android开发常用问题总结

android 学习笔记一 全屏显示以及获取屏幕大小

//不显示标题
requestWindowFeature(Window.FEATURE_NO_TITLE);

//设置窗口全屏显示
getWindow().setFlags(WindowManager.LayoutParams. FLAG_FULLSCREEN ,WindowManager.LayoutParams.FLAG_FULLSCREEN);

判断国家

String locale = context.getResources().getConfiguration().locale.getCountry();

String locale = context.getResources().getConfiguration().locale.getDisplayCountry();

TelephonyManager tm = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);
String countryCode = tm.getSimCountryIso();

关闭输入法

InputMethodManager inputMethodManager = (InputMethodManager)getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
inputMethodManager.hideSoftInputFromWindow(etEditText.getWindowToken(), 0);

设置输入格式过滤器

EditText::setInputType(InputType.TYPE_NULL); // 表示不显示输入法

//取得屏幕信息
DisplayMetrics dm = new DisplayMetrics();
dm = this.getResources().getDisplayMetrics();
//获得屏幕宽度
int screenWidth = dm.widthPixels;
//获得屏幕高度
int screenHeight = dm.heightPixels;

获取状态栏高度：

decorView是window中的最顶层view，可以从window中获取到decorView，然后decorView有个getWindowVisibleDisplayFrame方法可以获取到程序显示的区域，包括标题栏，但不包括状态栏。

Rectframe=newRect();

getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);

intstatusBarHeight=frame.top;

获取标题栏高度：

getWindow().findViewById(Window.ID_ANDROID_CONTENT)这个方法获取到的view就是程序不包括标题栏的部分，然后就可以知道标题栏的高度了。

intcontentTop=getWindow().findViewById(Window.ID_ANDROID_CONTENT).getTop();

//statusBarHeight是上面所求的状态栏的高度

inttitleBarHeight=contentTop-statusBarHeight;

intcontentTop=getWindow().findViewById(Window.ID_ANDROID_CONTENT).getTop();

//statusBarHeight是上面所求的状态栏的高度

inttitleBarHeight=contentTop-statusBarHeight;

屏幕方向更改

屏幕方向是横排(PORTRAIT)刚将屏幕方向更改为竖排(LANDSCAPE), 运用了getRequestedOrientation(),和setRequestedorientation()两个方法. 但是要利用这两个方法必须先在AndroidManiefst.xml设置一下屏幕方属性，不然程序将不能正常的工作.

//如果是竖排,则改为横排

if(getRequestedOrientation() == ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE) {

　　setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

}

//如果是横排,则改为竖排

else if(getRequestedOrientation() == ActivityInfo.SCREEN_ORIENTATION_PORTRAIT) {

　　setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

}

在AndroidManifest.xml文件里设置默认方向

< activity android:name=".XXXActivity"

　　android:label="@string/app_name"

　　android:screenOrientation="portrait" >

android 特殊符号的显示
在android values 的String中，如果想让特殊符号正常的显示，需要转义,通常一般字符都可以用 / 来转义例如 ' /' " /"
现在简单说说最常用的几个字符的其他转义
单引号 ' &apos;
双引号 " &quot;
> &gt;
< &lt;
& &amp;

Context Menu和Options Menu菜单的区别

1. ContextMenu–显示一个Activity中特定View的信息。在Android中，通过按下并Hold一段时间来激活上下文菜单。

2. OptionsMenu–显示当前Activity的信息。在Android中，通过按下MENU键来激活选项菜单。

3. OptionsMenu需要重写两个方法——onCreateOptionsMenu()和onOptionsItemSelected()。onCreateOptionsMenu()方法在MENU按钮被按下时调用。当一个菜单项被选中时，onOptionsItemSelected()方法会被调用。ContextMenu需要重写onCreateContextMenu()和onContextItemSelected()方法。在创建ContextMenu是调用onCreateContextMenu()，当选项被选中时调用onContextItemSelected()。

Android平台显示单位px和dip以及sp的区别

px (pixels)像素 -- 屏幕上的点, 一般我们HVGA代表320x480像素，这个用的比较多

dip或dp (device independent pixels)设备独立像素 -- 这个和设备硬件有关（与密度无关的像素），一般我们为了支持WVGA、HVGA和QVGA cwj推荐使用这个，不依赖像素, 一种基于屏幕密度的抽象单位。在每英寸160点的显示器上，1dp=1px。在大于160点的显示器上可能增大

sp (scaled pixels — best for text size)放大像素-- 主要处理字体的大小, （与刻度无关的像素）, 与dp类似，但是可以根据用户的字体大小首选项进行缩放

下面的几个是不常用的:

in（英寸）：长度单位。

mm（毫米）：长度单位

pt（磅）：1/72英寸

如何通过handler来更新线程

最常见的例子就是我们在更新UI时，由于AndroidUI操作并不是线程安全的并且这些操作必须在UI线程中执行。所以我们需要使用利用Handler来实现UI线程的更新的。（当然Handler的用处也不仅限于此）。下面是代码片段

1. //处理消息
2. HandlermyHandler=newHandler(){
3. publicvoidhandleMessage(Messagemsg){
4. switch(msg.what){
5. case100:
6. //更新线程
7. break;
8. }
9. super.handleMessage(msg);
10. }
11. };
12. //发送消息
13. Messagemessage=newMessage();
14. message.what=100;
15. myHandler.sendMessage(message);

以下源自：http://blog.csdn.net/mingxunzh/archive/2009/10/29/4745634.aspx

显示网页

Uriuri=Uri.parse("http://google.com");

Intentit=newIntent(Intent.ACTION_VIEW,uri);

startActivity(it);

显示地图
Uri uri = Uri.parse("geo:38.899533,-77.036476");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//其他 geo URI 範例
//geo:latitude,longitude
//geo:latitude,longitude?z=zoom
//geo:0,0?q=my+street+address
//geo:0,0?q=business+near+city
//google.streetview:cbll=lat,lng&cbp=1,yaw,,pitch,zoom&mz=mapZoom

拨打电话

//叫出撥號程式
Uri uri = Uri.parse("tel:[phone]");
Intent it = new Intent(Intent.ACTION_DIAL, uri);
startActivity(it);
//直接打電話出去
Uri uri = Uri.parse("tel:[phone]");
Intent it = new Intent(Intent.ACTION_CALL, uri);
startActivity(it);
//用這個，要在 AndroidManifest.xml 中，加上
//<uses-permission id="android.permission.CALL_PHONE" />

发送SMS/MMS
//需写号码SMS
Intent it = new Intent(Intent.ACTION_VIEW);
it.putExtra("sms_body", "The SMS text");
it.setType("vnd.android-dir/mms-sms");
startActivity(it);
//发送SMS
Uri uri = Uri.parse("smsto:0800000123");
Intent it = new Intent(Intent.ACTION_SENDTO, uri);
it.putExtra("sms_body", "The SMS text");
startActivity(it);
//发送MMS
Uri uri = Uri.parse("content://media/external/images/media/23");
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra("sms_body", "some text");
it.putExtra(Intent.EXTRA_STREAM, uri);
it.setType("image/png");
startActivity(it);

发送EMAIL
Uri uri = Uri.parse("mailto:[e-mail]");
Intent it = new Intent(Intent.ACTION_SENDTO, uri);
startActivity(it);
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra(Intent.EXTRA_EMAIL, "[e-mail]");
it.putExtra(Intent.EXTRA_TEXT, "The email body text");
it.setType("text/plain");
startActivity(Intent.createChooser(it, "Choose Email Client"));
Intent it=new Intent(Intent.ACTION_SEND);
String[] tos={"[e-mail]"};
String[] ccs={"[e-mail]"};
it.putExtra(Intent.EXTRA_EMAIL, tos);
it.putExtra(Intent.EXTRA_CC, ccs);
it.putExtra(Intent.EXTRA_TEXT, "The email body text");
it.putExtra(Intent.EXTRA_SUBJECT, "The email subject text");
it.setType("message/rfc822");
startActivity(Intent.createChooser(it, "Choose Email Client"));
//传送附件
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra(Intent.EXTRA_SUBJECT, "The email subject text");
it.putExtra(Intent.EXTRA_STREAM, "file:///sdcard/mysong.mp3");
sendIntent.setType("audio/mp3");
startActivity(Intent.createChooser(it, "Choose Email Client"));

播放多媒体
Intent it = new Intent(Intent.ACTION_VIEW);
Uri uri = Uri.parse("file:///sdcard/song.mp3");
it.setDataAndType(uri, "audio/mp3");
startActivity(it);
Uri uri = Uri.withAppendedPath(MediaStore.Audio.Media.INTERNAL_CONTENT_URI, "1");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);

Android Market
//寻找应用
Uri uri = Uri.parse("market://search?q=pname:pkg_name");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//where pkg_name is the full package path for an application
//显示应用详细列表
Uri uri = Uri.parse("market://details?id=app_id");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//where app_id is the application ID, find the ID
//by clicking on your application on Market home
//page, and notice the ID from the address bar

卸载应用

Uriuri=Uri.fromParts("package",strPackageName,null);

Intentit=newIntent(Intent.ACTION_DELETE,uri);

startActivity(it);

安装应用
Uri uri = Uri.parse("url_of_apk_file");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
it.setData(uri);
it.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
it.setClassName("com.android.packageinstaller",
"com.android.packageinstaller.PackageInstallerActivity");
startActivity(it);
//make sure the url_of_apk_file is readable for all users

检测到现在在电源状态:

IntentFiltermIntentFilter = new IntentFilter();

mIntentFilter.addAction(Intent.ACTION_BATTERY_CHANGED);
registerReceiver(mIntentReceiver, mIntentFilter);

//声明消息处理过程
private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
//要看看是不是我们要处理的消息
if (action.equals(Intent.ACTION_BATTERY_CHANGED)) {
//电池电量，数字
Log.d("Battery", "" + intent.getIntExtra("level", 0));
//电池最大容量
Log.d("Battery", "" + intent.getIntExtra("scale", 0));
//电池伏数
Log.d("Battery", "" + intent.getIntExtra("voltage", 0));
//电池温度
Log.d("Battery", "" + intent.getIntExtra("temperature", 0));

//电池状态，返回是一个数字
// BatteryManager.BATTERY_STATUS_CHARGING 表示是充电状态
// BatteryManager.BATTERY_STATUS_DISCHARGING 放电中
// BatteryManager.BATTERY_STATUS_NOT_CHARGING 未充电
// BatteryManager.BATTERY_STATUS_FULL 电池满
Log.d("Battery", "" + intent.getIntExtra("status", BatteryManager.BATTERY_STATUS_UNKNOWN));

//充电类型 BatteryManager.BATTERY_PLUGGED_AC 表示是充电器，不是这个值，表示是 USB
Log.d("Battery", "" + intent.getIntExtra("plugged", 0));

//电池健康情况，返回也是一个数字
//BatteryManager.BATTERY_HEALTH_GOOD 良好
//BatteryManager.BATTERY_HEALTH_OVERHEAT 过热
//BatteryManager.BATTERY_HEALTH_DEAD 没电
//BatteryManager.BATTERY_HEALTH_OVER_VOLTAGE 过电压
//BatteryManager.BATTERY_HEALTH_UNSPECIFIED_FAILURE 未知错误
Log.d("Battery", "" + intent.getIntExtra("health", BatteryManager.BATTERY_HEALTH_UNKNOWN));
}
}
};

USB充电插拔与USB Debugging connect提示

在 packages/apps/Settings/src/com/android/settings/DevelopmentSettings.java 找到关于 USB Debug Enable 的代码：
Settings.Secure.putInt(getContentResolver(),Settings.Secure.ADB_ENABLED, 0 );
别处将根据其值动态变化做出相应动作如状态栏消息提示。
void usbListener() {
ContentResolver resolver = mContext.getContentResolver();
resolver.registerContentObserver(Settings.Secure.getUriFor(
Settings.Secure.ADB_ENABLED), false, this);
updateUsbStatus();
}

@Override
public void onChange(boolean selfChange) {
updateUsbStatus();
}

public void updateUsbStatus() {
ContentResolver resolver = mContext.getContentResolver();
mAdbEnabled = Settings.Secure.getInt(resolver, Settings.Secure.ADB_ENABLED, 0) != 0;
}

通过HttpClient从指定server获取数据

DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet method = new HttpGet(“http://www.baidu.com/1.html”);
HttpResponse resp;
Reader reader = null;
try {
// AllClientPNames.TIMEOUT
HttpParams params = new BasicHttpParams();
params.setIntParameter(AllClientPNames.CONNECTION_TIMEOUT, 10000);
httpClient.setParams(params);
resp = httpClient.execute(method);
int status = resp.getStatusLine().getStatusCode();
if (status != HttpStatus.SC_OK) return false;

// HttpStatus.SC_OK;
return true;

} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (reader != null) try {
reader.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

application/SLA stl
application/STEP step
application/STEP stp
application/acad dwg
application/andrew-inset ez
application/clariscad ccad
application/drafting drw
application/dsptype tsp
application/dxf dxf
application/excel xls
application/i-deas unv
application/java-archive jar
application/mac-binhex40 hqx
application/mac-compactpro cpt
application/vnd.ms-powerpoint pot
application/vnd.ms-powerpoint pps
application/vnd.ms-powerpoint ppt
application/vnd.ms-powerpoint ppz
application/msword doc
application/octet-stream bin
application/octet-stream class
application/octet-stream dms
application/octet-stream exe
application/octet-stream lha
application/octet-stream lzh
application/oda oda
application/ogg ogg
application/ogg ogm
application/pdf pdf
application/pgp pgp
application/postscript ai
application/postscript eps
application/postscript ps
application/pro_eng prt
application/rtf rtf
application/set set
application/smil smi
application/smil smil
application/solids sol
application/vda vda
application/vnd.mif mif
application/vnd.ms-excel xlc
application/vnd.ms-excel xll
application/vnd.ms-excel xlm
application/vnd.ms-excel xls
application/vnd.ms-excel xlw
application/vnd.rim.cod cod
application/x-arj-compressed arj
application/x-bcpio bcpio
application/x-cdlink vcd
application/x-chess-pgn pgn
application/x-cpio cpio
application/x-csh csh
application/x-debian-package deb
application/x-director dcr
application/x-director dir
application/x-director dxr
application/x-dvi dvi
application/x-freelance pre
application/x-futuresplash spl
application/x-gtar gtar
application/x-gunzip gz
application/x-gzip gz
application/x-hdf hdf
application/x-ipix ipx
application/x-ipscript ips
application/x-javascript js
application/x-koan skd
application/x-koan skm
application/x-koan skp
application/x-koan skt
application/x-latex latex
application/x-lisp lsp
application/x-lotusscreencam scm
application/x-mif mif
application/x-msdos-program bat
application/x-msdos-program com
application/x-msdos-program exe
application/x-netcdf cdf
application/x-netcdf nc
application/x-perl pl
application/x-perl pm
application/x-rar-compressed rar
application/x-sh sh
application/x-shar shar
application/x-shockwave-flash swf
application/x-stuffit sit
application/x-sv4cpio sv4cpio
application/x-sv4crc sv4crc
application/x-tar-gz tar.gz
application/x-tar-gz tgz
application/x-tar tar
application/x-tcl tcl
application/x-tex tex
application/x-texinfo texi
application/x-texinfo texinfo
application/x-troff-man man
application/x-troff-me me
application/x-troff-ms ms
application/x-troff roff
application/x-troff t
application/x-troff tr
application/x-ustar ustar
application/x-wais-source src
application/x-zip-compressed zip
application/zip zip
audio/TSP-audio tsi
audio/basic au
audio/basic snd
audio/midi kar
audio/midi mid
audio/midi midi
audio/mpeg mp2
audio/mpeg mp3
audio/mpeg mpga
audio/ulaw au
audio/x-aiff aif
audio/x-aiff aifc
audio/x-aiff aiff
audio/x-mpegurl m3u
audio/x-ms-wax wax
audio/x-ms-wma wma
audio/x-pn-realaudio-plugin rpm
audio/x-pn-realaudio ram
audio/x-pn-realaudio rm
audio/x-realaudio ra
audio/x-wav wav
chemical/x-pdb pdb
chemical/x-pdb xyz
image/cmu-raster ras
image/gif gif
image/ief ief
image/jpeg jpe
image/jpeg jpeg
image/jpeg jpg
image/png png
image/tiff tif tiff
image/tiff tif
image/tiff tiff
image/x-cmu-raster ras
image/x-portable-anymap pnm
image/x-portable-bitmap pbm
image/x-portable-graymap pgm
image/x-portable-pixmap ppm
image/x-rgb rgb
image/x-xbitmap xbm
image/x-xpixmap xpm
image/x-xwindowdump xwd
model/iges iges
model/iges igs
model/mesh mesh
model/mesh msh
model/mesh silo
model/vrml vrml
model/vrml wrl
text/css css
text/html htm
text/html html htm
text/html html
text/plain asc txt
text/plain asc
text/plain c
text/plain cc
text/plain f90
text/plain f
text/plain h
text/plain hh
text/plain m
text/plain txt
text/richtext rtx
text/rtf rtf
text/sgml sgm
text/sgml sgml
text/tab-separated-values tsv
text/vnd.sun.j2me.app-descriptor jad
text/x-setext etx
text/xml xml
video/dl dl
video/fli fli
video/flv flv
video/gl gl
video/mpeg mp2
video/mp4 mp4
video/mpeg mpe
video/mpeg mpeg
video/mpeg mpg
video/quicktime mov
video/quicktime qt
video/vnd.vivo viv
video/vnd.vivo vivo
video/x-fli fli
video/x-ms-asf asf
video/x-ms-asx asx
video/x-ms-wmv wmv
video/x-ms-wmx wmx
video/x-ms-wvx wvx
video/x-msvideo avi
video/x-sgi-movie movie
www/mime mime
x-conference/x-cooltalk ice
x-world/x-vrml vrm
x-world/x-vrml vrml

public String getUserAgent() {
String user_agent = ProductProperties.get(ProductProperties.USER_AGENT_KEY, null);
return user_agent;
}

清空手机上Cookie

CookieSyncManager.createInstance(getApplicationContext());
CookieManager.getInstance().removeAllCookie();

建立GPRS连接

//Dial the GPRS link.
private boolean openDataConnection() {
// Set up data connection.
DataConnection conn = DataConnection.getInstance();
if (connectMode == 0) {
ret = conn.openConnection(mContext, "cmwap", "cmwap", "cmwap");
} else {
ret = conn.openConnection(mContext, "cmnet", "", "");
}

}