REST 查询语言 - 高级搜索操作

1. 概述

在本文中，我们将扩展之前实现的 REST 查询语言，支持更多的搜索操作。

目前已支持的操作包括：等于、不等于、大于、小于、开头匹配、结尾匹配、包含、模糊匹配（Like）。

在之前的系列文章中，我们尝试了三种实现方式：JPA Criteria、Spring Data JPA Specifications 和 Query DSL。本文我们选择使用 Specifications 实现，因为它结构清晰，扩展性强，适合构建灵活的查询条件。

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2. SearchOperation 枚举

我们首先定义一个枚举类 SearchOperation，用于表示所有支持的搜索操作：

public enum SearchOperation {
    EQUALITY, NEGATION, GREATER_THAN, LESS_THAN, LIKE, STARTS_WITH, ENDS_WITH, CONTAINS;

    public static final String[] SIMPLE_OPERATION_SET = { ":", "!", ">", "<", "~" };

    public static SearchOperation getSimpleOperation(char input) {
        switch (input) {
        case ':':
            return EQUALITY;
        case '!':
            return NEGATION;
        case '>':
            return GREATER_THAN;
        case '<':
            return LESS_THAN;
        case '~':
            return LIKE;
        default:
            return null;
        }
    }
}

我们把操作分为两类：

✅ 简单操作符（Single-character）：

操作	符号
等于	:
不等于	!
大于	>
小于	<
Like 模糊匹配	~

✅ 复杂操作（Multi-character）：

操作	示例表示
开头匹配	=prefix*
结尾匹配	=*suffix
包含	=*substring*

同时，我们修改 SearchCriteria 类，使用新的 SearchOperation：

public class SearchCriteria {
    private String key;
    private SearchOperation operation;
    private Object value;
}

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3. 修改 UserSpecification

接下来，我们在 UserSpecification 中加入对新操作的支持：

public class UserSpecification implements Specification<User> {

    private SearchCriteria criteria;

    @Override
    public Predicate toPredicate(
      Root<User> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
    
        switch (criteria.getOperation()) {
        case EQUALITY:
            return builder.equal(root.get(criteria.getKey()), criteria.getValue());
        case NEGATION:
            return builder.notEqual(root.get(criteria.getKey()), criteria.getValue());
        case GREATER_THAN:
            return builder.greaterThan(root.<String> get(
              criteria.getKey()), criteria.getValue().toString());
        case LESS_THAN:
            return builder.lessThan(root.<String> get(
              criteria.getKey()), criteria.getValue().toString());
        case LIKE:
            return builder.like(root.<String> get(
              criteria.getKey()), criteria.getValue().toString());
        case STARTS_WITH:
            return builder.like(root.<String> get(criteria.getKey()), criteria.getValue() + "%");
        case ENDS_WITH:
            return builder.like(root.<String> get(criteria.getKey()), "%" + criteria.getValue());
        case CONTAINS:
            return builder.like(root.<String> get(
              criteria.getKey()), "%" + criteria.getValue() + "%");
        default:
            return null;
        }
    }
}

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4. 持久层测试

我们编写了多个单元测试来验证这些操作是否生效。

✅ 4.1 测试等于（EQUALITY）

@Test
public void givenFirstAndLastName_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.EQUALITY, "john"));
    UserSpecification spec1 = new UserSpecification(
      new SearchCriteria("lastName", SearchOperation.EQUALITY, "doe"));
    List<User> results = repository.findAll(Specification.where(spec).and(spec1));

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

✅ 4.2 测试不等于（NEGATION）

@Test
public void givenFirstNameInverse_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.NEGATION, "john"));
    List<User> results = repository.findAll(Specification.where(spec));

    assertThat(userTom, isIn(results));
    assertThat(userJohn, not(isIn(results)));
}

✅ 4.3 测试大于（GREATER_THAN）

@Test
public void givenMinAge_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("age", SearchOperation.GREATER_THAN, "25"));
    List<User> results = repository.findAll(Specification.where(spec));

    assertThat(userTom, isIn(results));
    assertThat(userJohn, not(isIn(results)));
}

✅ 4.4 测试开头匹配（STARTS_WITH）

@Test
public void givenFirstNamePrefix_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.STARTS_WITH, "jo"));
    List<User> results = repository.findAll(spec);

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

✅ 4.5 测试结尾匹配（ENDS_WITH）

@Test
public void givenFirstNameSuffix_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.ENDS_WITH, "n"));
    List<User> results = repository.findAll(spec);

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

✅ 4.6 测试包含（CONTAINS）

@Test
public void givenFirstNameSubstring_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.CONTAINS, "oh"));
    List<User> results = repository.findAll(spec);

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

✅ 4.7 测试范围（Range）

@Test
public void givenAgeRange_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("age", SearchOperation.GREATER_THAN, "20"));
    UserSpecification spec1 = new UserSpecification(
      new SearchCriteria("age", SearchOperation.LESS_THAN, "25"));
    List<User> results = repository.findAll(Specification.where(spec).and(spec1));

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

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5. UserSpecificationsBuilder

我们修改 UserSpecificationsBuilder 来支持新的搜索操作：

public class UserSpecificationsBuilder {

    private List<SearchCriteria> params;

    public UserSpecificationsBuilder with(
      String key, String operation, Object value, String prefix, String suffix) {
    
        SearchOperation op = SearchOperation.getSimpleOperation(operation.charAt(0));
        if (op != null) {
            if (op == SearchOperation.EQUALITY) {
                boolean startWithAsterisk = prefix.contains("*");
                boolean endWithAsterisk = suffix.contains("*");

                if (startWithAsterisk && endWithAsterisk) {
                    op = SearchOperation.CONTAINS;
                } else if (startWithAsterisk) {
                    op = SearchOperation.ENDS_WITH;
                } else if (endWithAsterisk) {
                    op = SearchOperation.STARTS_WITH;
                }
            }
            params.add(new SearchCriteria(key, op, value));
        }
        return this;
    }

    public Specification<User> build() {
        if (params.size() == 0) {
            return null;
        }

        Specification result = new UserSpecification(params.get(0));
     
        for (int i = 1; i < params.size(); i++) {
            result = params.get(i).isOrPredicate()
              ? Specification.where(result).or(new UserSpecification(params.get(i))) 
              : Specification.where(result).and(new UserSpecification(params.get(i)));
        }

        return result;
    }
}

---

6. 控制器 UserController

接下来，我们在 UserController 中解析查询字符串，并构建 Specification：

@RequestMapping(method = RequestMethod.GET, value = "/users")
@ResponseBody
public List<User> findAllBySpecification(@RequestParam(value = "search") String search) {
    UserSpecificationsBuilder builder = new UserSpecificationsBuilder();
    String operationSetExper = Joiner.on("|").join(SearchOperation.SIMPLE_OPERATION_SET);
    Pattern pattern = Pattern.compile(
      "(\\w+?)(" + operationSetExper + ")(\\p{Punct}?)(\\w+?)(\\p{Punct}?),");
    Matcher matcher = pattern.matcher(search + ",");
    while (matcher.find()) {
        builder.with(
          matcher.group(1), 
          matcher.group(2), 
          matcher.group(4), 
          matcher.group(3), 
          matcher.group(5));
    }

    Specification<User> spec = builder.build();
    return dao.findAll(spec);
}

✅ 示例请求：

http://localhost:8082/spring-rest-query-language/auth/users?search=firstName:jo*,age<25

✅ 返回结果：

[{
    "id":1,
    "firstName":"john",
    "lastName":"doe",
    "email":"[email protected]",
    "age":24
}]

---

7. 接口测试

我们使用 RestAssured 编写 API 测试，验证接口是否按预期工作。

✅ 7.1 测试等于

@Test
public void givenFirstAndLastName_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName:john,lastName:doe");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}

✅ 7.2 测试不等于

@Test
public void givenFirstNameInverse_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName!john");
    String result = response.body().asString();

    assertTrue(result.contains(userTom.getEmail()));
    assertFalse(result.contains(userJohn.getEmail()));
}

✅ 7.3 测试大于

@Test
public void givenMinAge_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "age>25");
    String result = response.body().asString();

    assertTrue(result.contains(userTom.getEmail()));
    assertFalse(result.contains(userJohn.getEmail()));
}

✅ 7.4 测试开头匹配

@Test
public void givenFirstNamePrefix_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName:jo*");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}

✅ 7.5 测试结尾匹配

@Test
public void givenFirstNameSuffix_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName:*n");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}

✅ 7.6 测试包含

@Test
public void givenFirstNameSubstring_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName:*oh*");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}

✅ 7.7 测试范围

@Test
public void givenAgeRange_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "age>20,age<25");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}

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8. 总结

本文我们对 REST 查询语言进行了全面扩展，使其支持更多搜索操作。现在我们可以在接口中灵活组合多种查询条件，轻松地从数据集中精准筛选目标资源。

该项目完整实现可在 GitHub 仓库 获取，基于 Maven 构建，可直接导入运行。

如果你正在构建一个需要复杂查询支持的 REST API，这种方式非常值得借鉴。