Mega Code Archive
Proxy Pattern 2
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//[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 RunProxyPattern {
public static void main(String[] arguments) {
System.out.println("Example for the Proxy pattern");
System.out.println();
System.out.println("This code will demonstrate the use of a Proxy to");
System.out.println(" provide functionality in place of its underlying");
System.out.println(" class.");
System.out.println();
System.out
.println(" Initially, an AddressBookProxy object will provide");
System.out.println(" address book support without requiring that the");
System.out
.println(" AddressBookImpl be created. This could potentially");
System.out.println(" make the application run much faster, since the");
System.out
.println(" AddressBookImpl would need to read in all addresses");
System.out.println(" from a file when it is first created.");
System.out.println();
if (!(new File("data.ser").exists())) {
DataCreator.serialize("data.ser");
}
System.out.println("Creating the AddressBookProxy");
AddressBookProxy proxy = new AddressBookProxy("data.ser");
System.out.println("Adding entries to the AddressBookProxy");
System.out.println("(this operation can be done by the Proxy, without");
System.out.println(" creating an AddressBookImpl object)");
proxy.add(new AddressImpl("Sun Education [CO]", "500 El Dorado Blvd.",
"Broomfield", "CO", "80020"));
proxy.add(new AddressImpl("Apple Inc.", "1 Infinite Loop",
"Redwood City", "CA", "93741"));
System.out.println("Addresses created. Retrieving an address");
System.out
.println("(since the address is stored by the Proxy, there is");
System.out
.println(" still no need to create an AddressBookImpl object)");
System.out.println();
System.out.println(proxy.getAddress("Sun Education [CO]").getAddress());
System.out.println();
System.out
.println("So far, all operations have been handled by the Proxy,");
System.out
.println(" without any involvement from the AddressBookImpl.");
System.out.println(" Now, a call to the method getAllAddresses will");
System.out.println(" force instantiation of AddressBookImpl, and will");
System.out.println(" retrieve ALL addresses that are stored.");
System.out.println();
ArrayList addresses = proxy.getAllAddresses();
System.out.println("Addresses retrieved. Addresses currently stored:");
System.out.println(addresses);
}
}
interface Address extends Serializable {
public static final String EOL_STRING = System
.getProperty("line.separator");
public static final String SPACE = " ";
public static final String COMMA = ",";
public String getAddress();
public String getType();
public String getDescription();
public String getStreet();
public String getCity();
public String getState();
public String getZipCode();
public void setType(String newType);
public void setDescription(String newDescription);
public void setStreet(String newStreet);
public void setCity(String newCity);
public void setState(String newState);
public void setZipCode(String newZip);
}
interface AddressBook {
public void add(Address address);
public ArrayList getAllAddresses();
public Address getAddress(String description);
public void open();
public void save();
}
class FileLoader {
public static Object loadData(File inputFile) {
Object returnValue = null;
try {
if (inputFile.exists()) {
if (inputFile.isFile()) {
ObjectInputStream readIn = new ObjectInputStream(
new FileInputStream(inputFile));
returnValue = readIn.readObject();
readIn.close();
} else {
System.err.println(inputFile + " is a directory.");
}
} else {
System.err.println("File " + inputFile + " does not exist.");
}
} catch (ClassNotFoundException exc) {
exc.printStackTrace();
} catch (IOException exc) {
exc.printStackTrace();
}
return returnValue;
}
public static void storeData(File outputFile, Serializable data) {
try {
ObjectOutputStream writeOut = new ObjectOutputStream(
new FileOutputStream(outputFile));
writeOut.writeObject(data);
writeOut.close();
} catch (IOException exc) {
exc.printStackTrace();
}
}
}
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() {
ArrayList items = new ArrayList();
items.add(new AddressImpl("Home address", "1418 Appian Way",
"Pleasantville", "NH", "27415"));
items.add(new AddressImpl("Resort", "711 Casino Ave.", "Atlantic City",
"NJ", "91720"));
items.add(new AddressImpl("Vacation spot", "90 Ka'ahanau Cir.",
"Haleiwa", "HI", "41720"));
return items;
}
private static void serializeToFile(Serializable data, String fileName)
throws IOException {
ObjectOutputStream serOut = new ObjectOutputStream(
new FileOutputStream(fileName));
serOut.writeObject(data);
serOut.close();
}
}
class AddressImpl implements Address {
private String type;
private String description;
private String street;
private String city;
private String state;
private String zipCode;
public static final String HOME = "home";
public static final String WORK = "work";
public AddressImpl() {
}
public AddressImpl(String newDescription, String newStreet, String newCity,
String newState, String newZipCode) {
description = newDescription;
street = newStreet;
city = newCity;
state = newState;
zipCode = newZipCode;
}
public String getType() {
return type;
}
public String getDescription() {
return description;
}
public String getStreet() {
return street;
}
public String getCity() {
return city;
}
public String getState() {
return state;
}
public String getZipCode() {
return zipCode;
}
public void setType(String newType) {
type = newType;
}
public void setDescription(String newDescription) {
description = newDescription;
}
public void setStreet(String newStreet) {
street = newStreet;
}
public void setCity(String newCity) {
city = newCity;
}
public void setState(String newState) {
state = newState;
}
public void setZipCode(String newZip) {
zipCode = newZip;
}
public String toString() {
return description;
}
public String getAddress() {
return description + EOL_STRING + street + EOL_STRING + city + COMMA
+ SPACE + state + SPACE + zipCode + EOL_STRING;
}
}
class AddressBookProxy implements AddressBook {
private File file;
private AddressBookImpl addressBook;
private ArrayList localAddresses = new ArrayList();
public AddressBookProxy(String filename) {
file = new File(filename);
}
public void open() {
addressBook = new AddressBookImpl(file);
Iterator addressIterator = localAddresses.iterator();
while (addressIterator.hasNext()) {
addressBook.add((Address) addressIterator.next());
}
}
public void save() {
if (addressBook != null) {
addressBook.save();
} else if (!localAddresses.isEmpty()) {
open();
addressBook.save();
}
}
public ArrayList getAllAddresses() {
if (addressBook == null) {
open();
}
return addressBook.getAllAddresses();
}
public Address getAddress(String description) {
if (!localAddresses.isEmpty()) {
Iterator addressIterator = localAddresses.iterator();
while (addressIterator.hasNext()) {
AddressImpl address = (AddressImpl) addressIterator.next();
if (address.getDescription().equalsIgnoreCase(description)) {
return address;
}
}
}
if (addressBook == null) {
open();
}
return addressBook.getAddress(description);
}
public void add(Address address) {
if (addressBook != null) {
addressBook.add(address);
} else if (!localAddresses.contains(address)) {
localAddresses.add(address);
}
}
}
class AddressBookImpl implements AddressBook {
private File file;
private ArrayList addresses = new ArrayList();
public AddressBookImpl(File newFile) {
file = newFile;
open();
}
public ArrayList getAllAddresses() {
return addresses;
}
public Address getAddress(String description) {
Iterator addressIterator = addresses.iterator();
while (addressIterator.hasNext()) {
AddressImpl address = (AddressImpl) addressIterator.next();
if (address.getDescription().equalsIgnoreCase(description)) {
return address;
}
}
return null;
}
public void add(Address address) {
if (!addresses.contains(address)) {
addresses.add(address);
}
}
public void open() {
addresses = (ArrayList) FileLoader.loadData(file);
}
public void save() {
FileLoader.storeData(file, addresses);
}
}
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