Android知识点汇总集

1、目录Android知识点：3一：dom解析，以及写入数据到xml文件：3二：连接socket并获取返回值4三：创建socket服务器4四：获取本地设备信息;执行串口命令5五：获取设备当前时间5六：对于节省代码6七：访问网络权限6八：显示ProgressDialog6九：handle消息机制定义与对信息的处理6十：显示AlertDialog，以及对其进行按键处理7十一：判断网络是否连接8十二：判断是否连接有线网络8十三：判断是否能够ping通互联网：返回0则通，否则不通9十四：显示进度圈，防止用户继续其线程 start9十五：下载文件10十六：解析json文件（android中使用，解析本地文件

2、夹）11十七：解析服务器json文件，根据路径获取输入流并解析12十八：获取所有已经安装的apk的信息14十九：安装apk，分为静默安装与非静默安装，静默卸载15二零：发送与接收广播17二一：java中解析JSON文件18二二：获取文件列表19二三：DownloadManager21附件一：android-apkinfo.json23附件二：java_apkinfo_json24二四：复制assets中资源文件到sdcard或data/files目录下25二五：解析与重写xml文件27二六：设置Viewpager的Adapter适配器29二七：设置listView的Adapter适配器30二八

3、：设置按键监听器33二九：对于data中图片信息的处理与使用34三十：OnpageChangeListener页面切换监听器34三一：Activity之间数据的传递35三二：通过代码添加button36三三：文件的输入输出37三四：关于文件路径38三五：对sd卡的读写权限设置38三六：file.getCanonicalPath()39三七：命令行运行java文件39三八：activity无头标题40三九：activity全屏40四十：启动aitivity/service参数设置40四一：获取已经安装的apk信息40四二：Viewpager41四三：LayoutInflater42四四：mkdi

4、r与mkdirs42四五：创建对象Drawable与Bitmap43四六：获取屏幕分辨率43四七：消除EditText输入法弹框43四八：android:ellipsize的使用44四九：Edittext属性设置44五十：设置系统菜单语言45五一：android原生设置系统休眠时间45五二：判定ImageView是否可见45五三：关于fragment的使用46五四：打印全部的cursor信息47五五：拆分String，根据特殊符号48五六：获取与设置环境变量48五七：解析与获取文本信息48五八：实现本地升级功能49五九：获取挂载的存储设备的路径49六十：java反射机制，根据函数名调用函数50

5、六一：简单添加Menu选项51六二：获取当前显示的应用包名52六三：kill某一执行进程52常用C函数含义解析：541、memset542、snprintf54Android中遇到的小常识551，查看进程相关信息552，查看系统内存属性值553，修改文件权限以及分组55Android知识点：一：dom解析，以及写入数据到xml文件：获取输入流：File file = new File(String filepath);InputStream instream = new FileInputStream(file);private static void serialize(int data)

6、throws Exception logs(rewrite xmlFile);/ 由android.util.Xml创建一个XmlSerializer实例XmlSerializer serializer = Xml.newSerializer();StringWriter writer = new StringWriter();/ 设置输出方向为writerserializer.setOutput(writer);serializer.startDocument(UTF-8, true);serializer.startTag(, datas);serializer.startTag(, da

7、ta);serializer.text( + data);serializer.endTag(, data);serializer.endTag(, datas);serializer.endDocument();File file = new File(FILE_PATH + FILE_NAME);if (file.exists() file.delete();file.createNewFile();FileOutputStream io = new FileOutputStream(file);String xmlString = writer.toString();io.write(x

8、mlString.getBytes(UTF-8);/解析输入流，获取输入流中信息private static int parseXmlNative(InputStream is) throws Exception logs(parseXML in native);String data2 = null; / 获取最终使用期限/ 得到Dom解析对象工厂DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();/ 通过工厂创建Dom解析对象实例DocumentBuilder db = factory.newDocum

9、entBuilder();/ 将xml文件的输入流交给Dom解析对象进行解析，并将Dom树返回Document document = db.parse(is);/ 通过Dom树接收到根元素Element rootElement = document.getDocumentElement();NodeList nodeList = rootElement.getElementsByTagName(data);Log.i(TAG, length = + nodeList.getLength();data2 = nodeList.item(0).getFirstChild().getNodeValu

10、e();return Integer.parseInt(data2);二：连接socket并获取返回值try String sRead;/参数为ip与端口号Socket socket = new Socket(SERVER_IP, PORT);BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream();sRead = br.readLine();logs(sRead);socket.close();logs(socket is closed);serialize(Integer.par

11、seInt(sRead);logs(serialize in file, data = + Integer.parseInt(sRead);br.close(); catch (Exception e) logs(Exception);三：创建socket服务器public static void main(String args) try ServerSocket ss = new ServerSocket(30000); while (true) Socket s = ss.accept(); PrintStream ps = new PrintStream(s.getOutputStre

12、am(); ps.println(This is String in SocketMain!); ps.close(); s.close(); catch (IOException e) e.printStackTrace(); 当socket获取连接请求时，返回值为：This is String in SocketMain!四：获取本地设备信息;执行串口命令获取本地mac地址：private static String getEthMacAddress() try Process process = Runtime.getRuntime() .exec(busybox ifconfig et

13、h0); BufferedReader br = new BufferedReader(new InputStreamReader( process.getInputStream(); String inline = br.readLine(); String s = inline.split( ); String ethMac = ss.length - 1; br.close(); return ethMac; catch (IOException e) e.printStackTrace(); return null; 获取设备序列号：String serial = Build.SERI

14、AL;获取设备生产厂商String manufacturer = Build.MANUFACTURER;五：获取设备当前时间SimpleDateFormat format = new SimpleDateFormat(yyyyMMdd);Date curData = new Date(System.currentTimeMillis();String string_curtime = format.format(curData);int int_curime = Integer.parseInt(string_curtime);信息格式为yyyyMMdd(HHmmss)获取毫秒信息：Syste

15、m.currentTimeMillis();获取时间为自1970年1月1日0时0分起到当前的毫秒数之差。六：对于节省代码if（flag）return true;elsereturn false;等价于：return flag;七：访问网络权限八：显示ProgressDialog/显示正在检测网络提示，防止用户继续start该线程 mProgressDialog = new ProgressDialog(NetworkInforActivity.this, R.style.dialog);mProgressDialog.setCancelable(false);/阻止用户执行其他操作，但无法阻塞

16、home按键mProgressDialog.setMessage(getString(R.string.router_test);mProgressDialog.show();九：handle消息机制定义与对信息的处理mHandler.sendEmptyMessage(MSG_NETWORK_UNWAN);/发送消息，参数为(int)msg.whatprivate Handler mHandler = new Handler()Overridepublic void handleMessage(Message msg) super.handleMessage(msg);Log.i(TAG, 接

17、受信息为： + msg.what);switch (msg.what) case MSG_NETWORK_UNCONNECTED:mTvNetwork_type.setText(未连接);mTvNetwork_state.setText(未连接);mProgressDialog.dismiss();showFaildDialog();break;case MSG_NETWORK_ISETHERNET:mTvNetwork_type.setText(有线网络);mProgressDialog.dismiss();break;case MSG_NETWORK_UNETHERNET:mTvNetwo

18、rk_type.setText(无线网络);mProgressDialog.dismiss();break;case MSG_NETWORK_ISWAN:mTvNetwork_state.setText(互联网);mProgressDialog.dismiss();break;case MSG_NETWORK_UNWAN:mTvNetwork_state.setText(局域网);mProgressDialog.dismiss();default:break;十：显示AlertDialog，以及对其进行按键处理private void showFaildDialog() AlertDialog

19、.Builder dialog = new AlertDialog.Builder(this,R.style.dialog);dialog.setTitle(R.string.router_disconnect);dialog.setCancelable(false);dialog.setPositiveButton(R.string.button_testagain,new DialogInterface.OnClickListener() public void onClick(DialogInterface dialog, int whichButton) mProgressDialog

20、.show();new PingThread().start(););dialog.setNegativeButton(取消检测,new DialogInterface.OnClickListener() public void onClick(DialogInterface dialog, int whichButton) dialog.dismiss(););dialog.show();十一：判断网络是否连接/判断网络是否连接private boolean isNetConnected() isconnected = false; ConnectivityManager cm = (Con

21、nectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); if (cm = null) return false; NetworkInfo infos = cm.getAllNetworkInfo(); if (infos != null) for (NetworkInfo ni : infos) if (ni.isConnected() isconnected = true; return true; return false; 十二：判断是否连接有线网络/判断网络是否连接有线网络（Ethernet）private b

22、oolean isEthernetEnabled() ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); if (cm != null) NetworkInfo networkInfo = cm.getActiveNetworkInfo(); if (networkInfo != null & networkInfo.getType() = ConnectivityManager.TYPE_ETHERNET) isethernet = true; retur

23、n true; isethernet = false; return false; 十三：判断是否能够ping通互联网：返回0则通，否则不通/判断是否能够ping通互联网：返回0则通，否则不通public int isReachable(String remoteIpAddress, int pingTimes, double timeOut) int result = 1;String pingCommand = ping + -c + pingTimes + -i + timeOut + + remoteIpAddress;/该语句遵循linux中ping命令规则Runtime runti

24、me = Runtime.getRuntime();Process proc = null;try proc = runtime.exec(pingCommand);result = proc.waitFor(); catch (Exception e) e.printStackTrace();if (result = 0) isWAN = true;else isWAN = false;return result;十四：显示进度圈，防止用户继续其线程 startOverridepublic void onClick(View v) /显示进度圈，防止用户继续其线程 startmProgres

25、sDialog = new ProgressDialog(NetworkInforActivity.this, R.style.dialog);mProgressDialog.setCancelable(false);mProgressDialog.setMessage(getString(R.string.router_test);mProgressDialog.show();new PingThread().start();十五：下载文件下载指定路径（url）文件到目标路径（newUrl）private void download(String url, String newUrl) tr

26、y / 设置目标路径URL productUrl = new URL(url);/ 连接服务器URLConnection connection = productUrl.openConnection();/ 设置连接超时时间connection.setConnectTimeout(CONNECT_TIMEOUT);connection.setReadTimeout(READ_TIMEOUT);HttpURLConnection httpURLConnection = (HttpURLConnection) connection;logs( + productUrl);logs( + newUr

27、l);int responseCode = httpURLConnection.getResponseCode();logs( + responseCode);if (responseCode != HttpURLConnection.HTTP_OK) Log.e(TAG, Connect Error + url);return;InputStream in = httpURLConnection.getInputStream();logs(*begain download file: + url);logs(*begain download file: + newUrl);File f =

28、new File(newUrl);f.createNewFile();FileOutputStream fo = new FileOutputStream(f);byte buf = new byte1024;int len = 0;while (len = in.read(buf) != -1) fo.write(buf, 0, len);in.close();fo.close();downsuccess = true;Log.i(TAG, downLoad success); catch (Exception e) e.printStackTrace();logs(downLoader f

29、ailed);十六：解析json文件（android中使用，解析本地文件夹）private ArrayList JSONParse(String newUrl) ArrayList apkinfos = new ArrayList();/ReadFile()可以将路径为newUrl路径的文件数据转换为String类型数据String JsonContext = new FileToString().ReadFile(newUrl);try JSONArray jsonObjs = new JSONObject(JsonContext).getJSONArray(apk); for(int i

30、= 0; i jsonObjs.length() ; i+) JSONObject jsonObj = (JSONObject)jsonObjs.opt(i); ApkInfo apkInfo = new ApkInfo(); apkInfo.setFile_name(jsonObj.getString(file_name); logs(file_name = + jsonObj.getString(file_name); apkInfo.setPackage_name(jsonObj.getString(package_name); logs(package_name = + jsonObj

31、.getString(package_name); apkInfo.setVersionCode(Integer.parseInt(jsonObj.getString(versionCode); logs(versionCode = + Integer.parseInt(jsonObj.getString(versionCode); apkInfo.setVersionName(jsonObj.getString(versionName); logs(versionName = + jsonObj.getString(versionName); apkinfos.add(apkInfo); c

32、atch (JSONException e) System.out.println(Jsons parse error !); e.printStackTrace(); return apkinfos;public class FileToString /将指定路径的文件转换为String类型，并返回public String ReadFile(String Path) BufferedReader reader = null;String laststr = ;try FileInputStream fileInputStream = new FileInputStream(Path);In

33、putStreamReader inputStreamReader = new InputStreamReader(fileInputStream, UTF-8);reader = new BufferedReader(inputStreamReader);String tempString = null;while (tempString = reader.readLine() != null) laststr += tempString;reader.close(); catch (IOException e) e.printStackTrace(); finally if (reader

34、 != null) try reader.close(); catch (IOException e) e.printStackTrace();return laststr;十七：解析服务器json文件，根据路径获取输入流并解析/* * function: 解析json文件，其路径为newUrl，解析后将其存储到apkinfos中 * * param newUrl * param apkinfos * return */private ArrayList JSONParse(String apkInfoJSONPath) ArrayList apkinfos = new ArrayList()

35、;try URL productUrl = new URL(/app/apkinfo.json);/ 连接服务器URLConnection connection = productUrl.openConnection();/ 设置连接超时时间connection.setConnectTimeout(CONNECT_TIMEOUT);connection.setReadTimeout(READ_TIMEOUT);HttpURLConnection httpURLConnection = (HttpURLConnection) connection;int re

36、sponseCode = httpURLConnection.getResponseCode();logs( + responseCode);if (responseCode != HttpURLConnection.HTTP_OK) logs(connect error);return apkinfos;InputStream in = httpURLConnection.getInputStream();ByteArrayOutputStream outputStream = new ByteArrayOutputStream();byte data = new byte1024;int

37、len = 0;while (len = in.read(data) != -1) outputStream.write(data, 0, len);JSONArray jsonArray = new JSONObject(new String(outputStream.toByteArray().getJSONArray(apk);for (int i = 0; i jsonArray.length(); i+) JSONObject jsonObj = (JSONObject) jsonArray.opt(i);ApkInfo apkInfo = new ApkInfo();apkInfo

38、.setFile_name(jsonObj.getString(file_name);logs(file_name = + jsonObj.getString(file_name);apkInfo.setPackage_name(jsonObj.getString(package_name);logs(package_name = + jsonObj.getString(package_name);apkInfo.setVersionCode(Integer.parseInt(jsonObj.getString(versionCode);logs(versionCode = + Integer

39、.parseInt(jsonObj.getString(versionCode);apkInfo.setVersionName(jsonObj.getString(versionName);logs(versionName = + jsonObj.getString(versionName);apkinfos.add(apkInfo); catch (Exception e) e.printStackTrace();return apkinfos;十八：获取所有已经安装的apk的信息private ArrayList getAllApkInfo() PackageManager package

40、Manager = mContext.getPackageManager();ArrayList apkinfos = new ArrayList();List pack = packageManager.getInstalledPackages(PackageManager.GET_UNINSTALLED_PACKAGES);for (int i = 0; i pack.size(); i+) ApkInfo apkinfo = new ApkInfo();PackageInfo p = pack.get(i);String s = p.applicationInfo.sourceDir;L

41、og.v(tag, p.applicationInfo.sourceDir);File file = new File(s);if (file.isFile() apkinfo.setFile_name(+ p.applicationInfo.loadLabel(packageManager);logs( + p.applicationInfo.loadLabel(packageManager);apkinfo.setPackage_name(p.packageName);logs(p.packageName);apkinfo.setVersionCode(p.versionCode);log

42、s(p.versionCode + );apkinfo.setVersionName(p.versionName);logs(p.versionName);apkinfos.add(apkinfo);return apkinfos;十九：安装apk，分为静默安装与非静默安装，静默卸载/* * function：非静默安装，安装apkAbsolutePath处apk文件，路径含文件名 * param apkAbsolutePath */public void Install(String apkAbsolutePath) Intent intent = new Intent(Intent.ACT

43、ION_VIEW);intent.setDataAndType(Uri.fromFile(new File(apkAbsolutePath), application/vnd.android.package-archive);mContext.startActivity(intent);/* * function：静默安装，安装apkAbsolutePath处apk文件，路径含文件名 * param apkAbsolutePath * return */静默安装需要将该apk置于system/app下，并需要在源码环境下编译，与系统具有相同的签名方可public String SilenceI

44、nstall(String apkAbsolutePath) String args = pm, install, -r, apkAbsolutePath ;String result = ;ProcessBuilder processBuilder = new ProcessBuilder(args);Process process = null;InputStream errIs = null;InputStream inIs = null;try ByteArrayOutputStream byteArrayOutPutStream = new ByteArrayOutputStream

45、();int read = -1;process = processBuilder.start();errIs = process.getErrorStream();while (read = errIs.read() != -1) byteArrayOutPutStream.write(read);byteArrayOutPutStream.write(/n.getBytes();inIs = process.getInputStream();while (read = inIs.read() != -1) byteArrayOutPutStream.write(read);byte dat

46、a = byteArrayOutPutStream.toByteArray();result = new String(data); catch (IOException e) e.printStackTrace(); catch (Exception e) e.printStackTrace(); finally try if (errIs != null) errIs.close();if (inIs != null) inIs.close(); catch (IOException e) e.printStackTrace();if (process != null) process.destroy();return result;/静默卸载private boolean uninstallPkg(String packageName) /Create new intent to launch Uninstaller activity/Uri packageURI = Uri.parse(package: + packageName);/Intent uninstallIntent = new