android webview 前进按钮

Question

我想知道如何在 android 的私人浏览器中禁用和启用前进菜单按钮。我正在编写一个应用程序，其中显示 3 个 webview，我想合并 android 自己的浏览器选项的基本功能。到目前为止一切正常wrt 功能。唯一的问题是“前进”菜单项始终处于启用状态。我也提到了 if canGoFwd then goFwd 的条件。问题是，我单独定义了菜单项并单独编写了转发功能，问题是动态更改“转发”按钮的状态

Answer 1

private WebView webView;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.webview);

    webView = (WebView) findViewById(R.id.webView1);
    webView.getSettings().setJavaScriptEnabled(true);
    final Button previousButton =(Button) findViewById(R.id.previousButton);

    previousButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

               if(webView.canGoBack()){
                   webView.goBack();
               }
        }
    });
    final Button forwardButton =(Button) findViewById(R.id.forwardButton);

    forwardButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

               if(webView.canGoForward()){
                   webView.goForward();
               }
        }
    });
    webView.setWebViewClient( new WebViewClient() {



        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            // TODO Auto-generated method stub
            super.onPageStarted(view, url, favicon);
        }

        @Override
        public void onPageFinished( WebView view, String url ) {

            super.onPageFinished(webView, url );

            previousButton.setEnabled(view.canGoBack());
            forwardButton.setEnabled(view.canGoForward());

        }

        @Override
        public void onReceivedError( WebView view, int errorCode, String description, String failingUrl ) {

            super.onReceivedError( webView, errorCode, description, failingUrl );
            Toast.makeText( WebViewActivity.this, description, Toast.LENGTH_LONG );
        }
    } );
    webView.loadUrl("");

webview.xml 文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <WebView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/webView1"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" />

    <Button
        android:id="@+id/previousButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:enabled="false" 
        android:text="previous"/>

    <Button
        android:id="@+id/forwardButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_toRightOf="@+id/previousButton"
        android:text="forward"
        android:enabled="false" />
</RelativeLayout>