React-Native之TextInput组件的设置以及如何获取输入框的内容

TextInput组件的内容部分：
class Myinput extends Component{
    constructor(props){
        super(props);
        this._onChangeText = this._onChangeText.bind(this);
        this.state = {
            showValue:"",
        }
    }
    _onChangeText(inputData){
        console.log("输入的内容",inputData);
        //把获取到的内容，设置给showValue
        this.setState({showValue:inputData});
    }
    showData(){
        alert(this.state.showValue);//展示输入框的内容
    }
    render(){
        return (<View style={styles.mycontainer}>
                    <TextInput
                        placeholder="请输入用户名"
                        editable={true}//是否可编辑
                        style={styles.inputStyle}//input框的基本样式
                        onChangeText={this._onChangeText}//输入框改变触发的函数
                    />
                    <TouchableOpacity onPress={this.showData.bind(this)}>
                        <View style={styles.btn}>
                            <Text style={styles.wordC}>搜索</Text>
                        </View>
                    </TouchableOpacity>
                </View>)
    }
}
const styles = StyleSheet.create({
    mycontainer:{
      marginTop:30,
        flexDirection:"row",
    },
    inputStyle:{
        width:280,
        height:30,
        borderColor:"black",
        borderWidth:1,
        marginLeft:5,
    },
    btn:{
        width:85,
        height:30,
        justifyContent:"center",
        alignItems:"center",
        backgroundColor:"green",
        // borderRadius:5
    },
    wordC:{
        color:"white",
        fontSize:18,
    }
})

<TextInput
    style={styles.edit}
    underlineColorAndroid='transparent'/>
edit: {
        marginTop: 30,
        height: 40,
        fontSize: 20,
        backgroundColor: '#fff'
    },

<View style={styles.view}>
    <TextInput      
        style={styles.edit}
        underlineColorAndroid='transparent'/>
</View>
    edit: {
        height: 40,
        fontSize: 20,
        backgroundColor: '#fff',
        marginLeft: 10,  //左右留出一定的空间
        marginRight: 10
    },
    view: {
        flex: 1,
        marginTop: 10,
        backgroundColor: '#fff',
        height: 51,    //通过大于TextInput的高度来弥补上面的问题
        justifyContent: 'flex-end'  //放置到底部
    }