java 从指定行读文件，执行系统命令

 

import java.util.*;
import java.io.*;

public class Example {
    public static void main(String[] args){
        readFile("proxy.txt",0);
        readFile("proxy.txt",1);
        readFile("proxy.txt",4);
        execSystemCmd("notepad"); // windows cmd
        execSystemCmd("ls /home/whucs");
        execSystemCmd("tail -n /home/whucs/vote.py");
        execSystemCmd("wc -l php-fpm.log"); // count lines of a file. 500MB ~ 2s
    }
    
    public static void readFile(String path, int beginLine) {
        FileInputStream inputStream = null;
        Scanner sc = null;
        try {
            inputStream = new FileInputStream(path);
            sc = new Scanner(inputStream, "UTF-8");
            int begin = 0;
            if (beginLine == 0) beginLine = 1;
            while (sc.hasNextLine()) {
                begin ++;
                if (begin >= beginLine) {
                    String line = sc.nextLine();
                    // TODO...
                    System.out.println(line);
                } else {
                    sc.nextLine();
                }
            }
            if (begin < beginLine) {
                System.out.println("error! beginLine > file's total lines.");
            }
            inputStream.close();
            sc.close();
        } catch (IOException e) {
            System.out.println("FileReader IOException!");
            e.printStackTrace();
        }
    }
    
    public static void execSystemCmd(String cmd) {
        String outPut = null;
        System.out.println("cmd=" + cmd);
        try 
        {
            Process p = Runtime.getRuntime().exec(cmd);
            InputStream is = p.getInputStream();
            BufferedReader br = new BufferedReader(new InputStreamReader(is));
            StringBuilder buf = new StringBuilder();
            String line = null;
            while ((line = br.readLine()) != null)    buf.append(line + "\n");            
            outPut = buf.toString();
            System.out.printf("outPut = %s",outPut);
        } 
        catch (IOException e) 
        {
            e.printStackTrace();
        }
    }
    
}