前言：

SpringBoot以其强大的自动配置和丰富的生态系统成为Java开发的首选框架。除了核心功能外，SpringBoot及其依赖的Spring框架还包含大量实用工具类，它们可以显著简化日常开发工作。本文将介绍几个用工具类，并通过简洁的代码示例展示它们的基本用法。

字符串处理工具类

1.StringUtils

import org.springframework.util.StringUtils;

// 检查字符串是否为空

boolean isEmpty = StringUtils.isEmpty(null); // true

boolean isEmpty2 = StringUtils.isEmpty(""); // true

// 检查字符串是否有文本内容

boolean hasText = StringUtils.hasText(" "); // false

boolean hasText2 = StringUtils.hasText("hello"); // true

// 分割字符串

String[] parts = StringUtils.tokenizeToStringArray("a,b,c", ",");

// 清除首尾空白

String trimmed = StringUtils.trimWhitespace(" hello "); // "hello"

2.AntPathMatcher

import org.springframework.util.AntPathMatcher;

AntPathMatcher matcher = new AntPathMatcher();

boolean match1 = matcher.match("/users/*", "/users/123"); // true

boolean match2 = matcher.match("/users/**", "/users/123/orders"); // true

boolean match3 = matcher.match("/user?", "/user1"); // true

// 提取路径变量

Map<String, String> vars = matcher.extractUriTemplateVariables("/users/{id}", "/users/42"); // {id=42}

3. PatternMatchUtils

import org.springframework.util.PatternMatchUtils;

boolean matches1 = PatternMatchUtils.simpleMatch("user*", "username"); // true

boolean matches2 = PatternMatchUtils.simpleMatch("user?", "user1"); // true

boolean matches3 = PatternMatchUtils.simpleMatch(new String[]{"user*", "admin*"}, "username"); // true

集合和数组工具类

4. CollectionUtils

import org.springframework.util.CollectionUtils;

// 检查集合是否为空

boolean isEmpty = CollectionUtils.isEmpty(null); // true

boolean isEmpty2 = CollectionUtils.isEmpty(Collections.emptyList()); // true

// 集合操作

List<String> list1 = Arrays.asList("a", "b", "c");

List<String> list2 = Arrays.asList("b", "c", "d");

Collection<String> intersection = CollectionUtils.intersection(list1, list2); // [b, c]

// 合并集合

List<String> target = new ArrayList<>();

CollectionUtils.mergeArrayIntoCollection(new String[]{"a", "b"}, target);

5. MultiValueMap

import org.springframework.util.LinkedMultiValueMap;

import org.springframework.util.MultiValueMap;

MultiValueMap<String, String> map = new LinkedMultiValueMap<>();

map.add("colors", "red");

map.add("colors", "blue");

map.add("sizes", "large");

List<String> colors = map.get("colors"); // [red, blue]

6. ConcurrentReferenceHashMap

import org.springframework.util.ConcurrentReferenceHashMap;

// 创建高并发场景下的引用Map (类似WeakHashMap但线程安全)

Map<String, Object> cache = new ConcurrentReferenceHashMap<>();

cache.put("key1", new LargeObject());

反射和类处理工具

7.ReflectionUtils

import org.springframework.util.ReflectionUtils;

// 获取类的字段

Field field = ReflectionUtils.findField(Person.class, "name");

ReflectionUtils.makeAccessible(field);

ReflectionUtils.setField(field, person, "John");

// 调用方法

Method method = ReflectionUtils.findMethod(Person.class, "setAge", int.class);

ReflectionUtils.makeAccessible(method);

ReflectionUtils.invokeMethod(method, person, 30);

// 字段回调

ReflectionUtils.doWithFields(Person.class, field -> {

System.out.println(field.getName());

});

8.ClassUtils

import org.springframework.util.ClassUtils;

// 获取类名

String shortName = ClassUtils.getShortName("org.example.MyClass"); // "MyClass"

// 检查类是否存在

boolean exists = ClassUtils.isPresent("java.util.List", null); // true

// 获取所有接口

Class<?>[] interfaces = ClassUtils.getAllInterfaces(ArrayList.class);

// 获取用户定义的类加载器

ClassLoader classLoader = ClassUtils.getDefaultClassLoader();

9.BeanUtils

import org.springframework.beans.BeanUtils;

// 复制属性

Person source = new Person("John", 30);

Person target = new Person();

BeanUtils.copyProperties(source, target);

// 实例化类

Person newPerson = BeanUtils.instantiateClass(Person.class);

// 查找方法

Method method = BeanUtils.findMethod(Person.class, "setName", String.class);

I/O和资源工具

10.FileCopyUtils

import org.springframework.util.FileCopyUtils;

// 复制文件内容

byte[] bytes = FileCopyUtils.copyToByteArray(new File("input.txt"));

FileCopyUtils.copy(bytes, new File("output.txt"));

// 读取文本

String content = FileCopyUtils.copyToString(

new InputStreamReader(new FileInputStream("input.txt"), "UTF-8"));

// 流复制

FileCopyUtils.copy(inputStream, outputStream);

Web相关工具类

11. WebUtils

import org.springframework.web.util.WebUtils;

import javax.servlet.http.HttpServletRequest;

// 获取Cookie

Cookie cookie = WebUtils.getCookie(request, "sessionId");

// 获取请求路径

String path = WebUtils.getLookupPathForRequest(request);

// 从请求中获取参数

int pageSize = WebUtils.getIntParameter(request, "pageSize", 10);

12.UriUtils

import org.springframework.web.util.UriUtils;

// 编解码URI组件

String encoded = UriUtils.encodePathSegment("path with spaces", "UTF-8");

String decoded = UriUtils.decode(encoded, "UTF-8");

验证和断言工具

13.Assert

import org.springframework.util.Assert;

// 常用断言

Assert.notNull(object, "Object must not be null");

Assert.hasText(name, "Name must not be empty");

Assert.isTrue(amount > 0, "Amount must be positive");

Assert.notEmpty(items, "Items must not be empty");

Assert.state(isInitialized, "Service is not initialized");

14.ObjectUtils

import org.springframework.util.ObjectUtils;

// 对象工具

boolean isEmpty = ObjectUtils.isEmpty(null); // true

boolean isEmpty2 = ObjectUtils.isEmpty(new String[0]); // true

String nullSafe = ObjectUtils.nullSafeToString(null); // "null"

boolean equals = ObjectUtils.nullSafeEquals(obj1, obj2);

// 默认值

String value = ObjectUtils.getOrDefault(null, "default");

15. NumberUtils

import org.springframework.util.NumberUtils;

// 数字转换

Integer parsed = NumberUtils.parseNumber("42", Integer.class);

Double converted = NumberUtils.convertNumberToTargetClass(42, Double.class);

日期和时间工具

16.DateTimeUtils

import org.springframework.format.datetime.DateTimeFormatUtils;

import java.util.Date;

// 格式化日期

String formatted = DateTimeFormatUtils.getDateTimeInstance().format(new Date());

17.StopWatch

import org.springframework.util.StopWatch;

// 计时工具

StopWatch watch = new StopWatch("TaskName");

watch.start("phase1");

// 执行任务1

Thread.sleep(100);

watch.stop();

watch.start("phase2");

// 执行任务2

Thread.sleep(200);

watch.stop();

// 输出报告

System.out.println(watch.prettyPrint());

System.out.println("Total time: " + watch.getTotalTimeMillis() + "ms");

安全相关工具

18.Base64Utils

import org.springframework.util.Base64Utils;

// Base64编解码

byte[] data = "Hello World".getBytes();

String encoded = Base64Utils.encodeToString(data);

byte[] decoded = Base64Utils.decodeFromString(encoded);

JSON和数据转换工具

19.JsonUtils

import org.springframework.boot.json.JsonParser;

import org.springframework.boot.json.JsonParserFactory;

// JSON解析

JsonParser parser = JsonParserFactory.getJsonParser();

Map<String, Object> parsed = parser.parseMap("{"name":"John", "age":30}");

List<Object> parsedList = parser.parseList("[1, 2, 3]");

总结

这些工具类涵盖了Java开发中的大部分常见场景，从基础的字符串处理到高级的反射操作，从文件IO到安全加密，从Web开发到性能监控。熟练掌握这些工具类可以显著提高开发效率，减少样板代码。