建造者模式（Builder Pattern）是一种创建型设计模式，它允许你逐步构建复杂对象。建造者模式通过将对象的构建过程与其表示分离，使得相同的构建过程可以创建不同的表示。

在Java中，建造者模式通常用于构建具有多个可选参数的对象，尤其是在构造函数的参数较多时，使用建造者模式可以使代码更加清晰和易于维护。

下面是一个简单的Java示例，展示了如何使用建造者模式：

// 产品类
class Product {
    private String part1;
    private String part2;
    private String part3;

    public void setPart1(String part1) {
        this.part1 = part1;
    }

    public void setPart2(String part2) {
        this.part2 = part2;
    }

    public void setPart3(String part3) {
        this.part3 = part3;
    }

    @Override
    public String toString() {
        return "Product{" +
                "part1='" + part1 + '\'' +
                ", part2='" + part2 + '\'' +
                ", part3='" + part3 + '\'' +
                '}';
    }
}

// 抽象建造者类
abstract class Builder {
    protected Product product = new Product();

    public abstract void buildPart1();
    public abstract void buildPart2();
    public abstract void buildPart3();

    public Product getResult() {
        return product;
    }
}

// 具体建造者类
class ConcreteBuilder extends Builder {
    @Override
    public void buildPart1() {
        product.setPart1("Part 1");
    }

    @Override
    public void buildPart2() {
        product.setPart2("Part 2");
    }

    @Override
    public void buildPart3() {
        product.setPart3("Part 3");
    }
}

// 导演类
class Director {
    private Builder builder;

    public Director(Builder builder) {
        this.builder = builder;
    }

    public void construct() {
        builder.buildPart1();
        builder.buildPart2();
        builder.buildPart3();
    }
}

// 客户端代码
public class BuilderPatternDemo {
    public static void main(String[] args) {
        Builder builder = new ConcreteBuilder();
        Director director = new Director(builder);
        director.construct();

        Product product = builder.getResult();
        System.out.println(product);
    }
}