WebbView

public class WebViewShow extends AppCompatActivity {


    private WebView webView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        supportRequestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.recommend_webview);
        webView = (WebView) findViewById(R.id.re_web_view);
        //脚本
        webView.getSettings().setJavaScriptEnabled(true);
        Intent intent = getIntent();
        String url = intent.getStringExtra("url");
        webView.loadUrl(url);
        //缩放
        webView.getSettings().setBuiltInZoomControls(true);
        //可以访问的文件
        webView.getSettings().setAllowFileAccess(true);
        webView.setWebViewClient(new WebViewClient() {
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                view.loadUrl(url);
                return true;
            }
        });


    }


    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_BACK) && webView.canGoBack()) {
            webView.goBack();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

}

另一种

//初始化布局++++webview逻辑
private void initView() {
    webView = (WebView) findViewById(R.id.webView);
    WebSettings settings = webView.getSettings();
    // 允许javascript的执行
    settings.setJavaScriptEnabled(true);

    if (NetworkUtils.isNetworkAvailable(getApplicationContext())) {
        //有网络连接，设置默认缓存模式
        settings.setCacheMode(WebSettings.LOAD_DEFAULT);
    } else {
        //无网络连接，设置本地缓存模式
        settings.setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
    }

    //缩放
    settings.setBuiltInZoomControls(true);
    //不显示webview缩放按钮
    settings.setDisplayZoomControls(false);
    settings.setLayoutAlgorithm(WebSettings.LayoutAlgorithm.NARROW_COLUMNS);// 排版适应屏幕
    //webview的缓存模式
    settings.setCacheMode(WebSettings.LOAD_DEFAULT);
   /* Intent intent = getIntent();
    String url = intent.getStringExtra("url");
    webView.loadUrl(url);*/
    webView.loadUrl("http://www.lanougroup.com/?CPC-PC=baidu&plan=A1beijing-dashuju&unit=xingyeci-lejie-rumen&keyword=androidkaifarumen&e_creative=22949379798&e_keywordid=88361869070");

    //可以访问的文件
    settings.setAllowFileAccess(true);
    webView.setWebViewClient(new WebViewClient() {
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            view.loadUrl(url);
            return true;
        }
    });
}

当webview控件在主Activity时  先返回所有开启的H5页面  然后退出主程序

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK && webView.canGoBack()) {
        webView.goBack();
        return true;
    } else {
        // 判断是否在两秒之内连续点击返回键，是则退出，否则不退出
        if (System.currentTimeMillis() - exitTime > 2000) {
            Toast.makeText(getApplicationContext(), "再按一次退出程序", Toast.LENGTH_SHORT).show();
            // 将系统当前的时间赋值给exitTime
            exitTime = System.currentTimeMillis();
            return true;
        } else {
            finish();
        }
    }
    return super.onKeyDown(keyCode, event);
}