android 学习笔记有用代码片段(2)

apk代码混淆保护4.0
# To enable ProGuard to shrink and obfuscate your code, uncomment this (available properties: sdk.dir, user.home):
#proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt
proguard.config=${sdk.dir}/tools/proguard/proguard-android-optimize.txt:proguard-project.txt
# Project target.
target=android-17

如果有报异常，例如这样，
java.io.IOException: Please correct the above warnings first.
at proguard.Initializer.execute(Initializer.java:308)
at proguard.ProGuard.initialize(ProGuard.java:210)
at proguard.ProGuard.execute(ProGuard.java:85)
at proguard.ProGuard.main(ProGuard.java:499)

这是由于第三方jar包的原因哦，

你可以这样，
${sdk.dir}\tools\proguard\proguard-android.txt中加入
-dontwarn com.aa.bb.*
-keep class com.aa.bb.*{ *;}

Java 中.class文件保护
http://blog.sina.com.cn/s/blog_6dc41baf01010khy.html

判断指定的服务是否运行：

public static boolean isServiceRunning(Context ctx, String serviceName, String processName) {ActivityManager manager = (ActivityManager) ctx.getSystemService(Context.ACTIVITY_SERVICE);for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {if (serviceName.equals(service.service.getClassName()) && processName.equals(service.process))return true;}return false;}

判断指定进程是否正在运行：

public static boolean isProcessRunning(Context ctx, String name) {ActivityManager am = (ActivityManager) ctx.getSystemService(Context.ACTIVITY_SERVICE);List<RunningAppProcessInfo> apps = am.getRunningAppProcesses();for (RunningAppProcessInfo app : apps) {if (app.processName.equals(name)) {return true;}}return false;}

汉字转拼音：
百度搜素pinyin4j.jar 获取官网下载。添加至lib中

/** * 汉字转换为拼音 * @author Administrator * */ public class HanZiToPinYinUtil {        public static String toPinYin(String str) {               String py = "";               String[] t = new String[str.length()];               char [] hanzi=new char[str.length()];               for(int i=0;i<str.length();i++){                   hanzi[i]=str.charAt(i);               }                              net.sourceforge.pinyin4j.format.HanyuPinyinOutputFormat t1 = new HanyuPinyinOutputFormat();               t1.setCaseType(HanyuPinyinCaseType.LOWERCASE);               t1.setToneType(HanyuPinyinToneType.WITHOUT_TONE);               t1.setVCharType(HanyuPinyinVCharType.WITH_V);                              try {                   for (int i = 0; i < str.length(); i++) {                       if ((str.charAt(i) >= 'a' && str.charAt(i) < 'z')                               || (str.charAt(i) >= 'A' && str.charAt(i) <= 'Z')                               || (str.charAt(i) >= '0' && str.charAt(i) <= '9')) {                           py += str.charAt(i);                       } else {                               t = PinyinHelper.toHanyuPinyinStringArray(hanzi[i], t1);                               py=py+t[0];                           }                       }               } catch (BadHanyuPinyinOutputFormatCombination e) {                   e.printStackTrace();               }                      return py.trim().toString();           }                   public static void main(String args[]){                         System.out.println(HanZiToPinYinUtil.toPinYin("我屮艸芔茻"));                  }

开启飞行模式：

boolean isEnabled = Settings.System.getInt(                paramContext.getContentResolver(),                   Settings.System.AIRPLANE_MODE_ON, 0) == 1;        if(isEnabled==true)        {            Settings.System.putInt(                    paramContext.getContentResolver(),                  Settings.System.AIRPLANE_MODE_ON, isEnabled ? 0 : 1);            // Post an intent to reload            Intent intent = new Intent(Intent.ACTION_AIRPLANE_MODE_CHANGED);            intent.putExtra("state", !isEnabled);            paramContext.sendBroadcast(intent);        }        else        {            Settings.System.putInt(                    paramContext.getContentResolver(),                  Settings.System.AIRPLANE_MODE_ON, isEnabled ? 0 : 1);            // Post an intent to reload            Intent intent = new Intent(Intent.ACTION_AIRPLANE_MODE_CHANGED);            intent.putExtra("state", !isEnabled);            paramContext.sendBroadcast(intent);        }<uses-permission android:name="android.permission.WRITE_SETTINGS"/><uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS"/>

开机自启动：（注意：app一定要安装到内存中，在sd卡上无法自启动）

<receiver android:name="com.pioneersoft.aoc.ui.BootBroadcastReceiver" android:enabled="true" android:exported="true">            <intent-filter >                <action android:name="android.intent.action.BOOT_COMPLETED" />                <category android:name="android.intent.category.HOME" />            </intent-filter>        </receiver>

public class BootBroadcastReceiver extends BroadcastReceiver {//static final String action_boot="android.intent.action.BOOT_COMPLETED";     @Override    public void onReceive(Context context, Intent intent) { //       if (intent.getAction().equals(action_boot)){            Intent bootStartIntent=new Intent(context,MainActivity.class);            bootStartIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);            context.startActivity(bootStartIntent);//        }     }}

获取未安装apk信息：

/** 获取未安装的APK信息       * @param context       * @param archiveFilePath APK文件的路径。如：/sdcard /download/XX.apk       */        public void getUninatllApkInfo(Context context, String archiveFilePath){            PackageManager pm = context.getPackageManager();            PackageInfo info = pm.getPackageArchiveInfo(archiveFilePath, PackageManager.GET_ACTIVITIES);            if(info != null){                ApplicationInfo appInfo = info.applicationInfo;                String appName = pm.getApplicationLabel(appInfo).toString();                String packageName = appInfo.packageName;                Drawable icon = pm.getApplicationIcon(appInfo);            }        }

监听apk安装，卸载，替换行为：

private void registerIntentReceivers() {        IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED);        filter.addAction(Intent.ACTION_PACKAGE_REMOVED);        filter.addAction(Intent.ACTION_PACKAGE_CHANGED);        filter.addAction(Intent.ACTION_PACKAGE_REPLACED);        filter.addDataScheme("package");        registerReceiver(mApplicationsReceiver, filter);    } /**     * Receives notifications when applications are added/removed.     */    private class ApplicationsIntentReceiver extends BroadcastReceiver {        @Override        public void onReceive(Context context, Intent intent) {        // PackageManager manager = context.getPackageManager();                     if (intent.getAction().equals(Intent.ACTION_PACKAGE_ADDED)) {                 String packageName = intent.getData().getSchemeSpecificPart();                 Toast.makeText(context, "安装成功"+packageName, Toast.LENGTH_LONG).show();             }             if (intent.getAction().equals(Intent.ACTION_PACKAGE_REMOVED)) {                 String packageName = intent.getData().getSchemeSpecificPart();                 Toast.makeText(context, "卸载成功"+packageName, Toast.LENGTH_LONG).show();             }             if (intent.getAction().equals(Intent.ACTION_PACKAGE_REPLACED)) {                 String packageName = intent.getData().getSchemeSpecificPart();                 Toast.makeText(context, "替换成功"+packageName, Toast.LENGTH_LONG).show();             }        }    }

loadData()中的html data中不能包含'#', '%', '\', '?'四中特殊字符，出现这种字符就会出现解析错误，显示找不到网页还有部分html代码。需要如何处理呢？我们需要用UrlEncoder编码为%23, %25, %27, %3f 。
可以使用以下两种代码，data为string类型的html代码
1 webView.loadData(URLEncoder.encode(data, "utf-8"), "text/html", "utf-8");
这样一些背景效果什么的都不怎么好看了。不推荐。
2 webView.loadDataWithBaseURL(null,data, "text/html", "utf-8", null);

这样就会完美解析了。

计算网络接收byte[] 字节数组的实际接受内容大小：

public static void main(String[] args) {byte[] bt=new byte[1024];String msg="helo! you are very nice! have a good time! happy every day!";byte[] t=msg.getBytes();for(int i=0;i<t.length;i++){bt[i]=t[i];}String message=new String(bt).trim(); System.out.println(" msg= "+message+" len= "+message.length());}

获取现在正调用的方法名

String methodName =Thread.currentThread().getStackTrace()[1].getMethodName();  String methodName = Thread.currentThread().getStackTrace()[1].getMethodName();

/**     * 安装app     */    public static void openAPK(File f, Context context) {        context.startActivity(getInstallApp(f, context));    }    public static Intent getInstallApp(File f, Context context) {        Intent intent = new Intent();        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);            //设置应用的安装来源，例如谷歌市场        intent.putExtra("android.intent.extra.INSTALLER_PACKAGE_NAME", context.getPackageName());        intent.setAction(android.content.Intent.ACTION_VIEW);        /* 设置intent的file */        intent.setDataAndType(Uri.fromFile(f), "application/vnd.android.package-archive");        return intent;    }    /**     * 卸载APP     * @param context     * @param packageName     */    public static void uninstallApp(Context context,String packageName) {        Uri packageURI = Uri.parse("package:" + packageName);           Intent uninstallIntent = new Intent(Intent.ACTION_DELETE, packageURI);           uninstallIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);        context.startActivity(uninstallIntent);    }

Android屏幕解锁和锁定  //屏幕解锁  KeyguardManager keyguardManager = (KeyguardManager)getSystemService(KEYGUARD_SERVICE);  KeyguardLock keyguardLock = keyguardManager.newKeyguardLock(LOCK_TAG);  keyguardLock.disableKeyguard();  //屏幕锁定  keyguardLock.reenableKeyguard();  Android屏幕常亮/点亮  //保持屏幕常亮  PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);  mWakeLock = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, LOCK_TAG);    mWakeLock.acquire();  //释放屏幕常亮锁  if(null != mWakeLock) {      mWakeLock.release();  }/**     * 判断桌面是否已添加快捷方式     *      * @param cx     * @param titleName     *            快捷方式名称     * @return     */    public static boolean hasShortcut(Context cx) {        boolean result = false;        // 获取当前应用名称        String title = null;        try {            final PackageManager pm = cx.getPackageManager();            title = pm.getApplicationLabel(                    pm.getApplicationInfo(cx.getPackageName(),                            PackageManager.GET_META_DATA)).toString();        } catch (Exception e) {        }        final String uriStr;        if (android.os.Build.VERSION.SDK_INT < 8) {            uriStr = "content://com.android.launcher.settings/favorites?notify=true";        } else {            uriStr = "content://com.android.launcher2.settings/favorites?notify=true";        }        final Uri CONTENT_URI = Uri.parse(uriStr);        final Cursor c = cx.getContentResolver().query(CONTENT_URI, null,                "title=?", new String[] { title }, null);        if (c != null && c.getCount() > 0) {            result = true;        }        return result;    } /** *    * 为当前应用添加桌面快捷方式    *     * @param cx    * @param appName    *            快捷方式名称    */   public static void addShortcut(Context cx) {       Intent shortcut = new Intent("com.android.launcher.action.INSTALL_SHORTCUT");       Intent shortcutIntent = cx.getPackageManager()               .getLaunchIntentForPackage(cx.getPackageName());       shortcut.putExtra(Intent.EXTRA_SHORTCUT_INTENT, shortcutIntent);       // 获取当前应用名称       String title = null;       try {           final PackageManager pm = cx.getPackageManager();           title = pm.getApplicationLabel(                   pm.getApplicationInfo(cx.getPackageName(),                           PackageManager.GET_META_DATA)).toString();       } catch (Exception e) {       }       // 快捷方式名称       shortcut.putExtra(Intent.EXTRA_SHORTCUT_NAME, title);       // 不允许重复创建（不一定有效）       shortcut.putExtra("duplicate", false);       // 快捷方式的图标       Parcelable iconResource = Intent.ShortcutIconResource.fromContext(cx,               R.drawable.ic_launcher);       shortcut.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE, iconResource);       cx.sendBroadcast(shortcut);   } /***    * 删除当前应用的桌面快捷方式    *     * @param cx    */   public static void delShortcut(Context cx) {       Intent shortcut = new Intent(               "com.android.launcher.action.UNINSTALL_SHORTCUT");       // 获取当前应用名称       String title = null;       try {           final PackageManager pm = cx.getPackageManager();           title = pm.getApplicationLabel(                   pm.getApplicationInfo(cx.getPackageName(),                           PackageManager.GET_META_DATA)).toString();       } catch (Exception e) {       }       // 快捷方式名称       shortcut.putExtra(Intent.EXTRA_SHORTCUT_NAME, title);       Intent shortcutIntent = cx.getPackageManager()               .getLaunchIntentForPackage(cx.getPackageName());       shortcut.putExtra(Intent.EXTRA_SHORTCUT_INTENT, shortcutIntent);       cx.sendBroadcast(shortcut);   }相关权限配置    <uses-permission android:name="com.android.launcher.permission.INSTALL_SHORTCUT" />    <uses-permission android:name="com.android.launcher.permission.UNINSTALL_SHORTCUT" />    <uses-permission android:name="com.android.launcher.permission.READ_SETTINGS" />

 /**  * 添加快捷方式到桌面 要点：    * 1.给Intent指定action="com.android.launcher.INSTALL_SHORTCUT"  * 2.给定义为Intent.EXTRA_SHORTCUT_INENT的Intent设置与安装时一致的action(必须要有)    * 3.添加权限:com.android.launcher.permission.INSTALL_SHORTCUT  */ private void addShortcutToDesktop() {     Intent shortcut = new Intent("com.android.launcher.action.INSTALL_SHORTCUT");     // 不允许重建     shortcut.putExtra("duplicate", false);     // 设置名字     shortcut.putExtra(Intent.EXTRA_SHORTCUT_NAME,this.getString(R.string.app_name));     // 设置图标     shortcut.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE,Intent.ShortcutIconResource.fromContext(this,                     R.drawable.ic_launcher));     // 设置意图和快捷方式关联程序     shortcut.putExtra(Intent.EXTRA_SHORTCUT_INTENT,new Intent(this, this.getClass()).setAction(Intent.ACTION_MAIN));     // 发送广播     sendBroadcast(shortcut); }  方法二：首先在xml中设置IntentFilter<intent-filter><action android:name="android.intent.action.CREATE_SHORTCUT" /></intent-filter> if (Intent.ACTION_CREATE_SHORTCUT.equals(action)) {Intent shortcut = new Intent(Intent.ACTION_CREATE_SHORTCUT);     // 不允许重建     shortcut.putExtra("duplicate", false);     // 设置名字     shortcut.putExtra(Intent.EXTRA_SHORTCUT_NAME,             this.getString(R.string.app_name));     // 设置图标     shortcut.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE,             Intent.ShortcutIconResource.fromContext(this,                     R.drawable.ic_launcher));     // 设置意图和快捷方式关联的程序     shortcut.putExtra(Intent.EXTRA_SHORTCUT_INTENT,             new Intent(this, this.getClass()));             //将结果返回到launcher        setResult(RESULT_OK, intent);           }在launcher中我们运行程序就可以将快捷方式创建在桌面上。由于快捷方式launcher管理的，我们可以通过查看launcher中是否已经有此快捷方式数据，如果有就不在创建添加权限：<uses-permission android:name="com.android.launcher.permission.READ_SETTINGS"/> private boolean hasInstallShortcut() {     boolean hasInstall = false;     final String AUTHORITY = "com.android.launcher.settings";     Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY             + "/favorites?notify=true");     Cursor cursor = this.getContentResolver().query(CONTENT_URI,             new String[] { "title", "iconResource" }, "title=?",             new String[] { this.getString(R.string.app_name) }, null);     if (cursor != null && cursor.getCount() > 0) {         hasInstall = true;     }     return hasInstall; }

上传文件到服务器：

HttpURLConnection connection = null;DataOutputStream outputStream = null;DataInputStream inputStream = null;String pathToOurFile = "/data/file_to_send.mp3";String urlServer = "http://192.168.1.1/handle_upload.php";String lineEnd = "\r\n";String twoHyphens = "--";String boundary =  "*****"; int bytesRead, bytesAvailable, bufferSize;byte[] buffer;int maxBufferSize = 1*1024*1024; try{    FileInputStream fileInputStream = new FileInputStream(new File(pathToOurFile) );     URL url = new URL(urlServer);    connection = (HttpURLConnection) url.openConnection();     // Allow Inputs & Outputs.    connection.setDoInput(true);    connection.setDoOutput(true);    connection.setUseCaches(false);     // Set HTTP method to POST.    connection.setRequestMethod("POST");     connection.setRequestProperty("Connection", "Keep-Alive");    connection.setRequestProperty("Content-Type", "multipart/form-data;boundary="+boundary);     outputStream = new DataOutputStream( connection.getOutputStream() );    outputStream.writeBytes(twoHyphens + boundary + lineEnd);    outputStream.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\"" + pathToOurFile +"\"" + lineEnd);    outputStream.writeBytes(lineEnd);     bytesAvailable = fileInputStream.available();    bufferSize = Math.min(bytesAvailable, maxBufferSize);    buffer = new byte[bufferSize];     // Read file    bytesRead = fileInputStream.read(buffer, 0, bufferSize);     while (bytesRead > 0)    {        outputStream.write(buffer, 0, bufferSize);        bytesAvailable = fileInputStream.available();        bufferSize = Math.min(bytesAvailable, maxBufferSize);        bytesRead = fileInputStream.read(buffer, 0, bufferSize);    }     outputStream.writeBytes(lineEnd);    outputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);     // Responses from the server (code and message)    serverResponseCode = connection.getResponseCode();    serverResponseMessage = connection.getResponseMessage();     fileInputStream.close();    outputStream.flush();    outputStream.close();}catch (Exception ex){    //Exception handling}

需要授权用户：

tring usernamePassword = yourUsername + “:” + yourPassword;String encodedUsernamePassword = Base64.encodeToString(usernamePassword.getBytes(), Base64.DEFAULT);connection.setRequestProperty (“Authorization”, “Basic ” + encodedUsernamePassword);

创建两个对话框模式进度样式：

ProgressDialog pdialog = new ProgressDialog(SettingActivity.this，0);

ScrollView 嵌套 ListView GridView问题

public class MyListView extends ListView{ public MyListView(Context context, AttributeSet attrs) {        super(context, attrs);    }    public MyListView(Context context) {        super(context);    }    public MyListView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);    }    @Override    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        int expandSpec = MeasureSpec.makeMeasureSpec(                Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST);        super.onMeasure(widthMeasureSpec, expandSpec);    }}

设置texview 垂直滚动条
android:focusable="true"
android:focusableInTouchMode="true"
android:ellipsize="marquee"
android:marqueeRepeatLimit="marquee_forever"
android:scrollbars="vertical"
android:singleLine="false"

设置textview 文字水平自动滚动（跑马灯效果）
<com.example.playpic.MyTextView
android:id="@+id/myTv"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:textColor="#000000"

android:focusable="true"
android:focusableInTouchMode="true"
android:scrollHorizontally="true"
android:ellipsize="marquee"
android:marqueeRepeatLimit="marquee_forever"
android:singleLine="true"
/>

布局文件需添加属性：android:addStatesFromChildren="true"
修改的textview

public class MyTextView extends TextView {public MyTextView(Context context) {super(context);}public MyTextView(Context context, AttributeSet attrs) {super(context, attrs);}public MyTextView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);}@Overridepublic boolean isFocused() {return true;}}setContentView(R.layout.scrollview1);MyTextView tv=(MyTextView)findViewById(R.id.myTv);tv.setText(str);tv.setMovementMethod(ScrollingMovementMethod.getInstance());

大数据量提高sqlite数据存储效率：
在开发过程中解析xml中的数据有上万条之多，发现在想sqlite中插入的时候非常耗时，原因是没有使用事务，默认是每插入一次使用
一次事务，这样如果插入1w条数据，就要开启1w次事务，非常耗时，所以我们可以通过手动开启和关闭的方式控制事务。

public void insertAll(String databaseName,              ArrayList<ContentValues> valuesArr) {          SQLiteDatabase db = getWritableDatabase();          db.beginTransaction();          for (ContentValues val : valuesArr) {              db.insert(databaseName, null, val);          }            db.setTransactionSuccessful();          db.endTransaction();          db.close();      }

计算日期之间相隔几天：

public long compareDataToNow(String date){   SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");    Date passDate,nowDate;  long diff=-100l,days=-100l;   try { passDate = sdf.parse(date); String nowStr=sdf.format(new Date()); nowDate=sdf.parse(nowStr);     diff = passDate.getTime() - nowDate.getTime();       days = diff / (1000 * 60 * 60 * 24);     System.out.println( "相隔："+days+"天");} catch (ParseException e) {e.printStackTrace();} return diff;}

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