构建者模式
定义： 从一个简单对象一步一步构造复杂对象
优点及使用：
仅仅通过指定的类型和内容构建复杂对象，而且隐藏构造的实现细节解耦通过对象组件构造一个复杂对象的过程分离构造和显示的代码通过构造过程达到良好的控制相关模式有： 抽象工厂：重点是在工厂模式（简单工厂或者复杂工厂），而构建者模式重点是由简单对象构建复杂对象
复合模式：它经常被用来构建复杂对象
例子：
为了建设一座房子，我们需要按照以下步骤：
1.建设基础设施
2.建设主体框架
3.装修外部
4.装修内部
让我们用一个抽象类HouseBuilder来定义这四个步骤。任何HouseBuilder的子类需要根据这四个步骤建设房子（也就是在子类中实现这四个方法），接着我们用WorkShop来规范这四个步骤的顺序（也就是必须完成前三步才能装修内部）。类TestBuilder用来测试这些类的协调性和检查构建过程。
import java.util.*;class WorkShop{ //规范构建过程顺序 public void construnct(HouseBuilder hb){ hb.buildFoundation(); hb.buildFrame(); hb.buildExterior(); hb.buildInterior(); }}//定义建房子的方法abstract class HouseBuilder{ protected House house = new House(); protected String showProgress(){ return house.toString(); } abstract public void buildFoundation(); abstract public void buildFrame(); abstract public void buildExterior(); abstract public void buildInterior();}class OneStoryHouse extends HouseBuilder { public OneStoryHouse(String features) { house.setType(this.getClass() + " " + features); } public void buildFoundation() { //doEngineering() //doExcavating() //doPlumbingHeatingElectricity() //doSewerWaterHookUp() //doFoundationInspection() house.setProgress("foundation is done"); } public void buildFrame() { //doHeatingPlumbingRoof() //doElectricityRoute() //doDoorsWindows() //doFrameInspection() house.setProgress("frame is done"); } public void buildExterior() { //doOverheadDoors() //doBrickWorks() //doSidingsoffitsGutters() //doDrivewayGarageFloor() //doDeckRail() //doLandScaping() house.setProgress("Exterior is done"); } public void buildInterior() { //doAlarmPrewiring() //doBuiltinVacuum() //doInsulation() //doDryWall() //doPainting() //doLinoleum() //doCabinet() //doTileWork() //doLightFixtureBlinds() //doCleaning() //doInteriorInspection() house.setProgress("Interior is under going"); } }class TwoStoryHouse extends HouseBuilder { public TwoStoryHouse(String features) { house.setType(this.getClass() + " " + features); } public void buildFoundation() { //doEngineering() //doExcavating() //doPlumbingHeatingElectricity() //doSewerWaterHookUp() //doFoundationInspection() house.setProgress("foundation is done"); } public void buildFrame() { //doHeatingPlumbingRoof() //doElectricityRoute() //doDoorsWindows() //doFrameInspection() house.setProgress("frame is under construction"); } public void buildExterior() { //doOverheadDoors() //doBrickWorks() //doSidingsoffitsGutters() //doDrivewayGarageFloor() //doDeckRail() //doLandScaping() house.setProgress("Exterior is waiting to start"); } public void buildInterior() { //doAlarmPrewiring() //doBuiltinVacuum() //doInsulation() //doDryWall() //doPainting() //doLinoleum() //doCabinet() //doTileWork() //doLightFixtureBlinds() //doCleaning() //doInteriorInspection() house.setProgress("Interior is not started yet"); }}class House { private String type = null; private List features = new ArrayList(); public House() { } public House(String type) { this.type = type; } public void setType(String type) { this.type = type; } public String getType() { return type; } public void setProgress(String s) { features.add(s); } public String toString() { StringBuffer ff = new StringBuffer(); String t = type.substring(6); ff.append(t + "\n "); for (int i = 0; i < features.size(); i ++) { ff.append(features.get(i) + "\n "); } return ff.toString(); }}class TestBuilder { public static void main(String[] args) { HouseBuilder one = new OneStoryHouse("2 bedrooms, 2.5 baths, 2-car garage, 1500 sqft"); HouseBuilder two = new TwoStoryHouse("4 bedrooms, 4 baths, 3-car garage, 5000 sqft"); WorkShop shop = new WorkShop(); shop.construct(one); shop.construct(two); System.out.println("Check house building progress: \n"); System.out.println(one.showProgress()); System.out.println(two.showProgress()); }}//需要jdk1.5或者以上版本}