public class MainActivity extends AppCompatActivity {


    private WebView webview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webview = findViewById(R.id.wv);
        webview.loadUrl("這裡網址"
 
);
        webview.getSettings().setJavaScriptEnabled(true);
        webview.getSettings().setLayoutAlgorithm(WebSettings.LayoutAlgorithm.SINGLE_COLUMN);
        webview.getSettings().setLoadWithOverviewMode(true);

        //設定是否出現縮放工具
        webview.getSettings().setBuiltInZoomControls(true);
        //設定可以支援縮放
 

        webview.getSettings().setSupportZoom(true);
        //擴大比例的縮放
        webview.getSettings().setUseWideViewPort(true);

        //設定編碼為utf-8
        webview.getSettings().setDefaultTextEncodingName("utf-8");

        webview.getSettings().setJavaScriptEnabled(true);
        webview.getSettings().setAppCacheEnabled(true
 
);
        //設定 快取模式
        webview.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);
        // 開啟 DOM storage API 功能
        webview.getSettings().setDomStorageEnabled(true);


//這個不能少 點選事件，不然會手機瀏覽器開啟
        webview.setWebViewClient(new WebViewClient() {
            //覆蓋shouldOverrideUrlLoading 方法
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                view.loadUrl(url);
                return true;
            }
        });

    }

//回退鍵
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_BACK) && webview.canGoBack()) {
            webview.goBack();
            return true;
        }
        return false;
    }
}