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我正在使用Google Cloud SQL的應用程序。我正在使用Hibernate 4.2.0.Final，並且我注意到，在閒置8小時後，我的連接已關閉。我一直在互聯網上搜索，找不到有效解決這個問題的東西。我發現的所有信息總結如下：如何解決Google CloudSQL 8小時超時？
- 使用連接池，我應該指定更高的超時時間。我已經嘗試過c3p0和DBCP 2.1.1庫，但他們都沒有解決這個問題。
- 在某個查詢之前打開一個連接，然後關閉它。問題是我想使用EntityManager爲了使用實體查詢。
這裏是我用DBCP 2.1.1（http://mvnrepository.com/artifact/org.apache.commons/commons-dbcp2/2.1.1）所做的。問題是，當我嘗試在我的PersistenceService中嘗試使用findAll時，Goggle App Engine日誌顯示ExceptionInInitializerError。日誌還顯示我的DataSource（見下文）不能轉換爲String。我不明白爲什麼。
這是我使用的PersistenceService現在
package co.peewah.ems.utils;
import com.google.appengine.api.utils.SystemProperty;
import java.beans.PropertyVetoException;
import java.io.IOException;
import java.sql.SQLException;
import java.util.AbstractMap.SimpleEntry;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.UUID;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;
import javax.persistence.TypedQuery;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import org.hibernate.cfg.AvailableSettings;
/**
*
* @author Muacito
*/
public class PersistenceService
{
private static final EntityManagerFactory EMF = createEntityManagerFactory();
private static EntityManager entityManager = EMF.createEntityManager();
private static EntityManagerFactory createEntityManagerFactory()
{
//String mode = "";
/*
if (SystemProperty.environment.value() == SystemProperty.Environment.Value.Development)
{
mode = "dev.";
}
*/
Map<String, Object> properties = new HashMap<>();
//Properties properties = new Properties();
//properties.put("javax.persistence.jdbc.driver", System.getProperty("persistence." + mode + "db.driver"));
//properties.put("javax.persistence.jdbc.url", System.getProperty("persistence." + mode + "db.url"));
//properties.put("javax.persistence.jdbc.user", System.getProperty("persistence." + mode + "db.user"));
//properties.put("javax.persistence.jdbc.password", System.getProperty("persistence." + mode + "db.password"));
try
{
properties.put(AvailableSettings.DATASOURCE, DataSource.getInstance());
} catch (IOException | SQLException | PropertyVetoException e)
{
e.printStackTrace();
}
System.out.println("----------------------------");
System.out.println("----------------------------");
System.out.println(properties);
System.out.println("----------------------------");
System.out.println("----------------------------");
return Persistence.createEntityManagerFactory("Demo", properties);
}
private static EntityManager getEntityManager()
{
if (!PersistenceService.entityManager.isOpen())
{
PersistenceService.entityManager = PersistenceService.EMF.createEntityManager();
}
return PersistenceService.entityManager;
}
public static <T> void create(T entity)
{
try
{
if (entity.getClass().getMethod("getId").invoke(entity) == null)
{
entity.getClass().getMethod("setId", String.class).invoke(entity,
UUID.randomUUID().toString().replace("-", ""));
}
if (entity.getClass().getMethod("getCreated").invoke(entity) == null)
{
entity.getClass().getMethod("setCreated", Date.class).invoke(entity,
GregorianCalendar.getInstance().getTime());
}
getEntityManager().getTransaction().begin();
getEntityManager().persist(entity);
getEntityManager().flush();
getEntityManager().getTransaction().commit();
} catch (Exception ex)
{
Logger.getLogger(PersistenceService.class.getName()).log(Level.SEVERE, null, ex);
getEntityManager().getTransaction().rollback();
}
}
public static <T> void edit(T entity)
{
try
{
if (entity.getClass().getMethod("getUpdated").invoke(entity) == null)
{
entity.getClass().getMethod("setUpdated", Date.class).invoke(entity,
GregorianCalendar.getInstance().getTime());
}
getEntityManager().getTransaction().begin();
getEntityManager().merge(entity);
getEntityManager().flush();
getEntityManager().getTransaction().commit();
} catch (Exception ex)
{
Logger.getLogger(PersistenceService.class.getName()).log(Level.SEVERE, null, ex);
getEntityManager().getTransaction().rollback();
}
}
public static <T> void remove(T entity)
{
try
{
getEntityManager().getTransaction().begin();
getEntityManager().remove(entity);
getEntityManager().flush();
getEntityManager().getTransaction().commit();
} catch (Exception ex)
{
Logger.getLogger(PersistenceService.class.getName()).log(Level.SEVERE, null, ex);
getEntityManager().getTransaction().rollback();
}
}
public static <T> List<T> filter(Class<T> entityClass, String query, SimpleEntry<String, Object>... parameters)
{
TypedQuery<T> typedQuery = getEntityManager().createQuery(query, entityClass);
for (SimpleEntry<String, Object> param : parameters)
{
typedQuery.setParameter(param.getKey(), param.getValue());
}
return typedQuery.getResultList();
}
public static <T> T find(Class<T> entityClass, Object id)
{
T entity = getEntityManager().find(entityClass, id);
return entity;
}
public static <T> List<T> findBy(Class<T> entityClass, String criteria, Object value)
{
String c = criteria.replaceFirst(criteria.charAt(0) + "", (criteria.charAt(0) + "").toLowerCase());
TypedQuery<T> query = getEntityManager().createNamedQuery(entityClass.getSimpleName() + ".findBy" + criteria,
entityClass);
query.setParameter(c, value);
return query.getResultList();
}
public static <T> List<T> findAll(Class<T> entityClass)
{
CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
cq.select(cq.from(entityClass));
return getEntityManager().createQuery(cq).getResultList();
}
public static <T> List<T> findRange(Class<T> entityClass, int[] range)
{
CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
cq.select(cq.from(entityClass));
Query q = getEntityManager().createQuery(cq);
q.setMaxResults(range[1] - range[0] + 1);
q.setFirstResult(range[0]);
return q.getResultList();
}
public static <T> int count(Class<T> entityClass)
{
CriteriaQuery cq = getEntityManager().getCriteriaBuilder().createQuery();
Root<T> rt = cq.from(entityClass);
cq.select(getEntityManager().getCriteriaBuilder().count(rt));
Query q = getEntityManager().createQuery(cq);
return ((Long) q.getSingleResult()).intValue();
}
}
這是我對MySQL連接DataSource
package co.peewah.ems.utils;
import java.beans.PropertyVetoException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;
import org.apache.commons.dbcp.BasicDataSource;
import com.google.appengine.api.utils.SystemProperty;
/**
*
* @author csacanam
*
*/
public class DataSource
{
private static DataSource datasource;
private BasicDataSource ds;
private DataSource() throws IOException, SQLException, PropertyVetoException
{
ds = new BasicDataSource();
String mode = "";
if (SystemProperty.environment.value() == SystemProperty.Environment.Value.Development)
{
mode = "dev.";
}
String user = System.getProperty("persistence." + mode + "db.user");
String password = System.getProperty("persistence." + mode + "db.password");
String address = System.getProperty("persistence." + mode + "db.url");
String driver = System.getProperty("persistence." + mode + "db.driver");
// Create and configure DBCP DataSource
ds.setDriverClassName(driver);
ds.setUrl(address);
ds.setUsername(user);
ds.setPassword(password);
ds.setMinIdle(5);
ds.setMaxIdle(20);
ds.setMaxOpenPreparedStatements(180);
}
public static DataSource getInstance() throws IOException, SQLException, PropertyVetoException
{
if(datasource == null)
{
datasource = new DataSource();
}
return datasource;
}
public Connection getConnection() throws SQLException
{
return this.ds.getConnection();
}
}