{"id":564,"date":"2020-03-03T17:15:00","date_gmt":"2020-03-03T09:15:00","guid":{"rendered":"https:\/\/www.myway5.com\/?p=564"},"modified":"2023-07-05T21:31:51","modified_gmt":"2023-07-05T13:31:51","slug":"golang-error","status":"publish","type":"post","link":"https:\/\/www.myway5.com\/index.php\/2020\/03\/03\/golang-error\/","title":{"rendered":"Golang \u4e2d\u7684\u9519\u8bef\u5904\u7406\u5efa\u8bae"},"content":{"rendered":"

\u4e00\u3001\u6982\u8ff0<\/h2>\n

Golang \u7684\u9519\u8bef\u5904\u7406\u4e00\u76f4\u662f\u4e00\u4e2a\u6bd4\u8f83\u8ba8\u8bba\u6bd4\u8f83\u591a\u7684\u8bdd\u3002\u6211\u521a\u63a5\u89e6 Golang \u7684\u65f6\u5019\u4e5f\u770b\u8fc7\u5173\u4e8e\u9519\u8bef\u5904\u7406\u7684\u4e00\u4e9b\u6587\u6863\uff0c\u4f46\u662f\u5e76\u6ca1\u6709\u653e\u5728\u5fc3\u4e0a\u3002\u5728\u6211\u4f7f\u7528 Golang \u4e00\u6bb5\u65f6\u95f4\u4e4b\u540e\uff0c\u6211\u89c9\u5f97\u6211\u53ef\u80fd\u65e0\u6cd5\u5ffd\u7565\u8fd9\u4e2a\u95ee\u9898\u3002\u56e0\u6b64\uff0c\u8fd9\u7bc7\u6587\u7ae0\u4e3b\u8981\u662f\u4e3a\u4e86\u6574\u7406\u4e00\u4e9b\u5728 Golang \u4e2d\u5e38\u7528\u7684\u9519\u8bef\u5904\u7406\u6280\u5de7\u548c\u539f\u5219\u3002<\/p>\n

\u4e8c\u3001\u9519\u8bef\u5904\u7406\u7684\u6280\u5de7\u548c\u539f\u5219<\/h2>\n

2.1 \u4f7f\u7528\u5c01\u88c5\u6765\u907f\u514d\u91cd\u590d\u7684\u9519\u8bef\u5224\u65ad<\/h3>\n

\u5728 Golang \u7684\u9879\u76ee\u4e2d\uff0c\u6700\u591a\u7684\u4e00\u53e5\u4ee3\u7801\u80af\u5b9a\u662f if err != nil<\/code>\u3002Golang \u5c06\u9519\u8bef\u4f5c\u4e3a\u8fd4\u56de\u503c\uff0c\u56e0\u6b64\u4f60\u4e0d\u5f97\u4e0d\u5904\u7406\u8fd9\u4e9b\u9519\u8bef\u3002\u4f46\u662f\u6709\u7684\u65f6\u5019\uff0c\u9519\u8bef\u5904\u7406\u7684\u5224\u65ad\u53ef\u80fd\u4f1a\u5360\u636e\u4f60\u7684\u4ee3\u7801\u7684\u4e00\u534a\u7bc7\u5e45\uff0c\u8fd9\u4f7f\u5f97\u4ee3\u7801\u770b\u8d77\u6765\u4e71\u7cdf\u7cdf\u7684\u3002\u5728\u5b98\u65b9\u7684\u535a\u5ba2\u4e2d\u6709\u4e00\u4e2a\u8fd9\u6837\u7684\u4f8b\u5b50\uff1a<\/p>\n

_, err = fd.Write(p0[a:b])\nif err != nil {\n    return err\n}\n_, err = fd.Write(p1[c:d])\nif err != nil {\n    return err\n}\n_, err = fd.Write(p2[e:f])\nif err != nil {\n    return err\n}\n\/\/ and so on\n<\/code><\/pre>\n
\u662f\u7684\uff0c\u4f60\u6ca1\u6709\u770b\u9519\uff0c\u8fd9\u91cc\u5176\u5b9e\u5c31\u662f\u8c03\u7528\u4e86 3 \u884c fd.Write<\/code>\uff0c\u4f46\u662f\u4f60\u4e0d\u5f97\u4e0d\u5199\u4e0a 9 \u9519\u8bef\u5224\u65ad\u3002\u56e0\u6b64\u5b98\u65b9\u7684\u535a\u5ba2\u4e2d\u4e5f\u7ed9\u51fa\u4e86\u4e00\u4e2a\u6bd4\u8f83\u4f18\u96c5\u7684\u5904\u7406\u65b9\u6848\uff1a\u5c06 io.Writer<\/code> \u518d\u5c01\u88c5\u4e00\u5c42\u3002<\/p>\n
type errWriter struct {\n    w   io.Writer\n    err error\n}\n\nfunc (ew *errWriter) write(buf []byte) {\n    if ew.err != nil {\n        return\n    }\n    _, ew.err = ew.w.Write(buf)\n}\n\new := &errWriter{w: fd}\new.write(p0[a:b])\new.write(p1[c:d])\new.write(p2[e:f])\n\/\/ and so on\nif ew.err != nil {\n    return ew.err\n}\n<\/code><\/pre>\n
\u73b0\u5728\u770b\u4e0a\u53bb\u5c31\u597d\u591a\u4e86\uff0cwrite(buf []byte)<\/code> \u65b9\u6cd5\u5728\u5185\u90e8\u5224\u65ad\u4e86\u9519\u8bef\u503c\uff0c\u6765\u907f\u514d\u5728\u5916\u9762\u591a\u6b21\u7684\u9519\u8bef\u5224\u65ad\u3002\u5f53\u7136\uff0c\u8fd9\u79cd\u5199\u6cd5\u53ef\u80fd\u4e5f\u6709\u5b83\u7684\u5f0a\u7aef\uff0c\u6bd4\u5982\u4f60\u6ca1\u6709\u529e\u6cd5\u77e5\u9053\u51fa\u9519\u5728\u54ea\u4e00\u884c\u8c03\u7528\u3002\u5927\u591a\u6570\u60c5\u51b5\u4e0b\uff0c\u4f60\u53ea\u9700\u8981\u68c0\u67e5\u9519\u8bef\uff0c\u7136\u540e\u8fdb\u884c\u5904\u7406\u800c\u5df2\u3002\u56e0\u6b64\u8fd9\u79cd\u6280\u5de7\u8fd8\u662f\u5f88\u6709\u7528\u7684\u3002Golang \u7684\u6807\u51c6\u5e93\u4e5f\u6709\u5f88\u591a\u7c7b\u4f3c\u7684\u6280\u5de7\u3002\u6bd4\u5982<\/p>\n
b := bufio.NewWriter(fd)\nb.Write(p0[a:b])\nb.Write(p1[c:d])\nb.Write(p2[e:f])\n\/\/ and so on\nif b.Flush() != nil {\n    return b.Flush()\n}\n<\/code><\/pre>\n
\u5176\u4e2d b.Write<\/code> \u662f\u6709\u9519\u8bef\u503c\u8fd4\u56de\u7684\uff0c\u8fd9\u53ea\u662f\u4e3a\u4e86\u7b26\u5408 io.Writer<\/code> \u63a5\u53e3\u3002\u4f60\u53ef\u4ee5\u5728\u8c03\u7528 b.Flush()<\/code> \u7684\u65f6\u5019\u518d\u8fdb\u884c\u9519\u8bef\u503c\u7684\u5224\u65ad\u3002<\/p>\n
2.2 Golang 1.13 \u524d\u7684\u9519\u8bef\u5904\u7406<\/h3>\n
\u68c0\u9a8c\u9519\u8bef<\/h4>\n
\u5927\u591a\u6570\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u53ea\u9700\u8981\u5bf9\u9519\u8bef\u8fdb\u884c\u7b80\u5355\u7684\u5224\u65ad\u5373\u53ef\u3002\u56e0\u4e3a\u6211\u4eec\u4e0d\u9700\u8981\u5bf9\u9519\u8bef\u505a\u5176\u4ed6\u7684\u5904\u7406\uff0c\u53ea\u9700\u8981\u4fdd\u8bc1\u4ee3\u7801\u903b\u8f91\u6b63\u786e\u6267\u884c\u5373\u53ef\u3002<\/p>\n
if err != nil {\n    \/\/ something went wrong\n}\n<\/code><\/pre>\n
\u4f46\u6709\u7684\u65f6\u5019\u6211\u4eec\u9700\u8981\u6839\u636e\u9519\u8bef\u7c7b\u578b\u8fdb\u884c\u4e0d\u540c\u7684\u5904\u7406\uff0c\u6bd4\u5982\u7f51\u7edc\u8fde\u63a5\u672a\u8fde\u63a5\/\u65ad\u5f00\u5bfc\u81f4\u7684\u9519\u8bef\uff0c\u6211\u4eec\u5e94\u8be5\u5728\u5224\u65ad\u662f\u672a\u8fde\u63a5\/\u65ad\u5f00\u65f6\uff0c\u8fdb\u884c\u91cd\u8fde\u64cd\u4f5c\u3002 \u5728\u6d89\u53ca\u5230\u9519\u8bef\u7c7b\u578b\u7684\u5224\u65ad\u65f6\uff0c\u6211\u4eec\u901a\u5e38\u6709\u4e24\u79cd\u65b9\u6cd5<\/p>\n
    \n
  1. \u5c06\u9519\u8bef\u548c\u5df2\u77e5\u7684\u503c\u8fdb\u884c\u6bd4\u5bf9<\/li>\n<\/ol>\n
    var ErrNotFound = errors.New(\"not found\")\n\nif err == ErrNotFound {\n    \/\/ something wasn't found\n}\n<\/code><\/pre>\n
      \n
    1. \u5224\u65ad\u9519\u8bef\u7684\u5177\u4f53\u7c7b\u578b<\/li>\n<\/ol>\n
      type NotFoundError struct {\n    Name string\n}\n\nfunc (e *NotFoundError) Error() string { return e.Name + \": not found\" }\n\nif e, ok := err.(*NotFoundError); ok {\n    \/\/ e.Name wasn't found\n}\n<\/code><\/pre>\n
      \u6dfb\u52a0\u4fe1\u606f<\/h4>\n
      \u5f53\u4e00\u4e2a\u9519\u8bef\u5728\u7ecf\u8fc7\u591a\u5c42\u7684\u8c03\u7528\u6808\u5411\u4e0a\u8fd4\u56de\u65f6\uff0c\u6211\u4eec\u901a\u5e38\u4f1a\u5728\u8fd9\u4e2a\u9519\u8bef\u4e0a\u6dfb\u52a0\u4e00\u4e9b\u989d\u5916\u7684\u4fe1\u606f\uff0c\u4ee5\u5e2e\u52a9\u5f00\u53d1\u4eba\u5458\u5224\u65ad\u9519\u8bef\u51fa\u73b0\u65f6\u7a0b\u5e8f\u8fd0\u884c\u5230\u4e86\u54ea\u91cc\uff0c\u53d1\u751f\u4e86\u4ec0\u4e48\u3002\u6700\u7b80\u5355\u7684\u65b9\u5f0f\u662f\uff0c\u4f7f\u7528\u4e4b\u524d\u7684\u9519\u8bef\u4fe1\u606f\u6784\u9020\u65b0\u7684\u9519\u8bef\uff1a<\/p>\n
      if err != nil {\n    return fmt.Errorf(\"decompress %v: %v\", name, err)\n}\n<\/code><\/pre>\n
      \u4f7f\u7528 fmt.Errorf<\/code> \u53ea\u4fdd\u7559\u4e86\u4e0a\u4e00\u4e2a\u9519\u8bef\u7684\u6587\u672c\uff0c\u4e22\u5f03\u4e86\u5176\u4ed6\u6240\u6709\u7684\u4fe1\u606f\u3002\u5982\u679c\u6211\u4eec\u60f3\u4fdd\u7559\u4e0a\u4e00\u4e2a\u9519\u8bef\u7684\u6240\u6709\u4fe1\u606f\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u4e0b\u9762\u7684\u65b9\u5f0f\uff1a<\/p>\n
      type QueryError struct {\n    Query string\n    Err   error\n}\n\nif e, ok := err.(*QueryError); ok && e.Err == ErrPermission {\n    \/\/ query failed because of a permission problem\n}\n<\/code><\/pre>\n
      2.3 Golang 1.13 \u4e2d\u7684\u9519\u8bef\u5904\u7406<\/h3>\n
      Golang 1.13 \u4e2d\uff0c\u5982\u679c\u4e00\u4e2a\u9519\u8bef\u5305\u542b\u4e86\u53e6\u4e00\u4e2a\u9519\u8bef\uff0c\u5219\u53ef\u4ee5\u901a\u8fc7\u5b9e\u73b0 Unwrap()<\/code> \u65b9\u6cd5\u6765\u8fd4\u56de\u5e95\u5c42\u7684\u9519\u8bef\u3002\u5982\u679c e1.Unwrap()<\/code> \u8fd4\u56de\u4e86 e2\uff0c\u6211\u4eec\u5c31\u53ef\u4ee5\u8bf4 e1 \u5305\u542b\u4e86 e2\u3002<\/p>\n
      \u4f7f\u7528 Is \u548c As \u6765\u68c0\u9a8c\u9519\u8bef<\/h4>\n
      \u5728 2.2 \u4e2d\u63d0\u5230\u4e86\u9519\u8bef\u4fe1\u606f\u7684\u5e38\u89c1\u5904\u7406\u65b9\u5f0f\uff0c\u5728 Golang 1.13 \u4e2d\uff0c\u6807\u51c6\u5e93\u4e2d\u6dfb\u52a0\u4e86\u51e0\u4e2a\u65b9\u6cd5\u6765\u5e2e\u52a9\u6211\u4eec\u66f4\u5feb\u901f\u7684\u5b8c\u6210\u4ee5\u4e0a\u7684\u5de5\u4f5c\u3002\u5f53\u524d\u524d\u63d0\u662f\uff0c\u4f60\u7684\u81ea\u5b9a\u4e49 Error \u6b63\u786e\u7684\u5b9e\u73b0\u4e86 Unwrap()<\/code> \u65b9\u6cd5<\/p>\n
      errors.Is<\/code> \u7528\u6765\u5c06\u4e00\u4e2a\u9519\u8bef\u548c\u4e00\u4e2a\u503c\u8fdb\u884c\u5bf9\u6bd4\uff1a<\/p>\n
      \/\/ Similar to:\n\/\/   if err == ErrNotFound { \u2026 }\nif errors.Is(err, ErrNotFound) {\n    \/\/ something wasn't found\n}\n<\/code><\/pre>\n
      errors.As<\/code> \u7528\u6765\u5224\u65ad\u4e00\u4e2a\u9519\u8bef\u662f\u5426\u662f\u4e00\u4e2a\u7279\u5b9a\u7684\u7c7b\u578b\uff1a<\/p>\n
      \/\/ Similar to:\n\/\/   if e, ok := err.(*QueryError); ok { \u2026 }\nvar e *QueryError\nif errors.As(err, &e) {\n    \/\/ err is a *QueryError, and e is set to the error's value\n}\n<\/code><\/pre>\n
      \u5f53\u64cd\u4f5c\u4e00\u4e2a\u5305\u88c5\u4e86\u7684\u9519\u8bef\u65f6\uff0cIs<\/code> \u548c As<\/code> \u4f1a\u8003\u8651\u9519\u8bef\u94fe\u4e0a\u6240\u6709\u7684\u9519\u8bef\u3002\u4e00\u4e2a\u5b8c\u6574\u7684\u4f8b\u5b50\u5982\u4e0b\uff1a<\/p>\n
      type ErrorA struct {\n    Msg string\n}\n\nfunc (e *ErrorA) Error() string {\n    return e.Msg\n}\n\ntype ErrorB struct {\n    Msg string\n    Err *ErrorA\n}\n\nfunc (e *ErrorB) Error() string {\n    return e.Msg + e.Err.Msg\n}\n\nfunc (e *ErrorB) Unwrap() error {\n    return e.Err\n}\n\nfunc main() {\n    a := &ErrorA{\"error a\"}\n\n    b := &ErrorB{\"error b\", a}\n\n    if errors.Is(b, a) {\n        log.Println(\"error b is a\")\n    }\n\n    var tmpa *ErrorA\n    if errors.As(b, &tmpa) {\n        log.Println(\"error b as ErrorA\")\n    }\n}\n<\/code><\/pre>\n
      \u8f93\u51fa\u5982\u4e0b\uff1a<\/p>\n
      error b is a\nerror b as ErrorA\n<\/code><\/pre>\n
      \u4f7f\u7528 %w \u6765\u5305\u88c5\u9519\u8bef<\/h4>\n
      Go 1.13 \u4e2d\u589e\u52a0\u4e86 %w\uff0c\u5f53 %w \u51fa\u73b0\u65f6\uff0c\u7531 fmt.Errorf<\/code> \u8fd4\u56de\u7684\u9519\u8bef\uff0c\u5c06\u4f1a\u6709 Unwrap<\/code> \u65b9\u6cd5\uff0c\u8fd4\u56de\u7684\u662f %w \u5bf9\u5e94\u7684\u503c\u3002\u4e0b\u9762\u662f\u4e00\u4e2a\u7b80\u5355\u7684\u4f8b\u5b50\uff1a<\/p>\n
      type ErrorA struct {\n    Msg string\n}\n\nfunc (e *ErrorA) Error() string {\n    return e.Msg\n}\n\nfunc main() {\n    a := &ErrorA{\"error a\"}\n\n    b := fmt.Errorf(\"new error: %w\", a)\n\n    if errors.Is(b, a) {\n        fmt.Println(\"error b is a\")\n    }\n\n    var tmpa *ErrorA\n    if errors.As(b, &tmpa) {\n        fmt.Println(\"error b as ErrorA\")\n    }\n}\n<\/code><\/pre>\n
      \u8f93\u51fa\u5982\u4e0b\uff1a<\/p>\n
      error b is a\nerror b as ErrorA\n<\/code><\/pre>\n
      \u662f\u5426\u9700\u8981\u5bf9\u9519\u8bef\u8fdb\u884c\u5305\u88c5<\/h4>\n
      \u5f53\u4f60\u5411\u4e00\u4e2a error \u4e2d\u6dfb\u52a0\u989d\u5916\u7684\u4e0a\u4e0b\u6587\u4fe1\u606f\u65f6\uff0c\u8981\u4e48\u4f7f\u7528 fmt.Errorf<\/code>\uff0c\u8981\u4e48\u5b9e\u73b0\u4e00\u4e2a\u81ea\u5b9a\u4e49\u7684\u9519\u8bef\u7c7b\u578b\uff0c\u8fd9\u662f\u4f60\u5c31\u8981\u51b3\u5b9a\u8fd9\u4e2a\u65b0\u7684\u9519\u8bef\u662f\u5426\u5e94\u8be5\u5305\u88c5\u539f\u59cb\u7684\u9519\u8bef\u4fe1\u606f\u3002\u8fd9\u662f\u4e00\u4e2a\u6ca1\u6709\u6807\u51c6\u7b54\u6848\u7684\u95ee\u9898\uff0c\u5b83\u53d6\u51b3\u4e8e\u65b0\u9519\u8bef\u521b\u5efa\u7684\u4e0a\u4e0b\u6587\u3002<\/p>\n
      \u5305\u88c5\u4e00\u4e2a\u9519\u8bef\u662f\u4e3a\u4e86\u5c06\u5b83\u66b4\u9732\u7ed9\u8c03\u7528\u8005\u3002\u8fd9\u6837\u8c03\u7528\u8005\u5c31\u53ef\u4ee5\u6839\u636e\u4e0d\u540c\u7684\u539f\u59cb\u9519\u8bef\u4f5c\u51fa\u4e0d\u540c\u7684\u5904\u7406\uff0c\u6bd4\u5982 os.Open(file)<\/code> \u4f1a\u8fd4\u56de\u6587\u4ef6\u4e0d\u5b58\u5728\u8fd9\u79cd\u5177\u4f53\u7684\u9519\u8bef\uff0c \u8fd9\u6837\u8c03\u7528\u8005\u5c31\u53ef\u4ee5\u901a\u8fc7\u521b\u5efa\u6587\u4ef6\u6765\u8ba9\u4ee3\u7801\u53ef\u4ee5\u6b63\u786e\u5f80\u4e0b\u6267\u884c\u3002<\/p>\n
      \u5f53\u6211\u4eec\u4e0d\u60f3\u66b4\u9732\u5b9e\u73b0\u7ec6\u8282\u65f6\u5c31\u4e0d\u8981\u5305\u88c5\u9519\u8bef\u3002\u56e0\u4e3a\u66b4\u9732\u4e00\u4e2a\u5177\u5907\u7ec6\u8282\u7684\u9519\u8bef\uff0c\u5c31\u610f\u5473\u7684\u8c03\u7528\u8005\u548c\u6211\u4eec\u7684\u4ee3\u7801\u4ea7\u751f\u4e86\u8026\u5408\u3002\u8fd9\u4e5f\u8fdd\u53cd\u4e86\u62bd\u8c61\u7684\u539f\u5219\u3002<\/p>\n
      \u4e09\u3001\u53c2\u8003\u8d44\u6599<\/h2>\n