HarmonyOS：WebView中按返回键不能返回到上一界面

场景

  在Ability中，我们点击按钮进入到一个WebView中，在WebView中点击新的链接进入到另一个新的界面，这时按下返回键发现WebView并未返回到上一个浏览的界面，而是直接退出了WebView。

解决

  重写一下Ability的onKeyDown方法，对返回进行监听：

public boolean onKeyDown(int keyCode, KeyEvent keyEvent) {
   Navigator navigator = webView.getNavigator();
   if(keyCode == keyEvent.KEY_BACK && navigator.canGoBack()) {
       navigator.goBack();
       return true;
   }
   return super.onKeyDown(keyCode, keyEvent);
}

  通过getNavigator方法获取Navigator对象，如果用户当前按下了返回键并且WebView设置了能够返回，则调用navigator的goBack()方法进行返回。

布局文件

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:alignment="center"
    ohos:orientation="vertical">

    <ohos.agp.components.webengine.WebView
        ohos:id="$+id:web_view"
        ohos:height="match_parent"
        ohos:width="match_parent">
    </ohos.agp.components.webengine.WebView>
    
</DirectionalLayout>

Ability处理逻辑

package com.example.ncepu.Student.User;

import com.example.ncepu.ResourceTable;
import com.example.ncepu.Student.User.slice.优快云AbilitySlice;
import ohos.aafwk.ability.Ability;
import ohos.aafwk.content.Intent;
import ohos.agp.components.webengine.Navigator;
import ohos.agp.components.webengine.ResourceRequest;
import ohos.agp.components.webengine.WebAgent;
import ohos.agp.components.webengine.WebView;
import ohos.multimodalinput.event.KeyEvent;
import ohos.utils.net.Uri;

public class 优快云Ability extends Ability {

    private WebView webView;

    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setMainRoute(优快云AbilitySlice.class.getName());
        super.setUIContent(ResourceTable.Layout_ability_csdn);
        initViews();
    }

    private void initViews() {
        webView = (WebView) findComponentById(ResourceTable.Id_web_view);
        webView.getWebConfig().setJavaScriptPermit(true);  // 如果网页需要使用JavaScript，增加此行；如何使用JavaScript下文有详细介绍
        webView.setWebAgent(new MyWebAgent());
        final String url = "https://blog.youkuaiyun.com/Cyril_KI"; // EXAMPLE_URL由开发者自定义
        webView.load(url);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent keyEvent) {
        Navigator navigator = webView.getNavigator();
        if(keyCode == keyEvent.KEY_BACK && navigator.canGoBack()) {
            navigator.goBack();
            return true;
        }
        return super.onKeyDown(keyCode, keyEvent);
    }

    class MyWebAgent extends WebAgent {
        public static final String EXAMPLE_URL = "...";
        @Override
        public boolean isNeedLoadUrl(WebView webview, ResourceRequest request) {
            if (request == null || request.getRequestUrl() == null) {
                return false;
            }
            Uri uri = request.getRequestUrl();
            if (uri.getDecodedHost().equals(EXAMPLE_URL)) {
                return false;
            } else {
                return super.isNeedLoadUrl(webview, request);
            }
        }
    }
}