Android实用代码大全

1、 精确获取屏幕尺寸（例如：3.5、4.0、5.0寸屏幕）

public static double getScreenPhysicalSize(Activity ctx) {

DisplayMetrics dm = new DisplayMetrics();

ctx.getWindowManager().getDefaultDisplay().getMetrics(dm);

double diagonalPixels = Math.sqrt(Math.pow(dm.widthPixels, 2) + Math.pow(dm.heightPixels, 2));

return diagonalPixels / (160 * dm.density);

}

一般是7寸以上是平板

2、 判断是否是平板（官方用法）

public static boolean isTablet(Context context) {

return (context.getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_LARGE;

}

3、 文字根据状态更改颜色 android:textColor

<selector xmlns:android="http://schemas.android.com/apk/res/android">

<item android:color="#53c1bd" android:state_selected="true"/>

<item android:color="#53c1bd" android:state_focused="true"/>

<item android:color="#53c1bd" android:state_pressed="true"/>

<item android:color="#777777"/>

</selector>

放在res/color/目录下

4、背景色根据状态更改颜色 android:backgroup

<selector xmlns:android="http://schemas.android.com/apk/res/android">

<item android:state_selected="true"><shape>
<gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59f" />

</shape></item>

<item android:state_focused="true"><shape>

<gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59f" />

</shape></item>

<item android:state_pressed="true"><shape>

<gradient android:angle="0" android:centerColor="#00a59f" android:endColor="#00a59f" android:startColor="#00a59f" />

</shape></item>

<item><shape>

<gradient android:angle="0" android:centerColor="#00ff00" android:endColor="00ff00" android:startColor="00ff00" />

</shape></item>

</selector>

如果直接给背景色color会报错。

5、 启动APK的默认Activity

public static void startApkActivity(final Context ctx, String packageName) {

PackageManager pm = ctx.getPackageManager();

PackageInfo pi;

try {

pi = pm.getPackageInfo(packageName, 0);

Intent intent = new Intent(Intent.ACTION_MAIN, null);

intent.addCategory(Intent.CATEGORY_LAUNCHER);

intent.setPackage(pi.packageName);

List<ResolveInfo> apps = pm.queryIntentActivities(intent, 0);

ResolveInfo ri = apps.iterator().next();

if (ri != null) {

String className = ri.activityInfo.name;

intent.setComponent(new ComponentName(packageName, className));

ctx.startActivity(intent);

}

} catch (NameNotFoundException e) {

Log.e("startActivity", e);

}

}

6、计算字宽

public static float GetTextWidth(String text, float Size) {

TextPaint FontPaint = new TextPaint();

FontPaint.setTextSize(Size);

return FontPaint.measureText(text);

}

注意如果设置了textStyle，还需要进一步设置TextPaint。

7、获取应用程序下所有Activity

public static ArrayList<String> getActivities(Context ctx) {

ArrayList<String> result = new ArrayList<String>();

Intent intent = new Intent(Intent.ACTION_MAIN, null);

intent.setPackage(ctx.getPackageName());

for (ResolveInfo info : ctx.getPackageManager().queryIntentActivities(intent, 0)) {

result.add(info.activityInfo.name);

}

return result;

}

8、检测字符串中是否包含汉字

public static boolean checkChinese(String sequence) {

final String format = "[\\u4E00-\\u9FA5\\uF900-\\uFA2D]";

boolean result = false;

Pattern pattern = Pattern.compile(format);

Matcher matcher = pattern.matcher(sequence);

result = matcher.find();

return result;

}

9、检测字符串中只能包含：中文、数字、下划线(_)、横线(-)

public static boolean checkNickname(String sequence) {

final String format = "[^\\u4E00-\\u9FA5\\uF900-\\uFA2D\\w-_]";

Pattern pattern = Pattern.compile(format);

Matcher matcher = pattern.matcher(sequence);

return !matcher.find();

}

10、检查有没有应用程序来接受处理你发出的intent

public static boolean isIntentAvailable(Context context, String action) {
final PackageManager packageManager = context.getPackageManager();
final Intent intent = new Intent(action);
List<ResolveInfo> list = packageManager.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY);
return list.size() > 0;
}

11、使用TransitionDrawable实现图片显示的时候有渐变效果

private void setImageBitmap(ImageView imageView, Bitmap bitmap) {

// Use TransitionDrawable to fade in.

final TransitionDrawable td = new TransitionDrawable(new Drawable[] { new ColorDrawable(android.R.color.transparent), new BitmapDrawable(mContext.getResources(), bitmap) });

//noinspection deprecation

imageView.setBackgroundDrawable(imageView.getDrawable());

imageView.setImageDrawable(td);

td.startTransition(200);

}

比使用AlphaAnimation效果要好，可避免出现闪烁问题。

12、 扫描指定的文件

sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri));

用途：从本软件新增、修改、删除图片、文件某一个文件（音频、视频）需要更新系统媒体库时使用，不必扫描整个SD卡。

13、Dip转px

public static int dipToPX(final Context ctx, float dip) {

return (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dip, ctx.getResources().getDisplayMetrics());

}

用途：难免在Activity代码中设置位置、大小等，本方法就很有用了！

14、获取已经安装APK（列表）的路径

PackageManager pm = getPackageManager();

for (ApplicationInfo app : pm.getInstalledApplications(0)) {

Log.d("PackageList", "package: " + app.packageName + ", sourceDir: " + app.sourceDir);

}

输出：

package: com.tmobile.thememanager, sourceDir: /system/app/ThemeManager.apk

package: com.touchtype.swiftkey, sourceDir: /data/app/com.touchtype.swiftkey-1.apk

15、 多进程Preferences数据共享

public static void putStringProcess(Context ctx, String key, String value) {

SharedPreferences sharedPreferences = ctx.getSharedPreferences("preference_mu", Context.MODE_MULTI_PROCESS);

Editor editor = sharedPreferences.edit();

editor.putString(key, value);

editor.commit();

}

public static String getStringProcess(Context ctx, String key, String defValue) {

SharedPreferences sharedPreferences = ctx.getSharedPreferences("preference_mu", Context.MODE_MULTI_PROCESS);

return sharedPreferences.getString(key, defValue);

}

16、泛型ArrayList转数组

@SuppressWarnings("unchecked")

public static <T> T[] toArray(Class<?> cls, ArrayList<T> items) {

if (items == null || items.size() == 0) {

return (T[]) Array.newInstance(cls, 0);

}

return items.toArray((T[]) Array.newInstance(cls, items.size()));

}

17、 保存恢复ListView当前位置

private void saveCurrentPosition() {

if (mListView != null) {

int position = mListView.getFirstVisiblePosition();

View v = mListView.getChildAt(0);

int top = (v == null) ? 0 : v.getTop();

//保存position和top

}

}

private void restorePosition() {

if (mFolder != null && mListView != null) {

int position = 0;//取出保存的数据

int top = 0;//取出保存的数据

mListView.setSelectionFromTop(position, top);

}

}

18、调用 便携式热点和数据共享 设置

public static Intent getHotspotSetting() {

Intent intent = new Intent();

intent.setAction(Intent.ACTION_MAIN);

ComponentName com = new ComponentName("com.android.settings", "com.android.settings.TetherSettings");

intent.setComponent(com);

return intent;

}

19、 格式化输出IP地址

public static String getIp(Context ctx) {

return Formatter.formatIpAddress((WifiManager) ctx.getSystemService(Context.WIFI_SERVICE).getConnectionInfo().getIpAddress());

}

20、 ip地址转成8位十六进制串

/** ip转16进制 */

public static String ipToHex(String ips) {

StringBuffer result = new StringBuffer();

if (ips != null) {

StringTokenizer st = new StringTokenizer(ips, ".");

while (st.hasMoreTokens()) {

String token = Integer.toHexString(Integer.parseInt(st.nextToken()));

if (token.length() == 1)

token = "0" + token;

result.append(token);

}

}

return result.toString();

}

/** 16进制转ip */

public static String texToIp(String ips) {

try {

StringBuffer result = new StringBuffer();

if (ips != null && ips.length() == 8) {

for (int i = 0; i < 8; i += 2) {

if (i != 0)

result.append('.');

result.append(Integer.parseInt(ips.substring(i, i + 2), 16));

}

}

return result.toString();

} catch (NumberFormatException ex) {

Logger.e(ex);

}

return "";

}

ip:192.168.68.128 16 =>hex :c0a84480

21、 文件夹排序（先文件夹排序，后文件排序）

public static void sortFiles(File[] files) {

Arrays.sort(files, new Comparator<File>() {

@Override

public int compare(File lhs, File rhs) {

//返回负数表示o1 小于o2，返回0 表示o1和o2相等，返回正数表示o1大于o2。

boolean l1 = lhs.isDirectory();

boolean l2 = rhs.isDirectory();

if (l1 && !l2)

return -1;

else if (!l1 && l2)

return 1;

else {

return lhs.getName().compareTo(rhs.getName());

}

}

});

}

22、代码设置TextView的样式

使用过自定义Dialog可能马上会想到用如下代码：

new TextView(this,null,R.style.text_style);

但你运行这代码你会发现毫无作用！正确用法：

new TextView(new ContextThemeWrapper(this, R.style.text_style))

23、获取网络类型名称

public static String getNetworkTypeName(Context context) {

if (context != null) {

ConnectivityManager connectMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

if (connectMgr != null) {

NetworkInfo info = connectMgr.getActiveNetworkInfo();

if (info != null) {

switch (info.getType()) {

case ConnectivityManager.TYPE_WIFI:

return "WIFI";

case ConnectivityManager.TYPE_MOBILE:

return getNetworkTypeName(info.getSubtype());

}

}

}

}

return getNetworkTypeName(TelephonyManager.NETWORK_TYPE_UNKNOWN);

}

public static String getNetworkTypeName(int type) {

switch (type) {

case TelephonyManager.NETWORK_TYPE_GPRS:

return "GPRS";

case TelephonyManager.NETWORK_TYPE_EDGE:

return "EDGE";

case TelephonyManager.NETWORK_TYPE_UMTS:

return "UMTS";

case TelephonyManager.NETWORK_TYPE_HSDPA:

return "HSDPA";

case TelephonyManager.NETWORK_TYPE_HSUPA:

return "HSUPA";

case TelephonyManager.NETWORK_TYPE_HSPA:

return "HSPA";

case TelephonyManager.NETWORK_TYPE_CDMA:

return "CDMA";

case TelephonyManager.NETWORK_TYPE_EVDO_0:

return "CDMA - EvDo rev. 0";

case TelephonyManager.NETWORK_TYPE_EVDO_A:

return "CDMA - EvDo rev. A";

case TelephonyManager.NETWORK_TYPE_EVDO_B:

return "CDMA - EvDo rev. B";

case TelephonyManager.NETWORK_TYPE_1xRTT:

return "CDMA - 1xRTT";

case TelephonyManager.NETWORK_TYPE_LTE:

return "LTE";

case TelephonyManager.NETWORK_TYPE_EHRPD:

return "CDMA - eHRPD";

case TelephonyManager.NETWORK_TYPE_IDEN:

return "iDEN";

case TelephonyManager.NETWORK_TYPE_HSPAP:

return "HSPA+";

default:

return "UNKNOWN";

}

}

24、Android解压Zip包

/**

* 解压一个压缩文档 到指定位置

*

* @param zipFileString 压缩包的名字

* @param outPathString 指定的路径

* @throws Exception

*/

public static void UnZipFolder(String zipFileString, String outPathString) throws Exception {

java.util.zip.ZipInputStream inZip = new java.util.zip.ZipInputStream(new java.io.FileInputStream(zipFileString));

java.util.zip.ZipEntry zipEntry;

String szName = "";

while ((zipEntry = inZip.getNextEntry()) != null) {

szName = zipEntry.getName();

if (zipEntry.isDirectory()) {

// get the folder name of the widget

szName = szName.substring(0, szName.length() - 1);

java.io.File folder = new java.io.File(outPathString + java.io.File.separator + szName);

folder.mkdirs();

} else {

java.io.File file = new java.io.File(outPathString + java.io.File.separator + szName);

file.createNewFile();

// get the output stream of the file

java.io.FileOutputStream out = new java.io.FileOutputStream(file);

int len;

byte[] buffer = new byte[1024];

// read (len) bytes into buffer

while ((len = inZip.read(buffer)) != -1) {

// write (len) byte from buffer at the position 0

out.write(buffer, 0, len);

out.flush();

}

out.close();

}

}//end of while

inZip.close();

}//end of func

25、 从assets中读取文本和图片资源

/** 从assets 文件夹中读取文本数据 */

public static String getTextFromAssets(final Context context, String fileName) {

String result = "";

try {

InputStream in = context.getResources().getAssets().open(fileName);

// 获取文件的字节数

int lenght = in.available();

// 创建byte数组

byte[] buffer = new byte[lenght];

// 将文件中的数据读到byte数组中

in.read(buffer);

result = EncodingUtils.getString(buffer, "UTF-8");

in.close();

} catch (Exception e) {

e.printStackTrace();

}

return result;

}

/** 从assets 文件夹中读取图片 */

public static Drawable loadImageFromAsserts(final Context ctx, String fileName) {

try {

InputStream is = ctx.getResources().getAssets().open(fileName);

return Drawable.createFromStream(is, null);

} catch (IOException e) {

if (e != null) {

e.printStackTrace();

}

} catch (OutOfMemoryError e) {

if (e != null) {

e.printStackTrace();

}

} catch (Exception e) {

if (e != null) {

e.printStackTrace();

}

}

return null;

}

26、展开、收起状态栏

public static final void collapseStatusBar(Context ctx) {

Object sbservice = ctx.getSystemService("statusbar");

try {

Class<?> statusBarManager = Class.forName("android.app.StatusBarManager");

Method collapse;

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {

collapse = statusBarManager.getMethod("collapsePanels");

} else {

collapse = statusBarManager.getMethod("collapse");

}

collapse.invoke(sbservice);

} catch (Exception e) {

e.printStackTrace();

}

}

public static final void expandStatusBar(Context ctx) {

Object sbservice = ctx.getSystemService("statusbar");

try {

Class<?> statusBarManager = Class.forName("android.app.StatusBarManager");

Method expand;

if (Build.VERSION.SDK_INT >= 17) {

expand = statusBarManager.getMethod("expandNotificationsPanel");

} else {

expand = statusBarManager.getMethod("expand");

}

expand.invoke(sbservice);

} catch (Exception e) {

e.printStackTrace();

}

}

用途：可用于点击Notifacation之后收起状态栏

27、 获取状态栏高度

public static int getStatusBarHeight(Context context){

Class<?> c = null;

Object obj = null;

Field field = null;

int x = 0, statusBarHeight = 0;

try {

c = Class.forName("com.android.internal.R$dimen");

obj = c.newInstance();

field = c.getField("status_bar_height");

x = Integer.parseInt(field.get(obj).toString());

statusBarHeight = context.getResources().getDimensionPixelSize(x);

} catch (Exception e1) {

e1.printStackTrace();

}

return statusBarHeight;

}

28、ListView使用ViewHolder极简写法

public static <T extends View> T getAdapterView(View convertView, int id) {

SparseArray<View> viewHolder = (SparseArray<View>) convertView.getTag();

if (viewHolder == null) {

viewHolder = new SparseArray<View>();

convertView.setTag(viewHolder);

}

View childView = viewHolder.get(id);

if (childView == null) {

childView = convertView.findViewById(id);

viewHolder.put(id, childView);

}

return (T) childView;

}

用法：

@Override

public View getView(int position, View convertView, ViewGroup parent) {

if (convertView == null) {

convertView = LayoutInflater.from(getActivity()).inflate(R.layout.fragment_feed_item, parent, false);

}

ImageView thumnailView = getAdapterView(convertView, R.id.video_thumbnail);

ImageView avatarView = getAdapterView(convertView, R.id.user_avatar);

ImageView appIconView = getAdapterView(convertView, R.id.app_icon);
}

用起来非常简练，将ViewHolder隐于无形。

29、 设置Activity透明

<style name="TransparentActivity" parent="AppBaseTheme">

<item name="android:windowBackground">@android:color/transparent</item>

<item name="android:colorBackgroundCacheHint">@null</item>

<item name="android:windowIsTranslucent">true</item>

<item name="android:windowNoTitle">true</item>

<item name="android:windowContentOverlay">@null</item>

</style>

说明：AppBaseTheme一般是你application指定的android:theme是啥这里就是啥，否则Activity内部的空间风格可能不一致。

用途：用于模拟Dialog效果，比如再Service中没法用Dialog，就可以用Activity来模拟

30、 代码切换全屏

//切换到全屏

getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);

getActivity().getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

//切换到非全屏

getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

getWindow().addFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);

注意：切换到全屏时，底部的虚拟按键仍然是显示的。次方法可多次调用用于切换

用途：播放器界面经常会用到

转自：农民伯伯