Spring Bean 何时准备好：初始化与代理调用

import java.util.*;
public class Main {
    record Spec(String name, boolean failOpen, boolean failClose) {}
    static class Resource {
        final Spec spec; final List<String> log;
        Resource(Spec spec,List<String> log) { this.spec=spec; this.log=log; }
        void close() {
            log.add("close:"+spec.name());
            if (spec.failClose()) throw new IllegalStateException("close:"+spec.name());
        }
    }
    static class Group implements AutoCloseable {
        final List<Resource> owned=new ArrayList<>();
        boolean closed;
        static Group open(List<Spec> specs,List<String> log) {
            Group group=new Group();
            try {
                for (Spec s:specs) {
                    log.add("open:"+s.name());
                    if (s.failOpen()) throw new IllegalStateException("open:"+s.name());
                    // 只有完整获得后才转移资源所有权。
                    group.owned.add(new Resource(s,log));
                }
                return group;
            } catch (RuntimeException primary) {
                group.release(primary);
                throw primary; // 保持最初失败，清理原因附加其上。
            }
        }
        void release(RuntimeException primary) {
            if (closed) return;
            closed=true;
            for (int i=owned.size()-1;i>=0;i--) {
                try { owned.get(i).close(); }
                // 单项关闭失败不能阻止更早资源的释放。
                catch (RuntimeException error) { primary.addSuppressed(error); }
            }
        }
        public void close() {
            if (closed) return;
            RuntimeException failures=new IllegalStateException("cleanup");
            release(failures);
            if (failures.getSuppressed().length>0) throw failures;
        }
    }
    static Spec ok(String name) { return new Spec(name,false,false); }
    static void eq(Object expected,Object actual) {
        if (!Objects.equals(expected,actual)) throw new AssertionError(actual);
    }
    public static void main(String[] args) {
        List<String> log=new ArrayList<>();
        Group g=Group.open(List.of(ok("A"),ok("B")),log);
        g.close(); g.close();
        eq(List.of("open:A","open:B","close:B","close:A"),log);
        log.clear();
        try { Group.open(List.of(ok("A"),new Spec("B",true,false)),log); }
        catch (IllegalStateException e) { eq("open:B",e.getMessage()); }
        eq(List.of("open:A","open:B","close:A"),log);
        log.clear();
        try {
            Group.open(List.of(new Spec("A",false,true),new Spec("B",true,false)),log);
            throw new AssertionError("expected startup failure");
        } catch (IllegalStateException e) { eq(1,e.getSuppressed().length); }
        log.clear();
        Group h=Group.open(List.of(ok("A"),new Spec("B",false,true)),log);
        try { h.close(); throw new AssertionError("expected close failure"); }
        catch (IllegalStateException e) { eq(1,e.getSuppressed().length); }
        eq(List.of("open:A","open:B","close:B","close:A"),log);
        Group.open(List.of(),new ArrayList<>()).close();
        System.out.println("PASS 5 resource lifecycle scenarios");
    }
}