go http 下载文件

package main  
      
    import (  
        "fmt"  
        "io"  
        "net/http"  
        "os"  
        "strconv"  
    )  
/*
    var (  
        //url = "http://flv5.bn.netease.com/live163/store/208588/serverpush_18783_1521024752481_208588_0-1.ts"
        url  string = "http://flv5.bn.netease.com/live163/store/208588/serverpush_18783_1521024752481_208588_0-"
        url_suffix string = ".ts"
    )  
*/      
    func main() {
        fmt.Println("download begin.....")

        url := "http://flv5.bn.netease.com/live163/store/208588/serverpush_18783_1521024752481_208588_0-"
        url_suffix := ".ts"

        for i := 180; i <= 180; i++ {
            
            str_index := strconv.Itoa(i)        // 通过Itoa方法转换  
            //str2 := fmt.Sprintf("%d", i)      // 通过Sprintf方法转换  
            //fmt.Println(str_index)   // 打印str1  
    
            strFinal := url+str_index+ url_suffix

            res, err := http.Get(strFinal)  
            if err != nil {  
                panic(err)  
            }  
            f, err := os.Create(str_index+url_suffix)  
            if err != nil {  
                panic(err)  
            }  
            fileSize,writeErr := io.Copy(f, res.Body)

            fmt.Println(strFinal + " download done,", "file size(byte)=", fileSize)
            if writeErr != nil {  
                fmt.Println(strFinal + " download failed ",  "errorInfo=", writeErr.Error())
                panic(err)  
            }  
        }

        
        fmt.Println("download finish.")

    }