Created
July 19, 2018 21:33
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An example of QueryManager in Java for JPA
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import javax.persistence.EntityManager; | |
import javax.persistence.Query; | |
import java.util.HashMap; | |
import java.util.Map; | |
public class QueryBuilder { | |
private final EntityManager entityManager; | |
private final Map<String, Object> parameters = new HashMap<>(); | |
private String resultSetMapping; | |
private String query; | |
public QueryBuilder(EntityManager entityManager) { | |
this.entityManager = entityManager; | |
} | |
public QueryBuilder withQuery(String query) { | |
this.query = query; | |
return this; | |
} | |
public QueryBuilder withParameter(String key, Object value) { | |
parameters.put(key, value); | |
return this; | |
} | |
public QueryBuilder withResultSetMapping(String resultSetMapping) { | |
this.resultSetMapping = resultSetMapping; | |
return this; | |
} | |
public Query build() { | |
Query nativeQuery = entityManager.createNativeQuery(query, resultSetMapping); | |
for (String name : parameters.keySet()) { | |
nativeQuery.setParameter(name, parameters.get(name)); | |
} | |
return nativeQuery; | |
} | |
} |
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