android笔记
开发中经常要去寻找一些常用的方法，做个整理方便以后观看
1.获取当前屏幕宽高：
DisplayMetrics metric = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metric);
int width = metric.widthPixels; // 屏幕宽度（像素）
int height = metric.heightPixels; // 屏幕高度（像素）
float density = metric.density; // 屏幕密度（0.75 / 1.0 / 1.5）
int densityDpi = metric.densityDpi; // 屏幕密度DPI（120 / 160 / 240） 2.在代码中设置如何设置dip
设置10dip的像素，第一个参数是类型，第二个参数是设置的值，第三个获取当前的尺度
int screenPaading = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
10, getResources().getDisplayMetrics())3.在代码中设置TextView中画线和下划线
textView.getPaint().setFlags(Paint. UNDERLINE_TEXT_FLAG ); //下划线
textView.getPaint().setAntiAlias(true);//抗锯齿
textview.getPaint().setFlags(Paint. STRIKE_THRU_TEXT_FLAG); //中划线
setFlags(Paint. STRIKE_THRU_TEXT_FLAG|Paint.ANTI_ALIAS_FLAG); // 设置中划线并加清晰
textView.getPaint().setFlags(0); 4.在代码中设置文字样式
//第一步，在assets目录下新建fonts目录，把ttf字体文件放到这。
//第二步，程序中调用：
AssetManager mgr=getAssets();//得到AssetManager
Typeface tf=Typeface.createFromAsset(mgr, "fonts/ttf.ttf");//根据路径得到Typeface
tv.setTypeface(tf);//设置字体5.代码设置textview部分变色
textview.setText(Html.fromHtml("text1<font color=red>需要改变的字体font>"));6.获取sdcard路径
private String getSDCardPath() {
File sdcardDir = null;
// 判断SDCard是否存在
boolean sdcardExist = Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED);
if (sdcardExist) {
sdcardDir = Environment.getExternalStorageDirectory();
}
return sdcardDir.toString();
} 7.获取应用版本信息
/**
* 获取版本号
* @return 当前应用的版本号
*/
public void getVersion() {
try {
PackageManager manager = this.getPackageManager();
PackageInfo info = manager.getPackageInfo(this.getPackageName(), 0);
versionName = info.versionName;
versionCode = info.versionCode;
} catch (Exception e) {
e.printStackTrace();
}
}8.判断指定service是否在运行
/**
* 判断指定service是否已经在运行
* @param serviceName
* @return
*/
public boolean isWorked(String serviceName) {
ActivityManager myManager = (ActivityManager)this.getSystemService(Context.ACTIVITY_SERVICE);
ArrayList runningService = (ArrayList) myManager.getRunningServices(30);
for(int i = 0 ; iif (runningService.get(i).service.getClassName().toString().equals(serviceName)) {
return true;
}
} 9.判断是否要影藏软键盘
InputMethodManager imm = (InputMethodManager)
getSystemService(Context.INPUT_METHOD_SERVICE);
if (imm.isActive()) {
//隐藏软键盘
imm.toggleSoftInput(0, InputMethodManager.HIDE_NOT_ALWAYS);
} else if (!imm.isActive()) {
//显示软键盘
imm.toggleSoftInput(0, InputMethodManager.HIDE_NOT_ALWAYS);
}
10.判断网络是否连接
//是否连接网络
public boolean isNewworkConnect() {
ConnectivityManager manager = (ConnectivityManager) mContext.
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo net = manager.getActiveNetworkInfo();
if (net != null && net.isConnected()) {
return true;
}
return false;
}11. andorid 布局文件声明引用自定义属性标签
xmlns:app="http://schemas.android.com/apk/res-auto"12. andorid 文字适配多屏幕
res/values/dimens.xml
res/values-small/dimens.xml
res/values-normal/dimens.xml
res/values-large/dimens.xml
res/values-xlarge/dimens.xml13. andorid 异步线程 回调细节
//判断回调activity 是否已经被销毁
if (getActivity().isFinishing()) {
return;
}
14. andorid activity 跳转 不增加内存
Intent i = new Intent("com.you.yourActivityB");
i.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(i);15. andorid 获取 内部存储路径（data/data）
getFilesDir() //获取内部存储路径
或者
String filename = "myfile";
String string = "Hello world!";
FileOutputStream outputStream;
try {
outputStream = openFileOutput(filename, Context.MODE_PRIVATE);
outputStream.write(string.getBytes());
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}16. andorid 发送邮件
Intent intent = new Intent(Intent.ACTION_SENDTO);
intent.setType("message/rfc822");
intent.putExtra(Intent.EXTRA_EMAIL, email);
intent.setData(Uri.parse("mailto:"+email));
intent.putExtra(Intent.EXTRA_SUBJECT, emailSubject);
intent.putExtra(Intent.EXTRA_TEXT, emailContent);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.addFlags(Intent.FLAG_FROM_BACKGROUND);
try {
startActivity(intent);
} catch (android.content.ActivityNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.d("Email error:",e.toString());
}17. andorid 获取控件高宽
@Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
}
或
View.post(new Runnable() {
@Override
public void run() {
}
});18. andorid drawable.xml 多个背景切换
my_drawable.xml
<level-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:maxLevel="0">
<shape android:shape="oval">
<solid android:color="@color/red"/>
<stroke android:width="1sp" android:color="@color/border" />
shape>
item>
<item android:maxLevel="1">
<shape android:shape="oval">
<solid android:color="@color/green"/>
<stroke android:width="1sp" android:color="@color/border" />
shape>
item>
<item android:maxLevel="2">
<shape android:shape="oval">
<solid android:color="@color/blue"/>
<stroke android:width="1sp" android:color="@color/blue" />
shape>
item>
level-list>
MyActivity.java
// myView is a View (or a subclass of View)
// with background set to R.drawable.my_drawable
myView.getBackground().setLevel(0); // Set color to red
myView.getBackground().setLevel(1); // Set color to green
myView.getBackground().setLevel(2); // Set color to blue
// myImageView is an ImageView with its source
// set to R.drawable.my_drawable
myImageView.setImageLevel(0); // Set color to red
myImageView.setImageLevel(1); // Set color to green
myImageView.setImageLevel(2); // Set color to blue19. andorid 检测是否有符合条件的activity
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.parse(url), mimetype);
if (getPackageManager().resolveActivity(intent,
PackageManager.MATCH_DEFAULT_ONLY) != null) {
// someone knows how to handle this mime type with this scheme, don't download.
try {
startActivity(intent);
return;
} catch (ActivityNotFoundException ex) {
if (Config.LOGD) {
Log.d(LOGTAG, "activity not found for " + mimetype
+ " over " + Uri.parse(url).getScheme(), ex);
}
}
20. andorid activity 监听返回键
@Override
public void onBackPressed() {
}21. andorid 判断存储空间是否足够
public static boolean isEnoughSpace(long fileSize) { // 视频缓存是否有足够的空间
LogUtil.d(TAG, "fileSize=" + fileSize + ", 缓存可用=" + new File(getVideoCacheDir()).getUsableSpace());
return new File(getVideoCacheDir()).getUsableSpace() >= fileSize;
}22. android 利用反射检查当前app的通知消息是否被关闭
public class NotificationsUtils {
private static final String CHECK_OP_NO_THROW = "checkOpNoThrow";
private static final String OP_POST_NOTIFICATION = "OP_POST_NOTIFICATION";
public static boolean isNotificationEnabled() {
AppOpsManager mAppOps = (AppOpsManager) GlobalContext.getContext().getSystemService(Context.APP_OPS_SERVICE);
ApplicationInfo appInfo = GlobalContext.getContext().getApplicationInfo();
String pkg = GlobalContext.getContext().getApplicationContext().getPackageName();
int uid = appInfo.uid;
Class appOpsClass = null; /* Context.APP_OPS_MANAGER */
try {
appOpsClass = Class.forName(AppOpsManager.class.getName());
Method checkOpNoThrowMethod = appOpsClass.getMethod(CHECK_OP_NO_THROW, Integer.TYPE, Integer.TYPE, String.class);
Field opPostNotificationValue = appOpsClass.getDeclaredField(OP_POST_NOTIFICATION);
int value = (int)opPostNotificationValue.get(Integer.class);
return ((int)checkOpNoThrowMethod.invoke(mAppOps,value, uid, pkg) == AppOpsManager.MODE_ALLOWED);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return false;
}
}
21. andorid 隐藏软件盘
View view = activity.getCurrentFocus();
if (view == null) {
view = new View(this);
}
//隐藏软键盘
InputMethodManager imm = (InputMethodManager)
getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(view.getWindowToken(), InputMethodManager.HIDE_IMPLICIT_ONLY);
注意：在此activity 再 manifest中不能声明： android:windowSoftInputMode="stateHidden|adjustPan" 属性， 否则无效。21. andorid NestedScrollView 内嵌 viewPager
.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
.support.v4.view.ViewPager
android:id="@+id/other_person_page_viewpage"
android:layout_width="match_parent"
android:layout_height="wrap_content">
.support.v4.view.ViewPager>
.support.v4.widget.NestedScrollView>
22. 跳转到指定app设置页面（用于设置权限）
Intent intent = new Intent();
intent.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
Uri uri = Uri.fromParts("package", getPackageName(), null);
intent.setData(uri);
startActivity(intent);
23.String 便捷格式化
String month = String.format("%02d", (monthOfYear + 1)); //保留2位小数， example: 1 - 01, 10 - 10
String day = String.format("%02d", dayOfMonth);
24. mInflater.inflate返回值
View mView = mInflater.inflate(R.layout.xxxx, parentView); // mView = parentView
View mView = mInflater.inflate(R.layout.xxxx, parentView, false); // mView = R.layout.xxxx25. 计算汉字和英文混合长度
/**
* 计算位数
* @param str
* @return
*/
public static int calculatePlaces(String str)
{
int m = 0;
char arr[] = str.toCharArray();
for(int i=0;ichar c = arr[i];
if((c >= 0x0391 && c <= 0xFFE5)) //中文字符
{
m = m + 2;
}
else if((c>=0x0000 && c<=0x00FF)) //英文字符
{
m = m + 1;
}
}
return m;
} 26.TextView 部分可以点击
SpannableStringBuilder stringBuilder = new SpannableStringBuilder();
SpannableString spannableString;
String color;
int start, end = 0;
for (final EmployeeItem item : employeeEditList.getList()) {
spannableString = new SpannableString(item.getValue()+ "\n" );
color = TextUtils.isEmpty(item.getColor()) ? "a0a0a0" : item.getColor();
start = end;
end += spannableString.length();
spannableString.setSpan(new ForegroundColorSpan(Color.parseColor("#" + color)), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
if (!TextUtils.isEmpty(item.getAction())) {
spannableString.setSpan(new ClickableSpan() {
@Override
public void onClick(View widget) {
switch (item.getAction()) {
case PHONE:
Intent intent = new Intent(Intent.ACTION_DIAL);
intent.setData(Uri.parse("tel:" + item.getValue()));
context.startActivity(intent);
break;
case EMAIL:
Intent intentEmail = new Intent(Intent.ACTION_SENDTO);
intentEmail.setType("message/rfc822");
intentEmail.setData(Uri.parse("mailto:" + item.getValue()));
intentEmail.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intentEmail.addFlags(Intent.FLAG_FROM_BACKGROUND);
try {
EmployeeEditListActivity.this.startActivity(intentEmail);
} catch (ActivityNotFoundException exception) {
showToast("未发现邮件客服端");
}
}
}
}, start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
}
stringBuilder.append(spannableString);
}
mViewHolder.mContentText.setText(stringBuilder);
mViewHolder.mContentText.setMovementMethod(LinkMovementMethod.getInstance());26. 在editText中监听KeyBack返回事件（在输入法之前）。
/**
* Created by User on 2017/11/3.
* 监听输入法返回事件
*/
public class KeyBackEdit extends AppCompatEditText {
public KeyBackEdit(Context context) {
super(context);
}
public KeyBackEdit(Context context, AttributeSet attrs) {
super(context, attrs);
}
public KeyBackEdit(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
public boolean onKeyPreIme(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && mBackKeyListener != null) {
//在输入法之前，拦截返回事件
mBackKeyListener.onBackClick();
}
return super.onKeyPreIme(keyCode, event);
}
public interface BackKeyListener{
void onBackClick();
}
private BackKeyListener mBackKeyListener;
public void setBackKeyListener(BackKeyListener mBackKeyListener) {
this.mBackKeyListener = mBackKeyListener;
}
}27.获取状态栏高度
int statusBarHeight1 = 0;
int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android");
if (resourceId > 0) {
//根据资源ID获取响应的尺寸值
statusBarHeight1 = getResources().getDimensionPixelSize(resourceId);
}28.TextView多行ellipsize
if (textView.getLineCount() > 2) {
int lineEndIndex = textView.getLayout().getLineEnd(1);
String text = textView.getText().subSequence(0, lineEndIndex - 3) + "...";
textView.setText(text);
}29. Aapt2 Exception
由于 gradle 3.0默认开启了Aapt2
在gradle.properties中关闭即可：
android.enableAapt2=false
30.EidtText hint 光标靠右
android:textCursorDrawable="@null"