Golang实战项目之如何编写一个逐行读取并分析日志文件的工具

file, err := os.Open("app.log")
if err != nil {
    log.Fatal(err)
}
defer file.Close()

scanner := bufio.NewScanner(file)
for scanner.Scan() {
    line := scanner.Text()
    // 处理每一行
    fmt.Println(line)
}

if err := scanner.Err(); err != nil {
    log.Fatal(err)
}

pattern := `(\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2})\s+(\w+)\s+(.*)`
re := regexp.MustCompile(pattern)

match := re.FindStringSubmatch(line)
if len(match) == 4 {
    timestamp := match[1]
    level := match[2]
    message := match[3]
    // 可做进一步处理
}

counts := make(map[string]int)

for scanner.Scan() {
    line := scanner.Text()
    if strings.Contains(line, "ERROR") {
        counts["ERROR"]++
    } else if strings.Contains(line, "WARN") {
        counts["WARN"]++
    }
}

fmt.Printf("ERROR: %d, WARN: %d\n", counts["ERROR"], counts["WARN"])

keyword := flag.String("keyword", "", "filter log by keyword")
flag.Parse()

for scanner.Scan() {
    line := scanner.Text()
    if strings.Contains(line, *keyword) {
        fmt.Println(line)
    }
}

var wg sync.WaitGroup
for _, filename := range filenames {
    wg.Add(1)
    go func(file string) {
        defer wg.Done()
        processLog(file)
    }(filename)
}
wg.Wait()