import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
class IP implements Serializable {
private static final long serialVersionUID = -8903000680469719698L;
private String ip = "";
private int count;
public IP(String ip2, Integer integer) {
this.ip = ip2;
this.count = integer;
}
public int getCount() {
return count;
}
public String getIp() {
return ip;
}
public void setCount(int count) {
this.count = count;
}
public void setIp(String ip) {
this.ip = ip;
}
}
/**
* 1、海量日志数据，提取出某日访问百度次数最多的那个IP。
*
* 首先是这一天，并且是访问百度的日志中的IP取出来，逐个写入到一个大文件中。注意到IP是32位的，最多有个2^32个IP。同样可以采用映射的方法，
* 比如模1000
* ，把整个大文件映射为1000个小文件，再找出每个小文中出现频率最大的IP（可以采用hash_map进行频率统计，然后再找出频率最大的几个）及相应的频率
* 。然后再在这1000个最大的IP中，找出那个频率最大的IP
*
*
*/
public class No2 {
static String fileLoc = "D:\\bigdata_ip.txt";
public static void findIp() throws IOException, ClassNotFoundException {
long start = System.currentTimeMillis();
hashToSmallFiles();
long end1 = System.currentTimeMillis();
System.out.println("将大文件映射成小文件，用时：" + (end1 - start) + "毫秒");
System.out.println("映射到小文件完成，开始统计每个小文件中出现频率最高的ip");
long start1 = System.currentTimeMillis();
List<IP> list = countEverySmallFile();
long end2 = System.currentTimeMillis();
System.out.println("统计所有文件共用时：" + (end2 - start1) + " 毫秒");
System.out.println("统计完成，开始计算所有ip中出现频率最高的ip");
IP ip = calculateResult(list);
System.out.println("访问次数最多的ip是：" + ip.getIp() + ":" + ip.getCount());
long end = System.currentTimeMillis();
System.out.println("公用时：" + (end - start) + "毫秒");
}
/**
* 从每个文件出现频率最高ip中，计算出所有文件中出现频率最高ip。
*
* @param list
*/
private static IP calculateResult(List<IP> list) {
IP[] ips = new IP[list.size()];
ips = list.toArray(ips);
int max = 0;
for (int j = 1; j < ips.length; j++) {
if (ips[j].getCount() > ips[max].getCount()) {
max = j;
}
}
return ips[max];
}
/**
* 统计生成的每一个小文件，返回一个List,这个List的每一项就是每个小文件的统计结果，即每个小文件中出现频率最高的ip和出现次数
*
* @return
* @throws FileNotFoundException
* @throws IOException
*/
private static List<IP> countEverySmallFile() throws FileNotFoundException, IOException {
List<IP> list = new ArrayList<IP>();
for (int i = 0; i < 1024; i++) {
File file = new File(fileLoc + i + ".txt");
if (file.exists()) {
long startTime = System.currentTimeMillis();
BufferedReader br1 = new BufferedReader(new FileReader(file));
String ip1 = "";
HashMap<String, Integer> hm = new HashMap<String, Integer>();
while ((ip1 = br1.readLine()) != null) {
if (!hm.containsKey(ip1)) {
hm.put(ip1, 1);
} else {
hm.put(ip1, hm.get(ip1) + 1);
}
}
IP[] ips = new IP[hm.size()];
int index = 0;
for (String temp : hm.keySet()) {
ips[index] = new IP(temp, hm.get(temp));
index++;
}
int max = 0;
for (int j = 1; j < ips.length; j++) {
if (ips[j].getCount() > ips[max].getCount()) {
max = j;
}
}
list.add(ips[max]);
long endTime = System.currentTimeMillis();
System.out.println("已经统计文件：" + fileLoc + i + ".txt，用时：" + (endTime - startTime) + " 毫秒");
}
}
return list;
}
/**
* 将打文件hash成1024个小文件
*
* @throws FileNotFoundException
* @throws IOException
*/
private static void hashToSmallFiles() throws FileNotFoundException, IOException {
BufferedReader br = new BufferedReader(new FileReader(fileLoc));
String ip = "";
HashMap<String, FileWriter> fileWriters = new HashMap<String, FileWriter>();
while ((ip = br.readLine()) != null) {
int tmp = Math.abs(ip.hashCode() % 1024);
String fileName = fileLoc + tmp + ".txt";
FileWriter fw = null;
if (fileWriters.containsKey(fileName)) {
fw = fileWriters.get(fileName);
} else {
fw = new FileWriter(fileName, true);
fileWriters.put(fileName, fw);
}
fw.write(ip + "\n");
}
br.close();
for (FileWriter ff : fileWriters.values()) {
ff.close();
}
}
/**
* 随机生成ip地址，生成大文本文件
*
* @throws IOException
*/
private static void generateFile() throws IOException {
FileWriter fw = new FileWriter(fileLoc, true);
for (int i = 0; i < 100000000; i++) {
for (int j = 0; j < 100000000; j++) {
fw.write(generateIp() + "\n");
}
}
fw.close();
System.out.println("done");
}
/**
* 随机生成ip地址
*
* @return
*/
private static String generateIp() {
String ip = "";
for (int i = 0; i < 4; i++) {
int temp = (int) (Math.random() * 255);
ip += temp + ".";
}
return ip.substring(0, ip.length() - 1);
}
public static void main(String[] args) {
try {
findIp();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
