13-ReadPacketFile.md

介绍

从本文开始将对 Pcap4J（下文简称为 p4）提供的样例代码进行注释讲解，期间还包括了对 Pcap 原理的解读

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每篇文章讲解一个样例，目录如下： 目录

• ReadPacketFile
  • 原理
  • 步骤
  • 实现
  • 总结

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ReadPacketFile

原理

没有什么好介绍的原理，之前都说过了

步骤

略

实现

package org.pcap4j.sample;

import java.io.EOFException;
import java.util.concurrent.TimeoutException;
import org.pcap4j.core.NotOpenException;
import org.pcap4j.core.PcapHandle;
import org.pcap4j.core.PcapHandle.TimestampPrecision;
import org.pcap4j.core.PcapNativeException;
import org.pcap4j.core.Pcaps;
import org.pcap4j.packet.Packet;

@SuppressWarnings("javadoc")
public class ReadPacketFile {

  private static final int COUNT = 5;

  private static final String PCAP_FILE_KEY = ReadPacketFile.class.getName() + ".pcapFile";
  private static final String PCAP_FILE =
      System.getProperty(PCAP_FILE_KEY, "src/main/resources/echoAndEchoReply.pcap");

  private ReadPacketFile() {}

  public static void main(String[] args) throws PcapNativeException, NotOpenException {
    PcapHandle handle;
    try {
      // 时间戳精度为纳秒
      handle = Pcaps.openOffline(PCAP_FILE, TimestampPrecision.NANO);
    } catch (PcapNativeException e) {
      handle = Pcaps.openOffline(PCAP_FILE);
    }

    for (int i = 0; i < COUNT; i++) {
      try {
        Packet packet = handle.getNextPacketEx();
        System.out.println(packet);
      } catch (TimeoutException e) {
      } catch (EOFException e) {
        System.out.println("EOF");
        break;
      }
    }

    handle.close();
  }
}

总结

GetNextPacketEx 读取离线 pcap 文件