react native 设置登录验证码

constructor(props){
        super(props);
        this.state = {
            ucodeUri:SERVER+'/org/showimage.jsp?v='+Math.random(),
        }
    }



<TouchableOpacity 
    onPress={this._handle.bind(this, 2)}
     style={{alignItems: 'center',}}>
     
      <Image style={{height:30, width:65}}
             source={{uri:this.state.ucodeUri}}  resizeMode='contain'/>
  </TouchableOpacity>

  _handle(position){

      switch (position) {
        case 2:
          this.setState({
            ucodeUri:SERVER+'/org/showimage.jsp?v='+Math.random(),
          });
          break;
        default:

      }

    }