Golang学习笔记_19------Stringer
Golang学习笔记_20------error
Golang学习笔记_21------Reader
文章目录
-
- [`io.Reader` 示例](#
io.Reader示例) - 源码
- [`io.Reader` 示例](#
io.Reader 示例
从字符串中读取
go
func ReadFromStrDemo() {
str := "hello world"
reader := bufio.NewReader(strings.NewReader(str))
buf := make([]byte, 2)
for {
n, err := reader.Read(buf)
if err != nil && err != io.EOF {
fmt.Println("Error reading", err)
break
}
if n == 0 {
break
}
fmt.Println(string(buf[:n]))
if err == io.EOF {
break
}
}
}测试方法
go
func TestReadFromStrDemo(t *testing.T) {
ReadFromStrDemo()
}输出结果
=== RUN TestReadFromStrDemo
he
ll
o
wo
rl
d
--- PASS: TestReadFromStrDemo (0.00s)
PASS
从文件中读取
go
func ReadFromFileDemo() {
file, err := os.Open("test.txt")
if err != nil {
fmt.Println("Error opening file", err)
return
}
defer file.Close()
reader := bufio.NewReader(file)
buf := make([]byte, 1)
for {
n, err := reader.Read(buf)
if err != nil && err != io.EOF {
fmt.Println("Error reading", err)
break
}
if n == 0 {
break
}
fmt.Println(string(buf[:n]))
if err == io.EOF {
break
}
}
}测试方法
go
func TestReadFromFileDemo(t *testing.T) {
ReadFromFileDemo()
}输出结果
=== RUN TestReadFromFileDemo
h
e
l
l
o
i
o
.
R
e
a
d
e
r
--- PASS: TestReadFromFileDemo (0.00s)
PASS
从HTTP响应中读取
go
func ReadFromHTTPResponseDemo() {
resp, err := http.Get("https://www.bing.com")
if err != nil {
fmt.Println("Error", err)
return
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
fmt.Println("StatusCode", resp.StatusCode)
return
}
body, err := io.ReadAll(resp.Body)
if err != nil {
fmt.Println("Error", err)
return
}
fmt.Println(string(body))
}测试文件
go
func TestReadFromHTTPResponseDemo(t *testing.T) {
ReadFromHTTPResponseDemo()
}输出结果
=== RUN TestReadFromHTTPResponseDemo
<!doctype html><html lang="zh" dir="ltr"><head><meta name="theme-color" content="#4F4F4F" /><meta name="description" content="使用 Microsoft 必应进行搜索，并利用 AI 的强大功能查找信息、浏览网页、图像、视频、地图等。为永远充满好奇心的人提供的智能搜索引擎。" /><meta http-equiv="X-UA-Compatible" content="IE=edge" /><meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta property="fb:app_id" content="3732605936979161" /><meta property="og:type" content="website" /><meta property="og:title" content="变换的地平线" /><meta property="og:image" content="https://www.bing.com/th?id=OHR.NamibiaDunes_ZH-CN5102483490_tmb.jpg&rf=" /><meta property="og:image:width" content="1366" /><meta property="og:image:height" content="768" /><meta property="og:url" content="https://www.bing.com/?form=HPFBBK&ssd=20250108_1600&mkt=zh-CN" /><meta property="og:site_name" content="搜索 - Microsoft 必应" /><meta property="og:description" content="想象在日出时分，连绵起伏的沙丘泛着橙色光芒，延伸至视野尽头，欢迎来到横跨纳米比亚数千英里的纳米布沙漠" /><title>搜索 - Microsoft 必应</title><link href="https://cn.bing.com/" rel="canonical" /><link rel="preconnect" href="https://r.bing.com" /><link rel="preconnect" href="https://r.bing.com" crossorigin/><link rel="dns-prefetch" href="https://r.bing.com" /><link rel="dns-prefetch" href="https://r.bing.com" crossorigin/><link rel="stylesheet" href="/rp/RCJCS6O5TykkUhXX1pwc6RsdyuI.gz.css" type="text/css"/><script type="text/javascript" nonce="NswLywYcmcprKdDH3kMxFF5vl+yeKu1radXvoCmwxVY=">//<![CDATA[
var __assign=this&&this.__assign||function(){return __assign=Object.assign||function(n){for(var t,r,i=1,u=arguments.length;i<u;i++){t=arguments[i];for(r in t)Object.prototype.hasOwnProperty.call(t,r)&&(n[r]=t[r])}return n},__assign.apply(this,arguments)},logE=function(n,t,i){t===void 0&&(t=null);i===void 0&&(i="ClientInst");var r=[__assign({T:"CI.".concat(i),FID:"CI",Name:n},t&&{Text:t})],u="".concat(_G.lsUrl,"&Type=Event.ClientInst&DATA=").concat(encodeURIComponent(JSON.stringify(r)));(new Image).src=u},CSPIF;window.CSPEL=[];CSPIF=function(n){var t="clarity",i="CSPViolation",r,u;return(window[t]&&(window[t]("set",i,n.sample),window[t]("event",i)),r=["chrome-extension"],u=["javascript:void(0)","javascript: void(0)"],r.some(function(t){return n.sourceFile.includes(t)})||u.some(function(t){return n.sample.includes(t)}))?!0:window.CSPEL.includes(n.sample)?!0:(window.CSPEL.push(n.sample),!1)};try{var ignErr=["ResizeObserver loop","Script error"],ignCSPErr=["unsafe-eval"],maxErr=3,ignoreCurrentError=function(n,t){return(ignErr.some(function(t){return n.includes(t)})||ignCSPErr.some(function(t){return n.includes(t)}))?ignCSPErr.some(function(t){return n.includes(t)})&&t.filename&&!t.filename.includes("chrome-extension://")?!1:(t!=null&&(typeof sj_sp!="undefined"&&sj_sp(t),typeof sj_pd!="undefined"&&sj_pd(t)),!0):!1},regexEsc=function(n){return n.replace(/([.?*+^$&[\]\\(){}|<>-])/g,"\\$1")},ignoreCSPLog=function(n){return["javascript:void(0)","javascript: void(0)","javascript:void()"].some(function(t){return n.sample.includes(t)})};window.jsErrorHandler=function(n){var f,p,h,rt,ut,u,e,ft,o,a,v,s;try{if(f='"noMessage"',p=(n.error||n).message||f,ignoreCurrentError(p,n))return;if(h=(window.ERC?window.ERC:0)+1,window.ERC=h,h>maxErr){logE("max errors reached");return}var c=n.error||n,w=n.filename,b=n.lineno,k=n.colno,d=n.extra,l=c.severity||"Error",g=c.message||f,i=c.stack,t='"'+escape(g.replace(/"/g,""))+'"',nt=new RegExp(regexEsc(location.href),"g"),tt=window.lirab,it=window.liraa,r=tt?" hint == ["+tt:"";if(r=r+(it?", "+it+")":r?"]":""),i){for(rt=/\(([^\)]+):[0-9]+:[0-9]+\)/g,u={};(ut=rt.exec(i))!==null;)e=ut[1],u[e]?u[e]++:u[e]=1;o=0;for(a in u)u[a]>1&&(v=regexEsc(a),ft=new RegExp(v,"g"),i=i.replace(ft,o),i+="#"+o+"="+v,o++);i=i.replace(nt,"self").replace(/"/g,"");t+=',"Stack":"'+(escape(i)+'"')}if(w?t+=',"Meta":"'+escape(w.replace(nt,"self"))+r+'"':r&&(t+=',"Meta":"'+r+'"'),b&&(t+=',"Line":"'+b+'"'),k&&(t+=',"Char":"'+k+'"'),d&&(t+=',"ExtraInfo":"'+d+'"'),g===f)if(l="Warning",t+=',"ObjectToString":"'+n.toString()+'"',JSON&&JSON.stringify)t+=',"JSON":"'+escape(JSON.stringify(n))+'"';else for(s in n)n.hasOwnProperty(s)&&(t+=',"'+s+'":"'+n[s]+'"');var et=(new Date).getTime(),ot='"T":"CI.'+l+'","FID":"CI","Name":"JS'+l+'","Text":'+t+"",st="<E><T>Event.ClientInst<\/T><IG>"+_G.IG+"<\/IG><TS>"+et+"<\/TS><D><![CDATA[[{"+ot+"}]]\]><\/D><\/E>",ht="<ClientInstRequest><Events>"+st+"<\/Events><STS>"+et+"<\/STS><\/ClientInstRequest>",y=new XMLHttpRequest;y.open("POST","/fd/ls/lsp.aspx?",!0);y.setRequestHeader("Content-Type","text/xml");y.send(ht);typeof sj_evt!="undefined"&&sj_evt.fire("ErrorInstrumentation",t)}catch(ct){logE("MetaJSError","Failed to execute error handler. "+ct.message)}};window.CSPEH=function(n){CSPIF(n)||logE("CSPViolation",n.sample,"Error")};window.addEventListener&&(window.addEventListener("error",window.jsErrorHandler,!1),window.addEventListener("unhandledrejection",window.jsErrorHandler,!1),window.addEventListener("securitypolicyviolation",window.CSPEH))}catch(e){logE("MetaJSError","Failed to bind error handler "+e.message)};
//]]></script></head><body><div class="hp_body"><div class="hpl hp_cont"><div class="sbox"><form action="/search" id="sb_form" class="sb_form"><input id="sb_form_q" class="sb_form_q" name="q"
placeholder="" type="search" maxlength="1000" autocapitalize="off" autocomplete="off" spellcheck="false"
title="输入搜索词" autofocus="autofocus" ) /><input id="sb_form_go" type="submit"
title="搜索" name="search" value=""
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//]]></script><div id="aRmsDefer"><script type="text/rms" nonce="NswLywYcmcprKdDH3kMxFF5vl+yeKu1radXvoCmwxVY=">//<![CDATA[
Feedback.Bootstrap.InitializeFeedback({page:true},"sb_feedback",1,0,0);;
//]]></script></div></body></html>
--- PASS: TestReadFromHTTPResponseDemo (1.40s)
PASS
从内存的字节切片中读取
go
func ReadFromMemoryDemo() {
data := []byte("hello io.Reader")
reader := bytes.NewReader(data)
buf := make([]byte, 1)
for {
n, err := reader.Read(buf)
if err != nil && err != io.EOF {
fmt.Println("Error reading", err)
break
}
if n == 0 {
break
}
fmt.Println(string(buf[:n]))
if err == io.EOF {
break
}
}
}测试方法
go
func TestReadFromMemoryDemo(t *testing.T) {
ReadFromMemoryDemo()
}输出结果
=== RUN TestReadFromMemoryDemo
h
e
l
l
o
i
o
.
R
e
a
d
e
r
--- PASS: TestReadFromMemoryDemo (0.00s)
PASS
自定义io.Reader实现
go
// 自定义io.Reader实现
type myReader struct {
data []byte
pos int
}
func (mr *myReader) Read(p []byte) (int, error) {
n := copy(p, mr.data[mr.pos:])
mr.pos += n
if mr.pos >= len(mr.data) {
return n, io.EOF
}
return n, nil
}
func ReadFromMyReaderDemo() {
data := []byte("hello io.Reader")
reader := &myReader{data, 0}
buf := make([]byte, 1)
for {
n, err := reader.Read(buf)
if err != nil && err != io.EOF {
fmt.Println("Error reading", err)
break
}
if n == 0 {
break
}
fmt.Println(string(buf[:n]))
if err == io.EOF {
break
}
}
}测试方法
go
func TestReadFromMyReaderDemo(t *testing.T) {
ReadFromMyReaderDemo()
}输出结果
=== RUN TestReadFromMyReaderDemo
h
e
l
l
o
i
o
.
R
e
a
d
e
r
--- PASS: TestReadFromMyReaderDemo (0.00s)
PASS
源码
go
// reader_demo_2.go 文件
package reader_demo
import (
"bufio"
"bytes"
"fmt"
"io"
"net/http"
"os"
"strings"
)
func ReadFromStrDemo() {
str := "hello world"
reader := bufio.NewReader(strings.NewReader(str))
buf := make([]byte, 2)
for {
n, err := reader.Read(buf)
if err != nil && err != io.EOF {
fmt.Println("Error reading", err)
break
}
if n == 0 {
break
}
fmt.Println(string(buf[:n]))
if err == io.EOF {
break
}
}
}
func ReadFromFileDemo() {
file, err := os.Open("test.txt")
if err != nil {
fmt.Println("Error opening file", err)
return
}
defer file.Close()
reader := bufio.NewReader(file)
buf := make([]byte, 1)
for {
n, err := reader.Read(buf)
if err != nil && err != io.EOF {
fmt.Println("Error reading", err)
break
}
if n == 0 {
break
}
fmt.Println(string(buf[:n]))
if err == io.EOF {
break
}
}
}
func ReadFromHTTPResponseDemo() {
resp, err := http.Get("https://www.bing.com")
if err != nil {
fmt.Println("Error", err)
return
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
fmt.Println("StatusCode", resp.StatusCode)
return
}
body, err := io.ReadAll(resp.Body)
if err != nil {
fmt.Println("Error", err)
return
}
fmt.Println(string(body))
}
func ReadFromMemoryDemo() {
data := []byte("hello io.Reader")
reader := bytes.NewReader(data)
buf := make([]byte, 1)
for {
n, err := reader.Read(buf)
if err != nil && err != io.EOF {
fmt.Println("Error reading", err)
break
}
if n == 0 {
break
}
fmt.Println(string(buf[:n]))
if err == io.EOF {
break
}
}
}
// 自定义io.Reader实现
type myReader struct {
data []byte
pos int
}
func (mr *myReader) Read(p []byte) (int, error) {
n := copy(p, mr.data[mr.pos:])
mr.pos += n
if mr.pos >= len(mr.data) {
return n, io.EOF
}
return n, nil
}
func ReadFromMyReaderDemo() {
data := []byte("hello io.Reader")
reader := &myReader{data, 0}
buf := make([]byte, 1)
for {
n, err := reader.Read(buf)
if err != nil && err != io.EOF {
fmt.Println("Error reading", err)
break
}
if n == 0 {
break
}
fmt.Println(string(buf[:n]))
if err == io.EOF {
break
}
}
}
go
// readder_demo_2_test.go 文件
package reader_demo
import "testing"
func TestReadFromStrDemo(t *testing.T) {
ReadFromStrDemo()
}
func TestReadFromFileDemo(t *testing.T) {
ReadFromFileDemo()
}
func TestReadFromHTTPResponseDemo(t *testing.T) {
ReadFromHTTPResponseDemo()
}
func TestReadFromMemoryDemo(t *testing.T) {
ReadFromMemoryDemo()
}
func TestReadFromMyReaderDemo(t *testing.T) {
ReadFromMyReaderDemo()
}