react-组件间的传值

//父组件
class CommentList extends Component{
   render(){
return(
<div>
<Comment comment = {information} />
</div>
)
}
}

//子组件
class Comment extends Component{
render(){
return(
<div>
<p>{this.props.comment}</p>
</div>
)
}
}

//父组件
class CommentApp extends Component{
  constructor(props){
    super();
     this.state={
     comment:[]
    }
}
  printContent(comment){
     this.setState({comment});
  }
  render(){
      return(
      <div>
         <CommentInput onSubmit = {this.printContent.bind(this)} />
      </div>
      )
 }
}

//子组件

class CommentInput extends Component{
    constructor(){
        super();
        this.state = {
            usrName:‘‘,
            content:‘‘
        };
    }
    submit(){
        if(this.props.onSubmit){
            var {usrName,content} = this.state;
            this.props.onSubmit({usrName,content})
        }
        this.setState({content:‘‘});
    }
    render(){
        return(
              <div>
               <div>
                   <span>用户名：</span>
                   <div className="usrName">
                       <input type="text" value={this.state.usrName} />
                  </div>
               </div>
                <div>
                    <span>评论内容：</span>
                    <div className="content">
                       <textarea value={this.state.content} />
                   </div>
                </div>
                <button onClick={this.submit.bind(this)}>submit</button>
            </div>
        )
    }
}