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;

}