LoadingPage的抽取

抽取的动机

任何一个联网的view界面展示都有四种情况，

①正在加载

②加载失败

③加载成功，但是没有数据

④加载成功，同时返回数据

public abstract class LoadingPager extends FrameLayout {//1.定义4种不同的显示状态private static final int STATE_LOADING = 1;private static final int STATE_ERROR = 2;private static final int STATE_EMPTY = 3;private static final int STATE_SUCCESS = 4;private int state_current = STATE_LOADING;//默认情况下，当前状态为正在加载//2.提供4种不同的界面private View view_loading;private View view_error;private View view_empty;private View view_success;private LayoutParams params;public LoadingPager(Context context) {    this(context, null);}public LoadingPager(Context context, AttributeSet attrs) {    this(context, attrs, 0);}public LoadingPager(Context context, AttributeSet attrs, int defStyleAttr) {    super(context, attrs, defStyleAttr);    init();}//初始化方法private void init() {    //实例化view    //1.提供布局显示的参数    params = new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);    if (view_loading == null) {        //2.加载布局        view_loading = UIUtils.getView(R.layout.page_loading);        //3.添加到当前的frameLayout中        addView(view_loading, params);    }    if (view_empty == null) {        //2.加载布局        view_empty = UIUtils.getView(R.layout.page_empty);        //3.添加到当前的frameLayout中        addView(view_empty, params);    }    if (view_error == null) {        //2.加载布局        view_error = UIUtils.getView(R.layout.page_error);        //3.添加到当前的frameLayout中        addView(view_error, params);    }    showSafePage();}//保证如下的操作在主线程中执行的：更新界面private void showSafePage() {    UIUtils.runOnUiThread(new Runnable() {        @Override        public void run() {            //保证run()中的操作在主线程中执行            showPage();        }    });}private void showPage() {    //根据当前state_current的值，决定显示哪个view    view_loading.setVisibility(state_current == STATE_LOADING ? View.VISIBLE : View.INVISIBLE);    view_error.setVisibility(state_current == STATE_ERROR ? View.VISIBLE : View.INVISIBLE);    view_empty.setVisibility(state_current == STATE_EMPTY ? View.VISIBLE : View.INVISIBLE);    if (view_success == null) {        view_success = UIUtils.getView(layoutId());        addView(view_success, params);    }    view_success.setVisibility(state_current == STATE_SUCCESS ? View.VISIBLE : View.INVISIBLE);}public abstract int layoutId();private ResultState resultState;//在show()中实现联网加载数据public void show() {    String url = url();    if (TextUtils.isEmpty(url)) {        resultState = ResultState.SUCCESS;        resultState.setContent("");        loadImage();        return;    }    UIUtils.getHandler().postDelayed(new Runnable() {        @Override        public void run() {            //可以换成OKHttp,retrofit等其他框架            AsyncHttpClient client = new AsyncHttpClient();            client.get(url(), params(), new AsyncHttpResponseHandler() {                @Override                public void onSuccess(String content) {                    if (TextUtils.isEmpty(content)) {// "" or null                        //state_current = STATE_EMPTY;                        resultState = ResultState.EMPTY;                        resultState.setContent("");                    } else {                        //state_current = STATE_SUCCESS;                        resultState = ResultState.SUCCESS;                        resultState.setContent(content);                    }                    //showSafePage();                    loadImage();                }                @Override                public void onFailure(Throwable error, String content) {                    //state_current = STATE_ERROR;                    resultState = ResultState.ERROR;                    resultState.setContent("");                    // showSafePage();                    loadImage();                }            });        }    }, 2000);}private void loadImage() {    switch (resultState) {        case ERROR:            state_current = STATE_ERROR;            break;        case EMPTY:            state_current = STATE_EMPTY;            break;        case SUCCESS:            state_current = STATE_SUCCESS;            break;    }    //根据修改以后的state_current，更新视图的显示。    showSafePage();    if (state_current == STATE_SUCCESS) {        onSuccss(resultState, view_success);    }}protected abstract void onSuccss(ResultState resultState, View view_success);//提供联网的请求参数protected abstract RequestParams params();//提供联网的请求地址public abstract String url();//提供枚举类，封装联网以后的状态值和数据public enum ResultState {    ERROR(2), EMPTY(3), SUCCESS(4);    int state;    ResultState(int state) {        this.state = state;    }    private String content;    public String getContent() {        return content;    }    public void setContent(String content) {        this.content = content;    }}}

BaseFragment中简单使用

@Nullable@Overridepublic View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {  /*  View view= UIUtils.getView(getLayoutId());    unbinder = ButterKnife.bind(this, view);    initTitle();    initData();*/    loadingPager = new LoadingPager(container.getContext()) {        @Override        public int layoutId() {            return getLayoutId();        }        @Override        protected void onSuccss(ResultState resultState, View view_sucess) {            unbinder = ButterKnife.bind(BaseFragment.this, view_sucess);            initData(resultState.getContent());            initTitle();        }        @Override        protected RequestParams params() {            return getParams();        }        @Override        public String url() {            return geturl();        }    };    return loadingPager;}