log操作

log各种格式日志输出

package main

import (
    "bytes"
    "fmt"
    "log"
)

func ExampleLogger() {

    var (
        buf    bytes.Buffer
        logger = log.New(&buf, "logger: ", log.Lshortfile)
    )

    logger.Print("Hello, log file!\n")
    fmt.Print(&buf)

    var buf1 bytes.Buffer
    var logger1 = log.New(&buf1, "logger1: ", log.Ldate)
    logger1.Print("Hello, log file!\n")
    fmt.Print(&buf1)

    var buf2 bytes.Buffer
    var logger2 = log.New(&buf2, "logger2: ", log.Ltime)
    logger2.Print("Hello, log file!\n")
    fmt.Print(&buf2)

    var buf3 bytes.Buffer
    var logger3 = log.New(&buf3, "logger3: ", log.Lmicroseconds)
    logger3.Print("Hello, log file!\n")
    fmt.Print(&buf3)

    var buf4 bytes.Buffer
    var logger4 = log.New(&buf4, "logger4: ", log.Llongfile)
    logger4.Print("Hello, log file!\n")
    fmt.Print(&buf4)

    var buf5 bytes.Buffer
    var logger5 = log.New(&buf5, "logger5: ", log.Lshortfile)
    logger5.Print("Hello, log file!\n")
    fmt.Print(&buf5)

    var buf6 bytes.Buffer
    var logger6 = log.New(&buf6, "logger6: ", log.LUTC)
    logger6.Print("Hello, log file!\n")
    fmt.Print(&buf6)

    var buf7 bytes.Buffer
    var logger7 = log.New(&buf7, "logger7: ", log.LstdFlags)
    logger7.Print("Hello, log file!\n")
    fmt.Print(&buf7)

    // Output:
    // logger: example_test.go:19: Hello, log
}

func main() {
    ExampleLogger()
}

结果输出：
logger: main.go:16: Hello, log file!
logger1: 2018/01/27 Hello, log file!
logger2: 23:15:55 Hello, log file!
logger3: 23:15:55.273132 Hello, log file!
logger4: C:/Users/liyuan/go/src/file_io/main.go:36: Hello, log file!
logger5: main.go:41: Hello, log file!
logger6: Hello, log file!
logger7: 2018/01/27 23:15:55 Hello, log file!
成功: 进程退出代码 0.

------------------------------------------------------------------------

package main

import (
    "bytes"
    "fmt"
    "log"
)

func ExampleLogger_Output() {
    var (
        buf    bytes.Buffer
        logger = log.New(&buf, "INFO: ", log.Lshortfile)

        infof = func(info string) {
            logger.Output(2, info)
        }
    )

    infof("Hello world")

    fmt.Print(&buf)
    // Output:
    // INFO: example_test.go:36: Hello world
}

func main() {
    ExampleLogger_Output()
}

结果：
INFO: main.go:19: Hello world
成功: 进程退出代码 0.