Java设计模式之建造者模式

建造者模式结构：

Builder:抽象建造者

ConcretBuilder:具体建造者

Director:指挥者

Product:具体产品

UML图：

例子代码：

普通建造者：

public interface Builder {     void buildPartA();     void buildPartB();     void buildPartC();     Product getResult();}

public class ConcreteBuilder implements Builder {    Product product = new Product();    @Override    public void buildPartA() {        product.setPart1("编号：9527");    }    @Override    public void buildPartB() {        product.setPart2("颜色：红色");    }    @Override    public void buildPartC() {        product.setPart3("生产厂商：鸿基");    }    @Override    public Product getResult() {        return product;    }}

public class Director {    private Builder pbuilder;    public void construct(){        pbuilder.buildPartA();        pbuilder.buildPartB();        pbuilder.buildPartC();    }    public void setBuilder(Builder builder){        pbuilder = builder;    }}

public class Product {    /**     * 定义一些关于产品的操作     */    private String part1;    private String part2;    private String part3;    public String getPart3() {        return part3;    }    public void setPart3(String part3) {        this.part3 = part3;    }    public String getPart1() {        return part1;    }    public void setPart1(String part1) {        this.part1 = part1;    }    public String getPart2() {        return part2;    }    public void setPart2(String part2) {        this.part2 = part2;    }    @Override    public String toString() {        return "最终产品组成："+part1+" "+part2+" "+part3;    }}

public class BuilderTest {    public static void main(String[] args) {        ConcreteBuilder builder = new ConcreteBuilder();        Director director = new Director();        director.setBuilder(builder);        director.construct();        Product product = builder.getResult();        System.out.println(product.toString());    }}

结果打印：

集中建造者，一句代码即可配置建造模式：

public class InsuranceContract {    //保险合同编号    private String contractId;    /**     * 被保险人员的名称，同一份保险合同，要么跟人员签订，要么跟公司签订     * 也就是说，“被保险人员”和“被保险公司”这两个属性，不可能同时有值     */    private String personName;    //被保险公司的名称    private String companyName;    //保险开始生效日期    private long beginDate;    //保险失效日期，一定会大于保险开始生效日期    private long endDate;    //其他数据    private String otherData;    //私有构造方法    private InsuranceContract(ConcreteBuilder builder){        this.contractId = builder.contractId;        this.personName = builder.personName;        this.companyName = builder.companyName;        this.beginDate = builder.beginDate;        this.endDate = builder.endDate;        this.otherData = builder.otherData;    }    /**     * 保险合同的一些操作     */    public void someOperation(){        System.out.println("当前正在操作的保险合同编号为【"+this.contractId+"】");    }    public static class ConcreteBuilder{        private String contractId;        private String personName;        private String companyName;        private long beginDate;        private long endDate;        private String otherData;        /**         * 构造方法，传入必须要有的参数         * @param contractId     保险合同编号         * @param beginDate        保险合同开始生效日期         * @param endDate        保险合同失效日期         */        public ConcreteBuilder(String contractId,long beginDate,long endDate){            this.contractId = contractId;            this.beginDate = beginDate;            this.endDate = endDate;        }        //被保险人员的名称        public ConcreteBuilder setPersonName(String personName) {            this.personName = personName;            return this;        }        //被保险公司的名称        public ConcreteBuilder setCompanyName(String companyName) {            this.companyName = companyName;            return this;        }        //其他数据        public ConcreteBuilder setOtherData(String otherData) {            this.otherData = otherData;            return this;        }        /**         * 构建真正的对象并返回         * @return    构建的保险合同对象         */        public InsuranceContract build(){            if(contractId == null || contractId.trim().length()==0){                throw new IllegalArgumentException("合同编号不能为空");            }            boolean signPerson = (personName != null && personName.trim().length() > 0);            boolean signCompany = (companyName != null && companyName.trim().length() > 0);            if(signPerson && signCompany){                throw new IllegalArgumentException("一份保险合同不能同时与个人和公司签订");            }            if(signPerson == false && signCompany == false){                throw new IllegalArgumentException("一份保险合同不能没有签订对象");            }            if(beginDate <= 0 ){                throw new IllegalArgumentException("一份保险合同必须有开始生效的日期");            }            if(endDate <=0){                throw new IllegalArgumentException("一份保险合同必须有失效的日期");            }            if(endDate < beginDate){                throw new IllegalArgumentException("一份保险合同的失效日期必须大于生效日期");            }            return new InsuranceContract(this);        }    }}

public class InsuranceContractTest {    public static void main(String[] args) {        //创建构建器对象        InsuranceContract.ConcreteBuilder builder =                new InsuranceContract.ConcreteBuilder("9527", 123L, 456L);        //设置需要的数据，然后构建保险合同对象        InsuranceContract contract =                builder.setCompanyName("xiao")                .setOtherData("dd")                .build();        //操作保险合同对象的方法        contract.someOperation();    }}

结果打印：