GO语言学习群：721929980
**导入类库**
```
import (
"fmt"
"regexp"
"net/http"
"io/ioutil"
"strings"
"sync"
"time"
"strconv"
)
```
**定义全局数据**
```
var (
//存放图片链接
chanImgUrls chan string
//存放147个任务是否已完成
chanTask chan string
waitGroup sync.WaitGroup
)
```
**爬取一个页面上的全部图片链接，返回结果切片**
```
func SpiderPrettyImg(url string) (urls []string) {
pageStr := GetPageStr(url)
//fmt.Println(pageStr)
re := regexp.MustCompile(reImg)
results := re.FindAllStringSubmatch(pageStr, -1)
fmt.Printf("共找到%d条结果:\n", len(results))
for _, result := range results {
url := result[1]
fmt.Println(url)
urls = append(urls, url)
}
return
}
```
**从url中提取文件名称**
```
func GetFilenameFromUrl(url string, dirPath string) (filename string) {
lastIndex := strings.LastIndex(url, "/")
filename = url[lastIndex+1:]
timePrefix := strconv.Itoa(int(time.Now().UnixNano()))
filename = timePrefix + "_" + filename
filename = dirPath + filename
//fmt.Println(fileName)
return
}
```
**下载url对应的文件到指定路径**
```
func DownloadFile(url string, filename string) (ok bool) {
resp, err := http.Get(url)
if err != nil {
HandleError(err, "http.Get(url)")
return
}
defer resp.Body.Close()
//ioutil.ReadAll(resp.Body)read tcp 192.168.20.50:57178->175.6.244.4:80: wsarecv:
// An existing connection was forcibly closed by the remote host.
fBytes, e := ioutil.ReadAll(resp.Body)
HandleError(e, "ioutil.ReadAll(resp.Body)")
err = ioutil.WriteFile(filename, fBytes, 0644)
HandleError(err, "http.Get(url)")
if err != nil {
return false
} else {
return true
}
}
```
**爬取一个页面下的所有图片链接，并丢入全局待下载数据管道**
```
func SpiderImgUrls(url string) {
//获取一个页面下的所有图片链接
urls := SpiderPrettyImg(url)
//将所有图片超链接丢入数据管道
for _, url := range urls {
chanImgUrls <- url
}
//通知当前协程任务完成
chanTask <- url
waitGroup.Done()
}
```
**同步下载图片链接管道中的所有图片**
```
func DownloadImg() {
for url := range chanImgUrls {
filename := GetFilenameFromUrl(url, "D:/BJBlockChain1801/demos/W4/day4/img/")
ok := DownloadFile(url, filename)
if ok {
fmt.Printf("%s下载成功！\n", filename)
} else {
fmt.Printf("%s下载失败!!!!!!!!!!!!\n", filename)
}
}
waitGroup.Done()
}
```
**检查147个任务是否全部完成，完成则关闭数据管道**
```
func CheckIfAllSpidersOk() {
var count int
for {
url := <-chanTask
fmt.Printf("%s完成爬取任务\n", url)
count ++
if count == 147 {
close(chanImgUrls)
break
}
}
waitGroup.Done()
}
```
**主程序**
```
func main() {
//初始化数据管道
chanImgUrls = make(chan string, 1000000)
chanTask = make(chan string, 147)
//爬虫协程：源源不断地往管道中添加图片链接
for i := 1; i < 148; i++ {
waitGroup.Add(1)
go SpiderImgUrls("http://www.umei.cc/tags/meinv_" + strconv.Itoa(i) + ".htm")
}
//开辟任务统计协程，如果147个任务全部完成，则关闭数据管道
waitGroup.Add(1)
go CheckIfAllSpidersOk()
//下载协程：源源不断地从管道中读取地址并下载
for i := 0; i < 10; i++ {
waitGroup.Add(1)
go DownloadImg()
}
waitGroup.Wait()
}
```
GO语言学习Q群：721929980更多实战：https://blog.csdn.net/u010986776/article/category/8095305
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