Spring Data JPA为我们提供了Query With Example来实现动态条件查询，当查询条件为空的时候，我们不用做大量的条件判断。但是Query With Example却不支持范围查询(包括日期范围，数值范围查询)，本文通过Specification实现了既支持动态条件查询又支持范围查询的方法。
1 实现方式
1.1 范围对象Range定义
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import java.io.Serializable;
public class Range<E> implements Serializable {
private static final long serialVersionUID = 1L;
private String field;
private Comparable from;
private Comparable to;
private Boolean includeNull;
public Range(String field) {
this.field = field;
}
public Range(String field, Comparable from, Comparable to) {
this.field = field;
this.from = from;
this.to = to;
}
public Range(String field, Comparable from, Comparable to, Boolean includeNull) {
this.field = field;
this.from = from;
this.to = to;
this.includeNull = includeNull;
}
public Range(Range<E> other) {
this.field = other.getField();
this.from = other.getFrom();
this.to = other.getTo();
this.includeNull = other.getIncludeNull();
}
public String getField() {
return field;
}
public Comparable getFrom() {
return from;
}
public void setFrom(Comparable from) {
this.from = from;
}
public boolean isFromSet() {
return getFrom() != null;
}
public Comparable getTo() {
return to;
}
public void setTo(Comparable to) {
this.to = to;
}
public boolean isToSet() {
return getTo() != null;
}
public void setIncludeNull(boolean includeNull) {
this.includeNull = includeNull;
}
public Boolean getIncludeNull() {
return includeNull;
}
public boolean isIncludeNullSet() {
return includeNull != null;
}
public boolean isBetween() {
return isFromSet() && isToSet();
}
public boolean isSet() {
return isFromSet() || isToSet() || isIncludeNullSet();
}
public boolean isValid() {
if (isBetween()) {
return getFrom().compareTo(getTo()) <= 0;
}
return true;
}
}
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1.2 example的Specification
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import org.springframework.data.domain.Example;
import org.springframework.data.jpa.convert.QueryByExamplePredicateBuilder;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.util.Assert;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
/**
* Created by wangyunfei on 2017/6/6.
*/
public class ByExampleSpecification<T> implements Specification<T> {
private final Example<T> example;
public ByExampleSpecification(Example<T> example) {
Assert.notNull(example, "Example must not be null!");
this.example = example;
}
@Override
public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
return QueryByExamplePredicateBuilder.getPredicate(root, cb, example);
}
}
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1.3 Range的Specification
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import org.springframework.data.jpa.domain.Specification;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import java.util.List;
import static com.google.common.collect.Iterables.toArray;
import static com.google.common.collect.Lists.newArrayList;
import static java.lang.Boolean.FALSE;
import static java.lang.Boolean.TRUE;
/**
* Created by wangyunfei on 2017/6/6.
*/
public class ByRangeSpecification<T> implements Specification<T> {
private final List<Range<T>> ranges;
public ByRangeSpecification(List<Range<T>> ranges) {
this.ranges = ranges;
}
@Override
public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
List<Predicate> predicates = newArrayList();
for (Range<T> range : ranges) {
if (range.isSet()) {
Predicate rangePredicate = buildRangePredicate(range, root, builder);
if (rangePredicate != null) {
if (!range.isIncludeNullSet() || range.getIncludeNull() == FALSE) {
predicates.add(rangePredicate);
} else {
predicates.add(builder.or(rangePredicate, builder.isNull(root.get(range.getField()))));
}
}
if (TRUE == range.getIncludeNull()) {
predicates.add(builder.isNull(root.get(range.getField())));
} else if (FALSE == range.getIncludeNull()) {
predicates.add(builder.isNotNull(root.get(range.getField())));
}
}
}
return predicates.isEmpty() ? builder.conjunction() : builder.and(toArray(predicates, Predicate.class));
}
private Predicate buildRangePredicate(Range<T> range, Root<T> root, CriteriaBuilder builder) {
if (range.isBetween()) {
return builder.between(root.get(range.getField()), range.getFrom(), range.getTo());
} else if (range.isFromSet()) {
return builder.greaterThanOrEqualTo(root.get(range.getField()), range.getFrom());
} else if (range.isToSet()) {
return builder.lessThanOrEqualTo(root.get(range.getField()), range.getTo());
}
return null;
}
}
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1.4 自定义Repository与实现
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import org.springframework.data.domain.Example;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.repository.NoRepositoryBean;
import java.io.Serializable;
import java.util.List;
@NoRepositoryBean
public interface WiselyRepository<E, PK extends Serializable> extends JpaRepository<E, PK> {
Page<E> queryByExampleWithRange(Example example,List<Range<E>> ranges, Pageable pageable);
}
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import org.springframework.data.domain.Example;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.data.jpa.repository.support.JpaEntityInformation;
import org.springframework.data.jpa.repository.support.SimpleJpaRepository;
import javax.persistence.EntityManager;
import java.io.Serializable;
import java.util.List;
import static org.springframework.data.jpa.domain.Specifications.where;
public class WiselyRepositoryImpl<E, PK extends Serializable> extends SimpleJpaRepository<E, PK> implements
WiselyRepository<E, PK> {
private final EntityManager entityManager;
public WiselyRepositoryImpl(JpaEntityInformation entityInformation, EntityManager entityManager) {
super(entityInformation, entityManager);
this.entityManager = entityManager;
}
@Override
public Page<E> queryByExampleWithRange(Example example, List<Range<E>> ranges, Pageable pageable) {
Specification<E> byExample = new ByExampleSpecification<>(example);
Specification<E> byRanges = new ByRangeSpecification<>(ranges);
return findAll(where(byExample).and(byRanges),pageable);
}
}
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2 使用方式
2.1 开启支持
通过@EnableJpaRepositories(repositoryBaseClass = WiselyRepositoryImpl.class)开启对定义功能的支持。
2.2 示例
实体类
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@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Person {
@Id
@GeneratedValue
private Long id;
private String name;
private Integer height;
@DateTimeFormat(pattern = "yyyy-MM-dd")
private Date birthday;
}
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PersonRepository
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public interface PersonRepository extends WiselyRepository<Person,Long> {
}
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测试控制器
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@RestController
@RequestMapping("/people")
public class PersonController {
@Autowired
PersonRepository personRepository;
@PostMapping
public ResponseEntity<Person> save(@RequestBody Person person){
Person p = personRepository.save(person);
return new ResponseEntity<Person>(p, HttpStatus.CREATED);
}
@GetMapping
public ResponseEntity<Page<Person>> query(Person person,
@DateTimeFormat(pattern = "yyyy-MM-dd")Date startDate,
@DateTimeFormat(pattern = "yyyy-MM-dd")Date endDate,
Integer startHeight,
Integer endHeight,
Pageable pageable){
Example<Person> personExample = Example.of(person);
List<Range<Person>> ranges = newArrayList();
Range<Person> birthRange = new Range<Person>("birthday",startDate,endDate);
Range<Person> heightRange = new Range<Person>("height",startHeight,endHeight);
ranges.add(birthRange);
ranges.add(heightRange);
Page<Person> page = personRepository.queryByExampleWithRange(personExample,ranges,pageable);
return new ResponseEntity<Page<Person>>(page,HttpStatus.OK);
}
}
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源码地址：https://github.com/wiselyman/query_with_example_and_range
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持快网idc。
原文链接：http://www.wisely.top/2017/06/06/spring-data-jpa-dynamic-query-with-range/?utm_source=tuicool&utm_medium=referral
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