1)用java编写一个可执行程序 CSVSort.exe,用于CSV文件的
排序,并输出运行所需的时间(以毫秒为单位)。命令行如下:
(before.csv 中的内容是这样的;
"100,000","BBB","CCC"
"200,000","AAA","AAA"
)
CSVSort.exe <输入文件> <输出文件> <排序的列的编号>
《例子》下面的程序将before.csv的每行数据,按第2列排序,
结果输出到after.csv(如添付文件)
CSVSort.exe before.csv after.csv 22)用java编写一个CSV文件产生的程序,一共10000行,每行为
5列数字,每个数字取1到99999之间的随机数,按格式"XXXXX"输出,
如果不足5位,前面补零。比如说,一行的数据可能如下: "00001","12345","45678","00456","03456"
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Random;public class CSV2 { public static void main(String[] args) throws IOException {
long t0 = System.currentTimeMillis();
Random ran = new Random();
String line = System.getProperty("line.separator");
File file = new File("random.csv");
BufferedWriter bw = new BufferedWriter(new FileWriter(file));
for(int i=1; i<=50000;i++) {
int num = ran.nextInt(99999) + 1;
bw.write("\"");
bw.write(String.format("%05d",num));
bw.write("\"");
if(i%5!=0) {
bw.write(",");
}else{
bw.write(line);
}
}
bw.close();
long time = System.currentTimeMillis() - t0;
System.out.printf("耗时:%d(ms)%n", time);
}
}
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;public class CSVSort { public static void main(String[] args) {
long t0 = System.currentTimeMillis();
if (args.length != 3) {
System.out.println("错误[1]:参数不正确!");
System.out.println("使用方法: CSVSort <源文件名> <新文件名> <排序列号>");
System.exit(1);
}
File file1 = new File(args[0]);
if (!file1.exists()) {
System.out.println("错误[2]: " + args[0] + " 文件没有找到!");
System.exit(2);
}
File file2 = new File(args[1]);
if (file2.exists()) {
System.out.println("错误[3]: " + args[1] + " 文件已经存在!");
System.exit(3);
}
List<String> list = readFile(file1);
int tmp = list.get(0).split(",").length; // 计算总共的列数
int col = Integer.parseInt(args[2]);
if (col < 1 || col > tmp) {
list.clear();
System.out.println("错误[4]: 列号不正确!");
System.exit(4);
}
sort(list, col);
writeFile(file2, list);
long time = System.currentTimeMillis() - t0;
System.out.printf("耗时:%d(ms)%n", time);
} public static List<String> readFile(File file) {
BufferedReader br = null;
List<String> list = new ArrayList<String>();
try {
br = new BufferedReader(new FileReader(file));
String str = "";
while ((str = br.readLine()) != null) {
str = str.trim();
if (str.length() > 0) {
list.add(str);
}
}
br.close();
} catch (IOException e) {
e.printStackTrace();
}
return list;
} public static void writeFile(File file, List<String> list) {
BufferedWriter bw = null;
try {
String line = System.getProperty("line.separator");
bw = new BufferedWriter(new FileWriter(file));
for (String str : list) {
bw.write(str);
bw.write(line);
}
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
} public static void sort(List<String> list, final int column) {
Collections.sort(list, new Comparator<String>() {
public int compare(String str1, String str2) {
String[] str1s = str1.split(",");
String[] str2s = str2.split(",");
return str1s[column - 1].compareTo(str2s[column - 1]);
}
});
}
}随后编译一下,指定个 Main-Class,打个 jar 包,名为 CSVSort.jar,
再新建一个 sort.bat 文件,文件内容如下:[code=BatchFile]@echo off
java -jar CSVSort.jar %1 %2 %3
echo on[/code]然后使用 sort <文件1> <文件2> <列号> 就可以运行了。