自定义Toast

public class CustomToast extends Toast {

    TextView textView;
    /**
     * Construct an empty Toast object.  You must call {@link #setView} before you
     * can call {@link #show}.
     *
     * @param context The context to use.  Usually your {@link Application}
     *                or {@link Activity} object.
     */
    public CustomToast(Context context) {
        super(context);
        init(context);
    }

    private void init(Context context) {
        View view = View.inflate(context, R.layout.layout_global_toast,null);
        textView = (TextView) view.findViewById(R.id.content);
        setView(view);
    }

    @Override
    public void setText(CharSequence sequence){
        textView.setText(sequence);
    }

    @Override
    public void setText(int resId) {
        textView.setText(resId);
    }

}

控制Toast 的位置

public class CustomToastUtil extends Toast {
    private static String oldMsg;
    protected static Toast toast = null;
    private static long oneTime = 0;
    private static long twoTime = 0;

    /**
     * Construct an empty Toast object.  You must call {@link #setView} before you
     * can call {@link #show}.
     *
     * @param context The context to use.  Usually your {@link Application}
     *                or {@link Activity} object.
     */
    public CustomToastUtil(Context context) {
        super(context);
    }

    public static void showToast(Context context, int resId) {
        showToast(context, context.getString(resId));
    }

    public static void showToast(Context context, int resId, int gravity) {
        showToast(context, context.getString(resId), gravity, 0, 0);
    }

    public static void showToast(Context context, String s, int gravity) {
        showToast(context, s, gravity, 0, 0);
    }

    public static void showToast(Context context, int resId, int gravity, int offX, int offY) {
        showToast(context, context.getString(resId), gravity, offX, offY);
    }

    public static void showToast(Context context, String s) {
        if (TextUtils.isEmpty(s)) {
            return;
        }
        if (toast == null) {
            toast = new CustomToast(context);
            toast.setText(s);
            toast.setDuration(Toast.LENGTH_SHORT);
            toast.setMargin(0, 0);
            toast.setGravity(Gravity.TOP + Gravity.FILL_HORIZONTAL, 0, 150);
            toast.show();
            oneTime = System.currentTimeMillis();
        } else {
            twoTime = System.currentTimeMillis();
            if (s.equals(oldMsg)) {
                if (twoTime - oneTime > Toast.LENGTH_SHORT) {
                    toast.show();
                }
            } else {
                oldMsg = s;
                toast.setText(s);
                toast.show();
            }
        }
        oneTime = twoTime;


    }


    public static void showToast(Context context, String s, int gravity, int offX, int offY) {
        if (toast == null) {
            toast = new CustomToast(context);
            toast.setText(s);
            toast.setDuration(Toast.LENGTH_SHORT);
            toast.setGravity(gravity, offX, offY);
            toast.setMargin(1, 0);
            toast.show();
            oneTime = System.currentTimeMillis();
        } else {
            twoTime = System.currentTimeMillis();
            if (s.equals(oldMsg)) {
                if (twoTime - oneTime > Toast.LENGTH_SHORT) {
                    toast.show();
                }
            } else {
                oldMsg = s;
                toast.setText(s);
                toast.show();
            }
        }
        oneTime = twoTime;
    }
}

利用LiveData 观察者模式，封装到BaseActivity观察。LiveData抽取工具类思想实现全局控制

本来我们自定义Toast已经可以使用，但是不方便，toast也要在主线程显示，这个时候传入context需要activity，但是通过LiveData我们解决切线程传入必须Activity，有的地方又拿不到问题。

封装Content 内容

public class Content implements Publisher.Publishable {

    String content;

    public Content(String content) {
        this.content = content;
    }

    public String getContent() {
        return content;
    }
}

定义Publisher

public class Publisher {

    private final List<Observer> observers;

    public Publisher() {
        this.observers = new ArrayList<>();
    }

    /**
     * 注册
     *
     * @param observer
     */
    public void register(Observer observer) {
        if (!isRegistered(observer)) {
            observers.add(observer);
        }
    }

    /**
     * 注销
     *
     * @param observer
     */
    public void unRegister(Observer observer) {
        if (isRegistered(observer)) {
            observers.remove(observer);
        }
    }

    public boolean isRegistered(Observer observer) {
        return observers.contains(observer);
    }

    /**
     * 获取注册听众数量
     *
     * @return
     */
    public int getObserversCount() {
        return observers.size();
    }

    /**
     * 通知所有听众
     */
    public void notifyObservers(Object data) {
        if (observers.size() > 0) {
            for (Observer observer : observers) {
                if (observer != null) {
                    observer.update(data);
                }
            }
        }
    }

    public interface Observer {
        void update(Object data);
    }


    public interface Publishable {
    }

}

PuublishHolder

public class PublishableHolder<P extends Publisher.Publishable> {
    private final Publisher publisher;
    private P data;

    public PublishableHolder(Publisher publisher) {
        this.publisher = publisher;
    }

    public P getData() {
        return data;
    }

    public void setData(P data) {
        this.data = data;
        publisher.notifyObservers(this.data);
    }

    /**
     * 在data的引用地址不改变的情况下修改data内部的数据推荐调用此方法
     * 否则需要自行通知publisher
     *
     * @param changer
     */
    public void modifyData(DataChanger changer) {
        if (changer != null) {
            changer.doChange(data);
            publisher.notifyObservers(data);
        }
    }

    /**
     * 修改数据接口
     */
    public interface DataChanger<P extends Publisher.Publishable> {
        void doChange(P data);
    }

}

组合Publisher 和PublisherHolder

public class ToastPublisher {
    public static final Publisher publisher = new Publisher();
    public static final PublishableHolder<Content> data = new PublishableHolder(publisher);
}

扩展Holder的使用

public class PublishableListHolder<P extends Publisher.Publishable> {
    private final List<P> list;
    private final Publisher publisher;

    public PublishableListHolder(Publisher publisher) {
        list = new ArrayList<>();
        this.publisher = publisher;
    }

    public void setList(List<P> list) {
        this.list.clear();
        this.list.addAll(list);
        publisher.notifyObservers(this.list);
    }

    public List<P> getList(Publisher.Observer observer) {
        return list;
    }

    public void addItem(P publishable) {
        list.add(publishable);
        publisher.notifyObservers(list);
    }

    public void removeItem(P publishable) {
        if (list.contains(publishable)) {
            list.remove(publishable);
            publisher.notifyObservers(list);
        }
    }

    public void addAll(List<P> publishableList) {
        list.addAll(publishableList);
        publisher.notifyObservers(list);
    }

    public void removeAll(List<P> publishableList) {
        list.removeAll(publishableList);
        publisher.notifyObservers(list);
    }

    public void clear() {
        list.clear();
        publisher.notifyObservers(list);
    }
}

工具类调用

public static void showToast(String message) {
        ToastPublisher.data.setData(new Content(message));
    }

    public static void showToast(int resid) {
        ToastPublisher.data.setData(new Content(BaseApplication.getInstance().getString(resid)));

    }

    public static void showErrorToast(ApiException e) {
        if(e != null) {
            if(e.getCode() >= 500) {
                if(!TextUtils.isEmpty(e.getMessage())) {
                    showToast(e.getMessage());
                } else {
                    showToast("Server Exception");
                }
            } else {
                showToast("Request Exception");
            }

        } else {
            showToast("Unknown Exception");
            KLog.e("login-exception","Unknown Exception");


        }
    }

BaseActivity 中注册，解注册，统一调用

private ToastObserver toastObserver = new ToastObserver();
    private class ToastObserver implements Publisher.Observer{

        @Override
        public void update(Object data) {
            final Content content = (Content) data;
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    CustomToastUtil.showToast(BaseActivity.this, content.getContent());
                }
            });
        }
    }


onCreate中
        ToastPublisher.publisher.register(toastObserver);
onDestroy中
        ToastPublisher.publisher.unRegister(toastObserver);