如何使用 java 搜索文件中存在的日期格式 20180603？

Question

我有一个文件，其中的单词由“|”分隔。这里我需要搜索日期“20180603”。但是，我无法硬编码要搜索的值。日期格式固定为 YYYYDDMM，日期可以是任何格式。我需要将此处显示的日期转换为今天的日期（系统日期）。

我正在粘贴外部文件的外观（只是我在相关值周围添加了星号以强调）：

00000548|WILLIAM|HUBER|WH5718||N|**20180306**|SVP-TECHNICAL FIELD SERVICES|06|329000.00 |0.00 |0.00 |205440.00 |0.00 |0.00 |0.00 |0.00 |0.00 |55000.00 |0.00 |0.00 |0.00 |1600.00 |0.00 |0.00 |0.00 |0.00 |225502.08 |0.00 |0.00 |0.00 |27629.91 |36717.17 |0.00 |33.000 |0.000 |F
00000828|NORBERTA|NOGUERA|NN1413||N|**20180306**|VP-SPECIAL PROJECTS|05|213000.00 |0.00 |88464.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |86502.87 |0.00 |0.00 |0.00 |16811.41 |15023.40 |0.00 |33.000 |0.000 |F
00001308|ERROL|PHIPPS|EP4499||N|00000548|WILLIAM|HUBER|WH5718||N|20180306|SVP-TECHNICAL FIELD SERVICES|06|329000.00 |0.00 |0.00 |205440.00 |0.00 |0.00 |0.00 |0.00 |0.00 |55000.00 |0.00 |0.00 |0.00 |1600.00 |0.00 |0.00 |0.00 |0.00 |225502.08 |0.00 |0.00 |0.00 |27629.91 |36717.17 |0.00 |33.000 |0.000 |F
00000828|NORBERTA|NOGUERA|NN1413||N|**20180306**|VP-SPECIAL PROJECTS|05|213000.00 |0.00 |88464.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |0.00 |86502.87 |0.00 |0.00 |0.00 |16811.41 |15023.40 |0.00 |33.000 |0.000 |F
00001308|ERROL|PHIPPS|EP4499||N|**20180306**|VP-LEGAL BUSINESS HEAD|05|241000.00 |0.00 |94365.00 |0.00 |0.00 ||VP-LEGAL BUSINESS HEAD|05|241000.00 |0.00 |94365.00 |0.00 |0.00 |

我已经尝试了很多问题，但都没有成功。

下面是我试过的代码；

public class ReadFile {

    public static void main(String[] args) throws IOException {
        File f1= new File("C:/Users/kumar.sushobhan/Desktop/ESPYTR_Big_file_EXEC.dat");
        //File f1= new File("C:/Users/kumar.sushobhan/Desktop/h.txt");
        String words[]= null;
        FileReader fr= new FileReader(f1);
        BufferedReader br= new BufferedReader(fr);

        String s;
        int c = 0;

        String regex= "\d{4}\d{2}\d{2}";
        while((s= br.readLine())!=null)
        {
            words= s.split("|");
            for(String word: words)
            {
                //System.out.println(word);
                if(word.equals(regex))
                {
                    c++;
                }
            }
        }
        System.out.println(c);
        fr.close();
    }

}

我希望读取快照中的日期并将其更改为当前系统日期。

Answer 1

您可以使用如下正则表达式。

  String regex = "(19|20)[0-9][0-9](0[1-9]|1[0-2])(0[1-9]|1[0-9]|2[0-9]|30|31)";

它并不完美，但可以匹配大多数日期。例如，它将消除月份超过 12 的日期。此外，它适用于 2099 年之前的日期。它不处理像 6 月有 30 天这样的日期规则。它将匹配天数在 1-31 之间的任何日期。

您不能使用 equals 作为日期。您将不得不使用 Pattern.matches(regex, string)

Answer 2

这是一个基本算法，它会在管道分隔的文件中查找，用当前日期替换 "look like" 日期的值，然后将所有内容写回新文件。它使用您在问题中描述的 YYYYDDMM 格式，但它可能应该是 YYYYMMDD 并且我已经注意到您需要在哪里进行更改。这通过日期验证和错误处理减少了一些角落，以尽量保持相对较短，但我已经 over-commented 尝试解释所有内容：

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class DateReplacer
{
    private static final Pattern DATE_MATCHER =
            Pattern.compile("(?:(?:19|20)[0-9]{2})([0-9]{2})([0-9]{2})");

    public static void main(String... args)
            throws Exception
    {
        // These are the paths to our input and output files
        Path input = Paths.get("input.dat");
        Path output = Paths.get("output.dat");

        // We need to get today's date in YYYYDDMM format, so we create a
        // DateFormatter for that. If it turns out that your date format is
        // actually YYYYMMDD, you can just use DateFormatter.BASIC_ISO_DATE
        // instead.
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyddMM");
        String todaysDate = LocalDate.now().format(formatter);

        // Use try-with-resources to create a reader & writer
        try (BufferedReader reader = Files.newBufferedReader(input);
             BufferedWriter writer = Files.newBufferedWriter(output)) {
            String line;

            // Read lines until there are no more lines
            while ((line = reader.readLine()) != null) {
                // Split them on the | character, notice that it needs to be
                // escaped because it is a regex metacharacter
                String[] columns = line.split("\|");

                // Iterate over every column...
                for (int i = 0; i < columns.length; i++) {
                    // ... and if the value looks like a date ...
                    if (isDateLike(columns[i])) {
                        // ... overwrite with today's date.
                        columns[i] = todaysDate;
                    }
                }

                // Re-join the columns with the | character and write it out
                writer.write(String.join("|", columns));
                writer.newLine();
            }
        }
    }

    private static boolean isDateLike(String str)
    {
        // Avoid the regular expression if we can
        if (str.length() != 8) {
            return false;
        }

        Matcher matcher = DATE_MATCHER.matcher(str);
        if (matcher.matches()) {
            // If it turns out that your date format is actually YYYYMMDD
            // you will need to swap these two lines.
            int day = Integer.parseInt(matcher.group(1), 10);
            int month = Integer.parseInt(matcher.group(2), 10);

            // We don't need to validate year because we already know
            // it is between 1900 and 2099 inclusive
            return day >= 1 && day <= 31 && month >= 1 && month <= 12;
        }

        return false;
    }
}

本例使用a try-with-resources statement确保正确关闭输入和输出文件。

如何使用 java 搜索文件中存在的日期格式 20180603？

How to search the date format 20180603 present inside a file using java?

java

date

filereader