{"id":44210,"date":"2023-07-10T00:09:36","date_gmt":"2022-11-02T03:05:08","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/%e6%88%91%e8%af%95%e7%9d%80%e7%8e%a9%e4%ba%86%e4%b8%80%e4%b8%8b%e3%80%8aa-tour-of-go%e3%80%8b%e3%80%82\/"},"modified":"2024-04-30T12:46:53","modified_gmt":"2024-04-30T04:46:53","slug":"%e6%88%91%e8%af%95%e7%9d%80%e7%8e%a9%e4%ba%86%e4%b8%80%e4%b8%8b%e3%80%8aa-tour-of-go%e3%80%8b%e3%80%82","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/%e6%88%91%e8%af%95%e7%9d%80%e7%8e%a9%e4%ba%86%e4%b8%80%e4%b8%8b%e3%80%8aa-tour-of-go%e3%80%8b%e3%80%82\/","title":{"rendered":"\u6211\u8bd5\u7740\u73a9\u4e86\u4e00\u4e0b\u300aA Tour of Go\u300b"},"content":{"rendered":"

\u4e2a\u4eba\u7684\u60f3\u6cd5<\/h2>\n

\u8fd9\u6b21\u8bad\u7ec3\u7684\u4e3b\u9898\u5f88\u597d\u3002<\/p>\n

\u6211\u5199\u7684\u4ee3\u7801<\/h2>\n

\u5faa\u73af\u548c\u51fd\u6570\u3002<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> (<\/span>\r\n    \"fmt\"<\/span>\r\n    \"math\"<\/span>\r\n)<\/span>\r\n\r\nfunc<\/span> Sqrt<\/span>(<\/span>x<\/span> float64<\/span>)<\/span> float64<\/span> {<\/span>\r\n  z<\/span> :=<\/span> 1.0<\/span>\r\n  for<\/span> math<\/span>.<\/span>Abs<\/span>(<\/span>z<\/span>*<\/span>z<\/span> -<\/span> x<\/span>)<\/span> ><\/span> 1e-10<\/span> {<\/span>\r\n    z<\/span> -=<\/span> (<\/span>z<\/span>*<\/span>z<\/span> -<\/span> x<\/span>)<\/span> \/<\/span> (<\/span>2<\/span>*<\/span>z<\/span>)<\/span>\r\n    fmt<\/span>.<\/span>Println<\/span>(<\/span>z<\/span>)<\/span>\r\n  }<\/span>\r\n  return<\/span> z<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    fmt<\/span>.<\/span>Println<\/span>(<\/span>Sqrt<\/span>(<\/span>2<\/span>))<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u5207\u7247<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> \"golang.org\/x\/tour\/pic\"<\/span>\r\n\r\nfunc<\/span> Pic<\/span>(<\/span>dx<\/span>,<\/span> dy<\/span> int<\/span>)<\/span> [][]<\/span>uint8<\/span> {<\/span>\r\n    rows<\/span> :=<\/span> make<\/span>([][]<\/span>uint8<\/span>,<\/span> dy<\/span>)<\/span>\r\n    for<\/span> y<\/span>:=<\/span>0<\/span>;<\/span> y<\/span><<\/span>dy<\/span>;<\/span> y<\/span>++<\/span> {<\/span>\r\n        cols<\/span> :=<\/span> make<\/span>([]<\/span>uint8<\/span>,<\/span> dx<\/span>)<\/span>\r\n        for<\/span> x<\/span>:=<\/span>0<\/span>;<\/span> x<\/span><<\/span>dx<\/span>;<\/span> x<\/span>++<\/span> {<\/span>\r\n            cols<\/span>[<\/span>x<\/span>]<\/span> =<\/span> uint8<\/span>(<\/span>x<\/span>^<\/span>y<\/span>)<\/span>\r\n        }<\/span>\r\n        rows<\/span>[<\/span>y<\/span>]<\/span> =<\/span> cols<\/span>\r\n    }<\/span>\r\n    return<\/span> rows<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    pic<\/span>.<\/span>Show<\/span>(<\/span>Pic<\/span>)<\/span>\r\n}<\/span>k<\/span>\r\n<\/code><\/pre>\n
\u5730\u56fe (d\u00ec t\u00fa)<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> (<\/span>\r\n    \"golang.org\/x\/tour\/wc\"<\/span>\r\n    \"strings\"<\/span>\r\n)<\/span>\r\n\r\nfunc<\/span> WordCount<\/span>(<\/span>s<\/span> string<\/span>)<\/span> map<\/span>[<\/span>string<\/span>]<\/span>int<\/span> {<\/span>\r\n    m<\/span> :=<\/span> make<\/span>(<\/span>map<\/span>[<\/span>string<\/span>]<\/span>int<\/span>)<\/span>\r\n    for<\/span> _<\/span>,<\/span> x<\/span> :=<\/span> range<\/span> strings<\/span>.<\/span>Fields<\/span>(<\/span>s<\/span>)<\/span> {<\/span>\r\n        m<\/span>[<\/span>x<\/span>]<\/span>++<\/span>\r\n    }<\/span>\r\n    return<\/span> m<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    wc<\/span>.<\/span>Test<\/span>(<\/span>WordCount<\/span>)<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u6590\u6ce2\u90a3\u5951\u95ed\u5305<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> \"fmt\"<\/span>\r\n\r\n\/\/ fibonacci is a function that returns<\/span>\r\n\/\/ a function that returns an int.<\/span>\r\nfunc<\/span> fibonacci<\/span>()<\/span> func<\/span>()<\/span> int<\/span> {<\/span>\r\n    x0<\/span>,<\/span> x1<\/span> :=<\/span> 0<\/span>,<\/span> 1<\/span>\r\n    return<\/span> func<\/span>()<\/span> int<\/span> {<\/span>\r\n        v<\/span> :=<\/span> x0<\/span>\r\n        x0<\/span>,<\/span> x1<\/span> =<\/span> x1<\/span>,<\/span> x0<\/span>+<\/span>x1<\/span>\r\n        return<\/span> v<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    f<\/span> :=<\/span> fibonacci<\/span>()<\/span>\r\n    for<\/span> i<\/span> :=<\/span> 0<\/span>;<\/span> i<\/span> <<\/span> 10<\/span>;<\/span> i<\/span>++<\/span> {<\/span>\r\n        fmt<\/span>.<\/span>Println<\/span>(<\/span>f<\/span>())<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u7dda\u7d22\u8005<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> \"fmt\"<\/span>\r\n\r\ntype<\/span> IPAddr<\/span> [<\/span>4<\/span>]<\/span>byte<\/span>\r\n\r\n\/\/ TODO: Add a \"String() string\" method to IPAddr.<\/span>\r\nfunc<\/span> (<\/span>x<\/span> IPAddr<\/span>)<\/span> String<\/span>()<\/span> string<\/span> {<\/span>\r\n    return<\/span> fmt<\/span>.<\/span>Sprintf<\/span>(<\/span>\"%d.%d.%d.%d\"<\/span>,<\/span> x<\/span>[<\/span>0<\/span>],<\/span> x<\/span>[<\/span>1<\/span>],<\/span> x<\/span>[<\/span>2<\/span>],<\/span> x<\/span>[<\/span>3<\/span>])<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    hosts<\/span> :=<\/span> map<\/span>[<\/span>string<\/span>]<\/span>IPAddr<\/span>{<\/span>\r\n        \"loopback\"<\/span>:<\/span>  {<\/span>127<\/span>,<\/span> 0<\/span>,<\/span> 0<\/span>,<\/span> 1<\/span>},<\/span>\r\n        \"googleDNS\"<\/span>:<\/span> {<\/span>8<\/span>,<\/span> 8<\/span>,<\/span> 8<\/span>,<\/span> 8<\/span>},<\/span>\r\n    }<\/span>\r\n    for<\/span> name<\/span>,<\/span> ip<\/span> :=<\/span> range<\/span> hosts<\/span> {<\/span>\r\n        fmt<\/span>.<\/span>Printf<\/span>(<\/span>\"%v: %v<\/span>\\n<\/span>\"<\/span>,<\/span> name<\/span>,<\/span> ip<\/span>)<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u9519\u8bef<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> (<\/span>\r\n    \"fmt\"<\/span>\r\n    \"math\"<\/span>\r\n)<\/span>\r\n\r\ntype<\/span> ErrNegativeSqrt<\/span> float64<\/span>\r\n\r\nfunc<\/span> (<\/span>e<\/span> ErrNegativeSqrt<\/span>)<\/span> Error<\/span>()<\/span> string<\/span> {<\/span>\r\n    return<\/span> fmt<\/span>.<\/span>Sprintf<\/span>(<\/span>\"cannot Sqrt negative number: %v\"<\/span>,<\/span> float64<\/span>(<\/span>e<\/span>))<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> Sqrt<\/span>(<\/span>x<\/span> float64<\/span>)<\/span> (<\/span>float64<\/span>,<\/span> error<\/span>)<\/span> {<\/span>\r\n  if<\/span> x<\/span> <<\/span> 0<\/span> {<\/span>\r\n    return<\/span> x<\/span>,<\/span> ErrNegativeSqrt<\/span>(<\/span>x<\/span>)<\/span>\r\n  }<\/span>\r\n  z<\/span> :=<\/span> 1.0<\/span>\r\n  for<\/span> math<\/span>.<\/span>Abs<\/span>(<\/span>z<\/span>*<\/span>z<\/span> -<\/span> x<\/span>)<\/span> ><\/span> 1e-10<\/span> {<\/span>\r\n    z<\/span> -=<\/span> (<\/span>z<\/span>*<\/span>z<\/span> -<\/span> x<\/span>)<\/span> \/<\/span> (<\/span>2<\/span>*<\/span>z<\/span>)<\/span>\r\n  }<\/span>\r\n  return<\/span> z<\/span>,<\/span> nil<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    fmt<\/span>.<\/span>Println<\/span>(<\/span>Sqrt<\/span>(<\/span>2<\/span>))<\/span>\r\n    fmt<\/span>.<\/span>Println<\/span>(<\/span>Sqrt<\/span>(<\/span>-<\/span>2<\/span>))<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u8bfb\u8005 (d\u00fa zh\u011b)<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> \"golang.org\/x\/tour\/reader\"<\/span>\r\n\r\ntype<\/span> MyReader<\/span> struct<\/span>{}<\/span>\r\n\r\n\/\/ TODO: Add a Read([]byte) (int, error) method to MyReader.<\/span>\r\nfunc<\/span> (<\/span>r<\/span> MyReader<\/span>)<\/span> Read<\/span>(<\/span>bs<\/span> []<\/span>byte<\/span>)<\/span> (<\/span>int<\/span>,<\/span> error<\/span>)<\/span> {<\/span>\r\n    bs<\/span>[<\/span>0<\/span>]<\/span> =<\/span> 'A'<\/span>\r\n    return<\/span> 1<\/span>,<\/span> nil<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    reader<\/span>.<\/span>Validate<\/span>(<\/span>MyReader<\/span>{})<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u65cb\u8f6c3\u8bfb\u8005<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> (<\/span>\r\n    \"io\"<\/span>\r\n    \"os\"<\/span>\r\n    \"strings\"<\/span>\r\n)<\/span>\r\n\r\ntype<\/span> rot13Reader<\/span> struct<\/span> {<\/span>\r\n    r<\/span> io<\/span>.<\/span>Reader<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> (<\/span>reader<\/span> *<\/span>rot13Reader<\/span>)<\/span> Read<\/span>(<\/span>bs<\/span> []<\/span>byte<\/span>)<\/span> (<\/span>int<\/span>,<\/span> error<\/span>)<\/span> {<\/span>\r\n    bs2<\/span> :=<\/span> make<\/span>([]<\/span>byte<\/span>,<\/span> 100<\/span>)<\/span>\r\n    n<\/span>,<\/span> err<\/span> :=<\/span> reader<\/span>.<\/span>r<\/span>.<\/span>Read<\/span>(<\/span>bs2<\/span>)<\/span>\r\n    if<\/span> err<\/span> !=<\/span> nil<\/span> {<\/span>\r\n        return<\/span> 0<\/span>,<\/span> err<\/span>\r\n    }<\/span>\r\n\r\n    decode<\/span> :=<\/span> func<\/span>(<\/span>base<\/span> byte<\/span>,<\/span> c<\/span> byte<\/span>)<\/span> byte<\/span> {<\/span>\r\n        c<\/span> -=<\/span> base<\/span>\r\n        c<\/span> =<\/span> (<\/span>c<\/span> +<\/span> 13<\/span>)<\/span> %<\/span> 26<\/span>\r\n        return<\/span> c<\/span> +<\/span> base<\/span>\r\n    }<\/span>\r\n    for<\/span> i<\/span> :=<\/span> 0<\/span>;<\/span> i<\/span> <<\/span> n<\/span>;<\/span> i<\/span>++<\/span> {<\/span>\r\n        c<\/span> :=<\/span> bs2<\/span>[<\/span>i<\/span>]<\/span>\r\n        if<\/span> 'a'<\/span> <=<\/span> c<\/span> &&<\/span> c<\/span> <=<\/span> 'z'<\/span> {<\/span>\r\n            bs<\/span>[<\/span>i<\/span>]<\/span> =<\/span> decode<\/span>(<\/span>'a'<\/span>,<\/span> c<\/span>)<\/span>\r\n        }<\/span> else<\/span> if<\/span> 'A'<\/span> <=<\/span> c<\/span> &&<\/span> c<\/span> <=<\/span> 'Z'<\/span> {<\/span>\r\n            bs<\/span>[<\/span>i<\/span>]<\/span> =<\/span> decode<\/span>(<\/span>'A'<\/span>,<\/span> c<\/span>)<\/span>\r\n        }<\/span> else<\/span> {<\/span>\r\n            bs<\/span>[<\/span>i<\/span>]<\/span> =<\/span> c<\/span>\r\n        }<\/span>\r\n    }<\/span>\r\n    return<\/span> n<\/span>,<\/span> nil<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    s<\/span> :=<\/span> strings<\/span>.<\/span>NewReader<\/span>(<\/span>\"Lbh penpxrq gur pbqr!\"<\/span>)<\/span>\r\n    r<\/span> :=<\/span> rot13Reader<\/span>{<\/span>s<\/span>}<\/span>\r\n    io<\/span>.<\/span>Copy<\/span>(<\/span>os<\/span>.<\/span>Stdout<\/span>,<\/span> &<\/span>r<\/span>)<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u56fe\u50cf<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> (<\/span>\r\n    \"golang.org\/x\/tour\/pic\"<\/span>\r\n    \"image\"<\/span>\r\n    \"image\/color\"<\/span>\r\n)<\/span>\r\n\r\ntype<\/span> Image<\/span> struct<\/span> {<\/span>\r\n    width<\/span>  int<\/span>\r\n    height<\/span> int<\/span>\r\n    body<\/span>   [][]<\/span>uint8<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> (<\/span>i<\/span> Image<\/span>)<\/span> ColorModel<\/span>()<\/span> color<\/span>.<\/span>Model<\/span> {<\/span>\r\n    return<\/span> color<\/span>.<\/span>RGBAModel<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> (<\/span>i<\/span> Image<\/span>)<\/span> Bounds<\/span>()<\/span> image<\/span>.<\/span>Rectangle<\/span> {<\/span>\r\n    return<\/span> image<\/span>.<\/span>Rect<\/span>(<\/span>0<\/span>,<\/span> 0<\/span>,<\/span> i<\/span>.<\/span>width<\/span>,<\/span> i<\/span>.<\/span>height<\/span>)<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> (<\/span>i<\/span> Image<\/span>)<\/span> At<\/span>(<\/span>x<\/span>,<\/span> y<\/span> int<\/span>)<\/span> color<\/span>.<\/span>Color<\/span> {<\/span>\r\n    v<\/span> :=<\/span> i<\/span>.<\/span>body<\/span>[<\/span>y<\/span>][<\/span>x<\/span>]<\/span>\r\n    return<\/span> color<\/span>.<\/span>RGBA<\/span>{<\/span>v<\/span>,<\/span> v<\/span>,<\/span> 255<\/span>,<\/span> 255<\/span>}<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> genBody<\/span>(<\/span>dx<\/span>,<\/span> dy<\/span> int<\/span>)<\/span> [][]<\/span>uint8<\/span> {<\/span>\r\n    rows<\/span> :=<\/span> make<\/span>([][]<\/span>uint8<\/span>,<\/span> dy<\/span>)<\/span>\r\n    for<\/span> y<\/span> :=<\/span> 0<\/span>;<\/span> y<\/span> <<\/span> dy<\/span>;<\/span> y<\/span>++<\/span> {<\/span>\r\n        cols<\/span> :=<\/span> make<\/span>([]<\/span>uint8<\/span>,<\/span> dx<\/span>)<\/span>\r\n        for<\/span> x<\/span> :=<\/span> 0<\/span>;<\/span> x<\/span> <<\/span> dx<\/span>;<\/span> x<\/span>++<\/span> {<\/span>\r\n            cols<\/span>[<\/span>x<\/span>]<\/span> =<\/span> uint8<\/span>(<\/span>x<\/span> ^<\/span> y<\/span>)<\/span>\r\n        }<\/span>\r\n        rows<\/span>[<\/span>y<\/span>]<\/span> =<\/span> cols<\/span>\r\n    }<\/span>\r\n    return<\/span> rows<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    body<\/span> :=<\/span> genBody<\/span>(<\/span>100<\/span>,<\/span> 100<\/span>)<\/span>\r\n    image<\/span> :=<\/span> Image<\/span>{<\/span>100<\/span>,<\/span> 100<\/span>,<\/span> body<\/span>}<\/span>\r\n    pic<\/span>.<\/span>ShowImage<\/span>(<\/span>image<\/span>)<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u7b49\u503c\u7684\u4e8c\u8fdb\u5236\u6811<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> (<\/span>\r\n    \"fmt\"<\/span>\r\n    \"golang.org\/x\/tour\/tree\"<\/span>\r\n)<\/span>\r\n\r\n\/\/ Walk walks the tree t sending all values<\/span>\r\n\/\/ from the tree to the channel ch.<\/span>\r\nfunc<\/span> Walk<\/span>(<\/span>t<\/span> *<\/span>tree<\/span>.<\/span>Tree<\/span>,<\/span> ch<\/span> chan<\/span> int<\/span>)<\/span> {<\/span>\r\n    if<\/span> t<\/span>.<\/span>Left<\/span> !=<\/span> nil<\/span> {<\/span>\r\n        Walk<\/span>(<\/span>t<\/span>.<\/span>Left<\/span>,<\/span> ch<\/span>)<\/span>\r\n    }<\/span>\r\n    ch<\/span> <-<\/span> t<\/span>.<\/span>Value<\/span>\r\n    if<\/span> t<\/span>.<\/span>Right<\/span> !=<\/span> nil<\/span> {<\/span>\r\n        Walk<\/span>(<\/span>t<\/span>.<\/span>Right<\/span>,<\/span> ch<\/span>)<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n\r\n\/\/ Same determines whether the trees<\/span>\r\n\/\/ t1 and t2 contain the same values.<\/span>\r\nfunc<\/span> Same<\/span>(<\/span>t1<\/span>,<\/span> t2<\/span> *<\/span>tree<\/span>.<\/span>Tree<\/span>)<\/span> bool<\/span> {<\/span>\r\n    c1<\/span> :=<\/span> make<\/span>(<\/span>chan<\/span> int<\/span>)<\/span>\r\n    c2<\/span> :=<\/span> make<\/span>(<\/span>chan<\/span> int<\/span>)<\/span>\r\n    go<\/span> Walk<\/span>(<\/span>t1<\/span>,<\/span> c1<\/span>)<\/span>\r\n    go<\/span> Walk<\/span>(<\/span>t2<\/span>,<\/span> c2<\/span>)<\/span>\r\n\r\n    for<\/span> i<\/span> :=<\/span> 0<\/span>;<\/span> i<\/span> <<\/span> 10<\/span>;<\/span> i<\/span>++<\/span> {<\/span>\r\n        if<\/span> <-<\/span>c1<\/span> !=<\/span> <-<\/span>c2<\/span> {<\/span>\r\n            return<\/span> false<\/span>\r\n        }<\/span>\r\n    }<\/span>\r\n    return<\/span> true<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    t1<\/span> :=<\/span> tree<\/span>.<\/span>New<\/span>(<\/span>1<\/span>)<\/span>\r\n    t2<\/span> :=<\/span> tree<\/span>.<\/span>New<\/span>(<\/span>2<\/span>)<\/span>\r\n    fmt<\/span>.<\/span>Println<\/span>(<\/span>Same<\/span>(<\/span>t1<\/span>,<\/span> t2<\/span>))<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u7f51\u7edc\u722c\u866b<\/h3>\n
package<\/span> main<\/span>\r\n\r\nimport<\/span> (<\/span>\r\n    \"fmt\"<\/span>\r\n    \"sync\"<\/span>\r\n)<\/span>\r\n\r\ntype<\/span> Fetcher<\/span> interface<\/span> {<\/span>\r\n    \/\/ Fetch returns the body of URL and<\/span>\r\n    \/\/ a slice of URLs found on that page.<\/span>\r\n    Fetch<\/span>(<\/span>url<\/span> string<\/span>)<\/span> (<\/span>body<\/span> string<\/span>,<\/span> urls<\/span> []<\/span>string<\/span>,<\/span> err<\/span> error<\/span>)<\/span>\r\n}<\/span>\r\n\r\ntype<\/span> Cache<\/span> struct<\/span> {<\/span>\r\n    mu<\/span>   sync<\/span>.<\/span>Mutex<\/span>\r\n    urls<\/span> map<\/span>[<\/span>string<\/span>]<\/span>struct<\/span>{}<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> (<\/span>c<\/span> *<\/span>Cache<\/span>)<\/span> Has<\/span>(<\/span>url<\/span> string<\/span>)<\/span> bool<\/span> {<\/span>\r\n    c<\/span>.<\/span>mu<\/span>.<\/span>Lock<\/span>()<\/span>\r\n    defer<\/span> c<\/span>.<\/span>mu<\/span>.<\/span>Unlock<\/span>()<\/span>\r\n    _<\/span>,<\/span> ok<\/span> :=<\/span> c<\/span>.<\/span>urls<\/span>[<\/span>url<\/span>]<\/span>\r\n    return<\/span> ok<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> (<\/span>c<\/span> *<\/span>Cache<\/span>)<\/span> Add<\/span>(<\/span>url<\/span> string<\/span>)<\/span> {<\/span>\r\n    c<\/span>.<\/span>mu<\/span>.<\/span>Lock<\/span>()<\/span>\r\n    c<\/span>.<\/span>urls<\/span>[<\/span>url<\/span>]<\/span> =<\/span> struct<\/span>{}{}<\/span>\r\n    c<\/span>.<\/span>mu<\/span>.<\/span>Unlock<\/span>()<\/span>\r\n}<\/span>\r\n\r\n\/\/ Crawl uses fetcher to recursively crawl<\/span>\r\n\/\/ pages starting with url, to a maximum of depth.<\/span>\r\nfunc<\/span> Crawl<\/span>(<\/span>url<\/span> string<\/span>,<\/span> depth<\/span> int<\/span>,<\/span> fetcher<\/span> Fetcher<\/span>,<\/span> cache<\/span> *<\/span>Cache<\/span>,<\/span> wg<\/span> *<\/span>sync<\/span>.<\/span>WaitGroup<\/span>)<\/span> {<\/span>\r\n    defer<\/span> wg<\/span>.<\/span>Done<\/span>()<\/span>\r\n\r\n    if<\/span> depth<\/span> <=<\/span> 0<\/span> ||<\/span> cache<\/span>.<\/span>Has<\/span>(<\/span>url<\/span>)<\/span> {<\/span>\r\n        return<\/span>\r\n    }<\/span>\r\n    cache<\/span>.<\/span>Add<\/span>(<\/span>url<\/span>)<\/span>\r\n\r\n    body<\/span>,<\/span> urls<\/span>,<\/span> err<\/span> :=<\/span> fetcher<\/span>.<\/span>Fetch<\/span>(<\/span>url<\/span>)<\/span>\r\n    if<\/span> err<\/span> !=<\/span> nil<\/span> {<\/span>\r\n        fmt<\/span>.<\/span>Println<\/span>(<\/span>err<\/span>)<\/span>\r\n        return<\/span>\r\n    }<\/span>\r\n    fmt<\/span>.<\/span>Printf<\/span>(<\/span>\"found: %s %q<\/span>\\n<\/span>\"<\/span>,<\/span> url<\/span>,<\/span> body<\/span>)<\/span>\r\n    for<\/span> _<\/span>,<\/span> u<\/span> :=<\/span> range<\/span> urls<\/span> {<\/span>\r\n        wg<\/span>.<\/span>Add<\/span>(<\/span>1<\/span>)<\/span>\r\n        go<\/span> Crawl<\/span>(<\/span>u<\/span>,<\/span> depth<\/span>-<\/span>1<\/span>,<\/span> fetcher<\/span>,<\/span> cache<\/span>,<\/span> wg<\/span>)<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> main<\/span>()<\/span> {<\/span>\r\n    wg<\/span> :=<\/span> sync<\/span>.<\/span>WaitGroup<\/span>{}<\/span>\r\n    cache<\/span> :=<\/span> Cache<\/span>{<\/span>urls<\/span>:<\/span> make<\/span>(<\/span>map<\/span>[<\/span>string<\/span>]<\/span>struct<\/span>{})}<\/span>\r\n    wg<\/span>.<\/span>Add<\/span>(<\/span>1<\/span>)<\/span>\r\n    go<\/span> Crawl<\/span>(<\/span>\"https:\/\/golang.org\/\"<\/span>,<\/span> 4<\/span>,<\/span> fetcher<\/span>,<\/span> &<\/span>cache<\/span>,<\/span> &<\/span>wg<\/span>)<\/span>\r\n    wg<\/span>.<\/span>Wait<\/span>()<\/span>\r\n}<\/span>\r\n\r\n\/\/ fakeFetcher is Fetcher that returns canned results.<\/span>\r\ntype<\/span> fakeFetcher<\/span> map<\/span>[<\/span>string<\/span>]<\/span>*<\/span>fakeResult<\/span>\r\n\r\ntype<\/span> fakeResult<\/span> struct<\/span> {<\/span>\r\n    body<\/span> string<\/span>\r\n    urls<\/span> []<\/span>string<\/span>\r\n}<\/span>\r\n\r\nfunc<\/span> (<\/span>f<\/span> fakeFetcher<\/span>)<\/span> Fetch<\/span>(<\/span>url<\/span> string<\/span>)<\/span> (<\/span>string<\/span>,<\/span> []<\/span>string<\/span>,<\/span> error<\/span>)<\/span> {<\/span>\r\n    if<\/span> res<\/span>,<\/span> ok<\/span> :=<\/span> f<\/span>[<\/span>url<\/span>];<\/span> ok<\/span> {<\/span>\r\n        return<\/span> res<\/span>.<\/span>body<\/span>,<\/span> res<\/span>.<\/span>urls<\/span>,<\/span> nil<\/span>\r\n    }<\/span>\r\n    return<\/span> \"\"<\/span>,<\/span> nil<\/span>,<\/span> fmt<\/span>.<\/span>Errorf<\/span>(<\/span>\"not found: %s\"<\/span>,<\/span> url<\/span>)<\/span>\r\n}<\/span>\r\n\r\n\/\/ fetcher is a populated fakeFetcher.<\/span>\r\nvar<\/span> fetcher<\/span> =<\/span> fakeFetcher<\/span>{<\/span>\r\n    \"https:\/\/golang.org\/\"<\/span>:<\/span> &<\/span>fakeResult<\/span>{<\/span>\r\n        \"The Go Programming Language\"<\/span>,<\/span>\r\n        []<\/span>string<\/span>{<\/span>\r\n            \"https:\/\/golang.org\/pkg\/\"<\/span>,<\/span>\r\n            \"https:\/\/golang.org\/cmd\/\"<\/span>,<\/span>\r\n        },<\/span>\r\n    },<\/span>\r\n    \"https:\/\/golang.org\/pkg\/\"<\/span>:<\/span> &<\/span>fakeResult<\/span>{<\/span>\r\n        \"Packages\"<\/span>,<\/span>\r\n        []<\/span>string<\/span>{<\/span>\r\n            \"https:\/\/golang.org\/\"<\/span>,<\/span>\r\n            \"https:\/\/golang.org\/cmd\/\"<\/span>,<\/span>\r\n            \"https:\/\/golang.org\/pkg\/fmt\/\"<\/span>,<\/span>\r\n            \"https:\/\/golang.org\/pkg\/os\/\"<\/span>,<\/span>\r\n        },<\/span>\r\n    },<\/span>\r\n    \"https:\/\/golang.org\/pkg\/fmt\/\"<\/span>:<\/span> &<\/span>fakeResult<\/span>{<\/span>\r\n        \"Package fmt\"<\/span>,<\/span>\r\n        []<\/span>string<\/span>{<\/span>\r\n            \"https:\/\/golang.org\/\"<\/span>,<\/span>\r\n            \"https:\/\/golang.org\/pkg\/\"<\/span>,<\/span>\r\n        },<\/span>\r\n    },<\/span>\r\n    \"https:\/\/golang.org\/pkg\/os\/\"<\/span>:<\/span> &<\/span>fakeResult<\/span>{<\/span>\r\n        \"Package os\"<\/span>,<\/span>\r\n        []<\/span>string<\/span>{<\/span>\r\n            \"https:\/\/golang.org\/\"<\/span>,<\/span>\r\n            \"https:\/\/golang.org\/pkg\/\"<\/span>,<\/span>\r\n        },<\/span>\r\n    },<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
\u4e2a\u4eba\u7684\u60f3\u6cd5 \u8fd9\u6b21\u8bad\u7ec3\u7684\u4e3b\u9898\u5f88\u597d\u3002 \u6211\u5199\u7684\u4ee3\u7801 \u5faa\u73af\u548c\u51fd\u6570\u3002 package main import ( “fm […]<\/p>\n","protected":false},"author":9,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-44210","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"\n\u6211\u8bd5\u7740\u73a9\u4e86\u4e00\u4e0b\u300aA Tour of Go\u300b - Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/zh\/blog\/\u6211\u8bd5\u7740\u73a9\u4e86\u4e00\u4e0b\u300aa-tour-of-go\u300b\u3002\/\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"\u6211\u8bd5\u7740\u73a9\u4e86\u4e00\u4e0b\u300aA Tour of Go\u300b\" \/>\n<meta property=\"og:description\" content=\"\u4e2a\u4eba\u7684\u60f3\u6cd5 \u8fd9\u6b21\u8bad\u7ec3\u7684\u4e3b\u9898\u5f88\u597d\u3002 \u6211\u5199\u7684\u4ee3\u7801 \u5faa\u73af\u548c\u51fd\u6570\u3002 package main import ( "fm […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/zh\/blog\/\u6211\u8bd5\u7740\u73a9\u4e86\u4e00\u4e0b\u300aa-tour-of-go\u300b\u3002\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - 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