[组件生命周期]
一、理论
组件本质上是状态机，输入确定，输出一定确定
生命周期的三个阶段，三者时间是不固定的，只是在逻辑上的分类：
二、初始化阶段：
getDefaultProps:获取实例的默认属性(即使没有生成实例，组件的第一个实例被初始化CreateClass的时候调用，只调用一次,)
getInitialState:获取每个实例的初始化状态（每个实例自己维护）
componentWillMount：组件即将被装载、渲染到页面上（render之前最好一次修改状态的机会）
render:组件在这里生成虚拟的DOM节点（只能访问this.props和this.state；只有一个顶层组件，也就是说render返回值值职能是一个组件；不允许修改状态和DOM输出）
componentDidMount:组件真正在被装载之后，可以修改DOM
三、运行中状态：
componentWillReceiveProps:组件将要接收到属性的时候调用（赶在父组件修改真正发生之前,可以修改属性和状态）
shouldComponentUpdate:组件接受到新属性或者新状态的时候（可以返回false，接收数据后不更新，阻止render调用，后面的函数不会被继续执行了）
componentWillUpdate:不能修改属性和状态
render:只能访问this.props和this.state；只有一个顶层组件，也就是说render返回值只能是一个组件；不允许修改状态和DOM输出
componentDidUpdate:可以修改DOM
四、销毁阶段：
componentWillUnmount:开发者需要来销毁（组件真正删除之前调用，比如计时器和事件监听器）
五、demo查看：
5.1 简单查看组件的初始化阶段的各个方法
<!DOCTYPE html>
<html>
<head>
<meta http-equiv='Content-type' content='text/html; charset=utf-8'>
<title>daomul's example</title>
<link rel="stylesheet" href="../shared/css/base.css" />
</head>
<body>
<h1>Text demo</h1>
<div id="container"> </div> <script src="../shared/thirdparty/es5-shim.min.js"></script>
<script src="../shared/thirdparty/es5-sham.min.js"></script>
<script src="../shared/thirdparty/console-polyfill.js"></script>
<script src="../../build/react.js"></script>
<script src="../../build/JSXTransformer.js"></script>
<script type="text/jsx"> var style = {
color : "red",
border : "1px #000 solid",
}; var TextClass = React.createClass({
getDefaultProps:function(){
console.log("getDefaultProps,1");
},
getInitialState:function(){
console.log("getInitialState,2");
return null;
},
componentWillMount:function(){
console.log("componmentWillMount,3");
},
render:function(){
console.log("render,4");
return <p ref = "childp">Hello{(function (obj){
if (obj.props.name)
return obj.props.name
else
return "World"
})(this)} </p>;
},
componentDidMount:function(){
console.log("componmentDidMount,5");
},
}); React.render(<div style = {style}> <TextClass></TextClass> </div>,document.body); </script>
</body>
</html>
5.2 运行阶段的函数
<!DOCTYPE html>
<html>
<head>
<meta http-equiv='Content-type' content='text/html; charset=utf-8'>
<title>daomul's example</title>
<link rel="stylesheet" href="../shared/css/base.css" />
</head>
<body>
<h1>Text demo</h1>
<div id="container"> </div> <script src="../shared/thirdparty/es5-shim.min.js"></script>
<script src="../shared/thirdparty/es5-sham.min.js"></script>
<script src="../shared/thirdparty/console-polyfill.js"></script>
<script src="../../build/react.js"></script>
<script src="../../build/JSXTransformer.js"></script>
<script type="text/jsx"> var style = {
color : "red",
border : "1px #000 solid",
}; var TextClass = React.createClass({
componentWillReceiveProps:function(newProps){
console.log("componentWillReciveProps,1");
console.log(newProps);
},
shouldComponentUpdate:function(){
console.log("shouldComponentUdate,2");return true;
},
componentWillUpdate:function(){
console.log("componentWillUpdate,3");
},
render:function(){
console.log("render,4");
return <p>hello:{this.props.name ? this.props.name : "world!"}</p>;
},
componentDidUpdate:function(){
console.log("componentDidUpadate,5");
},
});
var TextSourceClass = React.createClass({
getInitialState:function(){
return {name :''};
},
handleChange:function(event){
this.setState({name : event.target.value});
},
render:function(){
return <div>
<TextClass name = {this.state.name}></TextClass>
<br/><input type="text"onChange = {this.handleChange}/>
</div>;
},
}); React.render(<div style = {style}> <TextSourceClass></TextSourceClass> </div>,document.body); </script>
</body>
</html>
5.3 销毁阶段
<!DOCTYPE html>
<html>
<head>
<meta http-equiv='Content-type' content='text/html; charset=utf-8'>
<title>daomul's example</title>
<link rel="stylesheet" href="../shared/css/base.css" />
</head>
<body>
<h1>Text demo</h1>
<div id="container"> </div> <script src="../shared/thirdparty/es5-shim.min.js"></script>
<script src="../shared/thirdparty/es5-sham.min.js"></script>
<script src="../shared/thirdparty/console-polyfill.js"></script>
<script src="../../build/react.js"></script>
<script src="../../build/JSXTransformer.js"></script>
<script type="text/jsx"> var style = {
color : "red",
border : "1px #000 solid",
}; var TextClass = React.createClass({ render:function(){
console.log("render,4");
return <p>hello:{this.props.name ? this.props.name : "world!"}</p>;
},
componentDidUpdate:function(){
console.log("componentDidUpadate,5");
},
});
var TextSourceClass = React.createClass({
getInitialState:function(){
return {name :''};
},
handleChange:function(event){
this.setState({name : event.target.value});
},
render:function(){
if(this.state.name == "1"){
return <div>123</div>;
}
return <div>
<TextClass name = {this.state.name}></TextClass>
<br/><input type="text"onChange = {this.handleChange}/>
</div>;
},
}); React.render(<div style = {style}> <TextSourceClass></TextSourceClass> </div>,document.body); </script>
</body>
</html>