Java:无法将 oracle clob 转换为 jsp 中的字符串

Question

出于某种原因，我尝试将 oracle clob 数据转换为 jsp 中的字符串。这是我的代码。

java-服务

Map<String, Object> bean = mapper.getData(); // bean has oracle clob values

java - util:此代码在 java 中运行

public static String clobToString(Clob clob) {
    try (Reader reader = clob.getCharacterStream()) { ...
    return string data;
}

顶级域名定义

<function>
    <description></description>
    <name>clobToString</name>
    <function-class>com.my.StringUtil</function-class>
    <function-signature>java.lang.String clobToString(java.sql.Clob)</function-signature>
    <example>
        ${my:clobToString(clob)}
    </example>
</function>

jsp

${my:clobToString(bean.clob)} << SQLException: Connection is Closed

方法 clobToString 在 java 中可以工作，当我尝试在jsp中调用它时，它会失败。

猜测 oracle.clob.getCharacterStream 丢失了数据库连接，并且失败...有谁知道为什么 oracle clob 对象丢失了数据库连接或...其他原因？

错误日志

java.sql.SQLException: Connection is Closed
    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.CLOB.getDBAccess(CLOB.java:1196)
    at oracle.sql.CLOB.getCharacterStream(CLOB.java:278)
    at com.my.StringUtil.clobToString(StringUtil.java:355)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.el.parser.AstFunction.getValue(AstFunction.java:132)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:190)
    at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:950)
    at org.apache.jsp.common.jsp.unit.dynamic.custom.goodPrice.list_jsp._jspx_meth_c_005fforEach_005f4(list_jsp.java:1036)
    at org.apache.jsp.common.jsp.unit.dynamic.custom.goodPrice.list_jsp._jspService(list_jsp.java:232)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:472)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:742)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:602)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:541)
    at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:903)
    at org.apache.jsp.common.jsp.unit.dynamic.custom.list_jsp._jspService(list_jsp.java:122)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:472)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:742)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:602)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:541)
    at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:903)
    at org.apache.jasper.runtime.PageContextImpl.doInclude(PageContextImpl.java:688)
    at org.apache.jasper.runtime.PageContextImpl.include(PageContextImpl.java:682)
    at org.apache.tiles.jsp.context.JspTilesRequestContext.include(JspTilesRequestContext.java:103)
    at org.apache.tiles.jsp.context.JspTilesRequestContext.dispatch(JspTilesRequestContext.java:96)
    at org.apache.tiles.renderer.impl.TemplateAttributeRenderer.write(TemplateAttributeRenderer.java:44)
    at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:106)
    at org.apache.tiles.renderer.impl.ChainedDelegateAttributeRenderer.write(ChainedDelegateAttributeRenderer.java:76)
    at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:106)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:670)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:336)
    at org.apache.tiles.template.InsertAttributeModel.renderAttribute(InsertAttributeModel.java:210)
    at org.apache.tiles.template.InsertAttributeModel.end(InsertAttributeModel.java:126)
    at org.apache.tiles.jsp.taglib.InsertAttributeTag.doTag(InsertAttributeTag.java:311)
    at org.apache.jsp.portal.jsp.layouts.templateSub_jsp._jspx_meth_tiles_005finsertAttribute_005f4(templateSub_jsp.java:582)
    at org.apache.jsp.portal.jsp.layouts.templateSub_jsp._jspService(templateSub_jsp.java:330)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:472)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    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.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:742)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:484)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:409)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:337)
    at org.apache.tiles.servlet.context.ServletTilesRequestContext.forward(ServletTilesRequestContext.java:241)
    at org.apache.tiles.servlet.context.ServletTilesRequestContext.dispatch(ServletTilesRequestContext.java:222)
    at org.apache.tiles.renderer.impl.TemplateAttributeRenderer.write(TemplateAttributeRenderer.java:44)
    at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:106)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:670)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:690)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:644)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:627)
    at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:321)
    at org.springframework.web.servlet.view.tiles2.TilesView.renderMergedOutputModel(TilesView.java:112)
    at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303)
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1286)
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1041)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:984)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    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$VirtualFilterChain.doFilter(FilterChainProxy.java:317)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:170)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:158)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter.doFilter(DefaultLoginPageGeneratingFilter.java:177)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:200)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:66)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.session.ConcurrentSessionFilter.doFilter(ConcurrentSessionFilter.java:155)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:214)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:177)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:347)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:263)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:265)
    at org.acegisecurity.securechannel.ChannelProcessingFilter.doFilter(ChannelProcessingFilter.java:138)
    at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
    at org.acegisecurity.util.FilterChainProxy.doFilter(FilterChainProxy.java:149)
    at org.acegisecurity.util.FilterToBeanProxy.doFilter(FilterToBeanProxy.java:98)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at com.navercorp.lucy.security.xss.servletfilter.XssEscapeServletFilter.doFilter(XssEscapeServletFilter.java:36)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.web.multipart.support.MultipartFilter.doFilterInternal(MultipartFilter.java:122)
    at com.my.MultipartFilter.doFilterInternal(MultipartFilter.java:33)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at com.my.DisableUrlSessionFilter.doFilter(DisableUrlSessionFilter.java:119)
    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:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:494)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:1025)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1137)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:319)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
enter code here
enter code here

Answer 1

由于数据库事务结束并且数据库连接在服务代码和 JSP 代码之间的某个位置关闭，因此服务代码不应返回 LOB 对象。

因此，要么更改 mapper(无论是什么)，不要获取 Clob 和 Blob 对象，或者对返回的 进行后处理> map ，例如像这样:

static Map<String, Object> convertLobs(Map<String, Object> bean) throws SQLException {
    Map<String, Object> newBean = new LinkedHashMap<>();
    for (Entry<String, Object> entry : bean.entrySet()) {
        Object value = entry.getValue();
        if (value instanceof Clob) { // handles NClob too
            Clob clob = (Clob) value;
            value = clob.getSubString(0, Math.toIntExact(clob.length()));
        } else if (value instanceof Blob) {
            Blob blob = (Blob) value;
            value = blob.getBytes(0, Math.toIntExact(blob.length()));
        }
        newBean.put(entry.getKey(), value);
    }
    return newBean;
}

使用

Map<String, Object> bean = mapper.getData();
bean = convertLobs(bean);

或者:

Map<String, Object> bean = convertLobs(mapper.getData());