一般在项目首页中，往往会有多个对话框需要弹出，比如活动弹窗、更新弹窗、评分弹窗等等，而且这些弹窗是有优先级顺序的。这些弹窗一般是通过接口请求后返回结果再显示的，如果只有几个弹窗还好处理，业务逻辑上判断一下先后显示就可以。如果有十几个或者更多，那么处理起来将非常麻烦，而且容易出现问题。
所以封装一个可以按照优先级顺序显示的弹窗功能就非常有必要，首先功能需求如下：
- 按优先级顺序阻塞式显示各种类型弹窗，默认从最高优先级开始显示
- 只有上一个高优先级弹窗显示完或者取消显示，下一个低优先级弹窗才可以显示
- 指定显示某一个弹窗的前提是没有更高优先级的弹窗需要显示
- 在显示一个弹窗之前需要判断是否能够或者需要显示
- 根据优先级去查找指定的弹窗，优先级相当于唯一ID
- 弹窗包括多种类型，Dialog、PopupWindow、Activity等等
接着开始编码去实现功能，先定一个枚举类，罗列出支持的弹窗类型，包括Dialog、PopupWindow、Activity等等。
public enum WindowType {
DIALOG,
POUPOWINDOW,
TOAST,
SNACKBAR,
WIDGET,
ACTIVITY,
OTHERS
}
然后定义弹窗接口IWindow，它定义了弹窗的基本功能。
public interface IWindow {
void show(Activity activity);
void dismiss();
void setOnWindowDismissListener(OnWindowDismissListener listener);
void setOnWindowShowListener(OnWindowShowListener listener);
}
以及弹窗显示和关闭的监听接口，
public interface OnWindowDismissListener {
void onDismiss();
}
public interface OnWindowShowListener {
void onShow();
}
接下来定义个包裹类WindowWrapper去封装弹窗相关的属性和状态，包括弹窗、优先级、能否显示、窗体类型等等，在处理弹窗显示逻辑时将会用到。
public class WindowWrapper {
private IWindow mWindow;
private int mPriority;
private boolean isShowing;
private boolean isCanShow;
private WindowType mWindowType;
private String mWindowName;
private WindowWrapper(Builder builder) {
mWindow = builder.window;
mPriority = builder.priority;
mWindowType = builder.windowType;
isCanShow = builder.isCanShow;
mWindowName = builder.windowName;
}
public IWindow getWindow() {
return mWindow;
}
public void setWindow(IWindow window) {
this.mWindow = window;
}
public int getPriority() {
return mPriority;
}
public void setPriority(int priority) {
this.mPriority = priority;
}
public boolean isShowing() {
return isShowing;
}
public void setShowing(boolean showing) {
isShowing = showing;
}
public WindowType getWindowType() {
return mWindowType;
}
public void setWindowType(WindowType mWindowType) {
this.mWindowType = mWindowType;
}
public boolean isCanShow() {
return isCanShow;
}
public void setCanShow(boolean canShow) {
isCanShow = canShow;
}
public String getWindowName() {
return mWindowName;
}
public void setWindowName(String mWindowName) {
this.mWindowName = mWindowName;
}
public static class Builder {
private IWindow window;
private int priority;
private WindowType windowType;
private boolean isCanShow;
private String windowName;
public Builder window(IWindow window) {
this.window = window;
return this;
}
public Builder priority(int priority) {
this.priority = priority;
return this;
}
public Builder windowType(WindowType type) {
this.windowType = type;
return this;
}
public Builder setCanShow(boolean canShow) {
isCanShow = canShow;
return this;
}
public String getWindowName() {
return windowName;
}
public Builder setWindowName(String windowName) {
this.windowName = windowName;
return this;
}
public WindowWrapper build() {
return new WindowWrapper(this);
}
}
}
最后通过WindowTaskManager类去统一组织管理弹窗的添加、显示、关闭等逻辑，
public class WindowTaskManager {
private List<WindowWrapper> mWindows;
private static WindowTaskManager mDefaultInstance;
private WindowTaskManager() {
}
public static WindowTaskManager getInstance() {
if (mDefaultInstance == null) {
synchronized (WindowTaskManager.class) {
if (mDefaultInstance == null) {
mDefaultInstance = new WindowTaskManager();
}
}
}
return mDefaultInstance;
}
public synchronized void addWindow(Activity activity, WindowWrapper windowWrapper) {
if (windowWrapper != null) {
if (mWindows == null) {
mWindows = new ArrayList<>();
}
if (windowWrapper.getWindow() != null) {
windowWrapper.getWindow().setOnWindowShowListener(new OnWindowShowListener() {
@Override
public void onShow() {
windowWrapper.setShowing(true);
}
});
windowWrapper.getWindow().setOnWindowDismissListener(new OnWindowDismissListener() {
@Override
public void onDismiss() {
windowWrapper.setShowing(false);
mWindows.remove(windowWrapper);
showNext(activity);
}
});
}
mWindows.add(windowWrapper);
}
}
public synchronized void enableWindow(Activity activity, int priority, IWindow window) {
WindowWrapper windowWrapper = getTargetWindow(priority);
if (windowWrapper != null) {
if (windowWrapper.getWindow() == null) {
window.setOnWindowShowListener(new OnWindowShowListener() {
@Override
public void onShow() {
windowWrapper.setShowing(true);
}
});
window.setOnWindowDismissListener(new OnWindowDismissListener() {
@Override
public void onDismiss() {
windowWrapper.setShowing(false);
mWindows.remove(windowWrapper);
showNext(activity);
}
});
}
windowWrapper.setCanShow(true);
windowWrapper.setWindow(window);
show(activity, priority);
}
}
public synchronized void disableWindow(int priority) {
WindowWrapper windowWrapper = getTargetWindow(priority);
if (windowWrapper != null && windowWrapper.getWindow() != null) {
if (mWindows != null) {
mWindows.remove(windowWrapper);
}
}
}
public synchronized void show(Activity activity) {
WindowWrapper windowWrapper = getMaxPriorityWindow();
if (windowWrapper != null && windowWrapper.isCanShow()) {
IWindow window = windowWrapper.getWindow();
if (window != null) {
window.show(activity);
}
}
}
public synchronized void show(Activity activity, int priorities) {
WindowWrapper windowWrapper = getTargetWindow(priorities);
if (windowWrapper != null && windowWrapper.getWindow() != null) {
WindowWrapper topShowWindow = getShowingWindow();
if (topShowWindow == null) {
int priority = windowWrapper.getPriority();
WindowWrapper maxPriorityWindow = getMaxPriorityWindow();
if (maxPriorityWindow != null && windowWrapper.isCanShow() && priority >= maxPriorityWindow.getPriority()) {
if (windowWrapper.getWindow() != null) {
windowWrapper.getWindow().show(activity);
}
}
}
}
}
public synchronized void clear() {
if (mWindows != null) {
for (int i = 0, size = mWindows.size(); i < size; i++) {
if (mWindows.get(i) != null) {
IWindow window = mWindows.get(i).getWindow();
if (window != null) {
window.dismiss();
}
}
}
mWindows.clear();
}
WindowHelper.getInstance().onDestroy();
}
public synchronized void clear(boolean dismiss) {
if (mWindows != null) {
if (dismiss) {
for (int i = 0, size = mWindows.size(); i < size; i++) {
if (mWindows.get(i) != null) {
IWindow window = mWindows.get(i).getWindow();
if (window != null) {
window.dismiss();
}
}
}
}
mWindows.clear();
}
WindowHelper.getInstance().onDestroy();
}
private synchronized void showNext(Activity activity) {
WindowWrapper windowWrapper = getMaxPriorityWindow();
if (windowWrapper != null && windowWrapper.isCanShow()) {
if (windowWrapper.getWindow() != null) {
windowWrapper.getWindow().show(activity);
}
}
}
private synchronized WindowWrapper getMaxPriorityWindow() {
if (mWindows != null) {
int maxPriority = -1;
int position = -1;
for (int i = 0, size = mWindows.size(); i < size; i++) {
WindowWrapper windowWrapper = mWindows.get(i);
if (i == 0) {
position = 0;
maxPriority = windowWrapper.getPriority();
} else {
if (windowWrapper.getPriority() >= maxPriority) {
position = i;
maxPriority = windowWrapper.getPriority();
}
}
}
if (position != -1) {
return mWindows.get(position);
} else {
return null;
}
}
return null;
}
private synchronized WindowWrapper getTargetWindow(int priority) {
if (mWindows != null) {
for (int i = 0, size = mWindows.size(); i < size; i++) {
WindowWrapper windowWrapper = mWindows.get(i);
if (windowWrapper != null && windowWrapper.getPriority() == priority) {
return windowWrapper;
}
}
}
return null;
}
private synchronized WindowWrapper getShowingWindow() {
if (mWindows != null) {
for (int i = 0, size = mWindows.size(); i < size; i++) {
WindowWrapper windowWrapper = mWindows.get(i);
if (windowWrapper != null && windowWrapper.getWindow() != null && windowWrapper.isShowing()) {
return windowWrapper;
}
}
}
return null;
}
}
WindowTaskManager类有三个主要方法：
- addWindow(Activity activity, WindowWrapper windowWrapper)
- enableWindow(Activity activity, int priority, IWindow window)
- disableWindow(int priority)
需要按顺序显示的对话框统一使用addWindow方法添加，这是还未进行网络请求之前就要调用的。作用是告诉WindowTaskManager一共有多少个弹窗需要按顺序显示。当网络请求返回之后，如果需要显示弹窗就调用enableWindow方法去显示，如果不需要显示弹窗就调用disableWindow方法，将这个弹窗从显示队列中移除。
以上就是按顺序显示弹窗的主要逻辑，使用的话窗体先继承IWindow，实现相关方法。然后通过操作WindowTaskManager类就可以了。具体使用方法参见源码。
项目地址：github.com/Geekince/Pr…
彩蛋：
需要在DialogFragment中显示DialogFragment时候，最好不要直接在DialogFragment启动显示，而是在DialogFragment的消失回调中启动显示。因为当前一个DialogFragment消失的时候，getChildFragmentManager可能会失效，应该在外层使用getFragmentManager。
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