1.目標

     androidannotation框架要促進Android應用程序的編寫和維護。相信簡單的代碼有明確的意圖是實現這些目標的最佳途徑。

   當我們都沉浸在開發Android應用程序時,我們常常會想:為什么我們總是需要反復寫相同的代碼嗎?為什么我們的應用越來越難維護呢？

   context和activity就像是神一樣的東西，我們被復雜的線程玩耍，難以參考的API，加載很多的無名監聽類，寫大量不需要的異常拋出..我們不能改善它們嗎？

2.怎么改善

    利用Java 注解機制，開發者能展示他們的意圖，還能讓androidannotation框架在編譯時繼承管道代碼。

3.特色

*依賴注入：注入view、extras數據、service、resource..

*簡單的線程模型：在方法名上注釋是在UI線程運行還是后臺線程運行

*事件綁定：注釋你的方法處理view的事件，不再有難看的匿名監聽類。

*REST客戶端：創建了一個客戶端接口，androidannotation繼承了springAndroid的接口。

*不是深不可測：因為AndroidAnnotations繼承子類在編譯時，你可以檢查代碼看看它是怎么工作的。

*AndroidAnnotation提供了這么多的好東西甚至它是小于50kb，在運行時沒有任何性能影響。

4.對比

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());
}

}</pre> <h1 style="margin:0px;font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;color:#333333;font-size:30px;line-height:36px;"><a name="t1"></a> After</h1>


    @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());
}

}</pre> <pre class="brush:java; toolbar: true; auto-links: false;">    @Rest("http://www.bookmarks.com")
public interface BookmarkClient {
@Get("/bookmarks/{userId}?search={search}")
Bookmarks getBookmarks(String search, String userId);

}</pre> <span style="font-size:18px;">需要注意的是androidannotation在編譯時會生成一個子類，子類的名字是在原有的名字后面加"_"，而且在AndroidManifest.xml中注冊加"_"的類，例如：</span> <pre style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;overflow:auto;font-size:14px;margin-top:0px;margin-bottom:0px;padding:16px;line-height:1.45;background-color:#f7f7f7;word-wrap:normal;word-break:normal;color:#333333;"><span class="nt" style="color:navy;"><activity</span> <span class="na" style="color:teal;">android:name=</span><span class="s" style="color:#dd1144;">".MyListActivity_"</span> <span class="nt" style="color:navy;">/></span></pre> <p style="text-align:justify;"><span style="font-family:Tahoma,Arial;font-size:18px;"><span style="line-height:24px;">跳轉activity時也有所不同：</span></span></p>


startActivity(this, MyListActivity_.class);
 從2.4版本后提供了一個簡便方法： 

MyListActivity_.intent(context).start();
 2.7版本之后可以使用： 

MyListActivity_.intent(context).startForResult();
 開啟service類似： 

MyService_.intent(context).start();
 
更多的注解使用方法請參考官方文檔。

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


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