Convert .p7b file to .pem

openssl pkcs7 -print_certs \
-in file.p7b \
-out file.pem

Export .pem with private key in .p12

openssl pkcs12 -export \
-name aliasName \
-in file.pem \
-inkey file.key \
-out file.p12

Import .p12 file in keystore

keytool -importkeystore \
-srcstoretype pkcs12 \
-srckeystore file.p12 \
-destkeystore file.jks