3.3.代码
1 显示图片所使用的uri：
String imageUri = "http://site.com/image.png"; // from Web
String imageUri = "file:///mnt/sdcard/image.png"; // from SD card
String imageUri = "content://media/external/audio/albumart/13"; // from content provider
String imageUri = "assets://image.png"; // from assets
String imageUri = "drawable://" + R.drawable.image; // from drawables (only images, non-9patch)
注意：使用drawable://除非你真的需要他。时刻要注意使用本地图片加载方法：setImageResource带代替ImageLoader。2 监听网络变化
系统常量：ConnectivityManager.CONNECTIVITY_ACTION action : "android.net.conn.CONNECTIVITY_CHANGE"
//在Androidmanifest中加入
//<uses-permission android:name="android.permission.ACCESS_NETWOR
// 注册网络监听广播
IntentFilter intentFilter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
mContext.registerReceiver(mNetWorkChangeReceiver, intentFilter);3 Toast消息框重复提示
//解决思路：判空处理
private Toast mToast;
public void showToast(String text) {
if(mToast == null) {
mToast = Toast.makeText(TestActivity.this, text, Toast.LENGTH_SHORT);
} else {
mToast.setText(text);
mToast.setDuration(Toast.LENGTH_SHORT);
}
mToast.show();
}
//SuperToast 类库 使用避免重复
if (mSuperToast!=null){
mSuperToast.setText("message:"+count);
mSuperToast .setDuration(AttributeUtils.getDuration(getActivity()));
mSuperToast .setFrame(AttributeUtils.getFrame(getActivity()));
mSuperToast .setColor(AttributeUtils.getColor(getActivity()));
mSuperToast .setAnimations(AttributeUtils.getAnimations(getActivity()));
}else{
mSuperToast= new SuperToast(getActivity());
mSuperToast.setText("SuperToast" + count);
mSuperToast .setDuration(AttributeUtils.getDuration(getActivity()));
mSuperToast .setFrame(AttributeUtils.getFrame(getActivity()));
mSuperToast .setColor(AttributeUtils.getColor(getActivity()));
mSuperToast .setAnimations(AttributeUtils.getAnimations(getActivity()));
// mSuperToast .setColor(AttributeUtils.getColor(getActivity()));
}
mSuperToast.cancelAllSuperToasts();
mSuperToast.show();4 TextView加粗字体
//在代码中设置：
TextView tv = (TextView)findViewById(R.id.tv);
TextPaint tp = tv.getPaint();
tp.setFakeBoldText(true);
//在xml中设置
android:textStyle="bold"5 监听Back键按下事件
/**
* 监听Back键按下事件,方法1:
* 注意:
* super.onBackPressed()会自动调用finish()方法,关闭
* 当前Activity.
* 若要屏蔽Back键盘,注释该行代码即可
*/
@Override
public void onBackPressed() {
super.onBackPressed();
System.out.println("按下了back键 onBackPressed()");
}
/**
* 监听Back键按下事件,方法2:
* 注意:
* 返回值表示:是否能完全处理该事件
* 在此处返回false,所以会继续传播该事件.
* 在具体项目中此处的返回值视情况而定.
*/
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
System.out.println("按下了back键 onKeyDown()");
return false;
}else {
return super.onKeyDown(keyCode, event);
}
} 6 判断Activity属于任务栈中
/**
* 判断是否存在Activity
*
* @param context 上下文
* @param packageName 包名
* @param className activity全路径类名
* @return {@code true}: 是<br>{@code false}: 否
*/
public static boolean isActivityExists(Context context, String packageName, String className) {
Intent intent = new Intent();
intent.setClassName(packageName, className);
return !(context.getPackageManager().resolveActivity(intent, 0) == null ||
intent.resolveActivity(context.getPackageManager()) == null ||
context.getPackageManager().queryIntentActivities(intent, 0).size() == 0);
}7 ActionBar 返回键处理
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home://关键代码
onBackPressed();
break;
}
return true;
}8 RecycleView加载更多
//原始分页
/* mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
private boolean loading = true;
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
int visible = layoutManager.getChildCount();
int total = layoutManager.getItemCount();
int past=layoutManager.findFirstCompletelyVisibleItemPosition();
if (loading) {
//previousTotal 未全局变量
if (total > previousTotal) {
loading = false;
previousTotal = total;
}
}
if (!loading&&((visible + past) >= total)){
Log.d("mRecyclerView", "visible:" + visible + " past:" + past + " total:" + total
+" previousTotal:"+ previousTotal+" loading："+loading);
mPage++;
startSearch();
loading = true;
}
}
});*/ 9 EditText获取焦点状态
EditText searchView = (EditText)findViewById(R.id.search_text);
searchView.setOnFocusChangeListener(new android.view.View.
OnFocusChangeListener() {
@Override
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus) {
// 此处为得到焦点时的处理内容
} else {
// 此处为失去焦点时的处理内容
}
}}); 10 SD卡总容量
public long getSDAllSize(){
//取得SD卡文件路径
File path = Environment.getExternalStorageDirectory();
StatFs sf = new StatFs(path.getPath());
//获取单个数据块的大小(Byte)
long blockSize = sf.getBlockSize();
//获取所有数据块数
long allBlocks = sf.getBlockCount();
//返回SD卡大小
//return allBlocks * blockSize; //单位Byte
//return (allBlocks * blockSize)/1024; //单位KB
return (allBlocks * blockSize)/1024/1024; //单位MB
} 11 SD卡剩余空间
SD卡剩余空间
public long getSDFreeSize(){
//取得SD卡文件路径
File path = Environment.getExternalStorageDirectory();
StatFs sf = new StatFs(path.getPath());
//获取单个数据块的大小(Byte)
long blockSize = sf.getBlockSize();
//空闲的数据块的数量
long freeBlocks = sf.getAvailableBlocks();
//返回SD卡空闲大小
//return freeBlocks * blockSize; //单位Byte
//return (freeBlocks * blockSize)/1024; //单位KB
return (freeBlocks * blockSize)/1024 /1024; //单位MB
} 12 SD卡是否存在
private boolean ExistSDCard() {
if(android.os.Environment.getExternalStorageState()
.equals(
android.os.Environment.MEDIA_MOUNTED)) {
return true;
} else
return false;
}13 判断是否为合法IP
/**
* 判断是否为合法IP
*
* @return the ip
*/
public static boolean isIP(String ipAddress) {
String ip ="((?:(?:25[0-5]|2[0-4]\d|((1\d{2})|([1-9]? \d)))\.){3}(?:25[0-5]|2[0-4]\d|((1\d{2})|([1-9]?\d))))";
Pattern pattern = Pattern.compile(ip);
Matcher matcher = pattern.matcher(ipAddress);
return matcher.matches();
} 14 获取手机可用内存和总内存：
private String[] getTotalMemory() {
String[] result = {"",""}; //1-total 2-avail
ActivityManager.MemoryInfo mi = new ActivityManager.MemoryInfo();
mActivityManager.getMemoryInfo(mi);
long mTotalMem = 0;
long mAvailMem = mi.availMem;
String str1 = "/proc/meminfo";
String str2;
String[] arrayOfString;
try {
FileReader localFileReader = new FileReader(str1);
BufferedReader localBufferedReader = new BufferedReader(localFileReader, 8192);
str2 = localBufferedReader.readLine();
arrayOfString = str2.split("\\s+");
mTotalMem = Integer.valueOf(arrayOfString[1]).intValue() * 1024;
localBufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
result[0] = Formatter.formatFileSize(this, mTotalMem);
result[1] = Formatter.formatFileSize(this, mAvailMem);
Log.i(TAG, "meminfo total:" + result[0] + " used:" + result[1]);
return result;
} 14 获取屏幕高度
private void getWeithAndHeight(){
//这种方式在service中无法使用，
DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
String width = dm.widthPixels; //宽
String height = dm.heightPixels; //高
//在service中也能得到高和宽
WindowManager mWindowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
width = mWindowManager.getDefaultDisplay().getWidth();
height = mWindowManager.getDefaultDisplay().getHeight();
} 15 获取屏幕密度
public static float getDensity(Context ctx) {
DisplayMetrics metrics = new DisplayMetrics();
WindowManager wm = (WindowManager) ctx.getSystemService(Context.WINDOW_SERVICE);
wm.getDefaultDisplay().getMetrics(metrics);
return metrics.density;}
16 应用于View的获取控件实例
/**
* 应用于View的获取控件实例
* @param view
* @param id
* @return
*/
@SuppressWarnings("unchecked")
public static <T extends View> T $(View view, int id) {
return (T) view.findViewById(id);
} 17 应用于Activity的获取控件实例
/**
* 应用于Activity的获取控件实例
*
* @param activity
* @param id
* @return
*/
@SuppressWarnings("unchecked")
public static <T extends View> T $(Activity activity, int id) {
return (T) activity.findViewById(id);
} 18 shouldOverrideUrlLoading(WebView view, String url)被废弃
在Android N中
shouldOverrideUrlLoading(WebView view, String url)被废弃，
改为shouldOverrideUrlLoading(WebView view, WebResourceRequest request)，
我们可以通过request.getUrl()来获取url。
@Override
public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
return shouldOverrideUrlLoading(view, request.getUrl().toString());
}19 Android系统键盘显示隐藏监听,显示则隐藏，没有显示则弹出
InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
imm.toggleSoftInput(0, InputMethodManager.HIDE_NOT_ALWAYS);
通过判断高度来判断键盘状态
detailMainRL = (RelativeLayout) findViewById(R.id.home_news_detail_main_rl);
detailMainRL.getViewTreeObserver().addOnGlobalLayoutListener(
new OnGlobalLayoutListener(){
@Override
public void onGlobalLayout()
{
int heightDiff = detailMainRL.getRootView().getHeight() - detailMainRL.getHeight();
Log.v(TAG, "detailMainRL.getRootView().getHeight() = " + detailMainRL.getRootView().getHeight());
Log.v(TAG, "detailMainRL.getHeight() = " + detailMainRL.getHeight());
if (heightDiff > 100)
{ // 说明键盘是弹出状态
Log.v(TAG, "键盘弹出状态");
commentBoxRL.setVisibility(View.VISIBLE);
} else{
Log.v(TAG, "键盘收起状态");
commentBoxRL.setVisibility(View.GONE);
}
}
}); 20 Android ActionBar 菜单隐藏
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
Log.e("isMenuShuffle",isMenuShuffle + "");
if(isMenuShuffle)
{
menu.findItem(R.id.main_toolbar_shuffle).setVisible(true);
}else
{
menu.findItem(R.id.main_toolbar_shuffle).setVisible(false);
}
return super.onPrepareOptionsMenu(menu);
} mPopupWindow=new PopupWindow(selectView, ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT,true);
mPopupWindow.setFocusable(false);
mPopupWindow.setOutsideTouchable(false);
// 这个是为了点击“返回Back”也能使其消失，并且并不会影响你的背景
mPopupWindow.setBackgroundDrawable(new BitmapDrawable());
//本方法必须写在最后，否则会存在部分手机兼容问题
mPopupWindow.showAtLocation(findViewById(R.id.EditActivity_rootView), Gravity.BOTTOM,0,0); //date中compareTo的用法。也是比较时间大小的，相等返回0，大于返回1，小于返回-1.
public class Demo8 {
public static void main(String[] args) throws ParseException {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
Date oldDate1 = format.parse("2012-05-12 15:16:00"); //这里时间可以自己定
Date oldDate2 = format.parse("2011-05-12 15:16:00"); //这里时间可以自己定
System.out.println(oldDate1.compareTo(oldDate2)); //判断,如果时间在这时间后,就执行后面操作
}
} 23 android 动态修改menu item的内容title
1）全局量：
MenuItem gMenuItem=NULL;
2）//创建菜单时keep
@Override
public boolean onCreatePanelMenu(int featureId, Menu menu){
getMenuInflater().inflate(R.menu.menu, menu);
gMenuItem= menu.findItem(R.id.action_Seach);
return true;
}
3）需要时修改
//ANY PLACE
if(gMenuItem!=NULL){
gMenuItem.setTitle("Changed");
}24 判断当前线程是否为主线程
public boolean isMainThread() {
return Looper.getMainLooper() == Looper.myLooper();
}Last updated
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