android小知识点

android小知识点：

requestWindowFeature(Window.FEATURE_NO_TITLE);

//隐藏标题栏。这行代码一定要在setContentView（）之前执行。

getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);//全屏显示

//获取屏幕信息

WindowManager windowManager =getWindowManager();

Display display = windowManager.getDefaultDisplay();

DisplayMetrics displayMetrics = new DisplayMetrics();

display.getMetrics(displayMetrics);

//获取屏幕宽高

int sw = displayMetrics.widthPixels;

int sh = displayMetrics.heightPixels;

//在应用程序中强制设置竖屏（portrait）或横屏（landscape）

//a，在activity类oncreate（）方法中添加：

setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

//b，在AndroidManifest.mxl里Activity定义中添加：

android：screenOrientation= “portrait”

//明文显示

editText.setTransformationMethod(HideReturnsTransformationMethod.getInstance());

//密文显示

editText.setTransformationMethod(PasswordTransformationMethod.getInstance());

// 切换后将EditText光标置于末尾

CharSequence charSequence = editText.getText();

if (charSequence instanceof Spannable) {

Spannable spanText = (Spannable) charSequence;

election.setSelection(spanText, charSequence.length());

}





Android快速开发系列 5个常用工具类

1，SD卡相关辅助类 SDCardUtils

import android.os.Environment;
import android.os.StatFs;
import java.io.File;

/**
* SD卡相关的辅助类
* Created by Administrator on 2016/12/21.
*/
public class SDCardUtils {

private SDCardUtils() {
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}

/**
* 判断SDCard是否可用
*
* @return
*/
public static boolean isSDCardEnable() {
return Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED);
}

/**
* 获取SD卡路径
*
* @return
*/
public static String getSDCardPath() {
return Environment.getExternalStorageDirectory().getAbsolutePath()
+ File.separator;
}

/**
* 获取SD卡的剩余容量 单位byte
*
* @return
*/
public static long getSDCardAllSize() {
if (isSDCardEnable()) {
StatFs stat = new StatFs(getSDCardPath());
// 获取空闲的数据块的数量
long availableBlocks = (long) stat.getAvailableBlocks() - 4;
// 获取单个数据块的大小（byte）
long freeBlocks = stat.getAvailableBlocks();
return freeBlocks * availableBlocks;
}
return 0;
}

/**
* 获取指定路径所在空间的剩余可用容量字节数，单位byte
*
* @param filePath
* @return 容量字节 SDCard可用空间，内部存储可用空间
*/
public static long getFreeBytes(String filePath) {
// 如果是sd卡的下的路径，则获取sd卡可用容量
if (filePath.startsWith(getSDCardPath())) {
filePath = getSDCardPath();
} else {// 如果是内部存储的路径，则获取内存存储的可用容量
filePath = Environment.getDataDirectory().getAbsolutePath();
}
StatFs stat = new StatFs(filePath);
long availableBlocks = (long) stat.getAvailableBlocks() - 4;
return stat.getBlockSize() * availableBlocks;
}

/**
* 获取系统存储路径
*
* @return
*/
public static String getRootDirectoryPath() {
return Environment.getRootDirectory().getAbsolutePath();
}
}

2，屏幕相关辅助类 ScreenUtils

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Rect;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.WindowManager;

/**
* 获得屏幕相关的辅助类
*/
public class ScreenUtils {

private ScreenUtils() {
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}

/**
* 获得屏幕高度
*
* @param context
* @return
*/
public static int getScreenWidth(Context context) {
WindowManager wm = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(outMetrics);
return outMetrics.widthPixels;
}

/**
* 获得屏幕宽度
*
* @param context
* @return
*/
public static int getScreenHeight(Context context) {
WindowManager wm = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(outMetrics);
return outMetrics.heightPixels;
}

/**
* 获得状态栏的高度
*
* @param context
* @return
*/
public static int getStatusHeight(Context context) {

int statusHeight = -1;
try {
Class<?> clazz = Class.forName("com.android.internal.R$dimen");
Object object = clazz.newInstance();
int height = Integer.parseInt(clazz.getField("status_bar_height")
.get(object).toString());
statusHeight = context.getResources().getDimensionPixelSize(height);
} catch (Exception e) {
e.printStackTrace();
}
return statusHeight;
}

/**
* 获取当前屏幕截图，包含状态栏
*
* @param activity
* @return
*/
public static Bitmap snapShotWithStatusBar(Activity activity) {
View view = activity.getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache();
Bitmap bmp = view.getDrawingCache();
int width = getScreenWidth(activity);
int height = getScreenHeight(activity);
Bitmap bp = null;
bp = Bitmap.createBitmap(bmp, 0, 0, width, height);
view.destroyDrawingCache();
return bp;
}

/**
* 获取当前屏幕截图，不包含状态栏
*
* @param activity
* @return
*/
public static Bitmap snapShotWithoutStatusBar(Activity activity) {
View view = activity.getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache();
Bitmap bmp = view.getDrawingCache();
Rect frame = new Rect();
activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
int statusBarHeight = frame.top;

int width = getScreenWidth(activity);
int height = getScreenHeight(activity);
Bitmap bp = null;
bp = Bitmap.createBitmap(bmp, 0, statusBarHeight, width, height
- statusBarHeight);
view.destroyDrawingCache();
return bp;
}
}

3，App相关辅助类 AppUtils

/**
* 跟App相关的辅助类
*
*
*
*/
public class AppUtils
{

private AppUtils()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");

}

/**
* 获取应用程序名称
*/
public static String getAppName(Context context)
{
try
{
PackageManager packageManager = context.getPackageManager();
PackageInfo packageInfo = packageManager.getPackageInfo(
context.getPackageName(), 0);
int labelRes = packageInfo.applicationInfo.labelRes;
return context.getResources().getString(labelRes);
} catch (NameNotFoundException e)
{
e.printStackTrace();
}
return null;
}

/**
* [获取应用程序版本名称信息]
*
* @param context
* @return 当前应用的版本名称
*/
public static String getVersionName(Context context)
{
try
{
PackageManager packageManager = context.getPackageManager();
PackageInfo packageInfo = packageManager.getPackageInfo(
context.getPackageName(), 0);
return packageInfo.versionName;

} catch (NameNotFoundException e)
{
e.printStackTrace();
}
return null;
}

}

4，软键盘相关辅助类 KeyBoardUtils

import android.content.Context;
import android.view.inputmethod.InputMethodManager;
import android.widget.EditText;

/**
* 打开或关闭软键盘
*
* @author zhy
*
*/
public class KeyBoardUtils
{
/**
* 打卡软键盘
*
* @param mEditText
*            输入框
* @param mContext
*            上下文
*/
public static void openKeybord(EditText mEditText, Context mContext)
{
InputMethodManager imm = (InputMethodManager) mContext
.getSystemService(Context.INPUT_METHOD_SERVICE);
imm.showSoftInput(mEditText, InputMethodManager.RESULT_SHOWN);
imm.toggleSoftInput(InputMethodManager.SHOW_FORCED,
InputMethodManager.HIDE_IMPLICIT_ONLY);
}

/**
* 关闭软键盘
*
* @param mEditText
*            输入框
* @param mContext
*            上下文
*/
public static void closeKeybord(EditText mEditText, Context mContext)
{
InputMethodManager imm = (InputMethodManager) mContext
.getSystemService(Context.INPUT_METHOD_SERVICE);

imm.hideSoftInputFromWindow(mEditText.getWindowToken(), 0);
}
}

5，网络相关辅助类 NetUtils

import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

/**
* 跟网络相关的工具类
*
*
*
*/
public class NetUtils
{
private NetUtils()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}

/**
* 判断网络是否连接
*
* @param context
* @return
*/
public static boolean isConnected(Context context)
{

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

if (null != connectivity)
{

NetworkInfo info = connectivity.getActiveNetworkInfo();
if (null != info && info.isConnected())
{
if (info.getState() == NetworkInfo.State.CONNECTED)
{
return true;
}
}
}
return false;
}

/**
* 判断是否是wifi连接
*/
public static boolean isWifi(Context context)
{
ConnectivityManager cm = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);

if (cm == null)
return false;
return cm.getActiveNetworkInfo().getType() == ConnectivityManager.TYPE_WIFI;

}

/**
* 打开网络设置界面
*/
public static void openSetting(Activity activity)
{
Intent intent = new Intent("/");
ComponentName cm = new ComponentName("com.android.settings",
"com.android.settings.WirelessSettings");
intent.setComponent(cm);
intent.setAction("android.intent.action.VIEW");
activity.startActivityForResult(intent, 0);
}

}