How to parse PCAP files ?

1). http://jnetpcap.com/node/907

If you are using Java:

1. you can read offline pcap file like this (all of the packets):
http://jnetpcap.com/node/905

2. Then, I have no Idea how to change the pcap file to Txt files but you can extract necessary information and save them one by one in the Txt files.

in order to extract information, you can do like this:
http://jnetpcap.com/tutorial/usage

2). https://github.com/kaitoy/pcap4j

Pcap4J is a Java library for capturing, crafting and sending packets. Pcap4J wraps a native packet capture library(libpcap or WinPcap) via JNA and provides you Java-Oriented APIs.