0

我试图向我的 android webview 添加一个后退按钮，但我遇到了这个错误：类型为 new WebViewClient(){} 的方法 onBackPressed() 必须覆盖或实现超类型方法

这是我的 Java 文件：

package sherdle.donald.duck.app;
import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;
public class WebPageLoader extends Activity
{
WebView webview;

final Activity activity = this;

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    this.getWindow().requestFeature(Window.FEATURE_PROGRESS);
    setContentView(R.layout.main);
    WebView webView = (WebView) findViewById(R.id.webview);
    webView.getSettings().setJavaScriptEnabled(true);

    webView.setWebChromeClient(new WebChromeClient() {
        public void onProgressChanged(WebView view, int progress)
        {
            activity.setTitle("Loading...");
            activity.setProgress(progress * 100);

            if(progress == 100)
                activity.setTitle(R.string.app_name);
        }
    });

    webView.setWebViewClient(new WebViewClient() {
        @Override
        public void onReceivedError(WebView view, int errorCode, String description,    String failingUrl)
        {
            // Handle the error
        }
        @Override
        public void onBackPressed() {
        // do something on back.
        return;
        }

        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url)
        {
            view.loadUrl(url);
            return true;
        }
    });

    webView.loadUrl("http://example.com");
   }
}

谢谢你的帮助。

4

4 回答 4

5

根据文档，类中没有onBackPressed方法WebViewClient。你想在你的活动上覆盖它吗？尝试这样的事情：

package sherdle.donald.duck.app;
import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;
public class WebPageLoader extends Activity
{
WebView webView;

final Activity activity = this;

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    this.getWindow().requestFeature(Window.FEATURE_PROGRESS);
    setContentView(R.layout.main);
    webView = (WebView) findViewById(R.id.webview);
    webView.getSettings().setJavaScriptEnabled(true);

    webView.setWebChromeClient(new WebChromeClient() {
        public void onProgressChanged(WebView view, int progress)
        {
            activity.setTitle("Loading...");
            activity.setProgress(progress * 100);

            if(progress == 100)
                activity.setTitle(R.string.app_name);
        }
    });

    webView.setWebViewClient(new WebViewClient() {
        @Override
        public void onReceivedError(WebView view, int errorCode, String description,    String failingUrl)
        {
            // Handle the error
        }

        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url)
        {
            view.loadUrl(url);
            return true;
        }
    });

    webView.loadUrl("http://example.com");
   }
    @Override
    public void onBackPressed (){
        if(webView.canGoBack()) webView.goBack();
        else super.onBackPressed();
    }
}
于 2012-07-14T19:25:12.297 回答
0

试试这个

 package sherdle.donald.duck.app;
 import android.app.Activity;
 import android.os.Bundle;
 import android.view.Window;
 import android.webkit.WebChromeClient;
 import android.webkit.WebView;
 import android.webkit.WebViewClient;
 public class WebPageLoader extends Activity
 {
 WebView webview;

  final Activity activity = this;

@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
this.getWindow().requestFeature(Window.FEATURE_PROGRESS);
setContentView(R.layout.main);
webView = (WebView) findViewById(R.id.webview);
webView.getSettings().setJavaScriptEnabled(true);
webView.loadUrl("http://example.com");
webView.setWebChromeClient(new WebChromeClient() {
    public void onProgressChanged(WebView view, int progress)
    {
        activity.setTitle("Loading...");
        activity.setProgress(progress * 100);

        if(progress == 100)
            activity.setTitle(R.string.app_name);
    }
});

webView.setWebViewClient(new WebViewClient() {
    @Override
    public void onReceivedError(WebView view, int errorCode, String description,    String failingUrl)
    {
        // Handle the error
    }


    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url)
    {
        view.loadUrl(url);
        return true;
    }
});

  }

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    switch (keyCode) {
    case KeyEvent.KEYCODE_BACK:
             if(mWebView.canGoBack() == true)

              webview.goBack();
              else finish();
               break;

    default:
        break;
    }
    return super.onKeyDown(keyCode, event);
}
}

并且这个方法应该在Activty.

于 2012-07-14T19:27:11.857 回答
0

您必须覆盖onkeyDown()Activity 中的方法。

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if(event.getAction() == KeyEvent.ACTION_DOWN){
        switch(keyCode)
        {
        case KeyEvent.KEYCODE_BACK:
            if(mWebView.canGoBack() == true){
                mWebView.goBack();
            }else{
                finish();
            }
            return true;
        }

    }
    return super.onKeyDown(keyCode, event);
}
于 2012-07-14T19:33:09.583 回答
0 
WebView webView = (WebView) findViewById(R.id.webview);

将其更改为：

webView = (WebView) findViewById(R.id.webview);

然后使用第二个答案 - 就像一个魅力！

于 2013-03-26T16:58:16.593 回答