概念                                                                                         

将一个复杂的构建与其表示相分离，使得同样的构建过程可以创建不同的表示。

类图                                                                                          

代码                                                                                          

public abstract class Computer {
    private String type;
    private String cpu;
    private String ram;
    private String os;
    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }
    public String getCpu() {
        return cpu;
    }
    public void setCpu(String cpu) {
        this.cpu = cpu;
    }
    public String getRam() {
        return ram;
    }
    public void setRam(String ram) {
        this.ram = ram;
    }
    public String getOs() {
        return os;
    }
    public void setOs(String os) {
        this.os = os;
    }
    
}

创建两种型号的计算机：

public class T410 extends Computer {
    private String hardDisk;

    public T410() {
        this.setType("ThinkPad T410i");
    }

    public String getHardDisk() {
        return hardDisk;
    }

    public void setHardDisk(String hardDisk) {
        this.hardDisk = hardDisk;
    }

    @Override
    public String toString() {
        return "T410 [hardDisk=" + hardDisk + ", getType()=" + getType()
                + ", getCpu()=" + getCpu() + ", getRam()=" + getRam()
                + ", getOs()=" + getOs() + ", getClass()=" + getClass()
                + ", hashCode()=" + hashCode() + "]";
    }
}

public class X201 extends Computer {

    public X201() {
        this.setType("Thinkpad X201i");
    }

    @Override
    public String toString() {
        return "X201 [getType()=" + getType() + ", getCpu()=" + getCpu()
                + ", getRam()=" + getRam() + ", getOs()=" + getOs()
                + ", getClass()=" + getClass() + ", hash