Go语言中字符串的拼装方法很多，那么问题来了，到底哪家性能好？
下面代码，分别比较了 fmt.Sprintf，string +，strings.Join，bytes.Buffer，方法是循环若干次比较总时间。
在VMWare下的Ubuntu 14.04下运行的结果表明：
- fmt.Sprintf 和 strings.Join 速度相当
- string + 比上述二者快一倍
- bytes.Buffer又比上者快约400-500倍
- 如果循环内每次都临时声明一个bytes.Buffer来使用，会比持续存在慢50%，但是仍然很快
测试代码如下：
package main
import (
"bytes"
"fmt"
"strings"
"time"
)
func benchmarkStringFunction(n int, index int) (d time.Duration) {
v := "ni shuo wo shi bu shi tai wu liao le a?"
var s string
var buf bytes.Buffer
t0 := time.Now()
for i := 0; i < n; i++ {
switch index {
case 0: // fmt.Sprintf
s = fmt.Sprintf("%s[%s]", s, v)
case 1: // string +
s = s + "[" + v + "]"
case 2: // strings.Join
s = strings.Join([]string{s, "[", v, "]"}, "")
case 3: // temporary bytes.Buffer
b := bytes.Buffer{}
b.WriteString("[")
b.WriteString(v)
b.WriteString("]")
s = b.String()
case 4: // stable bytes.Buffer
buf.WriteString("[")
buf.WriteString(v)
buf.WriteString("]")
}
if i == n-1 {
if index == 4 { // for stable bytes.Buffer
s = buf.String()
}
fmt.Println(len(s)) // consume s to avoid compiler optimization
}
}
t1 := time.Now()
d = t1.Sub(t0)
fmt.Printf("time of way(%d)=%v\n", index, d)
return d
}
func main() {
k := 5
d := [5]time.Duration{}
for i := 0; i < k; i++ {
d[i] = benchmarkStringFunction(10000, i)
}
for i := 0; i < k-1; i++ {
fmt.Printf("way %d is %6.1f times of way %d\n", i, float32(d[i])/float32(d[k-1]), k-1)
}
}
其中一次的结果如下：
[email protected]:~/work/go/test$ go run testBenchmark.go 410000 time of way(0)=1.199641573s 410000 time of way(1)=568.716669ms 410000 time of way(2)=1.197077483s 41 time of way(3)=2.277063ms 410000 time of way(4)=1.398864ms way 0 is 857.6 times of way 4 way 1 is 406.6 times of way 4 way 2 is 855.7 times of way 4 way 3 is 1.6 times of way 4
时间： 2024-10-03 21:54:13