那些遇到过的问题

如何在Hibernate中使用BLOB数据类型？

RBz*_*RBz 6 orm hibernate blob spring-mvc oracle10g

我正在从Oracle 10g数据库中检索包含JSON文件的blob字段.我想将它转换为我的DAO中的字符串并将其转发给传入的服务请求.我的实体类是:

@Lob
@Column(name = "DTA_BLOB")
private Blob DataBlob;

/**
* @return the DataBlob
*
*/
public Blob getDataBlob(){
    return DataBlob;

}
/**
* @param DataBlob the DataBlob to set
*/
public void setDataBlob(Blob DataBlob) {
    this.DataBlob = DataBlob;
}
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我的DAO有从blob获取字符串的方法,如下所示:

 @Override
    @Transactional
    public String getMenu(Long menuDataId) throws SQLException, IOException{

                MenuData menu_data = this.entityManager.find(MenuData.class,menuDataId);
                Blob menuData =menu_data.getDataBlob();
                byte[] bdata = menuData.getBytes(1, (int)menuData.length()); 
                String dataStr = new String(bdata);    
                return dataStr;

    }
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但是当我在部署此WAR之后尝试访问该服务时,我收到一个错误(并且我的tomcat崩溃了).在日志中它说:

Nov 06, 2014 3:47:34 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [spring] in context with path [/MyWarName] threw exception [Request processing failed; nested exception is java.sql.SQLException: Closed Connection] with root cause
java.sql.SQLException: Closed Connection
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:146)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:208)
    at oracle.sql.BLOB.getDBAccess(BLOB.java:955)
    at oracle.sql.BLOB.getBinaryStream(BLOB.java:229)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.hibernate.engine.jdbc.SerializableBlobProxy.invoke(SerializableBlobProxy.java:72)
    at $Proxy40.getBinaryStream(Unknown Source)
    at com.pack1.pack2.dao.MenuDataDaoImpl.getMenu(MenuDataDaoImpl.java:69)
    at com.pack1.pack2.controller.MenuController.getMenu(MenuController.java:46)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.ConcurrentSessionFilter.doFilter(ConcurrentSessionFilter.java:125)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2462)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2451)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)
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我的persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="2.0">
    <persistence-unit name="punit" transaction-type="RESOURCE_LOCAL">
        <class>com.pack1.pack2.entity.MenuData</class>
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.show_sql" value="true"/>
            <property name="hibernate.dialect"
              value="org.hibernate.dialect.Oracle10gDialect"/>
            <prop key="hibernate.jdbc.use_streams_for_binary">true</prop>
        </properties>
    </persistence-unit>
</persistence>
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我spring-core.xml有以下配置(仅用于确保我的数据库配置也正确):

<bean id="dataSource"   class="oracle.jdbc.pool.OracleDataSource">
    <property name="dataSourceName" value="schema"/>
    <property name="URL" value="jdbc:oracle:thin:@hostname:port:xe" /> 
    <property name="user" value="name" />
    <property name="password" value="pwd" />
</bean>
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我是否缺少Hibernate或数据库配置的配置细节？或者有没有任何Hibernate技术来做到这一点？

RBz*_*RBz 5

终于得到了答案，现在看起来很简单。

我将 oracle blob 映射到字节数组，将我的实体类更改为

@Lob
@Column(name = "DTA_BLOB")
private byte[] DataBlob;

/**
* @return the DataBlob
*/
public byte[] getDataBlob(){
    return DataBlob;
}

/**
* @param DataBlob the DataBlob to set
*/
public void setDataBlob(byte[] DataBlob) {
    this.DataBlob = DataBlob;
}
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DAO 将是这样的：

@Override
@Transactional
public byte[] getMenu(Long menuDataId) throws SQLException, IOException
{
    MenuData menu_data = this.entityManager.find(MenuData.class,menuDataId);  
    return menu_data.getDataBlob();
}
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  • 我仍然怀疑这是否是最好的方法。因为 byte[] 可以保存整个数据。随着文件大小的增加，它可能会占用更多的空间。欢迎提出任何改进建议。 (2认同)

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