安装应用一般需要添加的权限

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.REPLACE_EXISTING_PACKAGE" />
<uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />

在AndroidManifest.xml文件中application中添加如下权限，该权限适用于Android 10.0

android:requestLegacyExternalStorage="true"
android:usesCleartextTraffic="true"

判断点击文件是否为apk,并且适配Android 5.0 到Android 10.0

导入包：import androidx.core.content.FileProvider;

else if(TypeFilter.getInstance().isApkFile(item_ext)){
   
   if(file.exists()) {
      if(mReturnIntent) {
         returnIntentResults(file);
         
      } else {
try {
   Intent installIntent = new Intent();
   installIntent.setAction(Intent.ACTION_VIEW);
   Uri apkUri = FileProvider.getUriForFile(getApplicationContext(), "com.softwinner.explore.fileprovider", file);///-----ide文件提供者名
   int version = android.os.Build.VERSION.SDK_INT;
   if (version > 24) {//android 7.0-10.0及以上版本
      installIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
      installIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
      installIntent.setDataAndType(apkUri, "application/vnd.android.package-archive");
   } else {//android 5.0-7.0
      installIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
      installIntent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");

   }
   startActivity(installIntent);
}catch (IllegalArgumentException e){

}
      }
   }
}

在AndroidManifest.xml文件中添加provider

<provider
    android:authorities="com.softwinner.explore.fileprovider"
    android:name="androidx.core.content.FileProvider"
    android:exported="false"
    android:grantUriPermissions="true">
    <meta-data
        android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/filepaths" />
</provider>

在res目录下面创建一个xml文件，在该文件中创建filepaths文件

<?xml version="1.0" encoding="utf-8"?>

<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <root-path path="" name="cmrootfile" />
    <files-path path="" name="cmfiles" />
    <cache-path path="" name="cmcache" />
    <external-path path="" name="cmexternal" />
    <external-files-path path="" name="cmexternalfile" />
    <external-cache-path path="" name="cmexternalcache" />
</paths>

备注说明：
Android10 中使用FileProvider需要导入FileProvider包

import androidx.core.content.FileProvider;

在build.gradle文件中添加androidx的依赖

implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'