Golang学习笔记_17------方法
Golang学习笔记_18------接口
Golang学习笔记_19------Stringer
文章目录
error
在Go语言中，error 是一个内建的接口类型，用于表示和处理错误情况。它是Go语言错误处理机制的核心。下面将详细讲解Go语言中 error 的相关概念和用法。
1. 接口
error 接口非常简单，仅包含一个方法
go
type error interface {
Error() string
}2. 创建
go
import (
"errors"
"fmt"
)
func demo_1() {
err := errors.New("something went wrong")
if err != nil {
fmt.Println("Error:", err)
}
}测试方法
go
func Test_demo_1(t *testing.T) {
demo_1()
}输出结果
=== RUN Test_demo_1
Error: something went wrong
--- PASS: Test_demo_1 (0.00s)
PASS
3. 自定义错误
go
type MyError struct {
Code int
Message string
}
func (e *MyError) Error() string {
return fmt.Sprintf("code:%d \nmessage:%s", e.Code, e.Message)
}
func demo_2() {
err := &MyError{
Code: 1,
Message: "something went wrong",
}
fmt.Println(err)
}测试方法
go
func Test_demo_2(t *testing.T) {
demo_2()
}输出结果
=== RUN Test_demo_2
code:1
message:something went wrong
--- PASS: Test_demo_2 (0.00s)
PASS
4. 处理错误
在自定义错误代码的基础上，实现错误处理
go
func demo_3(err *MyError) {
if err != nil {
fmt.Println("Error:", err)
} else {
fmt.Println("No error")
}
}测试方法
go
func Test_demo_3(t *testing.T) {
type args struct {
err *MyError
}
tests := []struct {
name string
args args
}{
{
name: "error",
args: args{
err: &MyError{
Code: 1,
Message: "something went wrong",
},
},
},
{
name: "no error",
args: args{
err: nil,
},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
demo_3(tt.args.err)
})
}
}输出结果
=== RUN Test_demo_3
=== RUN Test_demo_3/error
Error: code:1
message:something went wrong
=== RUN Test_demo_3/no_error
No error
--- PASS: Test_demo_3 (0.00s)
--- PASS: Test_demo_3/error (0.00s)
--- PASS: Test_demo_3/no_error (0.00s)
PASS
5. 实现Error接口
go
// 定义一个表示文件错误的结构体
type FileError struct {
FileName string
ErrMsg string
}
// 实现 error 接口的 Error() 方法
func (e *FileError) Error() string {
return fmt.Sprintf("file error: %s - %s", e.FileName, e.ErrMsg)
}
func demo_4() {
err := &FileError{
FileName: "example.txt",
ErrMsg: "failed to open file",
}
fmt.Println(err)
}测试方法
go
func Test_demo_4(t *testing.T) {
demo_4()
}输出结果
=== RUN Test_demo_4
file error: example.txt - failed to open file
--- PASS: Test_demo_4 (0.00s)
PASS
源码
go
// error_demo.go 文件
package error_demo
import (
"errors"
"fmt"
)
func demo_1() {
err := errors.New("something went wrong")
if err != nil {
fmt.Println("Error:", err)
}
}
type MyError struct {
Code int
Message string
}
func (e *MyError) Error() string {
return fmt.Sprintf("code:%d \nmessage:%s", e.Code, e.Message)
}
func demo_2() {
err := &MyError{
Code: 1,
Message: "something went wrong",
}
fmt.Println(err)
}
func demo_3(err *MyError) {
if err != nil {
fmt.Println("Error:", err)
} else {
fmt.Println("No error")
}
}
// 定义一个表示文件错误的结构体
type FileError struct {
FileName string
ErrMsg string
}
// 实现 error 接口的 Error() 方法
func (e *FileError) Error() string {
return fmt.Sprintf("file error: %s - %s", e.FileName, e.ErrMsg)
}
func demo_4() {
err := &FileError{
FileName: "example.txt",
ErrMsg: "failed to open file",
}
fmt.Println(err)
}
go
// error_demo_test.go 文件
package error_demo
import (
"errors"
"testing"
)
func Test_demo_1(t *testing.T) {
demo_1()
}
func Test_demo_2(t *testing.T) {
demo_2()
}
func Test_demo_3(t *testing.T) {
type args struct {
err *MyError
}
tests := []struct {
name string
args args
}{
{
name: "error",
args: args{
err: &MyError{
Code: 1,
Message: "something went wrong",
},
},
},
{
name: "no error",
args: args{
err: nil,
},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
demo_3(tt.args.err)
})
}
}
func Test_demo_4(t *testing.T) {
demo_4()
}