Struts + Hibernate:@SessionTarget 不工作 [英] Struts + Hibernate: @SessionTarget not working

问题描述

我正在使用 struts2-fullhibernatecore-plugin-2.2.2-GA.jar 在我的 DAO 类中注入一个 session，如下所示:

I am using struts2-fullhibernatecore-plugin-2.2.2-GA.jar to inject a session in my DAO class like below:

public class UserDAO {
    @SessionTarget
    Session session;

    @TransactionTarget
    Transaction transaction;

    public List<User> getUsers() {
        return session.createQuery("from user").list();
    }
}

但是我得到了

java.lang.NullPointerException
  com.wudi.DAO.UserDAO.getUsers(UserDAO.java:28)
  com.wudi.action.UserListAction.execute(UserListAction.java:24)
  sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
  sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  java.lang.reflect.Method.invoke(Method.java:606)
  ...

根据调试输出，UserDAO中的session和transaction为null.

According to debugging output, session and transaction in the UserDAO are null.

一些文件供参考:

User.java:

@Entity
@Table(name = "user")
public class User implements Serializable {

    @Id
    @GeneratedValue
    private int id;

    @Column
    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }


}

UserListAction.java:

public class UserListAction extends ActionSupport {
    private List<User> users;
    private UserDAO userDAO = new UserDAO();

    @Override
    public String execute() throws Exception {
        users = userDAO.getUsers();
        return SUCCESS;
    }

}

hibernate.cfg.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
  <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/sample?zeroDateTimeBehavior=convertToNull</property>
    <property name="hibernate.connection.username">root</property>
    <property name="hibernate.connection.pool_size">10</property>

    <mapping class="com.wudi.model.User" />
  </session-factory>
</hibernate-configuration>

推荐答案

如果你想使用 Hibernate Session 和 Transaction 注入能力，你的动作映射包需要扩展包hibernate-default.

If you want to use the Hibernate Session and Transaction injection capability, your action mapping package need to extend the package hibernate-default.

关于hibernate-default 包的更多细节

该插件提供了一个名为 hibernate-default 的映射包.这具有三个用于注入功能的拦截器堆栈:

The plugin provides a mapping package called hibernate-default. And this has three interceptor stacks indicated for injection capabilities:

• basicStackHibernate:类似于 Struts2basickStack(没有验证！)，但具有 Hibernate 会话和事务注入功能.

• basicStackHibernate: Like Struts2basickStack (NO validations!), but with Hibernate session and transaction injections capability.

defaultStackHibernate:类似于 Struts2 defaultStack，但没有 Struts2 验证方法(注解和 XML).改用 Hibernate 验证框架.

defaultStackHibernate: Like Struts2 defaultStack, but without Struts2 validation methods (annotation and XML). Uses Hibernate Validation framework instead.

defaultStackHibernateStrutsValidation:Struts2 defaultStack+ 插件的basicStackHibernate.

defaultStackHibernateStrutsValidation: Struts2 defaultStack+ plugin's basicStackHibernate.

这个包扩展了 hibernate-default 包，所以如果需要，可以使用所有默认的 Struts2 配置.

This package extends the hibernate-default package, so all default Struts2 configurations can be used if you need.

hibernate-default 包是抽象的，所以你可以用其他包来扩展它.例如:

hibernate-default package is abstract, so you can extends this with other. For example:

<package name="default" extends="hibernate-default,json-default" >

要将 hibernate-default 与注释配置一起使用，请使用

To use hibernate-default with an annotation configuration use

@ParentPackage("hibernate-default")
@InterceptorRef("basicStackHibernate")
public class YourAction extends ActionSupport {}

这篇关于Struts + Hibernate:@SessionTarget 不工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！