Flutter ListView 列表点击和网页加载

上一篇讲了使用ListView加载列表数据，本篇，我们讲下列表项的点击，因为本篇的例子点击后是加载一个网页，所以本篇也讲下类似于Android的WebView和iOS的UIWebView加载网页。效果如下：

item点击

在Android中，您可以通过调用方法setOnClickListener将OnClick绑定到按钮等view上.
在Flutter中，添加触摸监听器有两种方法:
具体可以查阅我之前的博客Flutter中的点击、拖动和其它手势

上篇博客中我们使用了Row、Column等Widget绘制了item,我们再在原来的Widget的外层包装个GestureDetector，添加手势，然后使用onTap处理点击，完整代码如下：

 new GestureDetector(
          child: Padding(
            padding: new EdgeInsets.fromLTRB(10.0, 0.0, 10.0, 0.0),
            child: new Column(
              children: [
                new Row(
                  crossAxisAlignment: CrossAxisAlignment.start, //纵向对齐方式：起始边对齐
                  mainAxisSize: MainAxisSize.max,
                  children: [
                    new Expanded(
                      child: Container(
                        height: 95.0,
                        child: getImage(data.articleThumbnail),
                        alignment: FractionalOffset.center,
                      ),
                      flex: 1,
                    ),
                    new Expanded(
                      child: Container(
                        height: 95.0,
                        margin: new EdgeInsets.fromLTRB(5.0, 0.0, 0.0, 0.0),
                        child: new Column(
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: [
                            new Container(
                              child: new Text(
                                articleTitle,
                                style: new TextStyle(
                                    fontSize: 20.0,
                                    fontWeight: FontWeight.w700),
                                maxLines: 1,
                                overflow: TextOverflow.ellipsis,
                              ),
                              alignment: FractionalOffset.topLeft,
                            ),
                            new Container(
                              child: new Text("${data.articleBrief}",
                                  style: new TextStyle(fontSize: 16.0),
                                  maxLines: 2,
                                  overflow: TextOverflow.ellipsis),
                              alignment: Alignment.topLeft,
                            ),
                            new Expanded(
                              child: new Container(
                                margin:
                                    new EdgeInsets.fromLTRB(0.0, 5.0, 0.0, 0.0),
                                child: new Stack(
                                  children: [
                                    new Container(
                                      child: new Text("${data.articleAuthor}",
                                          style: new TextStyle(fontSize: 10.0)),
                                      alignment: FractionalOffset.bottomLeft,
                                    ),
                                    new Container(
                                      child: new Text(time_str,
                                          style: new TextStyle(fontSize: 10.0)),
                                      alignment: FractionalOffset.bottomRight,
                                    ),
                                  ],
                                ),
                              ),
                            )
                          ],
                        ),
                      ),
                      flex: 3,
                    ),
                  ],
                ),
                new Divider(), //分割线
              ],
            ),
          ),
          onTap: () {
            onItemClick(i, articleTitle); //处理点击事件
          });

点击事件进行页面跳转

  /**
   * 列表点击
   */
  void onItemClick(int i, String articleTitle) {
    String h5_url = (listData[i].data as Data).url;
    Navigator.push(
        context,
        new MaterialPageRoute(
            builder: (context) => new NewsWebPage(h5_url, articleTitle)));
  }

网页加载

网页加载使用组件flutter_webview_plugin
具体实现如下：

import 'dart:async';

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';

/**
 * @Description  新闻网页，h5
 * @Author  zhibuyu
 * @Date 2018/10/19  9:09
 * @Version  1.0
 */
class NewsWebPage extends StatefulWidget{
  String  news_url;
  String title;

  NewsWebPage(this.news_url,this.title);

  @override
  State createState()=>new NewsWebPageState(news_url,title);

}
class NewsWebPageState extends State{
  String  news_url;
  String title;
  // 标记是否是加载中
  bool loading = true;
  // 标记当前页面是否是我们自定义的回调页面
  bool isLoadingCallbackPage = false;
  GlobalKey scaffoldKey = new GlobalKey();
  // URL变化监听器
  StreamSubscription onUrlChanged;
  // WebView加载状态变化监听器
  StreamSubscription onStateChanged;
  // 插件提供的对象，该对象用于WebView的各种操作
  FlutterWebviewPlugin flutterWebViewPlugin = new FlutterWebviewPlugin();

  NewsWebPageState(this.news_url, this.title);

  @override
  void initState() {
    onStateChanged = flutterWebViewPlugin.onStateChanged.listen((WebViewStateChanged state){
      // state.type是一个枚举类型，取值有：WebViewState.shouldStart, WebViewState.startLoad, WebViewState.finishLoad
      switch (state.type) {
        case WebViewState.shouldStart:
        // 准备加载
          setState(() {
            loading = true;
          });
          break;
        case WebViewState.startLoad:
        // 开始加载
          break;
        case WebViewState.finishLoad:
        // 加载完成
          setState(() {
            loading = false;
          });
          if (isLoadingCallbackPage) {
            // 当前是回调页面，则调用js方法获取数据
            parseResult();
          }
          break;
      }
    });
  }
  // 解析WebView中的数据
  void parseResult() {
//    flutterWebViewPlugin.evalJavascript("get();").then((result) {
//      // result json字符串，包含token信息
//
//    });
  }

  @override
  Widget build(BuildContext context) {
    List titleContent = [];
    titleContent.add(new Text(
//      title,
      "新闻详情",
      style: new TextStyle(color: Colors.white),
    ));
    if (loading) {
      // 如果还在加载中，就在标题栏上显示一个圆形进度条
      titleContent.add(new CupertinoActivityIndicator());
    }
    titleContent.add(new Container(width: 50.0));
    // WebviewScaffold是插件提供的组件，用于在页面上显示一个WebView并加载URL
    return new WebviewScaffold(
      key: scaffoldKey,
      url:news_url, // 登录的URL
      appBar: new AppBar(
        title: new Row(
          mainAxisAlignment: MainAxisAlignment.center,
          children: titleContent,
        ),
        iconTheme: new IconThemeData(color: Colors.white),
      ),
      withZoom: true,  // 允许网页缩放
      withLocalStorage: true, // 允许LocalStorage
      withJavascript: true, // 允许执行js代码
    );
  }

  @override
  void dispose() {
    // 回收相关资源
    // Every listener should be canceled, the same should be done with this stream.
    onUrlChanged.cancel();
    onStateChanged.cancel();
    flutterWebViewPlugin.dispose();
    super.dispose();
  }
}

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