Android 应用程序常用工具类及功能包

记得我刚进公司实习的时候，总喜欢逮个人就问android应用程序是怎么样一步一步架构起来的，得到的却总是不太懂的回答。眨眼间已经毕业近半年
多，接触过两个慢慢成形的应用后，打算写一下自己的见解。

一、应用包目录

做过android应用开发的应该都知道，开发初期会大体上给应用分几个包，用来存储不同类别的.java文件，比如说com.lto.views用来存放自定义View，com.lto.adapter用来存放应用中各种AdapterView需要用到的Adapter等等。下面分下大家看看合理不。

1. ***.***.adapter
应用中会使用到的所有Adapter，尽量作为一个单独的类存放在此包中，能够让整个应用更清晰，后来者读起来也更易懂。
2.***.***.base
正如字面意思，这个包存放基础的东西，比如说整个应用的自定义Application、应用经常使用的Activity基类BaseActivity、自己应用整体配置aseConfig、以及其他类似的类。
3.***.***.activities
存放应用中所有的activity。
4.***.***.fragments
存放fragment。
5.***.***.utils
存放系统中常用的工具类，后面会详细介绍。
6.***.***.views
存放自定义View（ViewGroup）
7.***.***.db
存放与操作数据库相关的类。
8.***.***.model
存放数据类。
9.***.***.web
存放与网络访问有关的类。
10.***.***.manager
存放管理类，例如***ActivityManager,***DataManager,***SessionManager,***LocationManager……
11.***.***.custom.api
存放第三方api。
12.***.***.anim
存放各种动画类。
13.***.***.pay & ***.***.***.push
如果有需要涉及支付或者推送服务的，可以新建一个这样的包。

可能每个项目团队建包方式都不一样，博主这边也是根据自己项目给出的，大家可以看一下，如果有什么更好的建议可以给博主提一下，万分感谢 。

二、应用常用工具类（***.***.utils）

1.Constants

<span style="font-size:14px;"><span style="font-size:14px;">public class Constants {
/***************
* Log
********************/
public static final String LOG_TAG = "Note";
public static final String PREFERENCES_KEY = "note_heart";
/***************
* Calendar Events
********************/
public static final int MAX_EVENTS_COUNT = 15;
public static final int MAX_EVENTS_SCROLL_COUNT = 84000;// must include
public static final int MAX_WEEK_SCROLL_COUNT = MAX_EVENTS_SCROLL_COUNT / 7;
public static final int MAX_MONTH_SCROLL_COUNT = MAX_EVENTS_SCROLL_COUNT / 30;
public static final int MAX_EVENT_VIEWPAGER_COUNT = 3;
public static final int MONTH_CALENDAR_COLUMN = 7;
public static final int ROWS_OF_MONTH_CALENDAR = 6;

public final static int SELECT_TYPE_FROM_EVENTS_SCROLL = 0x0;
public final static int SELECT_TYPE_FROM_WEEK_CLICK = 0x1;
public final static int SELECT_TYPE_FROM_WEEK_SCROLL = 0x2;
public final static int SELECT_TYPE_FROM_MONTH_CLICK = 0x3;
public final static int SELECT_TYPE_FROM_MONTH_SCROLL = 0x4;
public final static int SELECT_TYPE_FROM_JUMP_TO = 0x5;

public final static int CALENDAR_UPDATE_CALENDAR = 0x7;
public final static int CALENDAR_UPDATE_WEEK = 0x9;
public final static int CALENDAR_UPDATE_MONTH = 0x10;
public final static int UPDATE_DATA = 0x11;
public final static int CALENDAR_UPDATE_EVENT_LIST = 0x12;

public static final int FIRST_DAY_OF_WEEK = Calendar.MONDAY;

/***************Intent Key********************/

/***************Net Url********************/

/***************Preferences********************/

/******************Net Post/Get Params*****************/

}</span></span>

2.LogUtils

<span style="font-size:14px;">public class LogUtils {</span>

<span style="font-size:14px;">        ／／自己修改Log Id</span>

<span style="font-size:14px;">	public static final String LOG_ID = "Note";

public static final boolean V = Log.VERBOSE >= NoteConfig.MIN_LOG_LEVEL;
public static final boolean D = Log.DEBUG >= NoteConfig.MIN_LOG_LEVEL;
public static final boolean I = Log.INFO >= NoteConfig.MIN_LOG_LEVEL;
public static final boolean W = Log.WARN >= NoteConfig.MIN_LOG_LEVEL;
public static final boolean DW = NoteConfig.DEV_BUILD
&& Log.WARN >= NoteConfig.MIN_LOG_LEVEL;
public static final boolean E = Log.ERROR >= NoteConfig.MIN_LOG_LEVEL;

private LogUtils() {
}

@SuppressWarnings("unused")
private static void log(int priority, String msg, Throwable throwable) {
try {
if (throwable != null)
Log.println(
priority,
LOG_ID,
new StringBuilder()
.append(msg)
.append(", exception:\n\t")
.append((priority >= Log.ERROR || NoteConfig.DEV_BUILD) ? Log
.getStackTraceString(throwable)
: throwable.toString()).toString());
else
Log.println(priority, LOG_ID, new StringBuilder().append(msg)
.toString());

} catch (Exception e) {
Log.e(LOG_ID, "Failed to log: " + e.getMes
e559
sage());
}
}

/**
* Warn the incomplete implemented of methods.
*/
public static void warnIncomplete() {
if (NoteConfig.LOG_LINE_NUMBER) {
StackTraceElement[] sts = Thread.currentThread().getStackTrace();
StackTraceElement st = null;
for (int i = 2; i < sts.length; ++i) {
StackTraceElement tmp = sts[i];
if (!tmp.getClassName().contains("LogUtils")) {
st = tmp;
break;
}
}
if (st != null)
Log.println(
Log.WARN,
LOG_ID,
new StringBuilder().append(st.getFileName())
.append(" line").append(st.getLineNumber())
.append(", ").append(st.getMethodName())
.append("(): incomplete implementation")
.toString());
else
Log.println(Log.WARN, LOG_ID, "incomplete implementation");
} else
Log.println(Log.WARN, LOG_ID, "incomplete implementation");
}

/**
* Output VERBOSE information in log.
*
* @param throwable
* @param format
* @param args
*/
@SuppressWarnings("unused")
public static void v(Throwable throwable, String format, Object... args) {
if (Log.VERBOSE >= NoteConfig.MIN_LOG_LEVEL)
try {
log(Log.VERBOSE, String.format(format, args), throwable);
} catch (Exception e) {
Log.e(LOG_ID, "Failed to v: " + e.getMessage());
}
}

/**
* Output VERBOSE information in log.
*
* @param format
* @param args
*/
public static void v(String format, Object... args) {
v(null, format, args);
}

/**
* Output DEBUG information in log.
*
* @param throwable
* @param format
* @param args
*/
public static void d(Throwable throwable, String format, Object... args) {
if (Log.DEBUG >= NoteConfig.MIN_LOG_LEVEL)
try {
if (args == null || args.length == 0)
log(Log.DEBUG, format, throwable);
else
log(Log.DEBUG, String.format(format, args), throwable);
} catch (Exception e) {
Log.e(LOG_ID, "Failed to d: " + e.getMessage());
}
}

/**
* Output DEBUG information in log.
*
* @param format
* @param args
*/
public static void d(String format, Object... args) {
d(null, format, args);
}

/**
* Output INFO information in log.
*
* @param throwable
* @param format
* @param args
*/
public static void i(Throwable throwable, String format, Object... args) {
if (Log.INFO >= NoteConfig.MIN_LOG_LEVEL)
try {
if (args == null || args.length == 0)
log(Log.INFO, format, throwable);
else
log(Log.INFO, String.format(format, args), throwable);
} catch (Exception e) {
Log.e(LOG_ID, "Failed to i: " + e.getMessage());
}
}

/**
* Output INFO information in log.
*
* @param format
* @param args
*/
public static void i(String format, Object... args) {
i(null, format, args);
}

/**
* Output WARN information in log.
*
* @param throwable
* @param format
* @param args
*/
public static void w(Throwable throwable, String format, Object... args) {
if (Log.WARN >= NoteConfig.MIN_LOG_LEVEL)
try {
if (args == null || args.length == 0)
log(Log.WARN, format, throwable);
else
log(Log.WARN, String.format(format, args), throwable);
} catch (Exception e) {
Log.e(LOG_ID, "Failed to w: " + e.getMessage());
}
}

/**
* Output WARN information in log.
*
* @param format
* @param args
*/
public static void w(String format, Object... args) {
w(null, format, args);
}

/**
* Output ERROR information in log
*
* @param throwable
* @param format
* @param args
*/
public static void e(Throwable throwable, String format, Object... args) {
if (Log.ERROR >= NoteConfig.MIN_LOG_LEVEL)
try {
String msg = format;
if (args != null && args.length > 0)
msg = String.format(format, args);

log(Log.ERROR, msg, throwable);
// if (NoteConfig.DEV_BUILD)
// ViewUtils.showToast(throwable == null ? msg : msg + " : " +
// throwable, Toast.LENGTH_LONG,
// true);

} catch (Exception e) {
Log.e(LOG_ID, "Failed to e: " + e.getMessage());
}
}

/**
* Output ERROR information in log.
*
* @param format
* @param args
*/
public static void e(String format, Object... args) {
e(null, format, args);
}

/**
* Output the assertion that something is true in log.
*
* @param bool
*/
public static void assertTrue(boolean bool) {
if (!bool)
LogUtils.e("Assertion failed");
}

/**
* Out put WARN & DEV_BUILD information in log.
*
* @param throwable
* @param format
* @param args
*/
public static void dw(Throwable throwable, String format, Object... args) {
if (DW)
try {
String msg = format;
if (args != null && args.length > 0)
msg = String.format(format, args);

log(Log.WARN, msg, throwable);

// if (NoteConfig.DEV_BUILD)
// ViewUtils.showToast(throwable == null ? msg : msg + " : " +
// throwable, Toast.LENGTH_LONG,
// true);
} catch (Exception e) {
Log.e(LOG_ID, "Failed to w: " + e.getMessage()); //$NON-NLS-1$
}
}

/**
* Out put WARN & DEV_BUILD information in log.
*
* @param format
* @param args
*/
public static void dw(String format, Object... args) {
dw(null, format, args);
}

/**
* Output in log that a specific feature is not supported.
*
* @param feature
*/
public static void missedFeature(String feature) {
e("%s is not supported in Social SDK", feature);
}
}</span><span style="font-size:18px;">
</span>

3.SystemUtils

<span style="font-size:14px;">public class SystemUtils {

public static String TELE_DEVICE_ID;
public static String ANDROID_ID;
public static String DEVICE_NAME;
public static String VERSION_NAME;
public static String WIFI_MAC;
public static String PHONE_NUMBER;
public static int WIDTH;
public static int HEIGHT;
public static float DENSITY;
public static boolean EXTERNAL_STORAGE_WRITABLE = false;

public static final int NETWORK_TYPE_NULL = 0;
public static final int NETWORK_TYPE_WIFI = 1;
public static final int NETWORK_TYPE_WAP = 2;
public static final int NETWORK_TYPE_NET = 3;

private SystemUtils() {
}

@SuppressWarnings("deprecation")
@SuppressLint("NewApi")
public static void initialize(Context ctx) {
try {
TelephonyManager tm = (TelephonyManager) ctx
.getSystemService(Context.TELEPHONY_SERVICE);
TELE_DEVICE_ID = tm.getDeviceId();
DEVICE_NAME = tm.getSubscriberId();
} catch (Exception e) {
LogUtils.d("Failed to get tele info: " + e);
}

try {
ANDROID_ID = Settings.Secure.getString(ctx.getContentResolver(),
Settings.Secure.ANDROID_ID);
} catch (Exception e) {
LogUtils.w(e, "Failed to get ANDROID_ID");
}

if (LangUtils.isEmpty(ANDROID_ID))
ANDROID_ID = "emulator";

if (DEVICE_NAME == null)
DEVICE_NAME = "";

VERSION_NAME = Build.VERSION.RELEASE;

try {
WindowManager wm = (WindowManager) ctx
.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
if (android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB_MR2) {
WIDTH = display.getWidth();
HEIGHT = display.getHeight();
} else {
Point size = new Point();
display.getSize(size);
WIDTH = size.x;
HEIGHT = size.y;
}
DisplayMetrics metric = new DisplayMetrics();
display.getMetrics(metric);
DENSITY = metric.densityDpi;
} catch (Exception e) {
LogUtils.e(e, "Failed to get display info");
}

try {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
File tmp = new File(Environment.getExternalStorageDirectory(),
"note_tmp");
if (tmp.exists())
tmp.delete();
if (tmp.createNewFile()) {
EXTERNAL_STORAGE_WRITABLE = true;
tmp.delete();
}
}
} catch (Exception e) {
LogUtils.d("Failed to test external storage writable: " + e);
}
try {
WifiManager wifi = (WifiManager) ctx
.getSystemService(Context.WIFI_SERVICE);
WifiInfo info = wifi.getConnectionInfo();
if (info.getMacAddress() != null) {
WIFI_MAC = info.getMacAddress();
} else {
WIFI_MAC = "";
}
} catch (Exception e) {
LogUtils.d("Failed to get WIFI MAC: " + e);
}

try {
TelephonyManager tm = (TelephonyManager) ctx
.getSystemService(Context.TELEPHONY_SERVICE);
if (tm.getLine1Number() != null) {
PHONE_NUMBER = tm.getLine1Number();
} else {
PHONE_NUMBER = "";
}
} catch (Exception e) {
LogUtils.d("Failed to get phone number: " + e);
}

}

/**
* get the ID of android device
*
* @param c
* @return
*/
public static String getDeviceID(Context c) {
String duid = Settings.Secure.getString(c.getContentResolver(),
Settings.Secure.ANDROID_ID);
return LangUtils.isEmpty(duid) ? "emulator" : duid;
}

/**
* get version name
*
* @param c
* @return
*/
public static String getVersionName(Context c) {
if (c == null)
c = NoteManager.getApplicationContext();
if (c == null)
Log.e(Constants.LOG_TAG, "made mistakes when getVersion name");
PackageManager pm = c.getPackageManager();
String versionName = "";
try {
PackageInfo info = pm.getPackageInfo(c.getPackageName(), 0);
versionName = info.versionName;
} catch (NameNotFoundException e) {
e.printStackTrace();
}
return versionName;
}

/**
* get the type of network
*
* @return
*/
public static int getNetWorkType() {
Context con = NoteManager.getApplicationContext();
ConnectivityManager conn = (ConnectivityManager) con
.getSystemService(Context.CONNECTIVITY_SERVICE);
if (conn == null)
return NETWORK_TYPE_NULL;
NetworkInfo info = conn.getActiveNetworkInfo();
if (info == null)
return NETWORK_TYPE_NULL;
String type = info.getTypeName();
if ("wifi".equals(type) || "WIFI".equals(type))
return NETWORK_TYPE_WIFI;
else if ("mobile".equals(type) || "MOBILE".equals(type)) {
String apn = info.getExtraInfo();
if (apn.contains("wap") && apn != null)
return NETWORK_TYPE_WAP;
else
return NETWORK_TYPE_NET;
}
return NETWORK_TYPE_NULL;
}
}</span>

4.ViewUtils

<span style="font-size:14px;">public class ViewUtils {

private static BaseHandler mHandler;
private static boolean initialized = false;
private static WeakReference<Thread> thread_ref;

private static Typeface lightTypeface, boldTypeface;

private ViewUtils() {
}

public static void initialize() {
if (!initialized) {
mHandler = new BaseHandler();
thread_ref = new WeakReference<Thread>(Thread.currentThread());
lightTypeface = Typeface.DEFAULT;
boldTypeface = Typeface.DEFAULT_BOLD;
initialized = true;
}
}

/**
* Get roboto-light typeface
*/
public static Typeface getLightTypeface() {
return lightTypeface;
}

/**
* Get roboto-medium typeface
*/
public static Typeface getBoldTypeface() {
return boldTypeface;
}

/**
* Post a command in handler thread.
*
* @param r
*/
public static void post(Runnable r) {
if (mHandler != null)
mHandler.post(r);
}

/**
* run in main thread
*
* @param r
*/
public static void runInMainThread(Runnable r) {
if (mHandler != null)
mHandler.runInMainThread(r);
}

public static void removeRunnable(Runnable r) {
if (mHandler != null)
mHandler.removeCallbacks(r);
}

/**
* judge if now in MainThreadd or not
*
* @return
*/
public static boolean isInMainThread() {
if (!initialized)
return true;
else if (thread_ref != null) {
return thread_ref.get() == Thread.currentThread();
}
return false;
}

/**
* remove view from its parent
*
* @param o
*/
private static void removeFromSuperView(Object o) {
if (o == null)
return;
if (o instanceof View) {
View view = (View) o;
final ViewParent parent = ((View) o).getParent();
if (parent == null)
return;
if (parent instanceof ViewGroup)
((ViewGroup) parent).removeView(view);
else
Log.e(Constants.LOG_TAG, String.format(
"the parent of view %s is not a viewgroup: %s", view,
parent));
} else if (o instanceof Dialog) {
((Dialog) o).hide();
}
}

/**
* add view to parent
*
* @param parent
* @param view
*/
public static void addView(ViewGroup parent, View view) {
addView(parent, view, false);
}

private static void addView(ViewGroup parent, View view, boolean force) {
if (parent == null || view == null)
return;
try {
if (view.getParent() == null) {
parent.addView(view);
}
if (force) {
if (view.getParent() != parent) {
removeFromSuperView(view);
parent.addView(view);
}
}
} catch (Exception e) {
Log.e(Constants.LOG_TAG,
String.format(
"Failed to addView, parent %s, view %s, force %b, layoutParams %s",
parent, view, force, view.getLayoutParams()));
}
}

/**
* convert dp to pixels
*
* @param dp
* @return
*/

public static int dp2pix(float dp) {
return dp2pix(NoteManager.getApplicationContext(), dp);
}

private static int dp2pix(Context c, float dp) {
if (c == null) {
c = NoteManager.getApplicationContext();
}
if (c == null) {
Log.e(Constants.LOG_TAG, "context is null for dp2pix");
return (int) dp;
}
return (int) (dp > 0 ? (c.getResources().getDisplayMetrics().density
* dp + 0.5f) : dp);
}

/**
* convert drwable to bitmap
*
* @param d
* @return
*/
public static Bitmap drawable2Bitmap(Drawable d) {
int height = d.getIntrinsicHeight();
int width = d.getIntrinsicWidth();
Bitmap bitmap = null;
try {
bitmap = Bitmap.createBitmap(width, height,
d.getOpacity() == PixelFormat.OPAQUE ? Config.ARGB_8888
: Config.RGB_565);
Canvas canvas = new Canvas(bitmap);
d.setBounds(0, 0, width, height);
d.draw(canvas);
} catch (IllegalArgumentException e) {
Log.e(Constants.LOG_TAG, String.format(
"to bitmap error w = %d h = %d", width, height));
return null;
}
return bitmap;
}

public static void showSoftKeyBoard(EditText et) {
try {
et.requestFocusFromTouch();
((InputMethodManager) et.getContext().getSystemService(
Context.INPUT_METHOD_SERVICE)).showSoftInput(et, 0);
} catch (Exception e) {
Log.e(Constants.LOG_TAG, "Failed to show soft keyboard");
}
}

public static void hideSoftKeyboard(Activity activity) {
InputMethodManager imm = (InputMethodManager) activity
.getSystemService(Context.INPUT_METHOD_SERVICE);
if (null != imm && imm.isActive()) {
View view = activity.getCurrentFocus();
if (null != view) {
imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
}
}
}

@SuppressWarnings("unchecked")
public static <T> T find(Activity a, int id) {
return (T) a.findViewById(id);
}

@SuppressWarnings("unchecked")
public static <T> T find(View v, int id) {
return (T) v.findViewById(id);
}

/**
* every Parent View can set only one time
*
* @param view
*/
public static void extendTouchArea(final View view) {
if (view == null)
return;
View parent = (View) view.getParent();
parent.post(new Runnable() {

@Override
public void run() {
Rect delegete = new Rect();
view.getHitRect(delegete);
delegete.bottom += 50;
delegete.top -= 50;
delegete.left -= 100;
delegete.right += 100;
TouchDelegate t = new TouchDelegate(delegete, view);
if (View.class.isInstance(view.getParent())) {
((View) view.getParent()).setTouchDelegate(t);
}
}
});
}

/**
* get color
*
* @param r
* @param g
* @param b
* @return
*/
public static int int2Color(int r, int g, int b) {
int R = Math.round(255 * r);
int G = Math.round(255 * g);
int B = Math.round(255 * b);

R = (R << 16) & 0x00FF0000;
G = (G << 8) & 0x0000FF00;
B = B & 0x000000FF;

return 0xFF000000 | R | G | B;
}

/**
* get picture by string
*
* @param s
* @return
*/
public static Drawable getDrawableByString(String s) {
Context ctx = NoteManager.getApplicationContext();
Resources res = ctx.getResources();
int resID = res.getIdentifier(s, "drawable", ctx.getPackageName());
try {
return ctx.getResources().getDrawable(resID);
} catch (NotFoundException e) {
return null;
}
}
}
</span>

5.WebUtils

<span style="font-size:14px;">public class WebUtils {
private WebUtils() {
}

public static boolean isNetWorkConnected(Context context) {
if (context != null) {
@SuppressWarnings("static-access")
ConnectivityManager mConnectivityManager = (ConnectivityManager) context
.getSystemService(context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = mConnectivityManager
.getActiveNetworkInfo();
if (networkInfo != null)
return networkInfo.isAvailable();
}
return false;
}

/**
* parse String to JSONObject
*
* @param str
* @return
*/
public static JSONObject parseJsonObject(String json) {
if (isEmpty(json)) {
return null;
}
try {
return new JSONObject(json);
} catch (Exception e) {
w(e, "Failed to parseJsonObject, %s", json);
return null;
}
}

/**
* parse String to JSONArray
*
* @param str
* @return
*/
public static JSONArray parseJsonArray(String json) {
if (isEmpty(json)) {
return null;
}
try {
return new JSONArray(json);
} catch (JSONException e) {
w(e, "Failed to parseJsonArray, %s", json);
return null;
}
}

public static ArrayList<?> jsonToArrayString(JSONArray array) {

try {
ArrayList<Object> ret = new ArrayList<Object>(array.length());
for (int i = 0; i < array.length(); i++) {
Object v = array.get(i);
if (v instanceof JSONArray) {
v = jsonToArrayString((JSONArray) v);
} else if (v instanceof JSONObject) {
v = jsonToMap((JSONObject) v);
}
ret.add(v);
}

return ret;
} catch (Exception e) {
e.printStackTrace();
}

return null;
}

/**
* Get Boolean from a JSON object.
*
* @param json
* @param key
* @return Boolean
*/
public static Boolean getJsonBoolean(JSONObject json, String key) {
return getJsonBoolean(json, key, false);
}

/**
* Get Boolean from a JSON object.
*
* @param json
* @param key
* @param defaultValue
* @return Boolean
*/
public static Boolean getJsonBoolean(JSONObject json, String key,
Boolean defaultValue) {
if (json == null)
return defaultValue;
try {
if (json.has(key)) {
Boolean value = json.getBoolean(key);
return value == null ? defaultValue : value;
}
} catch (JSONException e) {
e(e, "Failed to getJsonBoolean %s", key);
}

return defaultValue;
}

/**
* Get String from a JSON object.
*
* @param json
* @param key
* @return String
*/

public static String getJsonString(JSONObject json, String key) {
return getJsonString(json, key, null);
}

/**
* Get String from a JSON object.
*
* @param json
* @param key
* @param defaultValue
* @return String
*/

public static String getJsonString(JSONObject json, String key,
String defaultValue) {
if (json == null)
return defaultValue;
try {
if (json.has(key)) {
String value = json.getString(key);
return value == null ? defaultValue : value;
}
} catch (JSONException e) {
e(e, "Failed to getJsonString %s", key);
}

return defaultValue;
}

/**
* Get int from a JSON object.
*
* @param json
* @param key
* @return int
*/
public static int getJsonInt(JSONObject json, String key) {
return getJsonInt(json, key, -1);
}

/**
* Get int from a JSON object.
*
* @param json
* @param key
* @param defaultValue
* @return int
*/
public static int getJsonInt(JSONObject json, String key, int defaultValue) {
if (json == null)
return defaultValue;
if (json.has(key)) {
try {
int value = json.getInt(key);
return value;
} catch (JSONException e) {
e(e, "Failed to getJsonInt %s", key);
}
}

return defaultValue;
}

/**
* get float from json
*
* @param json
* @param key
* @param defaultValue
* @return
*/
public static double getJsonDouble(JSONObject json, String key,
double defaultValue) {
if (json == null)
return defaultValue;
if (json.has(key)) {
try {
double value = json.getDouble(key);
return value;
} catch (JSONException e) {
e(e, "Failed to getJsonInt %s", key);
}
}

return defaultValue;
}

/**
*
* @param json
* @param key
* @param defaultValue
* @return
*/
public static double getJsonFloat(JSONObject json, String key,
float defaultValue) {
if (json == null)
return defaultValue;
if (json.has(key)) {
try {
double value = json.getDouble(key);
return value;
} catch (JSONException e) {
e(e, "Failed to getJsonInt %s", key);
}
}

return defaultValue;
}

/**
* Get int from a JSON object.
*
* @param json
* @param key
* @param defaultValue
* @return int
*/
public static long getJsonLong(JSONObject json, String key,
Long defaultValue) {
if (json == null)
return defaultValue;
if (json.has(key)) {
try {
long value = json.getLong(key);
return value;
} catch (JSONException e) {
e(e, "Failed to getJsonInt %s", key);
}
}

return defaultValue;
}

/**
* get String from a JSONArray
*
* @param array
* @param index
* @return
*/
public static String getJsonString(JSONArray array, int index) {
return getJsonString(array, index, null);
}

public static String getJsonString(JSONArray array, int index,
String defaultValue) {
if (array == null)
return defaultValue;
try {
return array.getString(index);
} catch (JSONException e) {
e(e, "Failed to getJsonString %d, %d", array.length(), index);
}
return defaultValue;
}

/**
* Get int from a JSONArray.
*
* @param array
* @param index
* @return int
*/
public static int getJsonInt(JSONArray array, int index) {
return getJsonInt(array, index, -1);
}

/**
* Get int from a JSONArray.
*
* @param array
* @param index
* @param defaultValue
* @return int
*/
public static int getJsonInt(JSONArray array, int index, int defaultValue) {
if (array == null)
return defaultValue;
try {
return array.getInt(index);
} catch (JSONException e) {
e(e, "Failed to get JsonInt %d, %d", array.length(), index);
}

return defaultValue;
}

/**
* Get long from a JSONArray.
*
* @param array
* @param index
* @param defaultValue
* @return long
*/
public static long getJsonLong(JSONArray array, int index, long defaultValue) {
if (array == null)
return defaultValue;
try {
return array.getLong(index);
} catch (JSONException e) {
e(e, "Failed to get JsonInt %d, %d", array.length(), index);
}

return defaultValue;
}

}
</span>

以上工具类已经可以满足大多数android应用了，一般来说工具类中的每一个方法都需要深入研究一下，光会用肯定是不行的，你得了解其中的每个方法原理是怎么样的，在工作中不要总问别人或者百度找论坛解决，你得学着“Read the fucking source code”,不会阅读源码，就很难接近真相。
下次博客会挑取其中的某个知识点分析下，大家如果有什么见解或疑惑，欢迎留言，谢谢。