Question

Java格式字符串的语法可能会变得复杂，例如：

"|%1$-10s|%2$-10s|%3$-20s|\n"

有人创建一个流畅的DSL来帮助构建这些格式字符串似乎已经成熟（类似于Jooq对SQL的作用）。

这样的事情存在吗？

Answer 1

您可以使用fluflu创建此类API，这是一个流畅的API生成器，其灵感来自jOOQ's API和jOOQ's underlying API design techniques。

Fluflu提供使用APT工具处理的注释，以从API实现生成流畅的API。注释模拟有限状态机。这是他们维基的一个例子：

@Fluentize(className = "CoreClass", startState = "State0", startMethod = "start")
public abstract class ToBeFluentized implements Cloneable {

    @Transitions({ 
        @Transition(from = "State0", end = true),
        @Transition(from = "State1", end = true) 
    })
    public void end() {
    }

    protected String with = null;
    protected List<byte[]> b = new LinkedList<>();

    @Transition(from = { "State0", "State1" }, to = "State0")
    public abstract ToBeFluentized with(
        @AssignTo("with") String a, @AddTo("b") byte[] b
    );

    @Transition(from = "State1", to = "State0")
    public ToBeFluentized z() {
        return this;
    }

    Set<Integer> j = new HashSet<>(); 
    @Transition(from = "State1", to = "State1", name="a")
    public abstract ToBeFluentized z(@AddTo("j") int j);

    @Transition(from = "State0", to = "State1")
    public ToBeFluentized a() {
        return this;
    }

    @Transition(from = "State0", to = "State1")
    public ToBeFluentized b() {
        return this;
    }

    @Transition(from = "State0", to = "State1")
    public ToBeFluentized vari(String... strings) {
        return this;
    }
}

然后可以这样使用：

State0 c = CoreClass.start().a().z();
State0 d = c.b().with("z", "z".getBytes());
State0 e = c.b().with("q", new byte[]{0,0,1});
d.end();
e.end();

当然，您仍然需要编写实现： - ）

是否存在任何提供构建Java格式字符串的流畅方法的库？

1 个答案: