Added example code for Execute Around idiom.

iluwatar · iluwatar · commit 027fd9934bac · 2015-03-29T21:25:13.000+03:00
diff --git a/execute-around/pom.xml b/execute-around/pom.xml
@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>com.iluwatar</groupId>
+    <artifactId>java-design-patterns</artifactId>
+    <version>1.0-SNAPSHOT</version>
+  </parent>
+  <artifactId>execute-around</artifactId>
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+</project>
diff --git a/execute-around/src/main/java/com/iluwatar/App.java b/execute-around/src/main/java/com/iluwatar/App.java
@@ -0,0 +1,30 @@
+package com.iluwatar;
+
+import java.io.FileWriter;
+import java.io.IOException;
+
+/**
+ * The Execute Around idiom specifies some code to be executed before and after
+ * a method. Typically the idiom is used when the API has methods to be executed in
+ * pairs, such as resource allocation/deallocation or lock acquisition/release.
+ *
+ * In this example, we have SimpleFileWriter class that opens and closes the file
+ * for the user. The user specifies only what to do with the file by providing the
+ * FileWriterAction implementation.
+ *
+ */
+public class App {
+	
+    public static void main( String[] args ) throws IOException {
+
+    	new SimpleFileWriter("testfile.txt", new FileWriterAction() {
+
+    		@Override
+			public void writeFile(FileWriter writer) throws IOException {
+    			writer.write("Hello");
+    			writer.append(" ");
+    			writer.append("there!");
+			}
+    	});
+    }
+}
diff --git a/execute-around/src/main/java/com/iluwatar/FileWriterAction.java b/execute-around/src/main/java/com/iluwatar/FileWriterAction.java
@@ -0,0 +1,15 @@
+package com.iluwatar;
+
+import java.io.FileWriter;
+import java.io.IOException;
+
+/**
+ * 
+ * Interface for specifying what to do with the file resource.
+ *
+ */
+public interface FileWriterAction {
+
+	void writeFile(FileWriter writer) throws IOException;
+	
+}
diff --git a/execute-around/src/main/java/com/iluwatar/SimpleFileWriter.java b/execute-around/src/main/java/com/iluwatar/SimpleFileWriter.java
@@ -0,0 +1,23 @@
+package com.iluwatar;
+
+import java.io.FileWriter;
+import java.io.IOException;
+
+/**
+ * 
+ * SimpleFileWriter handles opening and closing file for the user. The user
+ * only has to specify what to do with the file resource through FileWriterAction
+ * parameter.
+ *
+ */
+public class SimpleFileWriter {
+
+	public SimpleFileWriter(String filename, FileWriterAction action) throws IOException {
+		FileWriter writer = new FileWriter(filename);
+		try {
+			action.writeFile(writer);
+		} finally {
+			writer.close();
+		}
+	}
+}
diff --git a/execute-around/src/test/java/com/iluwatar/AppTest.java b/execute-around/src/test/java/com/iluwatar/AppTest.java
@@ -0,0 +1,19 @@
+package com.iluwatar;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+/**
+ * 
+ * Tests execute-around example.
+ *
+ */
+public class AppTest {
+	
+	@Test
+	public void test() throws IOException {
+		String[] args = {};
+		App.main(args);
+	}
+}
diff --git a/pom.xml b/pom.xml
@@ -41,6 +41,7 @@
 		<module>null-object</module>
 		<module>event-aggregator</module>
 		<module>callback</module>
+    <module>execute-around</module>
   </modules>
 
 	<dependencyManagement>
