细细看，清单文件中先加权限
android.permission.REQUEST_INSTALL_PACKAGES
1保证已有外部读写权限：
2
implementation ‘com.yanzhenjie:permission:2.0.3’
3
安装apk相关代码

File file = ...;

AndPermission.with(this)
    .install()
    .file(file)
    .start();

​​https://yanzhenjie.com/AndPermission/cn/install/​​

​​https://github.com/yanzhenjie/AndPermission​​