Android Web 视图中的后退按钮？

Question

我无法让 Android 手机上的硬件返回键与 webView 一起使用。以下是我正在使用的代码。每次我运行该应用程序时，它都会强制关闭。

package com.knowideas.transithub;
import android.app.Activity;

import android.os.Bundle;

import android.os.Handler;

import android.util.Log;

import android.view.KeyEvent;

import android.webkit.WebChromeClient;

import android.webkit.WebSettings;

import android.webkit.WebView;

import android.webkit.WebViewClient;

public class WebViewDemo extends Activity {

    private static final String LOG_TAG = "WebViewDemo";

    private WebView mWebView;

    private Handler mHandler = new Handler();

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // Check if the key event was the BACK key and if there's history
        if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
            mWebView.goBack();
            return true;
        }
        // If it wasn't the BACK key or there's no web page history, bubble up to the default
        // system behavior (probably exit the activity)
        return super.onKeyDown(keyCode, event);
    }
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.main);
        mWebView = (WebView) findViewById(R.id.webView);

        WebSettings webSettings = mWebView.getSettings();
        webSettings.setSavePassword(false);
        webSettings.setSaveFormData(false);
        webSettings.setJavaScriptEnabled(true);
        webSettings.setSupportZoom(false);

        mWebView.setWebChromeClient(new WebChromeClient());

        mWebView.addJavascriptInterface(new DemoJavaScriptInterface(), "demo");

        mWebView.loadUrl("file:///android_asset/demo.html");
    }

    final class DemoJavaScriptInterface {

        DemoJavaScriptInterface() {
        }

        /**
         * This is not called on the UI thread. Post a runnable to invoke
         * loadUrl on the UI thread.
         */
        public void clickOnAndroid() {
            mHandler.post(new Runnable() {
                public void run() {
                    mWebView.loadUrl("javascript:wave()");
                }
            });

        }
    }
}

Answer 1

我的猜测是：

你试图抓住关键事件的时间太晚了。您需要在它到达网络视图之前抓取它。您可以通过设置 onKeyListener 来做到这一点。

方法如下：

    mWebView.setOnKeyListener(new OnKeyListener() {
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (keyCode == KeyEvent.KEYCODE_BACK) {
                    // ignore the back key 
                return true;
            }
            // process normally
            return false;
        }
    });

我不能做更多的事情，只是“阻止”它——这就是我试图在另一个问题中找出的答案。

贝斯特

-雅科夫

Answer 2

ON BACK PRESSED

//因此链接保留在 webview 中
webview.setWebViewClient(new WebViewClient());

webview.setOnKeyListener(new View.OnKeyListener() {
    @Override
    public boolean onKey(View view, int keyCode, KeyEvent event) {
        if (event.getAction() == KeyEvent.ACTION_DOWN) {
            WebView webView = (WebView) view;

            switch (keyCode) {
                case KeyEvent.KEYCODE_BACK:
                    if (webView.canGoBack()) {
                        webView.goBack();
                        return true;
                    }
                    break;
            }
        }
        return false;
    }
});