Java 使用JPA从表中删除所有行

我想使用JPA删除特定表中的所有行

我所做的：

public class EmptyBomTables extends HttpServlet {

    private static final long serialVersionUID = 1L;

    @PersistenceContext(unitName = "xxx")
    public EntityManager em;

    @Resource
    UserTransaction utx;

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        Query q1 = em.createQuery("DELETE FROM BomModule");
        Query q2 = em.createQuery("DELETE FROM BomItem");
        Query q3 = em.createQuery("DELETE FROM ItemModuleConnection");
        Query q4 = em.createQuery("DELETE FROM ModuleConnection");

        try {
            utx.begin();
        } catch (NotSupportedException | SystemException e) {
            e.printStackTrace();
        }

        q1.executeUpdate();
        q2.executeUpdate();
        q3.executeUpdate();
        q4.executeUpdate();

        try {
            utx.commit();
        } catch (SecurityException | IllegalStateException | RollbackException | HeuristicMixedException | HeuristicRollbackException | SystemException e) {
            e.printStackTrace();
        }
    }
}

错误：

   09:30:30,197 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/SSIS2].[EmptyBomTables]] (http-localhost-127.0.0.1-8080-1) Servlet.service() for servlet EmptyBomTables threw exception: javax.persistence.TransactionRequiredException: Executing an update/delete query
    at org.hibernate.ejb.AbstractQueryImpl.executeUpdate(AbstractQueryImpl.java:96) [hibernate-entitymanager-4.0.1.Final.jar:4.0.1.Final]
    at org.jboss.as.jpa.container.QueryNonTxInvocationDetacher.executeUpdate(QueryNonTxInvocationDetacher.java:80) [jboss-as-jpa-7.1.1.Final.jar:7.1.1.Final]
    at com.sicap.ssis2.bom.EmptyBomTables.doGet(EmptyBomTables.java:50) [classes:]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:734) [jboss-servlet-api_3.0_spec-1.0.0.Final.jar:1.0.0.Final]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.0.Final.jar:1.0.0.Final]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:397) [jbossweb-7.0.13.Final.jar:]
    at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.1.1.Final.jar:7.1.1.Final]
    at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:153) [jboss-as-web-7.1.1.Final.jar:7.1.1.Final]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.13.Final.jar:]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368) [jbossweb-7.0.13.Final.jar:]
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.13.Final.jar:]
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671) [jbossweb-7.0.13.Final.jar:]
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930) [jbossweb-7.0.13.Final.jar:]
    at java.lang.Thread.run(Thread.java:722) [rt.jar:1.7.0_09]

09:30:30,218 ERROR [org.jboss.as.txn] (http-localhost-127.0.0.1-8080-1) JBAS010152: APPLICATION ERROR: transaction still active in request with status 1

---

我做错了什么？

这就是问题所在，一切都必须处于相同的尝试/捕获状态：

try {

    utx.begin();

    Query q3 = em.createQuery("DELETE FROM ItemModuleConnection");
    Query q4 = em.createQuery("DELETE FROM ModuleConnection");
    Query q1 = em.createQuery("DELETE FROM BomModule");
    Query q2 = em.createQuery("DELETE FROM BomItem");

    q1.executeUpdate();
    q2.executeUpdate();
    q3.executeUpdate();
    q4.executeUpdate();

    utx.commit();
} catch (NotSupportedException | SystemException | SecurityException | IllegalStateException | RollbackException | HeuristicMixedException | HeuristicRollbackException e) {
    e.printStackTrace();
}

---

这不是：

TransactionRequiredException:执行更新/删除查询

给了您一个指示吗？它说需要一个事务，这就是为什么我添加了utx.begin和utx.commitAnd

utx

是什么？另外，为什么要分离

try catch

块？如何设置

utx

可以显示该代码？添加了上面的代码。由于问题使用了

createQuery

，我认为您的答案也应该使用

createQuery

而不是

createNativeQuery