以水果为例讲解简单工厂模式，其中有三种水果，
*葡萄 Grape
*草莓Strawberry
*苹果Apple
水果并无具体的对象，因此是一个各个水果都适用的接口，以便与其他植物分隔开来。
三种水果均有自己不同的属性，现在实现水果接口及其三种水果的源码。
Fruit：
package SimpleFactory;
public interface Fruit {
/**
* 生长
*/
void grow();
/**
* 收获
*/
void harvest();
/**
* 种植
*/
void plant();
}
Apple：
package SimpleFactory;
public class Apple implements Fruit {
private int treeAge; //苹果树的树龄
@Override
public void grow() {
log("Apple is growing");
}
@Override
public void harvest() {
log("Apple has been harvested");
}
@Override
public void plant() {
log("Apple has been planted");
}
public int getTreeAge() {
return treeAge;
}
public void setTreeAge(int treeAge) {
this.treeAge = treeAge;
}
private void log(String msg){
System.err.println(msg);
}
}
Grape:
package SimpleFactory;
public class Grape implements Fruit {
private boolean seedless; //葡萄有籽或者无籽
@Override
public void grow() {
log("Grape is growing...");
}
@Override
public void harvest() {
log("Grape has been harvested");
}
@Override
public void plant() {
log("Grape has been planted");
}
private void log(String msg){
System.err.println(msg);
}
public boolean isSeedless() {
return seedless;
}
public void setSeedless(boolean seedless) {
this.seedless = seedless;
}
}
Strawberry:
package SimpleFactory;
public class Strawberry implements Fruit {
@Override
public void grow() {
log("Strawberry is growing...");
}
@Override
public void harvest() {
log("Strawberry has been harvested.");
}
@Override
public void plant() {
log("Strawberry has been planted");
}
private void log(String msg){
System.err.println(msg);
}
}
实现这三种水果后，还需要一个园丁来照料他们，因此还有一个园丁类，源码为：
package SimpleFactory;
public class FruitGardener {
/**
* 静态工厂方法
* @param which
* @return
*/
public static Fruit factory(String which)throws BadFruitException{
if(which.equalsIgnoreCase("apple")){
return new Apple();
}else if(which.equalsIgnoreCase("strawberry")){
return new Strawberry();
}else if(which.equalsIgnoreCase("grape")){
return new Grape();
}else{
throw new BadFruitException("Bad fruit request");
}
}
}
里面有一个BadException，当出现在园子中没有出现的水果时，要抛出异常，因此还有一个异常类。
BadException:
package SimpleFactory;
public class BadFruitException extends Exception {
public BadFruitException(String msg){
super(msg);
}
}
当这些都实现后，便可使用此模式进行收获，源码为：
package SimpleFactory;
public class Client {
public static void main(String[] args) {
try {
FruitGardener.factory("grape");
FruitGardener.factory("apple");
FruitGardener.factory("strawberry");
} catch (BadFruitException e) {
}
}
}
如此，便实现简单的工厂模式。
原文地址：http://blog.csdn.net/u012734441/article/details/43917211
