环信即时通讯
Q：找不到AsyncTaskCompatl类 NoClassDefFoundError: support/v4/os/AsyncTaskCompat
A：因为AsyncTaskCompat此类已在API26.0.0以上中被弃用了，所以需要更改compileSdkVersion最高26，同理targetSdkVersion和其它依赖也需要适当降低版本。
Service里启动Activity延时问题
Q：Service里监听按键然后启动Activity，大约延时2-3s左右才启动
A：使用延时意图
intent intent = new Intent(context, AnotherActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);
try {
pendingIntent.send();
} catch (PendingIntent.CanceledException e) {
e.printStackTrace();
}
getSupportFragmentManager()报红
app包下FragmentManager用：
Fragmentmanager fragmentManager=getFragmentManager();
v-4包的FragmentManager用：
FragmentManager fragmentManager=getSupportFragmentManager() 获取
但是getSupportFragmentManager() 有其运用范围，只能在部分activity中运用。当遇到getSupportFragmentManager() 没定义的问题时，修改下activity为FragmentActivity或者AppCompatActivity。
旋转动画的时候会有停顿
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<rotate
android:duration="2000"
android:pivotX="50%"
android:pivotY="50%"
android:repeatCount="-1"
android:fromDegrees="0"
android:toDegrees="359" />
</set>
Animation rotateAnimation = AnimationUtils.loadAnimation(this, R.anim.rotate_anim);
//解决旋转有停顿
LinearInterpolator lir = new LinearInterpolator();
rotateAnimation.setInterpolator(lir);
mIvLoading.startAnimation(rotateAnimation);
Error: Program type already present: android.support.v4.app.INotificationSideChannel
当项目使用API28对应的是android9.0，当AndroidStudio运行项目的时候出现编译错误：Error: Program type already present: android.support.v4.app.INotificationSideChannel，这意思是v4包冲突了。
首先，查找一下自己的文件里是否存在v4包重复的，搜索之后发现没有出现重复，针对这个问题查看了网上一些资料，发现这个问题是AndroidX版本引起的。有以下两种解决方法：
1、Refactor-->Migrate to AndroidX
2、向gradle.properties添加以下内容：
android.enableJetifier=true
android.useAndroidX=true
Android与AndroidX包重复问题详情可查看这篇文章：https://www.jianshu.com/p/1466ebefe4d0
如果SDK不是28的版本，可在Terminal窗口复制命令gradlew clean build --stacktrace去查看详细信息针对性去解决问题~
zip4j jar包使用中遇到解压文件名字部分出现乱码
ZipFile zipFile = new ZipFile(zipfilenow.getAbsolutePath());
zipFile.setFileNameCharset(getCharset(zipfilenow.getPath()));
/**
* 判断文件的编码格式
*
* @param fileName
* @return
*/
public static String getCharset(String fileName) {
BufferedInputStream bis = null;
String charset = "GBK";
byte[] first3Bytes = new byte[3];
try {
boolean checked = false;
bis = new BufferedInputStream(new FileInputStream(fileName));
bis.mark(0);
int read = bis.read(first3Bytes, 0, 3);
if (read == -1)
return charset;
if (first3Bytes[0] == (byte) 0xFF && first3Bytes[1] == (byte) 0xFE) {
charset = "UTF-16LE";
checked = true;
} else if (first3Bytes[0] == (byte) 0xFE
&& first3Bytes[1] == (byte) 0xFF) {
charset = "UTF-16BE";
checked = true;
} else if (first3Bytes[0] == (byte) 0xEF
&& first3Bytes[1] == (byte) 0xBB
&& first3Bytes[2] == (byte) 0xBF) {
charset = "UTF-8";
checked = true;
}
bis.mark(0);
if (!checked) {
while ((read = bis.read()) != -1) {
if (read >= 0xF0)
break;
if (0x80 <= read && read <= 0xBF) // 单独出现BF以下的，也算是GBK
break;
if (0xC0 <= read && read <= 0xDF) {
read = bis.read();
if (0x80 <= read && read <= 0xBF) // 双字节 (0xC0 - 0xDF)
// (0x80 - 0xBF),也可能在GB编码内
continue;
else
break;
} else if (0xE0 <= read && read <= 0xEF) {// 也有可能出错，但是几率较小
read = bis.read();
if (0x80 <= read && read <= 0xBF) {
read = bis.read();
if (0x80 <= read && read <= 0xBF) {
charset = "UTF-8";
break;
} else
break;
} else
break;
}
}
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (bis != null) {
try {
bis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return charset;
}
