{"id":1121,"date":"2023-03-16T21:22:13","date_gmt":"2023-03-16T13:22:13","guid":{"rendered":"https:\/\/www.appblog.cn\/?p=1121"},"modified":"2023-04-29T10:16:57","modified_gmt":"2023-04-29T02:16:57","slug":"design-pattern-observer-mode","status":"publish","type":"post","link":"https:\/\/www.appblog.cn\/index.php\/2023\/03\/16\/design-pattern-observer-mode\/","title":{"rendered":"\u8bbe\u8ba1\u6a21\u5f0f\uff0812\uff09\u89c2\u5bdf\u8005\u6a21\u5f0f"},"content":{"rendered":"

\u89c2\u5bdf\u8005\u6a21\u5f0f\u662f\u4e00\u4e2a\u4f7f\u7528\u7387\u975e\u5e38\u9ad8\u7684\u6a21\u5f0f\uff0c\u5b83\u6700\u5e38\u7528\u5728GUI\u7cfb\u7edf\u3001\u8ba2\u9605\u2013\u53d1\u5e03\u7cfb\u7edf\u3002\u56e0\u4e3a\u8fd9\u4e2a\u6a21\u5f0f\u7684\u4e00\u4e2a\u91cd\u8981\u4f5c\u7528\u5c31\u662f\u89e3\u8026\uff0c\u5c06\u88ab\u89c2\u5bdf\u8005\u548c\u89c2\u5bdf\u8005\u89e3\u8026\uff0c\u4f7f\u5f97\u5b83\u4eec\u4e4b\u95f4\u7684\u4f9d\u8d56\u6027\u66f4\u5c0f\uff0c\u751a\u81f3\u505a\u5230\u6beb\u65e0\u4f9d\u8d56\u3002\u6bd4\u5982\u5b89\u5353\u7684\u5f00\u6e90\u9879\u76eeEventBus<\/code>\u3001Otto<\/code>\u3001AndroidEventBus<\/code>\u7b49\u4e8b\u4ef6\u603b\u7ebf\u7c7b\u7684\u548cRxJava<\/code>\u54cd\u5e94\u5f0f\u7f16\u7a0b\u5176\u6838\u5fc3\u90fd\u662f\u4f7f\u7528\u89c2\u5bdf\u8005\u6a21\u5f0f\u3002<\/p>\n

<\/p>\n

\u5b9a\u4e49<\/h2>\n

\u89c2\u5bdf\u8005\u6a21\u5f0f\u662f\u4e00\u79cd\u884c\u4e3a\u7c7b\u6a21\u5f0f\uff0c\u5b83\u5b9a\u4e49\u5bf9\u8c61\u95f4\u4e00\u79cd\u4e00\u5bf9\u591a\u7684\u4f9d\u8d56\u5173\u7cfb\uff0c\u4f7f\u5f97\u6bcf\u5f53\u4e00\u4e2a\u5bf9\u8c61\u6539\u53d8\u72b6\u6001\uff0c\u5219\u6240\u6709\u4f9d\u8d56\u4e8e\u5b83\u7684\u5bf9\u8c61\u90fd\u4f1a\u5f97\u5230\u901a\u77e5\u5e76\u88ab\u81ea\u52a8\u66f4\u65b0\u3002<\/p>\n

\u4f7f\u7528\u573a\u666f<\/h2>\n

\uff081\uff09\u5173\u8054\u884c\u4e3a\u573a\u666f\uff0c\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u5173\u8054\u884c\u4e3a\u662f\u53ef\u62c6\u5206\u7684\uff0c\u800c\u4e0d\u662f\u201c\u7ec4\u5408\u201d\u5173\u7cfb\u3002
\n\uff082\uff09\u4e8b\u4ef6\u591a\u7ea7\u89e6\u53d1\u573a\u666f\u3002
\n\uff083\uff09\u8de8\u7cfb\u7edf\u7684\u6d88\u606f\u4ea4\u6362\u573a\u666f\uff0c\u5982\u6d88\u606f\u961f\u5217\u3001\u4e8b\u4ef6\u603b\u7ebf\u7684\u5904\u7406\u673a\u5236\u3002<\/p>\n

\u7b80\u5355\u5b9e\u73b0<\/h2>\n

\u8fd9\u91cc\u4e3e\u4e00\u4e2a\u8ffd\u5267\u7684\u4f8b\u5b50\uff0c\u5e73\u5e38\u4e3a\u4e86\u4e0d\u9519\u8fc7\u6700\u65b0\u7684\u7535\u89c6\u5267\u6211\u4eec\u4f1a\u8ba2\u9605\u6216\u5173\u6ce8\u8fd9\u4e2a\u7535\u89c6\u5267\uff0c\u5f53\u7535\u89c6\u5267\u66f4\u65b0\u540e\u4f1a\u7b2c\u4e00\u65f6\u95f4\u63a8\u9001\u7ed9\u6211\u4eec\uff0c\u4e0b\u6765\u5c31\u7b80\u5355\u5b9e\u73b0\u4e00\u4e0b\u3002<\/p>\n

\u62bd\u8c61\u89c2\u5bdf\u8005\u7c7b<\/p>\n

\/**\n *  \u62bd\u8c61\u89c2\u5bdf\u8005\u7c7b\uff0c\u4e3a\u6240\u6709\u5177\u4f53\u89c2\u5bdf\u8005\u5b9a\u4e49\u4e00\u4e2a\u63a5\u53e3\uff0c\u5728\u5f97\u5230\u901a\u77e5\u65f6\u66f4\u65b0\u81ea\u5df1\n *\/\npublic interface Observer {\n    \/**\n     *  \u6709\u66f4\u65b0\n     *  \n     *  @param message \u6d88\u606f\n     *\/\n    public void update(String message);\n\n}<\/code><\/pre>\n
\u62bd\u8c61\u88ab\u89c2\u5bdf\u8005\u7c7b<\/p>\n
\/**\n * \u62bd\u8c61\u88ab\u89c2\u5bdf\u8005\u7c7b\n *\/\npublic interface Observable {\n\n    \/**\n     * \u63a8\u9001\u6d88\u606f\n     * \n     * @param message \u5185\u5bb9\n     *\/\n    void push(String message);\n\n    \/**\n     * \u8ba2\u9605\n     * \n     * @param observer \u8ba2\u9605\u8005\n     *\/\n    void register(Observer observer);\n}<\/code><\/pre>\n
\u5177\u4f53\u7684\u89c2\u5bdf\u8005\u7c7b<\/p>\n
\/**\n * \u5177\u4f53\u7684\u89c2\u5bdf\u8005\u7c7b\uff0c\u4e5f\u5c31\u662f\u8ba2\u9605\u8005\n *\/\npublic class User implements Observer {\n\n    @Override\n    public void update(String message) {\n        System.out.println(name + "," + message + "\u66f4\u65b0\u4e86\uff01");\n\n    }\n\n    \/\/ \u8ba2\u9605\u8005\u7684\u540d\u5b57\n    private String name;\n\n    public User(String name) {\n        this.name = name;\n    }\n}<\/code><\/pre>\n
\u5177\u4f53\u7684\u88ab\u89c2\u5bdf\u8005\u7c7b<\/p>\n
\/**\n *  \u5177\u4f53\u7684\u88ab\u89c2\u5bdf\u8005\u7c7b\uff0c\u4e5f\u5c31\u662f\u8ba2\u9605\u7684\u8282\u76ee\n *\/\npublic class Teleplay implements Observable {\n\n    private List<Observer> list = new ArrayList<Observer>(); \/\/\u50a8\u5b58\u8ba2\u9605\u8005\n\n    @Override\n    public void push(String message) {\n        for (Observer observer : list) {\n            observer.update(message);\n        }\n    }\n\n    @Override\n    public void register(Observer observer) {\n        list.add(observer);\n    }\n\n}<\/code><\/pre>\n
\u5b9e\u73b0<\/p>\n
public class Client {\n    public static void main(String[] args) {\n        \/\/\u88ab\u89c2\u5bdf\u8005\uff0c\u8fd9\u91cc\u5c31\u662f\u7528\u6237\u8ba2\u9605\u7684\u7535\u89c6\u5267\n        Teleplay teleplay = new Teleplay();\n        \/\/\u89c2\u5bdf\u8005\uff0c\u8fd9\u91cc\u5c31\u662f\u8ba2\u9605\u7528\u6237\n        User user1 = new User("\u5c0f\u660e");\n        User user2 = new User("\u5c0f\u5149");\n        User user3 = new User("\u5c0f\u5170");\n        \/\/\u8ba2\u9605\n        teleplay.register(user1);\n        teleplay.register(user2);\n        teleplay.register(user3);\n        \/\/\u63a8\u9001\u65b0\u6d88\u606f\n        teleplay.push("xxx\u7535\u89c6\u5267");\n    }\n}<\/code><\/pre>\n
\u7ed3\u679c<\/p>\n
\u5c0f\u660e,xxx\u7535\u89c6\u5267\u66f4\u65b0\u4e86\uff01\n\u5c0f\u5149,xxx\u7535\u89c6\u5267\u66f4\u65b0\u4e86\uff01\n\u5c0f\u5170,xxx\u7535\u89c6\u5267\u66f4\u65b0\u4e86\uff01<\/code><\/pre>\n
\u7531\u4e0a\u9762\u7684\u4ee3\u7801\u53ef\u4ee5\u770b\u51fa\u5b9e\u73b0\u4e86\u4e00\u5bf9\u591a\u7684\u6d88\u606f\u63a8\u9001\uff0c\u63a8\u9001\u6d88\u606f\u90fd\u662f\u4f9d\u8d56Observer<\/code>\u548cObservable<\/code>\u8fd9\u4e9b\u62bd\u8c61\u7c7b\uff0c\u800cUser\u548cTeleplay\u5b8c\u5168\u6ca1\u6709\u8026\u5408\uff0c\u4fdd\u8bc1\u4e86\u8ba2\u9605\u7cfb\u7edf\u7684\u7075\u6d3b\u6027\u548c\u53ef\u6269\u5c55\u6027\u3002<\/p>\n
Android\u6e90\u7801\u4e2d\u7684\u89c2\u5bdf\u8005\u6a21\u5f0f<\/h2>\n
    \n
  • BaseAdapter<\/li>\n<\/ul>\n
    BaseAdapter<\/code>\u6211\u76f8\u4fe1\u5927\u5bb6\u90fd\u4e0d\u964c\u751f\uff0c\u5728ListView<\/code>\u7684\u9002\u914d\u5668\u4e2d\u6211\u4eec\u90fd\u662f\u7ee7\u627f\u5b83\u3002\u4e0b\u9762\u6765\u7b80\u5355\u5206\u6790\u5206\u6790\u3002<\/p>\n
    BaseAdapter \u90e8\u5206\u4ee3\u7801\uff1a<\/p>\n
    public abstract class BaseAdapter implements ListAdapter, SpinnerAdapter {\n\n    \/\/\u6570\u636e\u96c6\u89c2\u5bdf\u8005\n    private final DataSetObservable mDataSetObservable = new DataSetObservable();\n\n    public boolean hasStableIds() {\n        return false;\n    }\n\n    public void registerDataSetObserver(DataSetObserver observer) {\n        mDataSetObservable.registerObserver(observer);\n    }\n\n    public void unregisterDataSetObserver(DataSetObserver observer) {\n        mDataSetObservable.unregisterObserver(observer);\n    }\n\n    \/**\n     * \u5f53\u6570\u636e\u96c6\u53d8\u5316\u65f6\uff0c\u901a\u77e5\u6240\u6709\u89c2\u5bdf\u8005\n     *\/\n    public void notifyDataSetChanged() {\n        mDataSetObservable.notifyChanged();\n    }\n}<\/code><\/pre>\n
    \u770b\u770bmDataSetObservable.notifyChanged()<\/code>\u65b9\u6cd5\uff1a<\/p>\n
    public class DataSetObservable extends Observable<DataSetObserver> {\n    \/**\n     * Invokes {@link DataSetObserver#onChanged} on each observer.\n     * Called when the contents of the data set have changed.  The recipient\n     * will obtain the new contents the next time it queries the data set.\n     *\/\n    public void notifyChanged() {\n        synchronized(mObservers) {\n            \/\/ since onChanged() is implemented by the app, it could do anything, including\n            \/\/ removing itself from {@link mObservers} - and that could cause problems if\n            \/\/ an iterator is used on the ArrayList {@link mObservers}.\n            \/\/ to avoid such problems, just march thru the list in the reverse order.\n            for (int i = mObservers.size() - 1; i >= 0; i--) {\n                mObservers.get(i).onChanged();\n            }\n        }\n    }\n}<\/code><\/pre>\n
    \u53ef\u4ee5\u770b\u51fa\u5728mDataSetObservable.notifyChanged()<\/code>\u4e2d\u904d\u5386\u6240\u6709\u89c2\u5bdf\u8005\uff0c\u5e76\u8c03\u7528\u4ed6\u4eec\u7684onChanged()<\/code>\uff0c\u4ece\u800c\u544a\u77e5\u89c2\u5bdf\u8005\u53d1\u751f\u4e86\u4ec0\u4e48\u3002<\/p>\n
    \u90a3\u4e48\u89c2\u5bdf\u8005\u600e\u4e48\u6765\u7684\uff0c\u90a3\u5c31\u662fsetAdapter<\/code>\u65b9\u6cd5\uff0c\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
    @Override\npublic void setAdapter(ListAdapter adapter) {\n    if (mAdapter != null && mDataSetObserver != null) {\n        mAdapter.unregisterDataSetObserver(mDataSetObserver);\n    }\n\n    resetList();\n    mRecycler.clear();\n\n    if (mHeaderViewInfos.size() > 0|| mFooterViewInfos.size() > 0) {\n        mAdapter = new HeaderViewListAdapter(mHeaderViewInfos, mFooterViewInfos, adapter);\n    } else {\n        mAdapter = adapter;\n    }\n\n    mOldSelectedPosition = INVALID_POSITION;\n    mOldSelectedRowId = INVALID_ROW_ID;\n\n    \/\/ AbsListView#setAdapter will update choice mode states.\n    super.setAdapter(adapter);\n\n    if (mAdapter != null) {\n        mAreAllItemsSelectable = mAdapter.areAllItemsEnabled();\n        mOldItemCount = mItemCount;\n        mItemCount = mAdapter.getCount();\n        checkFocus();\n\n        mDataSetObserver = new AdapterDataSetObserver();\n        mAdapter.registerDataSetObserver(mDataSetObserver);\/\/\u6ce8\u518c\u89c2\u5bdf\u8005\n\n        ......\u7701\u7565\n    }\n}<\/code><\/pre>\n
    AdapterDataSetObserver<\/code>\u5b9a\u4e49\u5728ListView<\/code>\u7684\u7236\u7c7bAbsListView<\/code>\u4e2d\uff0c\u662f\u4e00\u4e2a\u6570\u636e\u96c6\u89c2\u5bdf\u8005\uff0c\u4ee3\u7801\uff1a<\/p>\n
    class AdapterDataSetObserver extends AdapterView<ListAdapter>.AdapterDataSetObserver {\n    @Override\n    public void onChanged() {\n        super.onChanged();\n        if (mFastScroller != null) {\n            mFastScroller.onSectionsChanged();\n        }\n    }\n\n    @Override\n    public void onInvalidated() {\n        super.onInvalidated();\n        if (mFastScroller != null) {\n            mFastScroller.onSectionsChanged();\n        }\n    }\n}<\/code><\/pre>\n
    \u5b83\u7531\u7ee7\u627f\u81eaAbsListView<\/code>\u7684\u7236\u7c7bAdapterView<\/code>\u7684AdapterDataSetObserver<\/code>\uff0c\u4ee3\u7801\u5982\u4e0b :<\/p>\n
    class AdapterDataSetObserver extends DataSetObserver {\n\n    private Parcelable mInstanceState = null;\n    \/\/ \u4e0a\u6587\u6709\u8bf4\u9053\uff0c\u8c03\u7528Adapter\u7684notifyDataSetChanged\u7684\u65f6\u5019\u4f1a\u8c03\u7528\u6240\u6709\u89c2\u5bdf\u8005\u7684onChanged\u65b9\u6cd5\uff0c\u6838\u5fc3\u5b9e\u73b0\u5c31\u5728\u8fd9\u91cc\n    @Override\n    public void onChanged() {\n        mDataChanged = true;\n        mOldItemCount = mItemCount;\n        \/\/ \u83b7\u53d6Adapter\u4e2d\u6570\u636e\u7684\u6570\u91cf\n        mItemCount = getAdapter().getCount();\n\n        \/\/ Detect the case where a cursor that was previously invalidated has\n        \/\/ been repopulated with new data.\n        if (AdapterView.this.getAdapter().hasStableIds() && mInstanceState != null\n                && mOldItemCount == 0 && mItemCount > 0) {\n            AdapterView.this.onRestoreInstanceState(mInstanceState);\n            mInstanceState = null;\n        } else {\n            rememberSyncState();\n        }\n        checkFocus();\n        \/\/ \u91cd\u65b0\u5e03\u5c40ListView\u3001GridView\u7b49AdapterView\u7ec4\u4ef6\n        requestLayout();\n    }\n\n    \/\/ \u4ee3\u7801\u7701\u7565\n\n    public void clearSavedState() {\n        mInstanceState = null;\n    }\n}<\/code><\/pre>\n
    \u5f53ListView<\/code>\u7684\u6570\u636e\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u8c03\u7528Adapter<\/code>\u7684notifyDataSetChanged<\/code>\u51fd\u6570\uff0c\u8fd9\u4e2a\u51fd\u6570\u53c8\u4f1a\u8c03\u7528DataSetObservable<\/code>\u7684notifyChanged<\/code>\u51fd\u6570\uff0c\u8fd9\u4e2a\u51fd\u6570\u4f1a\u8c03\u7528\u6240\u6709\u89c2\u5bdf\u8005 (AdapterDataSetObserver)<\/code>\u7684onChanged<\/code>\u65b9\u6cd5\u3002\u8fd9\u5c31\u662f\u4e00\u4e2a\u89c2\u5bdf\u8005\u6a21\u5f0f\uff01<\/p>\n
    \u603b\u7ed3<\/h2>\n
      \n
    • \u4f18\u70b9<\/li>\n<\/ul>\n
      \uff081\uff09\u89c2\u5bdf\u8005\u548c\u88ab\u89c2\u5bdf\u8005\u4e4b\u95f4\u662f\u62bd\u8c61\u8026\u5408\uff0c\u5e94\u5bf9\u4e1a\u52a1\u53d8\u5316\u3002
      \n\uff082\uff09\u589e\u5f3a\u7cfb\u7edf\u7684\u7075\u6d3b\u6027\u548c\u53ef\u6269\u5c55\u6027\u3002<\/p>\n
        \n
      • \u7f3a\u70b9<\/li>\n<\/ul>\n
        \u5728\u5e94\u7528\u89c2\u5bdf\u8005\u6a21\u5f0f\u65f6\u9700\u8981\u8003\u8651\u4e00\u4e0b\u5f00\u53d1\u6548\u7387\u548c\u8fd0\u884c\u6548\u7387\u7684\u95ee\u9898\uff0c\u7a0b\u5e8f\u4e2d\u5305\u62ec\u4e00\u4e2a\u88ab\u89c2\u5bdf\u8005\u3001\u591a\u4e2a\u89c2\u5bdf\u8005\uff0c\u5f00\u53d1\u3001\u8c03\u8bd5\u7b49\u5185\u5bb9\u4f1a\u6bd4\u8f83\u590d\u6742\uff0c\u800c\u4e14\u5728Java\u4e2d\u6d88\u606f\u7684\u901a\u77e5\u4e00\u822c\u662f\u987a\u5e8f\u6267\u884c\uff0c\u90a3\u4e48\u4e00\u4e2a\u89c2\u5bdf\u8005\u5361\u987f\uff0c\u4f1a\u5f71\u54cd\u6574\u4f53\u7684\u6267\u884c\u6548\u7387\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u4e00\u822c\u4f1a\u91c7\u7528\u5f02\u6b65\u5b9e\u73b0\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
        \u89c2\u5bdf\u8005\u6a21\u5f0f\u662f\u4e00\u4e2a\u4f7f\u7528\u7387\u975e\u5e38\u9ad8\u7684\u6a21\u5f0f\uff0c\u5b83\u6700\u5e38\u7528\u5728GUI\u7cfb\u7edf\u3001\u8ba2\u9605\u2013\u53d1\u5e03\u7cfb\u7edf\u3002\u56e0\u4e3a\u8fd9\u4e2a\u6a21\u5f0f\u7684\u4e00\u4e2a\u91cd\u8981\u4f5c\u7528\u5c31\u662f\u89e3\u8026\uff0c […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[303],"tags":[],"class_list":["post-1121","post","type-post","status-publish","format-standard","hentry","category-design-pattern"],"_links":{"self":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/1121","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/comments?post=1121"}],"version-history":[{"count":0,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/1121\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/media?parent=1121"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/categories?post=1121"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/tags?post=1121"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}