小编Dho*_*ium的帖子

我目前在尝试使用实体管理器中的持久方法保存到数据库时遇到问题。执行它时，它不会产生异常，但不会将对象保存到我的数据库中。读取手动插入的对象确实有效。

通用DAOImpl

package be.greg.PaymentDatabase.DAO;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;

import javax.persistence.Entity;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
import javax.transaction.Transactional;

public abstract class GenericDaoImpl<T> implements GenericDao<T> {

    @PersistenceContext
    protected EntityManager em;

    private Class<T> type;

    String entity;

    @SuppressWarnings({ "unchecked", "rawtypes" })
    public GenericDaoImpl() {
        Type t = getClass().getGenericSuperclass();
        ParameterizedType pt = (ParameterizedType) t;
        type = (Class) pt.getActualTypeArguments()[0];
    }

    @Override
    public long countAll(final Map<String, Object> params) {

        final StringBuffer queryString = new StringBuffer(
                "SELECT count(o) from ");

        queryString.append(type.getSimpleName()).append(" o "); …