【React Native】React Native项目设计与知识点分享

  闲暇之余,写了一个React Native的demo,可以作为大家的入门学习参考。

  GitHub:https://github.com/xujianfu/ElmApp.git

  GitHub:https://github.com/xujianfu/React-Native-CarProject.git

  项目截图如下:

 

 一、项目界面设计

  1、React Navigation的应用

   React Navigation 源于 React Native 社区对一个可扩展且易于使用的导航解决方案的需求,它完全使用 JavaScript 编写(因此你可以阅读并理解所有源码)。支持iOS/Android.

   1、如何在项目进行使用?

yarn add react-navigation
# or with npm
# npm install --save react-navigation

  然后,安装 react-native-gesture-handler。 如果你正在使用 Expo managed workflow,那么你什么都不需要做, SDK 中已经包含了这些. 否则:  

yarn add react-native-gesture-handler
# or with npm
# npm install --save react-native-gesture-handler

  最后进行Link 所有的原生依赖

react-native link react-native-gesture-handler

  2、路由配置

  为某个模块创建StackNavigator导航

const HomeStack = createStackNavigator(
    {
        Home:{
            screen:HomeScreen,
            navigationOptions:()=>({
                headerBackTitle: null,
            })
        },
         //添加多个路由
        CarLoans:CarLoansScreen,
        CheckRules:CheckRulesScreen,
    },
)

......    

  将多个模块添加到TabNavigator上

const TabNavigator = createBottomTabNavigator(
    {
        Home:{
            screen:HomeStack,
            navigationOptions:({navigation}) => ({
                tabBarLabel:'首页',
                tabBarIcon:({focused}) => (
                    <Image source={{uri:focused ? 'ic_tab_home_h':'ic_tab_home_n.png'}} style={styles.iconStyle}/>
                ),
            }),
        },
        Mall:{
            screen:MallStack,
            navigationOptions:({navigation}) => ({
                tabBarLabel:'商城',
                tabBarIcon:({focused}) => (
                    <Image source={{uri:focused ? 'ic_tab_mall_h':'ic_tab_mall_n.png'}} style={styles.iconStyle}/>
                )
            }),
        },
        Publish:{
            screen:PublishStack,
            navigationOptions:({navigation}) => ({
                tabBarLabel:'发布',
                tabBarIcon:({focused}) => (
                    <Image source={{uri:focused ? 'ic_tab_release_h':'ic_tab_release_n.png'}} style={styles.iconStyle}/>
                )
            }),
        },
        Discover:{
            screen:DiscoverStack,
            navigationOptions:({navigation}) => ({
                tabBarLabel:'发现',
                tabBarIcon:({focused}) => (
                    <Image source={{uri:focused ? 'ic_tab_find_h':'ic_tab_find_n.png'}} style={styles.iconStyle}/>
                )
            }),
        },
        Mine:{
            screen:MineStack,
            navigationOptions:({navigation}) => ({
                tabBarLabel:'我的',
                tabBarIcon:({focused}) => (
                    <Image source={{uri:focused ? 'ic_tab_my_h':'ic_tab_my_n.png'}} style={styles.iconStyle}/>
                )
            }),
        },
    },
    {
        defaultNavigationOptions: ({ navigation }) => {
            let tabBarVisible = true;
            if (navigation.state.index > 0) {
                tabBarVisible = false;
            }
            return {
                tabBarVisible,
            };
        },
        tabBarPosition:'bottom',
        tabBarOptions: {
            activeTintColor: 'blue', //选中tabbar的文字颜色
            inactiveTintColor: 'gray',
            showIcon:true,

        },

    }
);

export default  createAppContainer(TabNavigator);

  2、选择相册照片或视频,或进行拍照

  (1)引入react-native-image-picker

yarn add react-native-image-picker
react-native link react-native-image-picker

  (2)在项目中使用react-native-image-picker

import ImagePicker from 'react-native-image-picker';

//选择图片
    selectPhotoTapped() {
        const options = {
            // 弹窗标题
            title: '选择图片',
            cancelButtonTitle: '取消',
            takePhotoButtonTitle: '拍照',
            chooseFromLibraryButtonTitle: '选择照片',
            // 自定义按钮
            customButtons: [
                {name: 'fb', title: 'Choose Photo from Facebook'},
            ],
            // 相机类型'front' 或者 'back'
            cameraType: 'back',
            // 图片或视频:'photo','video'
            mediaType: 'photo',
            // 视频质量
            videoQuality: 'high',
            //最大视频录制时间
            durationLimit: 10,
            //最长宽
            maxWidth: 300,
            //最长高,
            maxHeight: 300,
            //图片质量
            quality: 0.8,
            angle: 0,
            //是否可以编辑
            allowsEditing: false,
            //如果为真,则禁用data生成的base64字段
            noData: false,
            // 如果提供此密钥,该图像将被保存在Documents iOS 应用程序的目录中,或者保存在PicturesAndroid上的应用程序目录(而不是临时目录)
            storageOptions: {
                skipBackup: true
            }
        };

        ImagePicker.showImagePicker(options, (response) => {
            console.log('Response = ', response);

            if (response.didCancel) {
                console.log('User cancelled photo picker');
            }
            else if (response.error) {
                console.log('ImagePicker Error: ', response.error);
            }
            else if (response.customButton) {
                console.log('User tapped custom button: ', response.customButton);
            }
            else {
                let source = { uri: response.uri };

                // You can also display the image using data:
                // let source = { uri: 'data:image/jpeg;base64,' + response.data };

                this.setState({
                    avatarSource: source
                });
            }
        });
    }

    //选择视频
    selectVideoTapped() {
        const options = {

            title: '选择视频',
            cancelButtonTitle: '取消',
            takePhotoButtonTitle: '录制视频',
            chooseFromLibraryButtonTitle: '选择视频',
            mediaType: 'video',
            videoQuality: 'medium'
        };

        ImagePicker.showImagePicker(options, (response) => {
            console.log('Response = ', response);

            if (response.didCancel) {
                console.log('User cancelled video picker');
            }
            else if (response.error) {
                console.log('ImagePicker Error: ', response.error);
            }
            else if (response.customButton) {
                console.log('User tapped custom button: ', response.customButton);
            }
            else {
                this.setState({
                    videoSource: response.uri
                });
            }
        });
    }

 3、创建切换选项卡

  导入react-native-scrollable-tab-view

npm install react-native-scrollable-tab-view --save

  项目中引入

//引用插件
import ScrollableTabView, { ScrollableTabBar, DefaultTabBar } from 'react-native-scrollable-tab-view';

<ScrollableTabView
                    initialPage={0}
                    renderTabBar={() => <ScrollableTabBar style={{borderBottomWidth: 0,height: 44}}/>}
                    tabBarTextStyle={{fontSize:16}}
                    tabBarActiveTextColor={'#fdd000'}
                    tabBarInactiveTextColor={'#999999'}
                    tabBarUnderlineStyle={{backgroundColor:'#fdd000'}}
                >
                    {
                        label.map((item,index) =>{
                            if (index === 0) {
                                return <AllBusinessScreen tabLabel={item} key={index}/>
                            } else {
                                return <NearByBusinessScreen tabLabel={item} key={index}/>
                            }
                        })
                    }
                </ScrollableTabView>

  4、使用Modal组件

  Modal组件可以用来覆盖包含React Native根视图的原生视图(如UIViewController,Activity)。在嵌入React Native的混合应用中可以使用Modal。Modal可以使你应用中RN编写的那部分内容覆盖在原生视图上显示。  

<Modal
                    animationType={"slide"}
                    transparent={true}
                    visible={this.state.modalVisible}
                    onRequestClose={()=>{alert('modal has been closed')}}
                >
                        <View style={styles.modalStyle}>
                            <View style={styles.coverStyle}>
                                {this.renderItem()}
                            </View>
                        </View>


                </Modal>


......

renderItem(){
        let itemTitleArr = ['京','沪','浙','苏','粤','鲁','晋','冀',
            '豫','川','渝','辽','吉','黑','皖','鄂',
            '湘','赣','闽','陕','甘','宁','蒙','津',
            '贵','云','桂','琼','青','新','藏'];;
        var itemArr = [];
        for (var i = 0; i < itemTitleArr.length; i++) {
            itemArr.push(
                <TouchableHighlight onPress={this.callBack.bind(this,itemTitleArr[i])} key={i}>
                    <View style={styles.chooseItemStyle} >
                        <Text style={styles.chooseTitleStyle}>{itemTitleArr[i]}</Text>
                    </View>
                </TouchableHighlight>

            )
        }
        return itemArr;
    }

  5、下拉列表实现

import React, {Component} from 'react';
import {View, Text, Image, TouchableOpacity, ScrollView, Animated, Easing, StyleSheet} from 'react-native';
import PropTypes from 'prop-types';

class DropdownMenu extends Component {

    constructor(props, context) {
        super(props, context);

        var selectIndex = new Array(this.props.data.length);
        for (var i = 0; i < selectIndex.length; i++) {
            selectIndex[i] = 0;
        }
        this.state = {
            activityIndex: -1,
            selectIndex: selectIndex,
            rotationAnims: props.data.map(() => new Animated.Value(0))
        };

        this.defaultConfig = {
            bgColor: '#f5f5f5',
            tintColor: '#fdd000',
            activityTintColor: "red",
            arrowImg: 'ic_nav_down',
            checkImage: 'ic_nav_down'
        };

    }

    renderChcek(index, title) {
        var activityIndex = this.state.activityIndex;
        if (this.state.selectIndex[activityIndex] === index) {
            var checkImage = this.props.checkImage ? this.props.checkImage : this.defaultConfig.checkImage;
            return (
                <View style={{flex: 1, justifyContent: 'space-between', alignItems: "center", paddingHorizontal: 15, flexDirection: 'row'}} >
                    <Text
                        style={[
                            styles.item_text_style,
                            this.props.optionTextStyle,
                            {color: this.props.activityTintColor ? this.props.activityTintColor : this.defaultConfig.activityTintColor}
                        ]} >
                        {title}
                    </Text>
                    <Image
                        source={checkImage}
                        style={{tintColor: this.props.activityTintColor ? this.props.activityTintColor : this.defaultConfig.activityTintColor}} />
                </View>
            );
        } else {
            return (
                <View style={{flex: 1, justifyContent: 'space-between', alignItems: "center", paddingHorizontal: 15, flexDirection: 'row'}} >
                    <Text style={[
                        styles.item_text_style,
                        this.props.optionTextStyle,
                        {color: this.props.tintColor ? this.props.tintColor : this.defaultConfig.tintColor}
                    ]} >{title}</Text>
                </View>
            );
        }
    }

    renderActivityPanel() {
        if (this.state.activityIndex >= 0) {

            var currentTitles = this.props.data[this.state.activityIndex];

            var heightStyle = {};
            if (this.props.maxHeight && this.props.maxHeight < currentTitles.length * 44) {
                heightStyle.height = this.props.maxHeight;
            }

            return (
                <View style={{position: 'absolute', left: 0, right: 0, top: 40, bottom: 0}}>
                    <TouchableOpacity onPress={() => this.openOrClosePanel(this.state.activityIndex)} activeOpacity={1} style={{position: 'absolute', left: 0, right: 0, top: 0, bottom: 0}}>
                        <View style={{opacity: 0.4, backgroundColor: 'black', flex: 1 }} />
                    </TouchableOpacity>

                    <ScrollView style={[{position: 'absolute', top: 0, left: 0, right: 0, backgroundColor: 'white'}, heightStyle]} >
                        {
                            currentTitles.map((title, index) =>
                                <TouchableOpacity key={index} activeOpacity={1} style={{flex: 1, height: 44}} onPress={this.itemOnPress.bind(this, index)} >
                                    {this.renderChcek(index, title)}
                                    <View style={{backgroundColor: '#F6F6F6', height: 1, marginLeft: 15}} />
                                </TouchableOpacity>
                            )
                        }
                    </ScrollView>
                </View>
            );
        } else {
            return (null);
        }
    }

    openOrClosePanel(index) {

        this.props.bannerAction ? this.props.bannerAction() : null;

        // var toValue = 0.5;
        if (this.state.activityIndex == index) {
            this.closePanel(index);
            this.setState({
                activityIndex: -1,
            });
            // toValue = 0;
        } else {
            if (this.state.activityIndex > -1) {
                this.closePanel(this.state.activityIndex);
            }
            this.openPanel(index);
            this.setState({
                activityIndex: index,
            });
            // toValue = 0.5;
        }
        // Animated.timing(
        //   this.state.rotationAnims[index],
        //   {
        //     toValue: toValue,
        //     duration: 300,
        //     easing: Easing.linear
        //   }
        // ).start();
    }

    openPanel(index) {
        Animated.timing(
            this.state.rotationAnims[index],
            {
                toValue: 0.5,
                duration: 300,
                easing: Easing.linear
            }
        ).start();
    }

    closePanel(index) {
        Animated.timing(
            this.state.rotationAnims[index],
            {
                toValue: 0,
                duration: 300,
                easing: Easing.linear
            }
        ).start();
    }

    itemOnPress(index) {
        if (this.state.activityIndex > -1) {
            var selectIndex = this.state.selectIndex;
            selectIndex[this.state.activityIndex] = index;
            this.setState({
                selectIndex: selectIndex
            });
            if (this.props.handler) {
                this.props.handler(this.state.activityIndex, index);
            }
        }
        this.openOrClosePanel(this.state.activityIndex);
    }

    renderDropDownArrow(index) {
        var icon = this.props.arrowImg ? this.props.arrowImg : this.defaultConfig.arrowImg;
        return (
            <Animated.Image
                source={{uri:icon}}
                style={{
                    width:6,
                    height:4,
                    marginLeft: 8,
                    tintColor: (index === this.state.activityIndex) ? (this.props.activityTintColor ? this.props.activityTintColor : this.defaultConfig.activityTintColor) : (this.props.tintColor ? this.props.tintColor : this.defaultConfig.tintColor),
                    transform: [{
                        rotateZ: this.state.rotationAnims[index].interpolate({
                            inputRange: [0, 1],
                            outputRange: ['0deg', '360deg']
                        })
                    }]
                }} />
        );
    }

    render() {

        return (
            <View style={{flexDirection: 'column', flex: 1}} >
                <View style={{
                    flexDirection: 'row',
                    backgroundColor: this.props.bgColor ? this.props.bgColor : this.defaultConfig.bgColor}} >
                    {
                        this.props.data.map((rows, index) =>
                            <TouchableOpacity
                                activeOpacity={1}
                                onPress={this.openOrClosePanel.bind(this, index)}
                                key={index}
                                style={{flex: 1, height: 48, alignItems: "center", justifyContent: "center"}} >
                                <View style={{flexDirection: 'row', alignItems: "center", justifyContent: "center"}} >
                                    <Text
                                        style={[
                                            styles.title_style,
                                            this.props.titleStyle,
                                            {color: (index === this.state.activityIndex) ?
                                                    (this.props.activityTintColor ? this.props.activityTintColor : this.defaultConfig.activityTintColor)
                                                    :
                                                    (this.props.tintColor ? this.props.tintColor : this.defaultConfig.tintColor)}
                                        ]} >
                                        {rows[this.state.selectIndex[index]]}
                                    </Text>
                                    {this.renderDropDownArrow(index)}
                                </View>
                            </TouchableOpacity>
                        )
                    }
                </View>
                {this.props.children}

                {this.renderActivityPanel()}

            </View>
        );
    }

}

DropdownMenu.propTypes = {
    bgColor: PropTypes.string,
    tintColor: PropTypes.string,
    activityTintColor: PropTypes.string,
    arrowImg: PropTypes.number,
    checkImage: PropTypes.number,
    data: PropTypes.array,
    bannerAction: PropTypes.func,
    optionTextStyle: PropTypes.object,
    titleStyle: PropTypes.object,
    maxHeight: PropTypes.number
}

const styles = StyleSheet.create({
    title_style: {
        fontSize: 16
    },
    item_text_style: {
        color: '#fdd000',
        fontSize: 16
    }
});

export default DropdownMenu;
下拉列表封装

  如何使用?

render() {
        var data = [["分类", "分类", "分类", "分类"], ["价格", "价格"], ["筛选", "筛选"]];
        return (
            <View style={{flex: 1}}>
                <View style={styles.dropMenu}/>
                <DropMenu
                    style={{flex:1}}
                    bgColor={'white'}
                    tintColor={'#666666'}
                    activityTintColor={'#fdd000'}
                    // arrowImg={}
                    // checkImage={}
                    // optionTextStyle={{color: '#333333'}}
                    // titleStyle={{color: '#333333'}}
                    // maxHeight={300}
                    handler={(selection, row) => this.setState({text: data[selection][row]})}
                    data={data}
                >

                    <ListView
                        style={styles.listViewStyle}
                        dataSource={this.state.dataSource}
                        renderRow={this.renderRow}
                    />

                </DropMenu>
            </View>
        );
    }
下拉列表的使用

  6、React Native项目中“A+ListView”或“ListView + B”的界面搭建

  项目中ScrollView嵌套ListView会造成手势滑动冲突,可以使用“A+ListView”或“ListView + B”的样式进行搭建,

  通过:ListView的header或footer来实现。

  7、地图展示  

  项目中使用的通过jsp API接入到高德地图。

二、技术难点

  1、组件化思想

  React Native是React在移动端的跨平台方案。如果想更快地理解和掌握React Native开发,就必须先了解React。

  React是FaceBook开源的一个前端框架,它起源于 Facebook 的内部项目,并于 2013 年 5 月开源。因为React 拥有较高的性能,代码逻辑非常简单,所以越来越多的人已开始关注和使用它,目前该框架在Github上已经有7万+star。

  React采用组件化的方式开发,通过将view构建成组件,使得代码更加容易得到复用,能够很好的应用在大项目的开发中。有一句话说的很形象:在React中,构建应用就像搭积木一样。

  React认为一个组件应该具有以下特征:
  •  可组合:一个组件易于和其他组件一起使用,或者嵌套在另一个组件内部。如果一个组件内部创建了另外一个组件,那么父组件拥有它创建的子组件,通过这个特性,一个复杂的UI可以拆分成多个简单的UI组件;
  •    可重用:每个组件都是具有独立功能的,它可以被使用在多个UI场景;
  •    可维护:每个小的组件仅仅包含自身的逻辑,更容易被理解和维护。

  2、组件的属性与状态

  在React Native里,组件所持有的数据分为两种:

  1、属性(props):组件的props是不可变的,它只能从其他的组件(例如父组件)传递过来。

  2、状态(state):组建的state是可变的,它负责处理与用户的交互。在通过用户点击事件等操作以后,如果使得当前组件的某个state发生了改变,那么当前组件就会触发render()方法刷新自己。

  props:

  由于props是从其父组件传递过来的,那么可想而知,props的声明应该是当前组件的父组件来做。

  3、组件的生命周期

  请参考组件的生命周期

  4、搭建APP的框架:Tab Navigator 和 Stack Navigator  

  请参考学习:React Navigation的应用

  5、组件间通信

  组件间通信分为两大类;

  1、有直接关系或间接关系的组件之间通信

  2、无直接关系或间接关系的组件之间通信

posted @ 2019-06-04 14:42 零零圈圈 阅读(...) 评论(...) 编辑 收藏