspectj/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.8-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

Chapter_04/aop-aspectj/settings.gradle

@@ -0,0 +1,2 @@
+rootProject.name = 'aop'
+

Chapter_04/aop-aspectj/src/main/java/concert/CriticAspect.aj

@@ -0,0 +1,30 @@
+package concert;
+
+public aspect CriticAspect {
+    private CriticismEngine criticismEngine;
+
+    pointcut performance():execution(* concert.Performance.perform(..));
+
+    pointcut construct():execution(concert.CriticismEngineImpl.new());
+
+    after():performance(){
+        System.out.println(criticismEngine.getCriticism());
+    }
+
+    after():construct(){
+        System.out.println("After Performance constructor");
+    }
+
+
+    before():construct(){
+        System.out.println("Before Performance constructor");
+    }
+
+    public CriticismEngine getCriticismEngine() {
+        return this.criticismEngine;
+    }
+
+    public void setCriticismEngine(CriticismEngine criticismEngine) {
+        this.criticismEngine = criticismEngine;
+    }
+}

Chapter_04/aop-aspectj/src/main/java/concert/CriticismEngine.java

@@ -0,0 +1,5 @@
+package concert;
+
+public interface CriticismEngine {
+    String getCriticism();
+}

Chapter_04/aop-aspectj/src/main/java/concert/CriticismEngineImpl.java

@@ -0,0 +1,18 @@
+package concert;
+
+public class CriticismEngineImpl implements CriticismEngine {
+    private String[] criticismPool;
+
+    public CriticismEngineImpl() {
+    }
+
+    @Override
+    public String getCriticism() {
+        int i = (int) (Math.random() * criticismPool.length);
+        return criticismPool[i];
+    }
+
+    public void setCriticismPool(String[] criticismPool) {
+        this.criticismPool = criticismPool;
+    }
+}

Chapter_04/aop-aspectj/src/main/java/concert/Main.java

@@ -0,0 +1,13 @@
+package concert;
+
+import org.springframework.context.support.ClassPathXmlApplicationContext;
+
+public class Main {
+    public static void main(String[] args) {
+        ClassPathXmlApplicationContext context =
+                new ClassPathXmlApplicationContext("concert.xml");
+        Performance performance = context.getBean(Performance.class);
+        performance.perform();
+        context.close();
+    }
+}

Chapter_04/aop-aspectj/src/main/java/concert/Music.java

@@ -0,0 +1,11 @@
+package concert;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public class Music implements Performance {
+    @Override
+    public void perform() {
+        System.out.println("Piano Solo");
+    }
+}