在 WebView Android 上实现后退按钮 [英] Implement Back Button on WebView Android
问题描述
我试图在android webview上实现后退按钮,但它说
I tried to implement back button on android webview but it said that
error: method does not override or implement a method from a supertype
error: cannot find symbol method onBackPressed()
活动代码:
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.graphics.Bitmap;
import android.view.View;
import android.widget.ProgressBar;
import android.view.KeyEvent;
public class MainActivity extends AppCompatActivity {
String ShowOrHideWebViewInitialUse = "show";
private WebView webview ;
private ProgressBar spinner;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
webview =(WebView)findViewById(R.id.webView);
spinner = (ProgressBar)findViewById(R.id.progressBar1);
webview.setWebViewClient(new CustomWebViewClient());
webview.getSettings().setJavaScriptEnabled(true);
webview.getSettings().setDomStorageEnabled(true);
webview.setOverScrollMode(WebView.OVER_SCROLL_NEVER);
webview.loadUrl("http://web.com");
}
// This allows for a splash screen
// (and hide elements once the page loads)
private class CustomWebViewClient extends WebViewClient {
@Override
public void onPageStarted(WebView webview, String url, Bitmap favicon) {
// only make it invisible the FIRST time the app is run
if (ShowOrHideWebViewInitialUse.equals("show")) {
webview.setVisibility(webview.INVISIBLE);
}
}
@Override
public void onPageFinished(WebView view, String url) {
ShowOrHideWebViewInitialUse = "hide";
spinner.setVisibility(View.GONE);
view.setVisibility(webview.VISIBLE);
super.onPageFinished(view, url);
}
@Override
public void onBackPressed()
{
WebView webView = (WebView) findViewById(R.id.webView);
if(webView.canGoBack()){
webView.goBack();
}else{
super.onBackPressed();
}
}
}
}
我在 stackoverflow 上尝试了其他来源的方法,但仍然没有得到有效的答案.也许我的知识仍然无法与其他人相提并论.我希望这个社区中的某个人可以帮助我解决这个问题.还简要说明我应该怎么做才能使后退按钮在 webview 上工作
I tried approach from other source on stackoverflow but still not get a valid answer. Maybe my knowledge still not par with other. I hope that someone in this community can help me to solve this issue. Also a brief explanation about what should I do to make the back button work on webview
推荐答案
在 WebView
外部和 Activity
内部使用 onBackPressed()
方法类方法:
Use onBackPressed()
method outside of WebView
and inside the Activity
class method:
@Override
public void onBackPressed()
{
WebView webView = (WebView) findViewById(R.id.webView); // Remove this
if(webView.canGoBack()){
webView.goBack();
}else{
super.onBackPressed();
}
}
}
另外,尝试在 onCreate()
方法中初始化 WebView
并删除 onBackPressed()
中的第二个重复代码.
Also, try initializing WebView
inside onCreate()
method and remove the second duplicate code inside onBackPressed()
.
为了能够在整个Activity
中访问它,像这样初始化它:
To be able to access it inside whole Activity
, initialize it like this:
public class MainActivity extends AppCompatActivity {
String ShowOrHideWebViewInitialUse = "show";
private WebView webview;
private ProgressBar spinner;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
webview = (WebView) findViewById(R.id.webView);
}
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