小编ski*_*kip的帖子

有人可以帮我理解JavaEE 6 beanInterface中@EJB注释参数的使用吗？

我有一种情况,我有一个EJB,我希望它本地和远程访问.

我有一个MyBaseInterface然后两个MyEJBLocalInterface并且MyEJBRemoteInterface延伸MyBaseInterface.现在我有MyEJB这两种实现MyEJBLocalInterface和MyEJBRemoteInterface.

现在我有一种情况,我只想在MyEJB本地访问.

我可以通过以下方式实现同​​样的目标吗？

@EJB(beanInterface=MyEJBLocalInterface.class)
private MyBaseInterface instanceOfLocallyAccessedMyEJB;

有人可以帮我理解属性beanInterface参数的使用@EJB吗？

谢谢.

我提取了sia3-code ZIP文件,并在Eclipse Helios IDE中将提取的sia3-code文件夹导入为Existing Maven Projects.它导入很好,但我没有在构建路径中看到任何src文件夹,我无法运行测试类.

这是它的样子:

有人可以帮助我如何获得作为maven项目运行的书籍附带的源代码？

谢谢.

一切正常,直到我添加toSting()到我的实体类中.

之后我开始在运行时收到以下错误:

Exception in thread "main" java.lang.StackOverflowError
    at java.lang.AbstractStringBuilder.append(Unknown Source)
    at java.lang.StringBuilder.append(Unknown Source)
    at java.lang.StringBuilder.<init>(Unknown Source)
    at entity.Guide.toString(Guide.java:51)
    at java.lang.String.valueOf(Unknown Source)
    at java.lang.StringBuilder.append(Unknown Source)
    at entity.Student.toString(Student.java:45)
        ...

@Entity
public class Teacher {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;    

    private String name;

    @OneToMany(mappedBy="teacher", cascade={CascadeType.PERSIST})
    private Set<Student> students = new HashSet<Student>(); 

    public Teacher() {}
    public Teacher(String name) {
        this.name = name;
    }

    public Set<Student> getStudents() {
        return students;
    }       
    public void addStudent(Student student) {
        students.add(student);
        student.setTeacher(this);
    }
    @Override
    public String toString() …

有人可以解释为什么在映射继承时,InheritanceType.TABLE_PER_CLASS无法使用GenerationType.AUTO策略生成主键值吗？

我需要根据zipcode访问该站点的用户填充一些数据.

有人能告诉我如何检索该zipcode用户的位置吗？

我在我的应用程序上使用AngularJS.

有人可以帮助我使用 Hibernate/JPA 使用复合主键为以下关系进行双向一对一 JPA 映射吗？

嗨当我尝试使用JNDI连接到数据源时,我收到此错误:

    [org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
    at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1452)
    at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1371)
    at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
    at org.apache.roller.weblogger.business.DatabaseProvider.getConnection(DatabaseProvider.java:179)
    at org.apache.roller.weblogger.business.DatabaseProvider.<init>(DatabaseProvider.java:141)
    at org.apache.roller.weblogger.business.startup.WebloggerStartup.prepare(WebloggerStartup.java:171)
    at org.apache.roller.weblogger.ui.core.RollerContext.contextInitialized(RollerContext.java:138)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4205)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4704)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1079)
    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1002)
    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506)
    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1315)
    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1061)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
    at org.apache.catalina.core.StandardService.start(StandardService.java:525)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: java.lang.NullPointerException
    at …

我有一个基于 spring 框架 3 的 Maven Web 应用程序，当我maven-jetty-plugin通过运行命令在 jetty 上运行该应用程序时mvn -e clean jetty:run，它运行正常，但是当我tomcat-maven-plugin通过运行命令在 tomcat 上运行它时mvn -e clean tomcat:run，它给出了以下异常：

java.lang.ClassCastException: org.springframework.web.filter.HiddenHttpMethodFilter cannot be cast to javax.servlet.Filter
        at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:275)
        at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
        at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
        at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4001)
        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4651)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
        at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:445)
        at org.apache.catalina.startup.Embedded.start(Embedded.java:825)
        at org.codehaus.mojo.tomcat.AbstractRunMojo.startContainer(AbstractRunMojo.java:558)
        at org.codehaus.mojo.tomcat.AbstractRunMojo.execute(AbstractRunMojo.java:255)
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:319)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
        at …

刚刚安装了RAD 8.5的试用版，但是我看不到创建Portlet项目的任何选择。

我想念什么？

谢谢。

以下noGood方法给出了编译错误,因为它在返回类型之前省略了正式类型参数T.

public static T noGood(T t) {
  return t;
}

有人可以帮我理解为什么静态泛型方法在返回类型之前需要一个类型参数？非静态方法不需要它吗？