Lombok Builders 使用反射吗？

Question

或者它是否也添加了必要的代码预编译？

Answer 1

The official site 非常清楚 @Builder 的工作原理：

@Builder can be placed on a class, or on a constructor, or on a method. While the "on a class" and "on a constructor" mode are the most common use-case, @Builder is most easily explained with the "method" use-case.

A method annotated with @Builder (from now on called the target) causes the following 7 things to be generated:

An inner static class named FooBuilder, with the same type arguments as the static method (called the builder).

In the builder: One private non-static non-final field for each parameter of the target.

In the builder: A package private no-args empty constructor.

In the builder: A 'setter'-like method for each parameter of the target: It has the same type as that parameter and the same name. It returns the builder itself, so that the setter calls can be chained, as in the above example.

In the builder: A build() method which calls the method, passing in each field. It returns the same type that the target returns.

In the builder: A sensible toString() implementation.

In the class containing the target: A builder() method, which creates a new instance of the builder.

例如，它可能看起来像这样：

public static class FooBuilder {
    private String abc;
    private String def;

    FooBuilder() {}

    public FooBuilder abc(String abc) {
        this.abc = abc;
        return this;
    }

    public FooBuilder def(String def) {
        this.def = def;
        return this;
    }

    public Foo build() {
        return new Foo(abc, def);
    }

    @Override
    public String toString() {
        return "FooBuilder{abc: " + abc + ", def: " + def + "}";
    }
}

Answer 2

绝对没有反射，因为 Lombok 使用某种代码生成。它在 AST（抽象语法树）级别上工作，即，它在源代码和字节码之间的某个位置与解析后的源代码一起工作。

Lombok 的一部分是 delombok，它向您展示了生成的代码。

Lombok Builders 使用反射吗？

Do Lombok Builders use Reflection?

java

reflection

lombok