WebView相关研究

public class MainActivity extends AppCompatActivity {

private WebView webView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //全屏
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    //禁止休眠
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON, WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

    webView = (WebView)findViewById(R.id.web);
    // 如果页面中链接，如果希望点击链接继续在当前browser中响应，
    // 而不是新开Android的系统browser中响应该链接，必须覆盖webview的WebViewClient对象
    webView.setWebViewClient(new WebViewClient() {
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            //  重写此方法表明点击网页里面的链接还是在当前的webview里跳转，不跳到浏览器那边
            view.loadUrl(url);
            return true;
        }
    });
    //点击后退按钮,让WebView后退一页(也可以覆写Activity的onKeyDown方法)
    webView.setOnKeyListener(new View.OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (event.getAction() == KeyEvent.ACTION_DOWN) {
                if (keyCode == KeyEvent.KEYCODE_BACK && webView.canGoBack()) {  //表示按返回键

                    webView.goBack();   //后退

                    //webview.goForward();//前进
                    return true;    //已处理
                }
            }
            return false;
        }
    });

    webView.loadUrl("http://edu.5ge.cn/dp");
    webView.getSettings().setJavaScriptEnabled(true);
    webView.getSettings().setAppCacheEnabled(true);
    //设置缓存模式
    webView.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);

// //为25%，最小缩放等级 ，可以在这里根据需求来设置缩放比例.
// webView.setInitialScale(80);

// int screenDensity = getResources().getDisplayMetrics().densityDpi ;
// WebSettings.ZoomDensity zoomDensity = WebSettings.ZoomDensity.MEDIUM ;
// switch (screenDensity){
// case DisplayMetrics.DENSITY_LOW :
// zoomDensity = WebSettings.ZoomDensity.CLOSE;
// break;
// case DisplayMetrics.DENSITY_MEDIUM:
// zoomDensity = WebSettings.ZoomDensity.MEDIUM;
// break;
// case DisplayMetrics.DENSITY_HIGH:
// zoomDensity = WebSettings.ZoomDensity.FAR;
// case DisplayMetrics.DENSITY_TV:
// zoomDensity = WebSettings.ZoomDensity.;
// break ;
// }

// webView.getSettings().setUseWideViewPort(true);//让webview读取网页设置的viewport，pc版网页//
// webView.getSettings().setLoadWithOverviewMode(true);

    webView.getSettings().setLayoutAlgorithm(WebSettings.LayoutAlgorithm.NARROW_COLUMNS);//适应内容大小//
    webView.getSettings().setLayoutAlgorithm(WebSettings.LayoutAlgorithm.SINGLE_COLUMN);//适应屏幕，内容将自动缩放
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {

    // TODO Auto-generated method stub

    super.onCreateOptionsMenu(menu);

    int group1 = 1;

    int group2 = 2;

    menu.add(group1, 1, 1, "刷新");

    return true;

}

@Override

public boolean onOptionsItemSelected(MenuItem item) {

    // TODO Auto-generated method stub

    switch (item.getItemId()) {

        case 1: // do something here

            webView.reload();

            break;

        default:

            return super.onOptionsItemSelected(item);

    }
    return true;

}

}