官方Kotlin方式:

override fun onKeyDown(keyCode: Int, event: KeyEvent?): Boolean {
    // Check if the key event was the Back button and if there's history
    if (keyCode == KeyEvent.KEYCODE_BACK && myWebView.canGoBack()) {
        myWebView.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)
}

https://developer.android.com/guide/webapps/webview.html#NavigatingHistory

下面是Kotlin的解决方案:

override fun onKeyUp(keyCode: Int, event: KeyEvent?): Boolean {
    if (event?.action != ACTION_UP || event.keyCode != KEYCODE_BACK) {
        return super.onKeyUp(keyCode, event)
    }

    if (mWebView.canGoBack()) {
        mWebView.goBack()
    } else {
        finish()
    }
    return true
}

我使用类似这样的东西在我的活动与WebViews:

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

    }
    return super.onKeyDown(keyCode, event);
}

编辑:

为了让这段代码工作，你需要添加一个包含WebView的Activity字段:

private WebView mWebView;

在onCreate()方法中初始化它，您应该可以开始了。

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

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    // Check if the key event was the Back button and if there's history
    if ((keyCode == KeyEvent.KEYCODE_BACK) && myWebView.canGoBack()) {
        myWebView.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);
}

你应该在你的类中使用以下库来处理onBackKeyPressed。 canGoBack()检查webview是否可以引用前一页。如果可能，则使用goBack()函数引用前一页(返回)。

 @Override
        public void onBackPressed() {
          if( mWebview.canGoBack()){
               mWebview.goBack(); 
           }else{
            //Do something else. like trigger pop up. Add rate app or see more app
           }
  }

FoamyGuy的第一个答案是正确的，但我有一些补充;低声誉不允许我发表评论。如果由于某些原因您的页面加载失败，请确保您设置了一个标记来记录失败，然后在onBackPressed覆盖上检查它。否则，你的canGoBack()将永远执行而不前往实际的back活动，如果它在那里:

//flag with class wide access 
public boolean ploadFailFlag = false;

//your error handling override
@Override
public void onReceivedError(WebView view, WebResourceRequest req, WebResourceError rerr) {
    onReceivedError(view, rerr.getErrorCode(), rerr.getDescription().toString(), req.getUrl().toString());
    ploadFailFlag = true;       //note this change 
    .....
    .....
}

//finally to the answer to this question:
@Override
public void onBackPressed() {
    if(checkinWebView.canGoBack()){
        //if page load fails, go back for web view will not go back - no page to go to - yet overriding the super 
        if(ploadFailFlag){
            super.onBackPressed();
        }else {
            checkinWebView.goBack();
        }
    }else {
        Toast.makeText(getBaseContext(), "super:", Toast.LENGTH_LONG).show();
        super.onBackPressed();
    }
}