定義：定義一個(gè)用于創(chuàng)建對(duì)象的接口，讓子類決定實(shí)例化哪一個(gè)類。工廠方法使一個(gè)類的實(shí)例化延遲到其子類。
結(jié)構(gòu)：（書(shū)中圖，侵刪）
一個(gè)工廠的抽象接口
若干個(gè)具體的工廠類
一個(gè)需要?jiǎng)?chuàng)建對(duì)象的抽象接口
若干個(gè)所需創(chuàng)建的對(duì)象的類
較之簡(jiǎn)單工廠方法，多了一層抽象——將工廠也抽象了；由原來(lái)的一個(gè)萬(wàn)能工廠變?yōu)楝F(xiàn)在的若干個(gè)各司其職的工廠。
 
導(dǎo)致的結(jié)果就是：原本新增一個(gè)要?jiǎng)?chuàng)建的對(duì)象需要直接修改萬(wàn)能工廠類，增加判斷，違反了開(kāi)放-封閉原則；
現(xiàn)在工廠相關(guān)代碼不用改，只需要新增工廠類即可，同時(shí)將判斷轉(zhuǎn)移給了客戶端。
實(shí)例：既然是和簡(jiǎn)單工廠相對(duì)比，就還是延用之前計(jì)算器的例子：（同樣，為了代碼簡(jiǎn)潔不考慮輸入不合法等代碼健壯性）
抽象工廠接口：
package designpattern.factorymethod; import designpattern.staticfactorymethod.Calculate; public interface CalculateFactory { Calculate create(); } 若干工廠接口：
加
package designpattern.factorymethod; import designpattern.staticfactorymethod.Calculate; import designpattern.staticfactorymethod.Plus; public class PlusFactory implements CalculateFactory{ @Override public Calculate create() { return new Plus(); } } 
package designpattern.factorymethod; import designpattern.staticfactorymethod.Calculate; import designpattern.staticfactorymethod.Minus; public class MinusFactory implements CalculateFactory { @Override public Calculate create() { return new Minus(); } }
package designpattern.factorymethod; import designpattern.staticfactorymethod.Calculate; import designpattern.staticfactorymethod.Multiply; public class MultiplyFactory implements CalculateFactory { @Override public Calculate create() { return new Multiply(); } }
package designpattern.factorymethod; import designpattern.staticfactorymethod.Calculate; import designpattern.staticfactorymethod.Divide; public class DivideFactory implements CalculateFactory { @Override public Calculate create() { return new Divide(); } } 抽象計(jì)算類及若干具體計(jì)算類：（延用之前簡(jiǎn)單工廠方法的代碼）
抽象類：
package designpattern.staticfactorymethod; public abstract class Calculate { public double num1; public double num2; Calculate() { } Calculate(double num1, double num2) { this.num1 = num1; this.num2 = num2; } public abstract double calculate(); } 加： package designpattern.staticfactorymethod; public class Plus extends Calculate { public Plus() { } Plus(double num1, double num2) { super(num1, num2); } @Override public double calculate() { return num1 + num2; } }
package designpattern.staticfactorymethod; public class Minus extends Calculate { public Minus() { } Minus(double num1, double num2) { super(num1, num2); } @Override public double calculate() { return num1 - num2; } } 
package designpattern.staticfactorymethod; public class Multiply extends Calculate { public Multiply() { } Multiply(double num1, double num2) { super(num1, num2); } @Override public double calculate() { return num1 * num2; } }
package designpattern.staticfactorymethod; public class Divide extends Calculate { public Divide() { } Divide(double num1, double num2) { super(num1, num2); } @Override public double calculate() { return num1 / num2; } } 客戶端：
package designpattern.factorymethod; import java.util.Scanner; import designpattern.staticfactorymethod.Calculate; public class Client { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("請(qǐng)輸入一個(gè)數(shù)字"); double num1 = scanner.nextDouble(); System.out.println("請(qǐng)輸入一個(gè)運(yùn)算符：+、-、*、/"); String operator = scanner.next();// 不能用nextLine()，會(huì)把上一個(gè)回車給吸收 System.out.println("請(qǐng)輸入一個(gè)數(shù)字"); double num2 = scanner.nextDouble(); CalculateFactory calculateFactory = null; switch (operator) { case "+": calculateFactory = new PlusFactory(); break; case "-": calculateFactory = new MinusFactory(); break; case "*": calculateFactory = new MultiplyFactory(); break; case "/": calculateFactory = new DivideFactory(); break; default: break; } Calculate calculate = calculateFactory.create(); calculate.num1 = num1; calculate.num2 = num2; System.out.println(calculate.calculate()); scanner.close(); } } 總結(jié)：工廠方法模式就是在簡(jiǎn)單工廠方法模式的基礎(chǔ)上進(jìn)一步抽象，使其符合開(kāi)放-封閉原則。
個(gè)人理解，在輕量級(jí)系統(tǒng)，或者工廠所能創(chuàng)建的東西較少可能修改的情況下，可以考慮使用簡(jiǎn)單工廠模式；
否則，需要使用工廠方法模式。
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