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本文主要研究一下dubbo-go-proxy的jtypes
JTypeMapper
dubbo-go-proxy/pkg/common/constant/jtypes.go
// Object represents the java.lang.Object type
type Object interface{}
// JTypeMapper maps the java basic types to golang types
var JTypeMapper = map[string]reflect.Type{
"string": reflect.TypeOf(""),
"java.lang.String": reflect.TypeOf(""),
"char": reflect.TypeOf(""),
"short": reflect.TypeOf(int32(0)),
"int": reflect.TypeOf(int32(0)),
"long": reflect.TypeOf(int64(0)),
"float": reflect.TypeOf(float64(0)),
"double": reflect.TypeOf(float64(0)),
"boolean": reflect.TypeOf(true),
"java.util.Date": reflect.TypeOf(time.Time{}),
"date": reflect.TypeOf(time.Time{}),
"object": reflect.TypeOf([]Object{}).Elem(),
"java.lang.Object": reflect.TypeOf([]Object{}).Elem(),
}
JTypeMapper定义了个map,key为java类型,value为golang的reflect.Type
mapTypes
dubbo-go-proxy/pkg/client/dubbo/mapper.go
func mapTypes(jType string, originVal interface{}) (interface{}, error) {
targetType, ok := constant.JTypeMapper[jType]
if !ok {
return nil, errors.Errorf("Invalid parameter type: %s", jType)
}
switch targetType {
case reflect.TypeOf(""):
return cast.ToStringE(originVal)
case reflect.TypeOf(int32(0)):
return cast.ToInt32E(originVal)
case reflect.TypeOf(int64(0)):
return cast.ToInt64E(originVal)
case reflect.TypeOf(float64(0)):
return cast.ToFloat64E(originVal)
case reflect.TypeOf(true):
return cast.ToBoolE(originVal)
case reflect.TypeOf(time.Time{}):
return cast.ToBoolE(originVal)
default:
return originVal, nil
}
}
mapTypes方法先根据jType从JTypeMapper取出对应的golang的reflect.Type,然后挨个根据这个类型使用cast类库进行转换,转成golang的interface{}
caste.go
github.com/spf13/cast@v1.3.1/caste.go
// ToStringE casts an interface to a string type.
func ToStringE(i interface{}) (string, error) {
i = indirectToStringerOrError(i)
switch s := i.(type) {
case string:
return s, nil
case bool:
return strconv.FormatBool(s), nil
case float64:
return strconv.FormatFloat(s, 'f', -1, 64), nil
case float32:
return strconv.FormatFloat(float64(s), 'f', -1, 32), nil
case int:
return strconv.Itoa(s), nil
case int64:
return strconv.FormatInt(s, 10), nil
case int32:
return strconv.Itoa(int(s)), nil
case int16:
return strconv.FormatInt(int64(s), 10), nil
case int8:
return strconv.FormatInt(int64(s), 10), nil
case uint:
return strconv.FormatUint(uint64(s), 10), nil
case uint64:
return strconv.FormatUint(uint64(s), 10), nil
case uint32:
return strconv.FormatUint(uint64(s), 10), nil
case uint16:
return strconv.FormatUint(uint64(s), 10), nil
case uint8:
return strconv.FormatUint(uint64(s), 10), nil
case []byte:
return string(s), nil
case template.HTML:
return string(s), nil
case template.URL:
return string(s), nil
case template.JS:
return string(s), nil
case template.CSS:
return string(s), nil
case template.HTMLAttr:
return string(s), nil
case nil:
return "", nil
case fmt.Stringer:
return s.String(), nil
case error:
return s.Error(), nil
default:
return "", fmt.Errorf("unable to cast %#v of type %T to string", i, i)
}
}
github.com/spf13/cast提供了一系列的cast方法,用于将interface{}转换为指定的类型
小结
JTypeMapper定义了个map,key为java类型,value为golang的reflect.Type;mapTypes方法先根据jType从JTypeMapper取出对应的golang的reflect.Type,然后挨个根据这个类型使用cast类库进行转换,转成golang的interface{}。
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