Visitor Pattern 1
//[C] 2002 Sun Microsystems, Inc.---
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Iterator;
public class RunVisitorPattern {
public static void main(String[] arguments) {
System.out.println("Example for the Visitor pattern");
System.out.println();
System.out
.println("This sample will use a ProjectCostVisitor to calculate");
System.out.println(" the total amount required to complete a Project.");
System.out.println();
System.out.println("Deserializing a test Project for Visitor pattern");
System.out.println();
if (!(new File("data.ser").exists())) {
DataCreator.serialize("data.ser");
}
Project project = (Project) (DataRetriever.deserializeData("data.ser"));
System.out
.println("Creating a ProjectCostVisitor, to calculate the total cost of the project.");
ProjectCostVisitor visitor = new ProjectCostVisitor();
visitor.setHourlyRate(100);
System.out
.println("Moving throuhg the Project, calculating total cost");
System.out
.println(" by passing the Visitor to each of the ProjectItems.");
visitProjectItems(project, visitor);
System.out.println("The total cost for the project is: "
+ visitor.getTotalCost());
}
private static void visitProjectItems(ProjectItem item,
ProjectVisitor visitor) {
item.accept(visitor);
if (item.getProjectItems() != null) {
Iterator subElements = item.getProjectItems().iterator();
while (subElements.hasNext()) {
visitProjectItems((ProjectItem) subElements.next(), visitor);
}
}
}
}
interface Contact extends Serializable {
public static final String SPACE = " ";
public String getFirstName();
public String getLastName();
public String getTitle();
public String getOrganization();
public void setFirstName(String newFirstName);
public void setLastName(String newLastName);
public void setTitle(String newTitle);
public void setOrganization(String newOrganization);
}
class Task implements ProjectItem {
private String name;
private ArrayList projectItems = new ArrayList();
private Contact owner;
private double timeRequired;
public Task() {
}
public Task(String newName, Contact newOwner, double newTimeRequired) {
name = newName;
owner = newOwner;
timeRequired = newTimeRequired;
}
public String getName() {
return name;
}
public ArrayList getProjectItems() {
return projectItems;
}
public Contact getOwner() {
return owner;
}
public double getTimeRequired() {
return timeRequired;
}
public void setName(String newName) {
name = newName;
}
public void setOwner(Contact newOwner) {
owner = newOwner;
}
public void setTimeRequired(double newTimeRequired) {
timeRequired = newTimeRequired;
}
public void addProjectItem(ProjectItem element) {
if (!projectItems.contains(element)) {
projectItems.add(element);
}
}
public void removeProjectItem(ProjectItem element) {
projectItems.remove(element);
}
public void accept(ProjectVisitor v) {
v.visitTask(this);
}
}
class Deliverable implements ProjectItem {
private String name;
private String description;
private Contact owner;
private double materialsCost;
private double productionCost;
public Deliverable() {
}
public Deliverable(String newName, String newDescription, Contact newOwner,
double newMaterialsCost, double newProductionCost) {
name = newName;
description = newDescription;
owner = newOwner;
materialsCost = newMaterialsCost;
productionCost = newProductionCost;
}
public String getName() {
return name;
}
public String getDescription() {
return description;
}
public Contact getOwner() {
return owner;
}
public double getMaterialsCost() {
return materialsCost;
}
public double getProductionCost() {
return productionCost;
}
public void setMaterialsCost(double newCost) {
materialsCost = newCost;
}
public void setProductionCost(double newCost) {
productionCost = newCost;
}
public void setName(String newName) {
name = newName;
}
public void setDescription(String newDescription) {
description = newDescription;
}
public void setOwner(Contact newOwner) {
owner = newOwner;
}
public void accept(ProjectVisitor v) {
v.visitDeliverable(this);
}
public ArrayList getProjectItems() {
return null;
}
}
interface ProjectVisitor {
public void visitDependentTask(DependentTask p);
public void visitDeliverable(Deliverable p);
public void visitTask(Task p);
public void visitProject(Project p);
}
interface ProjectItem extends Serializable {
public void accept(ProjectVisitor v);
public ArrayList getProjectItems();
}
class ContactImpl implements Contact {
private String firstName;
private String lastName;
private String title;
private String organization;
public ContactImpl() {
}
public ContactImpl(String newFirstName, String newLastName,
String newTitle, String newOrganization) {
firstName = newFirstName;
lastName = newLastName;
title = newTitle;
organization = newOrganization;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
public String getTitle() {
return title;
}
public String getOrganization() {
return organization;
}
public void setFirstName(String newFirstName) {
firstName = newFirstName;
}
public void setLastName(String newLastName) {
lastName = newLastName;
}
public void setTitle(String newTitle) {
title = newTitle;
}
public void setOrganization(String newOrganization) {
organization = newOrganization;
}
public String toString() {
return firstName + SPACE + lastName;
}
}
class DataCreator {
private static final String DEFAULT_FILE = "data.ser";
public static void main(String[] args) {
String fileName;
if (args.length == 1) {
fileName = args[0];
} else {
fileName = DEFAULT_FILE;
}
serialize(fileName);
}
public static void serialize(String fileName) {
try {
serializeToFile(createData(), fileName);
} catch (IOException exc) {
exc.printStackTrace();
}
}
private static Serializable createData() {
Contact contact = new ContactImpl("Test", "Subject", "Volunteer",
"United Patterns Consortium");
Project project = new Project("Project 1", "Test Project");
Task task1 = new Task("Task 1", contact, 1);
Task task2 = new Task("Task 2", contact, 1);
project.addProjectItem(new Deliverable("Deliverable 1",
"Layer 1 deliverable", contact, 50.0, 50.0));
project.addProjectItem(task1);
project.addProjectItem(task2);
project.addProjectItem(new DependentTask("Dependent Task 1", contact,
1, 1));
Task task3 = new Task("Task 3", contact, 1);
Task task4 = new Task("Task 4", contact, 1);
Task task5 = new Task("Task 5", contact, 1);
Task task6 = new Task("Task 6", contact, 1);
DependentTask dtask2 = new DependentTask("Dependent Task 2", contact,
1, 1);
task1.addProjectItem(task3);
task1.addProjectItem(task4);
task1.addProjectItem(task5);
task1.addProjectItem(dtask2);
dtask2.addDependentTask(task5);
dtask2.addDependentTask(task6);
dtask2.addProjectItem(new Deliverable("Deliverable 2",
"Layer 3 deliverable", contact, 50.0, 50.0));
task3.addProjectItem(new Deliverable("Deliverable 3",
"Layer 3 deliverable", contact, 50.0, 50.0));
task4.addProjectItem(new Task("Task 7", contact, 1));
task4.addProjectItem(new Deliverable("Deliverable 4",
"Layer 3 deliverable", contact, 50.0, 50.0));
return project;
}
private static void serializeToFile(Serializable content, String fileName)
throws IOException {
ObjectOutputStream serOut = new ObjectOutputStream(
new FileOutputStream(fileName));
serOut.writeObject(content);
serOut.close();
}
}
class DataRetriever {
public static Object deserializeData(String fileName) {
Object returnValue = null;
try {
File inputFile = new File(fileName);
if (inputFile.exists() && inputFile.isFile()) {
ObjectInputStream readIn = new ObjectInputStream(
new FileInputStream(fileName));
returnValue = readIn.readObject();
readIn.close();
} else {
System.err.println("Unable to locate the file " + fileName);
}
} catch (ClassNotFoundException exc) {
exc.printStackTrace();
} catch (IOException exc) {
exc.printStackTrace();
}
return returnValue;
}
}
class DependentTask extends Task {
private ArrayList dependentTasks = new ArrayList();
private double dependencyWeightingFactor;
public DependentTask() {
}
public DependentTask(String newName, Contact newOwner,
double newTimeRequired, double newWeightingFactor) {
super(newName, newOwner, newTimeRequired);
dependencyWeightingFactor = newWeightingFactor;
}
public ArrayList getDependentTasks() {
return dependentTasks;
}
public double getDependencyWeightingFactor() {
return dependencyWeightingFactor;
}
public void setDependencyWeightingFactor(double newFactor) {
dependencyWeightingFactor = newFactor;
}
public void addDependentTask(Task element) {
if (!dependentTasks.contains(element)) {
dependentTasks.add(element);
}
}
public void removeDependentTask(Task element) {
dependentTasks.remove(element);
}
public void accept(ProjectVisitor v) {
v.visitDependentTask(this);
}
}
class Project implements ProjectItem {
private String name;
private String description;
private ArrayList projectItems = new ArrayList();
public Project() {
}
public Project(String newName, String newDescription) {
name = newName;
description = newDescription;
}
public String getName() {
return name;
}
public String getDescription() {
return description;
}
public ArrayList getProjectItems() {
return projectItems;
}
public void setName(String newName) {
name = newName;
}
public void setDescription(String newDescription) {
description = newDescription;
}
public void addProjectItem(ProjectItem element) {
if (!projectItems.contains(element)) {
projectItems.add(element);
}
}
public void removeProjectItem(ProjectItem element) {
projectItems.remove(element);
}
public void accept(ProjectVisitor v) {
v.visitProject(this);
}
}
class ProjectCostVisitor implements ProjectVisitor {
private double totalCost;
private double hourlyRate;
public double getHourlyRate() {
return hourlyRate;
}
public double getTotalCost() {
return totalCost;
}
public void setHourlyRate(double rate) {
hourlyRate = rate;
}
public void resetTotalCost() {
totalCost = 0.0;
}
public void visitDependentTask(DependentTask p) {
double taskCost = p.getTimeRequired() * hourlyRate;
taskCost *= p.getDependencyWeightingFactor();
totalCost += taskCost;
}
public void visitDeliverable(Deliverable p) {
totalCost += p.getMaterialsCost() + p.getProductionCost();
}
public void visitTask(Task p) {
totalCost += p.getTimeRequired() * hourlyRate;
}
public void visitProject(Project p) {
}
}
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