利用多线程读取文件，记录单词出现的次数

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.LineNumberReader;
import java.io.OutputStreamWriter;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

public class Test2 {
public static void main(String[] args) throws Exception {
//开启3个线程读取文件不同位置的数据

    Thread t1=new Thread(new Runnable() {
                public void run() {
                    try {
                        mapTask(1,100,"E:\\java增强\\day06\\day06\\words.txt");
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }

            });

Thread t2=new Thread(new Runnable() {
                public void run() {
                    try {
                        mapTask(101,200,"E:\\java增强\\day06\\day06\\words.txt");
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }

            });

Thread t3=new Thread(new Runnable() {
                public void run() {
                    try {
                        mapTask(201,400,"E:\\java增强\\day06\\day06\\words.txt");
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            });

//开启线程

t1.start();
    t2.start();
    t3.start();

//谁调用join就先执行完，然后回到主线程（主线程main）

t1.join();
    t2.join();
    t3.join();

//开启汇总的reduce任务

Thread t4=new Thread(new Runnable() {
        public void run() {
            try {
                reduceTask("E:\\\\java增强\\\\day06\\\\day06\\\\result.txt");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
    t4.start();
}

//读取文件的方法

public static void mapTask(int StartNum,int EndNum,String path) throws Exception {
    Map<String,Integer>map=new HashMap<>();

//读取文件（一行一行的读）

LineNumberReader lr = new LineNumberReader(new FileReader(new File(path)));
    //lr.getLineNumber();
    String line=null;
    while((line=lr.readLine())!=null) {

//获取当前行号

int num=lr.getLineNumber();
        if(num>=StartNum && num<=EndNum) {
            String[] words = line.split("\\s");
            for (String word : words) {
                Integer n = map.getOrDefault(word, 0);
                n++;
                map.put(word, n);
                }

                }   
            }

    BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(
                 new FileOutputStream(new File("E:\\java增强\\day06\\day06\\result.txt"),true)));
            Set<Entry<String, Integer>> entrySet = map.entrySet();
            for (Entry<String, Integer> entry : entrySet) {
                //System.out.println(entry.toString());
                bw.write(entry.toString());
                bw.newLine();
            }
            bw.flush();//通过将所有已缓冲输出写入底层流来刷新此流。
            bw.close();
            lr.close();

            }

//读取新文件，遍历，并排序

public static void reduceTask(String path) throws Exception {
        Map<String,Integer>map=new HashMap<>();
        BufferedReader br = new BufferedReader(new FileReader(path));
        String line=null;
        while((line=br.readLine())!=null) {
            String[] words = line.split("=");
            Integer count = map.getOrDefault(words[0], 0);
            count+=Integer.parseInt(words[1]);
            map.put(words[0], count);
        }
        Set<Entry<String, Integer>> entrySet = map.entrySet();
        for (Entry<String, Integer> entry : entrySet) {
            System.out.println(entry);
        }
        br.close();

        }
}