關于Android實戰(zhàn)篇系列，一直不知從何入手寫。基本概念介紹對于實戰(zhàn)篇系列來講沒有太大意義，本系列一如SPRing實戰(zhàn)篇系列所倡導的理念一樣：知其然知其所以然，難點、疑點一網打盡（有點狂妄了）。還是決定從頭開始，這里對基本概念不做過多介紹，主要介紹使用。

一、背景知識

說到Activity，做Android的一點都不會陌生，真正項目開發(fā)中不止會用到Activity，而且會抽象出BaseActivity，其中處理公共部分（比如標題、回調函數等），具體部分還是有具體的Activity處理，這里也是利用了java中的設計模式——策略模式

二、BaseActivity配置

/** * 基本Activity，供其他Activity繼承，實現了回調及title設置、返回按鍵等 */public class BaseActivity extends Activity  implements TextWatcher,RetrofitCallBack {	protected ProgressDialog waitDialog;	/**	 * 標記標題左右兩邊的類型:文字	 */	protected final int TITLE_TYPE_TEXT = 0;	/**	 * 標記標題左右兩邊的類型:圖片	 */	protected final int TITLE_TYPE_IMG = 1;	public Myapplication application;	@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		application = (MyApplication) getApplicationContext();	}	@Override	protected void onDestroy() {		super.onDestroy();		dismissWaitDialog();	}	@Override	protected void onPause() {		super.onPause();	}	@Override	protected void onResume() {		super.onResume();		// 判斷界面再次轉到前臺的時候,主題是否發(fā)生改變.如果改變了,則需要重新加載activity		// this.recreate();	}	@Override	protected void onStop() {		super.onStop();	}	/**	 * 需在setContentView方法之后調用. 設置后,如果不對左側的事件進行監(jiān)聽,默認的點擊事件是結束當前界面.	 * <p>	 * 標題傳資源id和字符串皆可.	 * <p>	 * 如果某一側顯示的是圖片,則那一側只能傳對應的圖片資源id.如果是文字,則資源id和字符串皆可.	 * 	 * @param title	 *            標題	 * @param left	 *            是否顯示左側的部分	 * @param leftType	 *            左側的類型	 * @param l	 *            左側部分內容	 * @param right	 *            是否顯示右側的部分	 * @param rightType	 *            右側的類型	 * @param r	 *            右側部分的內容	 */	protected void setTitle(Object title, boolean left, int leftType, Object l,			boolean right, int rightType, Object r) {		try {			TextView tvTitle = (TextView) findViewById(R.id.tv_title);			TextView tvLeft = (TextView) findViewById(R.id.tv_title_left);			LinearLayout llLeft = (LinearLayout) findViewById(R.id.ll_title_left);			ImageView ivLeft = (ImageView) findViewById(R.id.iv_title_left);			TextView tvRight = (TextView) findViewById(R.id.tv_title_right);			ImageView ivRight = (ImageView) findViewById(R.id.iv_title_right);			LinearLayout llRight = (LinearLayout) findViewById(R.id.ll_title_right);			if (title != null && title instanceof String) {				if (!TextUtils.isEmpty((String) title)) {					tvTitle.setVisibility(View.VISIBLE);					tvTitle.setText((String) title);				} else {					tvTitle.setVisibility(View.INVISIBLE);				}			} else if (title != null && title instanceof Integer) {				if (((Integer) title) > 0) {					tvTitle.setVisibility(View.VISIBLE);					tvTitle.setText((Integer) title);				} else {					tvTitle.setVisibility(View.INVISIBLE);				}			}			if (left) {				llLeft.setVisibility(View.VISIBLE);				if (leftType == TITLE_TYPE_TEXT) {					ivLeft.setVisibility(View.GONE);					tvLeft.setVisibility(View.VISIBLE);					if (l instanceof String) {						tvLeft.setText((String) l);					} else if (l instanceof Integer) {						tvLeft.setText((Integer) l);					}				} else if (leftType == TITLE_TYPE_IMG) {					ivLeft.setVisibility(View.VISIBLE);					tvLeft.setVisibility(View.GONE);					if (l instanceof Integer) {						ivLeft.setImageResource((Integer) l);					}				}			} else {				llLeft.setVisibility(View.INVISIBLE);			}			if (right) {				llRight.setVisibility(View.VISIBLE);				if (rightType == TITLE_TYPE_TEXT) {					ivRight.setVisibility(View.GONE);					tvRight.setVisibility(View.VISIBLE);					if (r instanceof String) {						tvRight.setText((String) r);					} else if (r instanceof Integer) {						tvRight.setText((Integer) r);					}				} else if (rightType == TITLE_TYPE_IMG) {					ivRight.setVisibility(View.VISIBLE);					tvRight.setVisibility(View.GONE);					if (r instanceof Integer) {						ivRight.setImageResource((Integer) r);					}				}			} else {				llRight.setVisibility(View.INVISIBLE);			}		} catch (Exception e) {		}	}	/**	 * 設置點擊左上角的返回事件.默認是finish界面	 */	protected void registerBack() {		LinearLayout llLeft = (LinearLayout) findViewById(R.id.ll_title_left);		llLeft.setOnClickListener(new View.OnClickListener() {			@Override			public void onClick(View view) {				BaseActivity.this.finish();			}		});	}	/**	 * 設置點擊右上角的返回事件.	 */	protected void rightDo() {		LinearLayout llRight = (LinearLayout) findViewById(R.id.ll_title_right);		llRight.setOnClickListener(new View.OnClickListener() {			@Override			public void onClick(View view) {				rightDoWhat();			}		});	}	protected void rightDoWhat() {	}	// 封裝跳轉	public void openActivity(Class<?> c) {		openActivity(c, null);	}	// 跳轉 傳遞數據 bundel	public void openActivity(Class<?> c, Bundle b) {		openActivity(c, b, null);	}	public void openActivity(Class<?> c, Bundle b, Uri uri) {		Intent intent = new Intent(this, c);		if (b != null) {			intent.putExtras(b);		}		if (uri != null) {			intent.setData(uri);		}		startActivity(intent);	}	/**	 * 跳轉登錄界面	 */	protected void goLogin() {		Intent intent = new Intent(this, LoginActivity.class);		intent.putExtra(Constant.NEEDLOGIN, true);		startActivityForResult(intent, 33);	}	/**	 * 全局等待對話框	 */	public void showWaitDialog() {		this.runOnUiThread(new Runnable() {			@Override			public void run() {				if (waitDialog == null || !waitDialog.isShowing()) {					waitDialog = new ProgressDialog(BaseActivity.this);					waitDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);					waitDialog.setCanceledOnTouchOutside(false);					ImageView view = new ImageView(BaseActivity.this);					view.setLayoutParams(new LayoutParams(							LayoutParams.WRAP_CONTENT,							LayoutParams.WRAP_CONTENT));					Animation loadAnimation = AnimationUtils.loadAnimation(							BaseActivity.this, R.anim.rotate);					view.startAnimation(loadAnimation);					loadAnimation.start();					view.setImageResource(R.drawable.loading);					// waitDialog.setCancelable(false);					waitDialog.show();					waitDialog.setContentView(view);					LogUtil.i("waitDialong.......");				}			}		});	}	public void dismissWaitDialog() {		this.runOnUiThread(new Runnable() {			@Override			public void run() {				if (waitDialog != null && waitDialog.isShowing()) {					waitDialog.dismiss();					waitDialog = null;				}			}		});	}	/**	 * textWatcher的實現類，用于監(jiān)聽Editable的變化	 * @param s	 * @param start	 * @param count     * @param after     */	@Override	public void beforeTextChanged(CharSequence s, int start, int count, int after) {	}	@Override	public void onTextChanged(CharSequence s, int start, int before, int count) {	}	@Override	public void afterTextChanged(Editable s) {	}	/**	 * retrofitcallback方法實現，將response返回給Activity	 * @param response  返回數據	 * @param method    回調方法標志     */	@Override	public void onResponse(Response response, int method) {		dismissWaitDialog();	}	@Override	public void onFailure(Response response, int method) {		dismissWaitDialog();	}	public static int px2dip(Context context, float pxValue) {		final float scale = context.getResources().getDisplayMetrics().density;		return (int) (pxValue / scale + 0.5f);	}}
其中BaseActivity繼承了Activity（這個是必須滴，凡是Activity都要集成SDK中的Activity），實現了TextWatcher（監(jiān)聽Editable變化，后面會介紹），實現了RetrofitCallBack（retrofit的回調接口，這個在后面說道retrofit的時候會說明）；除此之外，還設置了共用的title，返回鍵，openActivity，goLogin，等待對話框等。
三、BaseActivity的使用
下面以登錄界面為例，介紹BaseActivity的使用
1）先看界面
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="@color/grey_light" >    <include        android:id="@+id/title"        android:layout_alignParentTop="true"        layout="@layout/layout_stub_title" />    <LinearLayout        android:orientation="vertical"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_marginTop="@dimen/distanse60">        <EditText            android:id="@+id/et_account"            android:layout_width="match_parent"            android:layout_height="@dimen/distanse50"            android:background="@drawable/reg_input_bg2"            android:drawableLeft="@drawable/phone"            android:drawablePadding="@dimen/distanse10"            android:hint="請輸入手機/用戶名"            android:paddingLeft="@dimen/distanse15"            android:paddingRight="@dimen/distanse10"            android:textColor="@color/lightblack" />        <View android:layout_width="match_parent" android:layout_height="1dp"            android:background="#ccc" />        <EditText            android:id="@+id/et_pwd"            android:layout_width="match_parent"            android:layout_height="@dimen/distanse50"            android:background="@drawable/reg_input_bg2"            android:drawableLeft="@drawable/passWord"            android:drawablePadding="@dimen/distanse10"            android:hint="登錄密碼"            android:inputType="textPassword"            android:paddingLeft="@dimen/distanse15"            android:paddingRight="@dimen/distanse10"            android:textColor="@color/lightblack" />        <TextView            android:id="@+id/tv_sure"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:layout_marginLeft="@dimen/distanse10"            android:layout_marginRight="@dimen/distanse10"            android:layout_marginTop="@dimen/distanse50"            android:padding="@dimen/distanse10"            android:background="@drawable/buttonstyle"            android:enabled="false"            android:gravity="center"            android:text="確定"            android:textColor="@color/white"            android:textSize="@dimen/text_size16" />        <LinearLayout            android:orientation="horizontal"            android:layout_width="match_parent"            android:layout_height="wrap_content">            <TextView                android:id="@+id/tv_reset"                android:layout_width="match_parent"                android:layout_height="@dimen/distanse40"                android:layout_marginLeft="@dimen/distanse15"                android:layout_marginRight="@dimen/distanse15"                android:layout_marginTop="@dimen/distanse10"                android:drawablePadding="@dimen/distanse5"                android:gravity="right"                android:text="忘記密碼"                android:textColor="@color/light_blue"                android:textSize="@dimen/text_size15"                android:layout_weight="1" />        </LinearLayout>        <LinearLayout            android:orientation="vertical"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:gravity="center"            android:layout_marginTop="@dimen/distanse10">            <TextView                android:id="@+id/tv_reg"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:gravity="center"                android:padding="@dimen/distanse10"                android:text="還沒有賬號？現在注冊"                android:textColor="@color/light_blue"                android:textSize="@dimen/text_size14"                android:layout_weight="1" />        </LinearLayout>    </LinearLayout></RelativeLayout> 
其中引入了共用title布局
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/rl_title"    android:layout_width="match_parent"    android:layout_height="44dp"    android:background="@color/blue1"    android:gravity="center_vertical" >    <TextView        android:id="@+id/tv_title"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_centerHorizontal="true"        android:layout_centerVertical="true"        android:layout_toLeftOf="@+id/ll_title_right"        android:layout_toRightOf="@+id/ll_title_left"        android:ellipsize="end"        android:gravity="center"        android:text="New Text"        android:textColor="@color/white"        android:textSize="20sp" />    <LinearLayout        android:id="@+id/ll_title_left"        android:layout_width="wrap_content"        android:layout_height="fill_parent"        android:layout_alignParentLeft="true"        android:layout_alignParentTop="true"        android:gravity="center_vertical|left"        android:minWidth="80dp"        android:orientation="horizontal" >        <ImageView            android:id="@+id/iv_title_left"            android:layout_width="wrap_content"            android:layout_height="fill_parent"            android:paddingLeft="10dp"            android:paddingRight="10dp"            android:src="@drawable/to_left" />        <TextView            android:id="@+id/tv_title_left"            android:layout_width="wrap_content"            android:layout_height="fill_parent"            android:gravity="center_vertical|left"            android:paddingLeft="10dp"            android:paddingRight="10dp"            android:text="New Text"            android:textColor="@color/white"            android:textSize="16sp"            android:visibility="gone" />    </LinearLayout>    <LinearLayout        android:id="@+id/ll_title_right"        android:layout_width="wrap_content"        android:layout_height="fill_parent"        android:layout_alignParentRight="true"        android:layout_alignParentTop="true"        android:gravity="center_vertical|right"        android:minWidth="80dp"        android:orientation="horizontal" >        <ImageView            android:id="@+id/iv_title_right"            android:layout_width="wrap_content"            android:layout_height="fill_parent"            android:paddingLeft="10dp"            android:paddingRight="10dp"            android:src="@drawable/to_left" />        <TextView            android:id="@+id/tv_title_right"            android:layout_width="wrap_content"            android:layout_height="fill_parent"            android:gravity="center_vertical|right"            android:paddingRight="10dp"            android:text="New Text"            android:textColor="@color/white"            android:textSize="16sp"            android:visibility="gone" />    </LinearLayout></RelativeLayout>
2）LoginActivity
public class LoginActivity extends BaseActivity {    @BindView(R.id.et_account)    EditText etAccount;    @BindView(R.id.et_pwd)    EditText etPwd;    @BindView(R.id.tv_reg)    TextView tvReg;    @BindView(R.id.tv_sure)    TextView tvSure;    private String account, pwd, userId, password;    private boolean needLogin;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.layout_login);    //set布局        ButterKnife.bind(this);        setTitle(R.string.login, true, TITLE_TYPE_IMG, R.drawable.to_left,                true, TITLE_TYPE_TEXT, "");       //基類方法，設置title        initView();        initData();    }    private void initView() {        registerBack();        //設置text變化監(jiān)聽器        etAccount.addTextChangedListener(this);        etPwd.addTextChangedListener(this);        tvReg.getPaint().setFlags(Paint.UNDERLINE_TEXT_FLAG);// 下劃線    }    /**     * 根據是否輸入值，判斷是否顯示確定按鈕     * @param s     */    @Override    public void afterTextChanged(Editable s) {        super.afterTextChanged(s);        String userStr = etAccount.getText().toString();        String pwdStr = etPwd.getText().toString();        if(userStr.length() * pwdStr.length() != 0){            tvSure.setEnabled(true);        }else{            tvSure.setEnabled(false);        }    }    private void initData() {        account = application.getUserinfobean().getPhoneNumber();        if (!StringUtil.isEmpty(account)) {            etAccount.setText(account);        }        Intent intent = getIntent();        if (intent.hasExtra(Constant.NEEDLOGIN)) {            needLogin = intent.getBooleanExtra(Constant.NEEDLOGIN, false);        }    }    @OnClick({R.id.tv_sure, R.id.tv_reset, R.id.tv_reg})    public void onClick(View view) {        account = etAccount.getText() + "";        switch (view.getId()) {            case R.id.tv_sure:                pwd = etPwd.getText() + "";                if (StringUtil.isEmpty(account)) {                    ToastUtil.makeShortText(this, "請輸入登錄賬號");                    return;                }                if (StringUtil.isEmpty(pwd)) {                    ToastUtil.makeShortText(this, "請輸入登錄密碼");                    return;                }                if (pwd.length() < 6 || pwd.length() > 16) {                    ToastUtil.makeShortText(this, "密碼不能小于6位或大于16位");                    return;                }                getUserById(account);                break;            case R.id.tv_reg:                openActivity(RegisterActivity.class);                break;            case R.id.tv_reset:                openActivity(ResetPwdActivity.class);                break;            default:                break;        }    }    private void getLogin(String userId, String password, String loginType) {        showWaitDialog();        Map<String, Object> signMap = new HashMap<String, Object>();        signMap.put("name", userId);        signMap.put("pwd", password);        signMap.put("loginType", loginType);        Map<String, String> reqMap = SignUtil.jsonmd5(signMap);        RetrofitHttpRequest.addToEnqueue(RetrofitHttpRequest.getInstance().mHttpService.login(reqMap),                this, HttpStaticApi.HTTP_LOGIN);    }    /**     * 根據用戶名獲取userId，加密用md5（userId+pwd）     */    private void getUserById(String name) {        showWaitDialog();        Map<String, Object> signMap = new HashMap<String, Object>();        signMap.put("name", name);        Map<String, String> reqMap = SignUtil.jsonMd5(signMap);        RetrofitHttpRequest.addToEnqueue(RetrofitHttpRequest.getInstance().mHttpService.getUserById(reqMap),                this, HttpStaticApi.HTTP_GETUSERBYID);    }    @Override    public void onResponse(Response response, int method) {        super.onResponse(response, method);        switch (method) {            case HttpStaticApi.HTTP_GETUSERBYID:                UserIdBean userIdBean = (UserIdBean) response.body();                UserIdBean.ResDataBean resDataBean = userIdBean.getResData();                if (HttpConst.STATUS_SUC.equals(resDataBean.getStatus())) {                    userId = resDataBean.getData();                    password = StringUtil.md5(userId + pwd);                    LogUtil.e(password);                    getLogin(account, password, "1");                } else {                    ToastUtil.makeShortText(this, resDataBean.getMessage());                }                break;            case HttpStaticApi.HTTP_LOGIN:                UserBean userBean = (UserBean) response.body();                UserBean.ResDataBean resDataBean1 = userBean.getResData();                if (HttpConst.STATUS_SUC.equals(resDataBean1.getStatus())) {                    UserBean.ResDataBean.DataBean dataBean = resDataBean1.getData();                    Bundle bundle = new Bundle();                    bundle.putString("user_id", userId);                    bundle.putString("user_name", dataBean.getCustomerName());                    bundle.putString("phone", dataBean.getMobile());                    bundle.putString("nickName", dataBean.getNickName());                    bundle.putString("email", dataBean.getEmail());                    bundle.putBoolean("isBinding", dataBean.getIsbinding().equals("1") ? true : false);                    application.getUserinfobean().setaccess(bundle);                    //從需要登錄頁跳轉的返回目標頁，直接點擊登錄的跳轉首頁                    if (!needLogin){                        openActivity(MainActivity.class);                    }                    finish();                } else {                    ToastUtil.makeShortText(this, "登錄失敗" + resDataBean1.getMessage());                }                break;            default:                break;        }    }
后面retrofit相關是和服務器通信的，這個后面會有專題介紹。還看到控件的獲取和點擊事件的設置用了Butterknife，@BindView和@OnClick，這個將在下一章進行介紹Butterknife的使用
四、AndroidManifest.xml
當然不要忘了在AndroidManifest.xml進行設置，否則無法啟動
<activity            android:name="com.xxx.xxx.login.LoginActivity"            android:screenOrientation="portrait"            android:windowSoftInputMode="adjustPan|stateHidden" />
運行效果圖