理念:
当我使用 hibernate 时,我看到每次我必须编写某种代码。因此,我将它们移至另一种方法作为包装器。哪里会有功能接口(interface)作为参数,以便我可以在这些上下文方法中附加一些代码。
问题:
这是我的两种方法。一个返回 Object,而另一个返回 List。我如何才能将这两种方法准确地泛化并将其合二为一,这样我就可以避免代码重复。
public Object objectReturnContext(Function<Session, Object> function) {
Object object = null;
Transaction transaction = null;
try {
Session session = HibernateUtil.sessionFactory().getCurrentSession();
transaction = session.beginTransaction();
object = function.apply(session);
transaction.commit();
} catch (NoResultException exception) {
if (transaction != null) transaction.rollback();
return object;
} catch (HibernateException exception) {
if (transaction != null) transaction.rollback();
exception.getStackTrace();
}
return object;
}
public List<T> listReturnContext(Function<Session, List<T>> function) {
List<T> object = null;
Transaction transaction = null;
try {
Session session = HibernateUtil.sessionFactory().getCurrentSession();
transaction = session.beginTransaction();
object = function.apply(session);
transaction.commit();
} catch (NoResultException exception) {
if (transaction != null) transaction.rollback();
return object;
} catch (HibernateException exception) {
if (transaction != null) transaction.rollback();
exception.getStackTrace();
}
return object;
}
为了更好地理解,这是我的整个类(class)。如果有人可以建议我任何更好的方法,我将非常感激。最近几天我一直在研究这个。package com.go_task.database;
import javax.persistence.Table;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;
import javax.persistence.NoResultException;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;
import java.util.function.Function;
public abstract class QueryExecutionContext <T> {
public Class<T> entity;
public String tableName;
public QueryExecutionContext(Class<T> entity) {
this.entity = entity;
this.tableName = entity.getAnnotation(Table.class).name();
}
public List<T> criteriaContext(CriteriaContextRunner<Session, Root<T>,
CriteriaQuery<T>, CriteriaBuilder, List<T>> runner) {
List<T> data = new ArrayList<>();
Transaction transaction = null;
try {
Session session = HibernateUtil.sessionFactory().getCurrentSession();
transaction = session.beginTransaction();
CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();
CriteriaQuery<T> criteriaQuery =
criteriaBuilder.createQuery(entity);
Root<T> root = criteriaQuery.from(entity);
data = runner.apply(session, root, criteriaQuery, criteriaBuilder);
transaction.commit();
} catch (HibernateException exception) {
if (transaction != null) transaction.rollback();
exception.getStackTrace();
}
return data;
}
public Object singleCriteriaContext(CriteriaContextRunner<Session, Root<T>,
CriteriaQuery<T>, CriteriaBuilder, Object> runner) {
Object data = null;
Transaction transaction = null;
try {
Session session = HibernateUtil.sessionFactory().getCurrentSession();
transaction = session.beginTransaction();
CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();
CriteriaQuery<T> criteriaQuery =
criteriaBuilder.createQuery(entity);
Root<T> root = criteriaQuery.from(entity);
data = runner.apply(session, root, criteriaQuery, criteriaBuilder);
transaction.commit();
} catch (HibernateException exception) {
if (transaction != null) transaction.rollback();
exception.getStackTrace();
}
return data;
}
public Object objectReturnContext(Function<Session, Object> function) {
Object object = null;
Transaction transaction = null;
try {
Session session = HibernateUtil.sessionFactory().getCurrentSession();
transaction = session.beginTransaction();
object = function.apply(session);
transaction.commit();
} catch (NoResultException exception) {
if (transaction != null) transaction.rollback();
return object;
} catch (HibernateException exception) {
if (transaction != null) transaction.rollback();
exception.getStackTrace();
}
return object;
}
public List<T> listReturnContext(Function<Session, List<T>> function) {
List<T> object = null;
Transaction transaction = null;
try {
Session session = HibernateUtil.sessionFactory().getCurrentSession();
transaction = session.beginTransaction();
object = function.apply(session);
transaction.commit();
} catch (NoResultException exception) {
if (transaction != null) transaction.rollback();
return object;
} catch (HibernateException exception) {
if (transaction != null) transaction.rollback();
exception.getStackTrace();
}
return object;
}
public void noReturnContext(Consumer<Session> consumer) {
Transaction transaction = null;
try {
Session session = HibernateUtil.sessionFactory().getCurrentSession();
transaction = session.beginTransaction();
consumer.accept(session);
transaction.commit();
} catch (HibernateException exception) {
if (transaction != null) transaction.rollback();
exception.getStackTrace();
}
}
}
稍后我在 BaseDaoImpl.java 中扩展了 QueryExecutionContext。所以我需要知道两件事。最佳答案
Object
/List<T>
参数可以是通用参数U
:
public <U> U returnContext(Function<Session, U> function) {
U object = null;
Transaction transaction = null;
try {
Session session = HibernateUtil.sessionFactory().getCurrentSession();
transaction = session.beginTransaction();
object = function.apply(session);
transaction.commit();
} catch (NoResultException exception) {
if (transaction != null) transaction.rollback();
return object;
} catch (HibernateException exception) {
if (transaction != null) transaction.rollback();
exception.getStackTrace();
}
return object;
}
U
将根据 function
进行推断你传入方法。如果你这样称呼它:Object o = returnContext(s -> {
...
return new Object(); // just an example
});
然后U
是 Object
.如果你这样称呼它:
List<T> list = returnContext(s -> {
...
return new ArrayList<T>(); // just an example
});
然后U
是 ArrayList<T>
.
关于java - 如何避免在 Java 中具有相同方法主体但返回类型不同的重复代码?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/64172046/