MCPInstall

guava-patterns

by full-stack-skillsBackend & APIs

Google Guava 最佳实践模式。从官方 wiki 提炼，覆盖 Immutable集合的 of/copyOf/builder 三模式与防御性拷贝规则、Cache 选择决策(LoadingCache vs Cache vs Caffeine)、Joiner/Splitter 不可变流水线、CharMatcher 替代正则、Preconditions 格式化消息校验、CaseFormat 命名互转。 纠正 LLM 误用：手写不可变集合、ConcurrentHashMap 替代 Cache、不知 CharMatcher。

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Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/full-stack-skills/java-skills --skill guava-patterns
  1. 01

    Install

    Run the command in your project. The CLI asks which agents to install for.

  2. 02

    Describe the task

    Ask your agent for something this skill covers. It loads guava-patterns automatically when relevant.

  3. 03

    Review the result

    The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

Google Guava 最佳实践模式

来源: Guava Wiki | GitHub: google/guava

Capability Boundaries

✅ Strong Suits

  1. Immutable集合三模式 — of()静态常量 / copyOf()防御性拷贝 / builder()渐进构建
  2. Cache模式选择 — Cache(无默认加载) vs LoadingCache(有默认加载函数) vs Caffeine(高性能)
  3. Joiner/Splitter流水线 — 函数式组合，实例线程安全可作 static final 常量
  4. CharMatcher — 预定义字符类操作，比正则更可读更安全
  5. Preconditions — checkArgument/checkNotNull/checkState 三剑客，格式化消息(类似printf)
  6. CaseFormat — LOWER_CAMEL/UPPER_UNDERSCORE 等 ASCII 命名风格互转

❌ Out of Scope

  1. ListenableFuture → 已被 Java8 CompletableFuture 替代，不要再用
  2. EventBus → 仅进程内，跨服务用 kafka-patterns
  3. 高性能缓存 → caffeine-patterns(API兼容Guava，性能更好)

核心模式

模式 1: Immutable 集合三选择

// ✅ of() — 编译期已知元素(作静态常量)
public static final ImmutableSet<String> COLORS = ImmutableSet.of("red","green","blue");

// ✅ copyOf() — 防御性拷贝(接收外部集合)
class Foo {
    final ImmutableSet<Bar> bars;
    Foo(Set<Bar> bars) { this.bars = ImmutableSet.copyOf(bars); }
}

// ✅ builder() — 渐进构建(合并多来源)
ImmutableSet<Color> colors = ImmutableSet.<Color>builder()
    .addAll(WEBSAFE_COLORS).add(new Color(0,191,255)).build();

// ❌ Collections.unmodifiableXXX — 冗长/不安全(持有引用仍可改)/低效(保留并发检查)

模式 2: Cache 选择决策

有明确的"未命中→加载"函数 → LoadingCache (get(key)自动加载)
加载函数因key而异 → Cache (get(key, callable)每次指定)
高频+高并发+追求性能 → Caffeine (API兼容,窗口TinyLFU)
多实例共享 → Redis

// ✅ LoadingCache: 统一加载函数
LoadingCache<String, User> cache = CacheBuilder.newBuilder()
    .maximumSize(1000).expireAfterWrite(10, TimeUnit.MINUTES)
    .build(new CacheLoader<>() { public User load(String k) { return loadDB(k); }});
User u = cache.get("user:1");  // 自动加载+缓存

// ✅ 异步刷新(旧值仍可用，后台加载新值)
LoadingCache<String, Config> cfg = CacheBuilder.newBuilder()
    .refreshAfterWrite(1, TimeUnit.MINUTES)
    .build(new CacheLoader<>() { public Config load(String k) { ... }});

// ✅ RemovalListener: 异步拆除资源避免阻塞缓存
RemovalListener<String, Conn> listener = RemovalListeners.asynchronous(
    notif -> notif.getValue().close(), executor);

模式 3: Joiner/Splitter 不可变流水线

// Joiner: 实例不可变，可作 static final 常量
private static final Joiner JOINER = Joiner.on(",").skipNulls();
JOINER.join(list);                                    // "a,b,c"
Joiner.on("; ").useForNull("N/A").join("a",null,"c");  // "a; N/A; c"

// Splitter: 链式修饰 trimResults → omitEmptyStrings → limit
List<String> parts = Splitter.on(',').trimResults()
    .omitEmptyStrings().splitToList("foo,bar,,  qux");  // ["foo","bar","qux"]

// Map Splitter: URL参数解析
Map<String,String> m = Splitter.on('&')
    .withKeyValueSeparator('=').split("id=123&name=foo");

// 固定长度切分
Splitter.fixedLength(3).splitToList("abcdefg");  // ["abc","def","g"]

模式 4: CharMatcher 替代正则

// ✅ CharMatcher — 编译期类型安全，比正则更可读
CharMatcher.digit().retainFrom("abc123");           // "123"
CharMatcher.javaIsoControl().removeFrom(string);     // 删除控制字符
CharMatcher.whitespace().trimAndCollapseFrom(" foo   bar ", ' '); // "foo bar"
CharMatcher.inRange('a','z').or(CharMatcher.is('_')).matchesAllOf(input);

// ❌ 反模式：Pattern.compile("\\d+") — CharMatcher 更优

模式 5: Preconditions vs Objects

// ✅ Guava Preconditions: 格式化消息(类似printf)
checkNotNull(obj, "参数不能为空: %s", userId);
checkArgument(age > 0, "年龄必须>0: %s", age);

// ✅ Java Objects: 简单非空(无格式化)
Objects.requireNonNull(obj, "参数不能为空");
// 选择: 需要消息格式化 → Preconditions; 简单判空 → Objects

Gotchas

  1. ImmutableList.of() 不接受 null — 含null抛NPE，需null用Collections.unmodifiableList
  2. Cache.get() 加载异常抛 ExecutionException — 需要try-catch或getUnchecked()
  3. expireAfterAccess vs expireAfterWrite — access适合频繁读(会话)，write适合稳定数据
  4. refreshAfterWrite 必须小于 expireAfterWrite — 否则刷新在过期后执行，无意义
  5. Guava Reflect/ListenableFuture 已被 JDK 替代 — Java8+ 不要再用Guava版本
  6. Caffeine 性能优于 Guava Cache — 新项目优先Caffeine，仅旧项目兼容用Guava
  7. CharMatcher 只匹配单个字符 — 多字符模式(如关键词匹配)仍需正则

Data Privacy

本技能不收集、存储或传输任何用户数据。

FAQ

What does the guava-patterns skill do?

Google Guava 最佳实践模式。从官方 wiki 提炼，覆盖 Immutable集合的 of/copyOf/builder 三模式与防御性拷贝规则、Cache 选择决策(LoadingCache vs Cache vs Caffeine)、Joiner/Splitter 不可变流水线、CharMatcher 替代正则、Preconditions 格式化消息校验、CaseFormat 命名互转。 纠正 LLM 误用：手写不可变集合、ConcurrentHashMap 替代 Cache、不知 CharMatcher。

How do I install guava-patterns?

Run npx skills add https://github.com/full-stack-skills/java-skills --skill guava-patterns in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/guava-patterns/ (personal) or .claude/skills/guava-patterns/ (project).

Which AI agents can use guava-patterns?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is guava-patterns safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains guava-patterns?

It is published by full-stack-skills in full-stack-skills/java-skills. It has 93 recorded installs.

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