只渲染一次 importReact,{useEffect,useState}from"react";interfaceIHelloProps{message?:string;}constMouseButton:React.FC=()=>{const[like,setLike]=useState(0);const[positions,setPosition]=useState({x:0,y:0})useEffect(()=>{constupdateMouse=(e:MouseEvent)=>{setPosition({x:e.clientX,y:e.cl...
importReact,{useState}from"react";interfaceIHelloProps{message?:string;}constLikeButton:React.FC=()=>{const[like,setLike]=useState(0);return(<div><div>111</div><buttononClick={()=>{setLike(like+1)}}>111</button></div>)};exportdefaultLikeButton;
importReactfrom"react";interfaceIHelloProps{message?:string;}constHello:React.FunctionComponent<IHelloProps>=(props)=>{return<h2>{props.message}</h2>}Hello.defaultProps={message:"HelloGeyao"}exportdefaultHello
//将图片路径转base64functiongetBase64(img,callback){constreader=newFileReader();reader.addEventListener('load',()=>callback(reader.result));reader.readAsDataURL(img);}//点击了上传图片consthandleChange=info=>{if(info.file.status='uploading'){setLoading(true)return;}if(info.file.status='done'){//Getthis...
importjava.util.Scanner;publicclassDemo02{publicstaticvoidmain(String[]args){Scannerscnner=newScanner(System.in);System.out.println("使用next修改");if(scnner.hasNext()){Stringgeyao=scnner.next();System.out.println("输出的内容为"+geyao);}scnner.close();}}
<p>点击下方修改头像：</p><Uploadname="avatar"listType="picture-card"className="avatar-uploader"showUploadList={false}action="/api/upload"beforeUpload={beforeUpload}onChange={handleChange}headers={{"cms-token":localStorage.getItem('cms-token')}}>{imageUrl?<imgsrc={imageUrl}alt="avata...
Youdon'tneedtopassitagainsinceyoualreadypassedittocreatetheroot 解决 root.render(<Router/>,document.getElementById('root')); 这边写错了
//表单提交的事件constonFinish=(values)=>{//如果表单的username有值，并且不等于初始化时拿到的username，同时密码非空if(values.username&&values.username!sessionStorage.getItem('username')&&values.password.trim()!""){//做表单的提交...ChangeUserDataApi({username:values.username,password:values.password}).then(res=>{co...
表空间是oracle内部定义的一个概念,是为了统一oracle物理和逻辑上的结构而专门建立的,从物理上来说,一个表空间是由具体的一个或多个磁盘上数据文件构成的(至少1对1,可以1对多),从逻辑上来说一个表空间是由具体的一个或多个用户模式下的表,索引等等里面的数据所构成的.因此从用户的角度来看是不应该看到磁盘上物理的数据文件的,其从小到大的视角是这样的关系:字段值-->记录值-->表数据-->用户-->表空间-->ORACLE而从一个ORACLEDBA的视角来看应是这样的关系:数据文件-->表空间-->ORACLE 综合一下,也就是说在ORACLE中...
//模拟componentDidUpdateuseEffect(()=>{getList(current)},[update])//删除constdelFn=(id)=>{ArticleDelApi({id}).then(res=>{if(res.errCode=0){message.success(res.message)//重新刷页面，要么重新请求这个列表的数据window.reload调用getList(1)增加变量的检测setUpdate(update+1)}else{message.success(res.message)}})}
return(<Spacesize="middle">{/text.key就是id/}<Buttontype='primary'onClick={()=>navigate('/edit/'+text.key)}>编辑</Button><Buttontype='danger'onClick={()=>delFn(text.key)}>删除</Button></Space>)
publicclassDemo05{publicstaticvoidmain(String[]args){//定义一个数组1，2，3，4，5，6，7，8，9，10int[]arr={1,2,3,4,5};for(inti=0;i<arr.length;i){if(arr[i]%20){arr[i]=arr[i]/2;}else{arr[i]=arr[i]2;}}for(inti=0;i<arr.length;i){System.out.println(arr[i]);}}}
importReact,{useEffect,useState}from"react";importaxiosfrom"axios"constuseMouseButton=(url:string,deps:any[]=[])=>{const[data,setData]=useState<any>(null);const[loading,setLoading]=useState(false)useEffect(()=>{setLoading(true)axios.get(url).then(res=>{setData(res.data)setLoadin...
functiongetLength(input:string|number):number{//conststr=inputasString//if(str.length){//returnstr.length//}else{//constnumber=inputasNumber//returnnumber.toString().length//}if((<string>input).length){return(<string>input).length}else{returninput.toString().length}}
<!DOCTYPEhtml><htmllang="en"><head><metacharset="UTF-8"><metahttp-equiv="X-UA-Compatible"content="IE=edge"><metaname="viewport"content="width=device-width,initial-scale=1.0"><title>Document</title></head><body><script>varnewArr=a...
publicclassDemo07{publicstaticvoidmain(String[]args){intarr[]={44,22,33,66,77};intmax=arr[0];for(inti=0;i<arr.length;i){if(max<arr[i]){max=arr[i];}}System.out.println(max);}} 打印结果:77
publicclassHelloWorld{publicstaticvoidmain(String[]args){System.out.print("helloworld");}}
importReact,{useEffect,useState}from"react";constuseMouseButton:React.FC=()=>{const[like,setLike]=useState(0);const[positions,setPosition]=useState({x:0,y:0})useEffect(()=>{constupdateMouse=(e:MouseEvent)=>{setPosition({x:e.clientX,y:e.clientY})}document.addEventListener("mousemove",up...
typePluType=(x:number,y:number)=>numberfunctionsum(x:number,y:number):number{returnx+y}constsum2:PluType=sumtypeNameResolver=()=>stringtypeNameOrResolver=string|NameResolverfunctiongetName(n:NameOrResolver):string{if(typeofn="string"){returnn}else{returnn()}}
类组件 importReact,{Component,Fragment,useState}from"react"classAppextendsComponent{state={num:1}onClick=()=>{this.setState({num:this.state.number+1})}render(){return(<><h1>{this.state.number}</h1><buttononClick={this.onClick.bind(this)}></button></>)}}export...