Android 开发中的一些小技巧
dip转px
public int convertDipOrPx(int dip) {
float scale = MarketApplication.getMarketApplicationContext()
.getResources().getDisplayMetrics().density;
return (int) (dip * scale + 0.5f * (dip >= 0 ? 1 : -1));
}
获取当前窗体,并添加自定义view:
getWindowManager()
.addView(
overlay,
new WindowManager.LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT,
WindowManager.LayoutParams.TYPE_APPLICATION,
WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
| WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE,
PixelFormat.TRANSLUCENT));
自定义fastScrollBar图片样式：
try {
Field f = AbsListView.class.getDeclaredField("mFastScroller");
f.setAccessible(true);
Object o = f.get(listView);
f = f.getType().getDeclaredField("mThumbDrawable");
f.setAccessible(true);
Drawable drawable = (Drawable) f.get(o);
drawable = getResources().getDrawable(R.drawable.ic_launcher);
f.set(o, drawable);
Toast.makeText(this, f.getType().getName(), 1000).show();
} catch (Exception e) {
throw new RuntimeException(e);
}
=网络==================================
判断网络是否可用：
/**
* 网络是否可用
*
* @param context
* @return
*/
public static boolean isNetworkAvailable(Context context) {
ConnectivityManager mgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo[] info = mgr.getAllNetworkInfo();
if (info != null) {
for (int i = 0; i < info.length; i++) {
if (info[i].getState() == NetworkInfo.State.CONNECTED) {
return true;
}
}
}
return false;
}
方法二：
/*
* 判断网络连接是否已开 2012-08-20true 已打开 false 未打开
*/
public static boolean isConn(Context context) {
boolean bisConnFlag = false;
ConnectivityManager conManager = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo network = conManager.getActiveNetworkInfo();
if (network != null) {
bisConnFlag = conManager.getActiveNetworkInfo().isAvailable();
}
return bisConnFlag;
}
判断是不是Wifi连接：
public static boolean isWifiActive(Context icontext) {
Context context = icontext.getApplicationContext();
ConnectivityManager connectivity = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo[] info;
if (connectivity != null) {
info = connectivity.getAllNetworkInfo();
if (info != null) {
for (int i = 0; i < info.length; i++) {
if (info[i].getTypeName().equals("WIFI")
&& info[i].isConnected()) {
return true;
}
}
}
}
return false;
}
判断当前网络类型
/**
* 网络方式检查
*/
private static int netCheck(Context context) {
ConnectivityManager conMan = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
State mobile = conMan.getNetworkInfo(ConnectivityManager.TYPE_MOBILE)
.getState();
State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI)
.getState();
if (wifi.equals(State.CONNECTED)) {
return DO_WIFI;
} else if (mobile.equals(State.CONNECTED)) {
return DO_3G;
} else {
return NO_CONNECTION;
}
}
获取下载文件的真实名字
public String getReallyFileName(String url) {
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectDiskReads().detectDiskWrites().detectNetwork() // 这里可以替换为detectAll()
// 就包括了磁盘读写和网络I/O
.penaltyLog() // 打印logcat，当然也可以定位到dropbox，通过文件保存相应的log
.build());
StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder()
.detectLeakedSqlLiteObjects() // 探测SQLite数据库操作
.penaltyLog() // 打印logcat
.penaltyDeath().build());
String filename = "";
URL myURL;
HttpURLConnection conn = null;
if (url == null || url.length() < 1) {
return null;
}
try {
myURL = new URL(url);
conn = (HttpURLConnection) myURL.openConnection();
conn.connect();
conn.getResponseCode();
URL absUrl = conn.getURL();// 获得真实Url
// 打印输出服务器Header信息
// Map<String, List<String>> map = conn.getHeaderFields();
// for (String str : map.keySet()) {
// if (str != null) {
// Log.e("H3c", str + map.get(str));
// }
// }
filename = conn.getHeaderField("Content-Disposition");// 通过Content-Disposition获取文件名，这点跟服务器有关，需要灵活变通
if (filename == null || filename.length() < 1) {
filename = URLDecoder.decode(absUrl.getFile(), "UTF-8");
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (conn != null) {
conn.disconnect();
conn = null;
}
}
return filename;
}
=图片==========================
bitmap转Byte数组(微信分享就需要用到)
public byte[] bmpToByteArray(final Bitmap bmp, final boolean needRecycle) {
ByteArrayOutputStream output = new ByteArrayOutputStream();
bmp.compress(CompressFormat.PNG, 100, output);
if (needRecycle) {
bmp.recycle();
}
byte[] result = output.toByteArray();
try {
output.close();
} catch (Exception e) {
e.printStackTrace();
}
return result;
}Resources转Bitmap
public Bitmap loadBitmap(Resources res, int id) {
BitmapFactory.Options opt = new BitmapFactory.Options();
opt.inPreferredConfig = Bitmap.Config.RGB_565;
opt.inPurgeable = true;
opt.inInputShareable = true;
InputStream is = res.openRawResource(id);// 获取资源图片
return BitmapFactory.decodeStream(is, null, opt);
}保存图片到SD卡
public void saveBitmapToFile(String url, String filePath) {
File iconFile = new File(filePath);
if (!iconFile.getParentFile().exists()) {
iconFile.getParentFile().mkdirs();
}
if (iconFile.exists() && iconFile.length() > 0) {
return;
}
FileOutputStream fos = null;
InputStream is = null;
try {
fos = new FileOutputStream(filePath);
is = new URL(url).openStream();
int data = is.read();
while (data != -1) {
fos.write(data);
data = is.read();
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (is != null) {
is.close();
}
if (fos != null) {
fos.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
=系统==============================
根据包名打开一个应用程序
public boolean openApp(String packageName) {
PackageInfo pi = null;
try {
pi = mPM.getPackageInfo(packageName, 0);
} catch (NameNotFoundException e) {
e.printStackTrace();
return false;
}
if (pi == null) {
return false;
}
Intent resolveIntent = new Intent(Intent.ACTION_MAIN, null);
resolveIntent.addCategory(Intent.CATEGORY_LAUNCHER);
resolveIntent.setPackage(pi.packageName);
List<ResolveInfo> apps = mPM.queryIntentActivities(resolveIntent, 0);
ResolveInfo ri = null;
try {
ri = apps.iterator().next();
} catch (Exception e) {
return true;
}
if (ri != null) {
String tmpPackageName = ri.activityInfo.packageName;
String className = ri.activityInfo.name;
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
ComponentName cn = new ComponentName(tmpPackageName, className);
intent.setComponent(cn);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
MarketApplication.getMarketApplicationContext().startActivity(
intent);
} else {
return false;
}
return true;
}
判断是否APK是否安装过
public boolean checkApkExist(Context context, String packageName) {
if (packageName == null || "".equals(packageName))
return false;
try {
ApplicationInfo info = context.getPackageManager()
.getApplicationInfo(packageName,
PackageManager.GET_UNINSTALLED_PACKAGES);
return true;
} catch (NameNotFoundException e) {
return false;
} catch (NullPointerException e) {
return false;
}
}
安装APK
public void installApk(Context context, String strFileAllName) {
File file = new File(strFileAllName);
Intent intent = new Intent();
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setAction(Intent.ACTION_VIEW);
String type = "application/vnd.android.package-archive";
intent.setDataAndType(Uri.fromFile(file), type);
context.startActivity(intent);
}
卸载APK
public void UninstallApk(Context context, String strPackageName) {
Uri packageURI = Uri.parse("package:" + strPackageName);
Intent uninstallIntent = new Intent(Intent.ACTION_DELETE, packageURI);
context.startActivity(uninstallIntent);
}
判断SD卡是否可用
public boolean CheckSD() {
if (android.os.Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED)) {
return true;
} else {
return false;
}
}
创建快捷方式：
public void createShortCut(Context contxt) {
// if (isInstallShortcut()) {// 如果已经创建了一次就不会再创建了
// return;
// }
Intent sIntent = new Intent(Intent.ACTION_MAIN);
sIntent.addCategory(Intent.CATEGORY_LAUNCHER);// 加入action,和category之后，程序卸载的时候才会主动将该快捷方式也卸载
sIntent.setClass(contxt, Login.class);
Intent installer = new Intent();
installer.putExtra("duplicate", false);
installer.putExtra("android.intent.extra.shortcut.INTENT", sIntent);
installer.putExtra("android.intent.extra.shortcut.NAME", "名字");
installer.putExtra("android.intent.extra.shortcut.ICON_RESOURCE",
Intent.ShortcutIconResource
.fromContext(contxt, R.drawable.icon));
installer.setAction("com.android.launcher.action.INSTALL_SHORTCUT");
contxt.sendBroadcast(installer);
}
判断快捷方式是否创建：
private boolean isInstallShortcut() {
boolean isInstallShortcut = false;
final ContentResolver cr = MarketApplication
.getMarketApplicationContext().getContentResolver();
String AUTHORITY = "com.android.launcher.settings";
Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY
+ "/favorites?notify=true");
Cursor c = cr.query(CONTENT_URI,
new String[] { "title", "iconResource" }, "title=?",
new String[] { "名字" }, null);
if (c != null && c.getCount() > 0) {
isInstallShortcut = true;
}
if (c != null) {
c.close();
}
if (isInstallShortcut) {
return isInstallShortcut;
}
AUTHORITY = "com.android.launcher2.settings";
CONTENT_URI = Uri.parse("content://" + AUTHORITY
+ "/favorites?notify=true");
c = cr.query(CONTENT_URI, new String[] { "title", "iconResource" },
"title=?", new String[] { "名字" }, null);
if (c != null && c.getCount() > 0) {
isInstallShortcut = true;
}
if (c != null) {
c.close();
}
AUTHORITY = "com.baidu.launcher";
CONTENT_URI = Uri.parse("content://" + AUTHORITY
+ "/favorites?notify=true");
c = cr.query(CONTENT_URI, new String[] { "title", "iconResource" },
"title=?", new String[] { "名字" }, null);
if (c != null && c.getCount() > 0) {
isInstallShortcut = true;
}
if (c != null) {
c.close();
}
return isInstallShortcut;
}
过滤特殊字符：
private String StringFilter(String str) throws PatternSyntaxException {
// 只允许字母和数字
// String regEx = "[^a-zA-Z0-9]";
// 清除掉所有特殊字符
String regEx = "[`~!@#$%^&*()+=|{}':;',//[//].<>/?~！@#￥%……&*（）——+|{}【】‘；：”“’。，、？]";
Pattern p = Pattern.compile(regEx);
Matcher m = p.matcher(str);
return m.replaceAll("").trim();
}
执行shell语句：
public int execRootCmdSilent(String cmd) {
int result = -1;
DataOutputStream dos = null;
try {
Process p = Runtime.getRuntime().exec("su");
dos = new DataOutputStream(p.getOutputStream());
dos.writeBytes(cmd + "\n");
dos.flush();
dos.writeBytes("exit\n");
dos.flush();
p.waitFor();
result = p.exitValue();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (dos != null) {
try {
dos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return result;
}
获得文件MD5值：
public String getFileMD5(File file) {
if (!file.isFile()) {
return null;
}
MessageDigest digest = null;
FileInputStream in = null;
byte buffer[] = new byte[1024];
int len;
try {
digest = MessageDigest.getInstance("MD5");
in = new FileInputStream(file);
while ((len = in.read(buffer, 0, 1024)) != -1) {
digest.update(buffer, 0, len);
}
} catch (Exception e) {
e.printStackTrace();
return null;
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
BigInteger bigInt = new BigInteger(1, digest.digest());
return bigInt.toString(16);
}