在父类中反射获取泛型类型

　　使用Struts2时做CRUD时，每个action都需要写相同重复的代码，于是就想着将这些个代码放到一个父类中，子类直接使用父类中的方法。

　　但是由于保存的时候需要传递一个具体的实体，而每个action功能不一样，传递的实体也不一样，于是就想到了反射。

　　子类：

public class UserAction extends BaseAction<User> {}

　　父类

public abstract class BaseAction<T> extends ActionSupport implements RequestAware, ModelDriven<T> {protected Map<String, Object> request;

    protected Long id;

    private Class<T> clazz = null;



    public BaseAction() {

        // TODO Auto-generated constructor stub

        ParameterizedType pt = (ParameterizedType) this.getClass()

                .getGenericSuperclass(); //获取泛型类型数组

        this.clazz = (Class<T>) pt.getActualTypeArguments()[0]; //获取泛型类型

    }



    protected T model;



    @Override

    public T getModel() { //通过传入不同的泛型类型，获取具体的实例 try {

            model = clazz.newInstance();

        } catch (Exception e) {

            throw new RuntimeException(e);

        }

        if (id != null) {

            if (model instanceof Department) {

                model = (T) departmentService.getById(id);

            } else if (model instanceof Role) {

                model = (T) roleService.getById(id);

            } else if (model instanceof User) {

                model = (T) userService.getById(id);

            } else if (model instanceof Privilege) {

                model = (T) privilegeService.getById(id);

            }

        }

        return model;

    }



    @Override

    public void setRequest(Map<String, Object> arg0) {

        request = arg0;

    }



    public Long getId() {

        return id;

    }



    public void setId(Long id) {

        this.id = id;

    }



    @Resource

    protected IDepartmentService departmentService;

    @Resource

    protected IRoleService roleService;

    @Resource

    protected IUserService userService;

    @Resource

    protected IPrivilegeService privilegeService;



}