Question

android webview 回退和退出的代码不能实现

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;

public class zy extends AppCompatActivity {
private WebView webView;
private long mExitTime = System.currentTimeMillis();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_zy);
WebView webView = (WebView) findViewById(R.id.webview);
webView.getSettings().setJavaScriptEnabled(true);
webView.setWebViewClient(new WebViewClient());
webView.loadUrl("http://baidu.com");
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK) && webView.canGoBack()) {
webView.goBack();
return true;
} else if (keyCode == KeyEvent.KEYCODE_BACK && ((System.currentTimeMillis() - mExitTime) > 2000)) {
Toast.makeText(this, "再按一次退出程序", Toast.LENGTH_SHORT).show();
mExitTime = System.currentTimeMillis();
} else {
finish();
}
return true;
}
}

Answer 1

1.MainActivity代码（具体的使用Web布局和详解）
2.Xml布局
3.注意点

MainActivity的代码：

详细