Android(安卓)BaseFragment封装

1.一般的封装。这种封装每次切换都会重新加载数据。有两种实现方式：
a.让子类传递一个View(一般是一个加载的布局)

public abstract class BaseFragment extends Fragment {    protected Activity mActivity;    @Override    public void onAttach(Context context) {        super.onAttach(context);        mActivity = (AppCompatActivity) context;    }    @Override    public void onCreate(@Nullable Bundle savedInstanceState) {        super.onCreate(savedInstanceState);    }    @Nullable    @Override    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        return setLayoutView(inflater,container,savedInstanceState);    }    @Override    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {        findViewById(view);        setViewData(view);        setClickEvent(view);    }    /**     * 设置布局     *     * @return     * @param inflater     * @param container     */    public abstract View setLayoutView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState);    /**     * findViewById     */    public void findViewById(View view){}    /**     * setViewData     */    public void setViewData(View view){}    /**     * setClickEvent     */    public void setClickEvent(View view){}}

b.让子类传递一个id(一般是一个布局的id)

public abstract class BaseFragment1 extends Fragment {    protected Activity mActivity;    @Override    public void onAttach(Context context) {        super.onAttach(context);        mActivity = (AppCompatActivity) context;    }    @Override    public void onCreate(@Nullable Bundle savedInstanceState) {        super.onCreate(savedInstanceState);    }    @Nullable    @Override    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        return inflater.inflate(setLayoutId(), container, false);//        return setLayoutView(inflater,container,savedInstanceState);    }    @Override    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {        findViewById(view);        setViewData(view);        setClickEvent(view);    }    /**     * 设置布局     *     * @return     */    public abstract int setLayoutId();    /**     * findViewById     */    public void findViewById(View view){}    /**     * setViewData     */    public void setViewData(View view){}    /**     * setClickEvent     */    public void setClickEvent(View view){}}

2.加强版封装。在实际项目中，我们不需要每次切换都加载数据，这时候就需要用到赖加载。这里采用继承basefragment的方式实现，因此，也有两种实现方式
a.继承BaseFragment

/** * 创建日期：2018/11/28 on 11:02 * 描述: 赖加载 */public abstract class BaseLazyFragment1 extends BaseFragment {    View view = null;    @Nullable    @Override    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        if (null != view) {            ViewGroup parent = (ViewGroup) view.getParent();            if (null != parent) {                parent.removeView(view);            }        } else {            view=setLayoutView(inflater,container,savedInstanceState);            initView(view);        }        return view;    }    protected abstract void initView(View view);}

2.继承BaseFragment1

/** * 创建日期：2018/11/28 on 11:02 * 描述: 赖加载：子类传递id */public abstract class BaseLazy1Fragment1 extends BaseFragment1 {    View view=null;    @Nullable    @Override    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        if (null != view) {            ViewGroup parent = (ViewGroup) view.getParent();            if (null != parent) {                parent.removeView(view);            }        } else {            view=inflater.inflate(getLayoutViewId(), container, false);            initView(view);        }        return view;    }    //初始化控件    protected abstract void initView(View view);}

3.懒加载并不能满足我们的需求。因为在使用fragment和viewpage进行导航栏功能的时候，Android会默认预加载当前页面的前后各一页的数据，有时候我们不需要这种预加载，我们希望能够滑到那一页才进行网络请求加载数据，这样使用我们的APP时间间隔很少的情况下异步请求多次。
同样有两种实现方式，但是不同于第2中懒加载方式，这里可以随意继承上面两种懒加载。
a.继承BaseLazyFragment1 或者BaseLazy1Fragment1。

/** * 创建日期：2018/11/28 on 11:02 * 描述: 赖加载+取消预加载 */public abstract class BaseLazyFragment2 extends BaseLazyFragment1 {    /**     * 是否初始化过布局     */    protected boolean isViewInitiated;    /**     * 当前界面是否可见     */    protected boolean isVisibleToUser;    /**     * 是否加载过数据     */    protected boolean isDataInitiated;    @Override    public void onActivityCreated(@Nullable Bundle savedInstanceState) {        super.onActivityCreated(savedInstanceState);        isViewInitiated=true;        prepareFetchData();    }    @Override    public void setUserVisibleHint(boolean isVisibleToUser) {        super.setUserVisibleHint(isVisibleToUser);        this.isVisibleToUser = isVisibleToUser;        if (isVisibleToUser) {            prepareFetchData();        }    }    /**     * 懒加载     *///    public abstract void fetchData();    protected abstract void loadData();    public void prepareFetchData() {        prepareFetchData(false);    }    /**     * 判断懒加载条件     *     * @param forceUpdate 强制更新，好像没什么用？     */    public void prepareFetchData(boolean forceUpdate) {        if (isVisibleToUser && isViewInitiated && (!isDataInitiated || forceUpdate)) {            loadData();            isDataInitiated = true;        }    }}

b.继承BaseLazyFragment1 或者BaseLazy1Fragment1。

/** * 创建日期：2018/11/28 on 11:02 * 描述: 赖加载+取消预加载 */public abstract class BaseLazy2Fragment2 extends BaseLazyFragment1 {    private boolean isPrepared;    private boolean isFirstVisible = true;    private boolean isFirstInvisible = true;    @Override    public void onActivityCreated(@Nullable Bundle savedInstanceState) {        super.onActivityCreated(savedInstanceState);        initPrepare();    }    private synchronized void initPrepare() {        if (isPrepared) {            onFirstUserVisible();        } else {            isPrepared = true;        }    }    @Override    public void setUserVisibleHint(boolean isVisibleToUser) {        super.setUserVisibleHint(isVisibleToUser);        if (isVisibleToUser) {            if (isFirstVisible) {                isFirstVisible = false;                initPrepare();            } else {                onUserVisible();            }        } else {            if (isFirstInvisible) {                isFirstInvisible = false;                onFirstUserInvisible();            } else {                onUserInvisible();            }        }    }    protected abstract void onFirstUserVisible();//加载数据，开启动画/广播..    protected  void onUserVisible(){}///开启动画/广播..    private void onFirstUserInvisible() {    }    protected void onUserInvisible(){}//暂停动画，暂停广播}

注意：fragment中的onViewCreated每次切换都会调用，在懒加载的时候如果在该方法中初始化控件，初始化数据，网络请求等操作就起不到懒加载的效果

总结：fragment的封装基本可以按照上面的方式使用，当然那是最基本的，需要根据自己的需要增加。如果有什么不当之处欢迎指出。

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