1.目标

     androidannotation框架要促进Android应用程序的编写和维护。相信简单的代码有明确的意图是实现这些目标的最佳途径。

   当我们都沉浸在开发Android应用程序时,我们常常会想:为什么我们总是需要反复写相同的代码吗?为什么我们的应用越来越难维护呢？

   context和activity就像是神一样的东西，我们被复杂的线程玩耍，难以参考的API，加载很多的无名监听类，写大量不需要的异常抛出..我们不能改善它们吗？

2.怎么改善

    利用Java 注解机制，开发者能展示他们的意图，还能让androidannotation框架在编译时继承管道代码。

3.特色

*依赖注入：注入view、extras数据、service、resource..

*简单的线程模型：在方法名上注释是在UI线程运行还是后台线程运行

*事件绑定：注释你的方法处理view的事件，不再有难看的匿名监听类。

*REST客户端：创建了一个客户端接口，androidannotation继承了springAndroid的接口。

*不是深不可测：因为AndroidAnnotations继承子类在编译时，你可以检查代码看看它是怎么工作的。

*AndroidAnnotation提供了这么多的好东西甚至它是小于50kb，在运行时没有任何性能影响。

4.对比

Before

---

    public class BookmarksToClipboardActivity extends Activity {      BookmarkAdapter adapter;             ListView bookmarkList;             EditText search;             BookmarkApplication application;             Animation fadeIn;             ClipboardManager clipboardManager;             @Override      protected void onCreate(Bundle savedInstanceState) {      super.onCreate(savedInstanceState);             requestWindowFeature(Window.FEATURE_NO_TITLE);      getWindow().setFlags(FLAG_FULLSCREEN, FLAG_FULLSCREEN);             setContentView(R.layout.bookmarks);             bookmarkList = (ListView) findViewById(R.id.bookmarkList);      search = (EditText) findViewById(R.id.search);      application = (BookmarkApplication) getApplication();      fadeIn = AnimationUtils.loadAnimation(this, anim.fade_in);      clipboardManager = (ClipboardManager) getSystemService(CLIPBOARD_SERVICE);             View updateBookmarksButton1 = findViewById(R.id.updateBookmarksButton1);      updateBookmarksButton1.setOnClickListener(new OnClickListener() {             @Override      public void onClick(View v) {      updateBookmarksClicked();      }      });             View updateBookmarksButton2 = findViewById(R.id.updateBookmarksButton2);      updateBookmarksButton2.setOnClickListener(new OnClickListener() {             @Override      public void onClick(View v) {      updateBookmarksClicked();      }      });             bookmarkList.setOnItemClickListener(new OnItemClickListener() {             @Override      public void onItemClick(AdapterView<?> p, View v, int pos, long id) {      Bookmark selectedBookmark = (Bookmark) p.getAdapter().getItem(pos);      bookmarkListItemClicked(selectedBookmark);      }      });             initBookmarkList();      }             void initBookmarkList() {      adapter = new BookmarkAdapter(this);      bookmarkList.setAdapter(adapter);      }             void updateBookmarksClicked() {      UpdateBookmarksTask task = new UpdateBookmarksTask();             task.execute(search.getText().toString(), application.getUserId());      }      private static final String BOOKMARK_URL = //      "http://www.bookmarks.com/bookmarks/{userId}?search={search}";      class UpdateBookmarksTask extends AsyncTask<String, Void, Bookmarks> {             @Override      protected Bookmarks doInBackground(String... params) {      String searchString = params[0];      String userId = params[1];             RestTemplate client = new RestTemplate();      HashMap<String, Object> args = new HashMap<String, Object>();      args.put("search", searchString);      args.put("userId", userId);      HttpHeaders httpHeaders = new HttpHeaders();      HttpEntity<Bookmarks> request = new HttpEntity<Bookmarks>(httpHeaders);      ResponseEntity<Bookmarks> response = client.exchange( //      BOOKMARK_URL, HttpMethod.GET, request, Bookmarks.class, args);      Bookmarks bookmarks = response.getBody();             return bookmarks;      }             @Override      protected void onPostExecute(Bookmarks result) {      adapter.updateBookmarks(result);      bookmarkList.startAnimation(fadeIn);      }      }             void bookmarkListItemClicked(Bookmark selectedBookmark) {      clipboardManager.setText(selectedBookmark.getUrl());      }             }

After

---

    @NoTitle      @Fullscreen      @EActivity(R.layout.bookmarks)      public class BookmarksToClipboardActivity extends Activity {      BookmarkAdapter adapter;      @ViewById      ListView bookmarkList;             @ViewById      EditText search;      @App      BookmarkApplication application;      @RestService      BookmarkClient restClient;             @AnimationRes      Animation fadeIn;      @SystemService      ClipboardManager clipboardManager;             @AfterViews      void initBookmarkList() {      adapter = new BookmarkAdapter(this);      bookmarkList.setAdapter(adapter);      }      @Click({R.id.updateBookmarksButton1, R.id.updateBookmarksButton2})      void updateBookmarksClicked() {      searchAsync(search.getText().toString(), application.getUserId());      }      @Background      void searchAsync(String searchString, String userId) {      Bookmarks bookmarks = restClient.getBookmarks(searchString, userId);      updateBookmarks(bookmarks);      }             @UiThread      void updateBookmarks(Bookmarks bookmarks) {      adapter.updateBookmarks(bookmarks);      bookmarkList.startAnimation(fadeIn);      }      @ItemClick      void bookmarkListItemClicked(Bookmark selectedBookmark) {      clipboardManager.setText(selectedBookmark.getUrl());      }             }

    @Rest("http://www.bookmarks.com")      public interface BookmarkClient {      @Get("/bookmarks/{userId}?search={search}")      Bookmarks getBookmarks(String search, String userId);             }

需要注意的是androidannotation在编译时会生成一个子类，子类的名字是在原有的名字后面加"_"，而且在AndroidManifest.xml中注册加"_"的类，例如：

<activity android:name=".MyListActivity_" />

跳转activity时也有所不同：

startActivity(this, MyListActivity_.class);

从2.4版本后提供了一个简便方法：

MyListActivity_.intent(context).start();

2.7版本之后可以使用：

MyListActivity_.intent(context).startForResult();

开启service类似：

MyService_.intent(context).start();

更多的注解使用方法请参考官方文档。

https://github.com/excilys/androidannotations/wiki/Cookbook

 

来自：https://github.com/excilys/androidannotations