Spring Generic Dao类名

问题描述

我为spring / hibernate项目配置了一个自定义通用服务DAO - 这个想法是我可以从我的控制器轻松地重用它。

I have configured a custom generic service DAO for my spring / hibernate project - the idea being that I can reuse it easily from my controllers.

它基本上看起来像这个：

It essentially looks like this:

public class DefaultService<T> {

private Class<T> e;

public String className(Class<T> e) {
    String clip = e.getName();
    clip = clip.substring(clip.lastIndexOf('.') + 1, clip.length());
    return clip;
}
public List<T> getAll(Integer status) {
    Session session = sessionFactory.getCurrentSession();
    Query query = session.createQuery("FROM " + className(e) + " WHERE status = " + status);
    return query.list();
}
...

引用的是：

@Autowired
public DefaultService<Address> addressService;
addressService.get(1);

然而字符串剪辑= e.getName（） line抛出Null指针异常。如果我将类移动到属性部分（因此 addressService.get（Address.class，1）），我可以让它工作，但我发现这有些不整洁，特别是在那里是否有多个不同的类被调用。

However the String clip = e.getName() line throws a Null pointer exception. I can get this to work if I move the class into the attributes section (so addressService.get(Address.class, 1) but I find this somewhat untidy, especially when there are multiple different classes being called upon.

有没有办法让类正确生成一个值而不必重复添加到我的所有函数中？

Is there some way to get the class to generate a value correctly without repeatedly adding it into all my functions?

提前致谢。

推荐答案

我做了类似的事情，你需要通用类来也是一个构造函数参数，我使用hibernate实体，但你可以传入表名字符串。

I did something similar, you need the generic class to be a constructor argument as well, mine uses hibernate entities, but you could pass in the string of table name.

public class DomainRepository<T> {

    @Resource(name = "sessionFactory")
    protected SessionFactory sessionFactory;

 public DomainRepository(Class genericType) {
        this.genericType = genericType;
    }

 @Transactional(readOnly = true)
    public T get(final long id) {
        return (T) sessionFactory.getCurrentSession().get(genericType, id);
    }

然后您可以进行子类化（如果需要）来自定义或只是设置你在bean中的bean配置如下：t：

You can then subclass (if you need to) to customize or simply set up you bean in the spring config like below t :

<bean id="tagRepository" class="com.yourcompnay.data.DomainRepository">
        <constructor-arg value="com.yourcompnay.domain.Tag"/>
</bean>

因此，在您的代码中，您可以像这样引用tagRepository（不需要其他代码，而不是上面发布的代码） ，以及）：

So in your code you could then reference tagRepository like so (no other cod eis needed than that posted above, and below) :

@Resource(name = "tagRepository")
private DomainRepository<Tag> tagRepository;

此外，我将其称为存储库而非服务，服务处理不同类型及其交互（不只是一个）。特别是使用SQL字符串的示例：

Also, I would call it a repository not a service, a service deals with different types and their interactions (not just one). And for specifically your example using SQL strings :

public final String tableName;
public DomainRepository(String tableName) {
      this.tableName = tableName;
}
public List<T> getAll(Integer status) {
    Session session = sessionFactory.getCurrentSession();
    Query query = session.createQuery("FROM " + tableName + " WHERE status = " + status);
    return query.list();
}

并让你的bean定义如此

and have your beans defined like so

<bean id="addressRepository" class="com.yourcompnay.data.DomainRepository">
  <constructor-arg value="address"/>
</bean>

然后你也可以在必要时自己创建子类：

And then you can alsow create subclasses youself where necessary :

public class PersonRepository extends DomainRepository<Person> {
    public PersonRepository(){
        super("person"); //assumes table name is person
    }

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