add spring jpa specifications test

spring-jpa/src/main/java/org/baeldung/config/PersistenceJPAConfig.java

@@ -12,6 +12,7 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.PropertySource;
 import org.springframework.core.env.Environment;
 import org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor;
+import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
 import org.springframework.jdbc.datasource.DriverManagerDataSource;
 import org.springframework.orm.jpa.JpaTransactionManager;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
@@ -25,6 +26,7 @@ import com.google.common.base.Preconditions;
 @EnableTransactionManagement
 @PropertySource({ "classpath:persistence-mysql.properties" })
 @ComponentScan({ "org.baeldung.persistence" })
+@EnableJpaRepositories(basePackages = "org.baeldung.persistence.dao")
 public class PersistenceJPAConfig {
 
     @Autowired

spring-jpa/src/main/java/org/baeldung/persistence/dao/UserRepository.java

@@ -0,0 +1,9 @@
+package org.baeldung.persistence.dao;
+
+import org.baeldung.persistence.model.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
+
+public interface UserRepository extends JpaRepository<User, Long>, JpaSpecificationExecutor<User> {
+
+}

spring-jpa/src/main/java/org/baeldung/persistence/dao/UserSpecifications.java

@@ -0,0 +1,45 @@
+package org.baeldung.persistence.dao;
+
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Predicate;
+import javax.persistence.criteria.Root;
+
+import org.baeldung.persistence.model.User;
+import org.baeldung.persistence.model.User_;
+import org.springframework.data.jpa.domain.Specification;
+
+public class UserSpecifications {
+    public static Specification<User> firstNameIsLike(final String term) {
+
+        return new Specification<User>() {
+            @Override
+            public Predicate toPredicate(final Root<User> root, final CriteriaQuery<?> query, final CriteriaBuilder cb) {
+                return cb.like(root.get(User_.firstName), "%"+term+"%");
+            }
+
+        };
+    }
+
+    public static Specification<User> lastNameIsLike(final String term) {
+
+        return new Specification<User>() {
+            @Override
+            public Predicate toPredicate(final Root<User> root, final CriteriaQuery<?> query, final CriteriaBuilder cb) {
+                return cb.like(root.get(User_.lastName), "%" + term + "%");
+            }
+
+        };
+    }
+
+    public static Specification<User> ageIsGreaterThan(final int minAge) {
+
+        return new Specification<User>() {
+            @Override
+            public Predicate toPredicate(final Root<User> root, final CriteriaQuery<?> query, final CriteriaBuilder cb) {
+                return cb.greaterThanOrEqualTo(root.get(User_.age), minAge);
+            }
+
+        };
+    }
+}

spring-jpa/src/main/java/org/baeldung/persistence/model/User_.java

@@ -0,0 +1,11 @@
+package org.baeldung.persistence.model;
+
+import javax.persistence.metamodel.SingularAttribute;
+import javax.persistence.metamodel.StaticMetamodel;
+
+@StaticMetamodel(User.class)
+public class User_ {
+    public static volatile SingularAttribute<User, String> firstName;
+    public static volatile SingularAttribute<User, String> lastName;
+    public static volatile SingularAttribute<User, Integer> age;
+}