react native實現登入功能，包括ui的封裝、網路請求的封裝、導航器的實現、點選事件。

後臺如果是springmvc實現的需要配置上如下程式碼

  <!--加入multipart 的解析器,這個必須配置，一會在controller裡抓取上傳檔案時要用。否則會報錯。-->
    <bean id="multipartResolver"  class="org.springframework.web.multipart.commons.CommonsMultipartResolver">

        <property name="maxUploadSize"
 
 value="102400"></property>

        <property name="defaultEncoding" value="utf-8"/><!--屬性：編碼-->

    </bean>

1.實現的介面

2.完整目錄

3.主介面的程式碼實現

import React, { Component } from 'react';
import {
  ToolbarAndroid,
  AppRegistry,
  StyleSheet,
  Text,
  View,
  Image,
  TextInput,
  TouchableOpacity
} from 'react-native'
 
;
import EditView from '../lib/EditView';
import LoginButton from '../lib/LoginButton';
import LoginSuccess from '../ui/LoginSuccess';
import NetUitl from '../lib/NetUtil';
export default class LoginActivity extends Component {
  constructor(props) {
    super(props);
    this.userName = "";
    this.password = ""
 
;
  }

  render() {
      return (

    <View style={LoginStyles.loginview}>
     <View   style={{flexDirection: 'row',height:100,marginTop:1,
        justifyContent: 'center',
        alignItems: 'flex-start',}}>
       <Image source={require('../image/login.png')}/>
     </View>
     <View style={{marginTop:80}}>
       <EditView  name='輸入使用者名稱/註冊手機號' onChangeText={(text) => {
            this.userName = text;
        }}/>
       <EditView name='輸入密碼' onChangeText={(text) => {
            this.password = text;
        }}/>
        <LoginButton name='登入' onPressCallback={this.onPressCallback}/>
        <Text style={{color:"#4A90E2",textAlign:'center',marginTop:10}} >忘記密碼？</Text>
      </View>
     </View>
   )
  }


  onPressCallback = () => {
    let formData = new FormData();
    formData.append("loginName",this.userName);
    formData.append("pwd",this.password);
    let url = "http://localhost:8080/loginApp";
    NetUitl.postJson(url,formData,(responseText) => {
          alert(responseText);
          this.onLoginSuccess();
    })


  };

  //跳轉到第二個頁面去
    onLoginSuccess(){
     const { navigator } = this.props;
     if (navigator) {
       navigator.push({
         name : 'LoginSuccess',
         component : LoginSuccess,
       });
     }
   }

}

class loginLineView extends Component {
  render() {
    return (
        <Text >
            沒有帳號
          </Text>
    );
  }
}

const LoginStyles = StyleSheet.create({
  loginview: {
    flex: 1,
    padding: 30,
      backgroundColor: '#ffffff',
  },
});

說明：
1.使用了線性佈局，從上往下依次Image，EditView，LoginButton，Text
2.EditView和LoginButton 為自定義控制元件，實現輸入框，和按鈕的封裝。

4.EditView.js

import React, { Component } from 'react';
import {
  ToolbarAndroid,
  AppRegistry,
  StyleSheet,
  Text,
  View,
  Image,
  TextInput,
  TouchableOpacity
} from 'react-native';
export default class EditView extends Component {
  constructor(props) {
   super(props);
   this.state = {text: ''};
 }

  render() {
    return (
      <View style={LoginStyles.TextInputView}>
       <TextInput style={LoginStyles.TextInput}
         placeholder={this.props.name}
         onChangeText={
           (text) => {
             this.setState({text});
             this.props.onChangeText(text);
           }
        }
       />
       </View>
    );
  }
}


const LoginStyles = StyleSheet.create({
  TextInputView: {
    marginTop: 10,
    height:50,
    backgroundColor: '#ffffff',
    borderRadius:5,
    borderWidth:0.3,
    borderColor:'#000000',
    flexDirection: 'column',
    justifyContent: 'center',
  },

  TextInput: {
    backgroundColor: '#ffffff',
    height:45,
    margin:18,
  },
});

說明：
1.利用TextInput的onChangeText 方法獲取到輸入框中輸入的資料，在利用EditView 傳入的onChangeText回撥方法，把資料回調出封裝的EditView，在外部獲取到TextInput輸入的資料。

5.LoginButton.js

import React, { Component } from 'react';
import {
  ToolbarAndroid,
  AppRegistry,
  StyleSheet,
  Text,
  View,
  Image,
  TextInput,
  TouchableOpacity
} from 'react-native';
export default class LoginButton extends Component {
  constructor(props) {
   super(props);
   this.state = {text: ''};
  }
  render() {
    return (
      <TouchableOpacity onPress={this.props.onPressCallback} style={LoginStyles.loginTextView}>
        <Text style={LoginStyles.loginText} >
            {this.props.name}
        </Text>
      </TouchableOpacity>
    );
  }
}
const LoginStyles = StyleSheet.create({

  loginText: {
    color: '#ffffff',
     fontWeight: 'bold',
     width:30,
  },
  loginTextView: {
    marginTop: 10,
    height:50,
    backgroundColor: '#3281DD',
    borderRadius:5,
    flexDirection: 'row',
    justifyContent: 'center',
    alignItems:'center',
  },
});

說明：
1.利用TouchableOpacity包住Text實現點選效果，onPress是點選時呼叫，當點選時onPress觸發，呼叫外部傳入的onPressCallback 方法實現觸發事件在封裝的LoginButton外部定義觸發的效果。

6.NetUtil.js

let NetUtil = {
  postJson(url, data, callback){
        var fetchOptions = {
          method: 'POST',
          headers: {
            'Accept': 'application/json',
            'Content-Type': 'multipart/form-data;boundary=6ff46e0b6b5148d984f148b6542e5a5d'
          },
          body:data
        };

        fetch(url, fetchOptions)
        .then((response) => response.text())
        .then((responseText) => {
         //  callback(JSON.parse(responseText));
           callback(responseText);
        }).done();
  },
}
export default NetUtil;

說明：網路方法，依次傳入請求地址，請求引數，成功回撥事件

7.LoginSuccess.js

import React from 'react';
import {
    View,
    Navigator,
    TouchableOpacity,
    ToolbarAndroid,
    Text
} from 'react-native';
export default class LoginSuccess extends React.Component {
    constructor(props){
        super(props);
        this.state = {};

    }
    //回到第一個頁面去
    onJump(){
        const { navigator } = this.props;
        if (navigator) {
            navigator.pop();
        }
    }

    render(){
        return (

            <View >
                <TouchableOpacity onPress = {this.onJump.bind(this)}>
                    <Text> 登入成功，點選返回登入頁面 </Text>
                </TouchableOpacity>
            </View>


        );

    }

}

說明：登入成功後跳轉的介面

8.navigator.js

導航器控制類。利用name，component 實現導航（可以自己隨便定義命名，只要後面的類中訪問同樣的命名即可，課參考LoginSuccess.js 中的返回功能）

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View,
  Navigator
} from 'react-native';
import Main from './ui/main';
export default class navigator extends Component {
   constructor(props) {
     super(props);
   }
   render() {
    let defaultName = 'Main';
    let defaultComponent = Main;
    return (
      <Navigator
        initialRoute = {{name : defaultName , component: defaultComponent}}
        configureScene = {(route) => {
          return Navigator.SceneConfigs.VerticalDownSwipeJump;
        }}
        renderScene={(route,navigator) => {
            let Component = route.component;
            return <Component {...route.params} navigator = {navigator} />
        }}
        />
    );
  }

};

8.index.android.js

規定的類

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */
import React, { Component } from 'react';
import {
  ToolbarAndroid,
  AppRegistry,
  StyleSheet,
  Text,
  View,
  Image,
  TextInput,
  TouchableOpacity
} from 'react-native';
import Navigator from './app/navigator';
AppRegistry.registerComponent('AwesomeProject', () => Navigator);