Golang学习笔记_20——error

Golang学习笔记_17------方法
Golang学习笔记_18------接口
Golang学习笔记_19------Stringer

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文章目录

• • error
  • • [1. 接口](#1. 接口)
    • [2. 创建](#2. 创建)
    • [3. 自定义错误](#3. 自定义错误)
    • [4. 处理错误](#4. 处理错误)
    • [5. 实现`Error`接口](#5. 实现Error接口)
  • 源码

---

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

type error interface {
    Error() string
}

2. 创建

import (
    "errors"
    "fmt"
)

func demo_1() {
    err := errors.New("something went wrong")
    if err != nil {
        fmt.Println("Error:", err)
    }
}

测试方法

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

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

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

func demo_3(err *MyError) {

	if err != nil {
		fmt.Println("Error:", err)
	} else {
		fmt.Println("No error")
	}
}

测试方法

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

// 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

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

// 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)
}

// 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()
}