android通过WebView的evaluateJavascript调用JS

因为该方法的执行不会使页面刷新，而方法（loadUrl ）的执行则会使页面刷新。

Android 4.4 后才可使用

public class MainActivity extends Activity {
    WebView webView;
    Button buttonLeft, buttonRight;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        (savedInstanceState);
        setContentView(.activity_main);
 
        webView = findViewById();
        buttonLeft = findViewById();
        buttonRight = findViewById();
 
        WebSettings webSettings = ();
        //允许使用JS
        (true);
        // 设置允许JS弹窗
        (true);
 
        ("file:///android_asset/");
 
        (new () {
            @Override
            public void onClick(View view) {
                (new Runnable() {
                    @Override
                    public void run() {
                        ("javascript:callJS()", new ValueCallback<String>() {
                            @Override
                            public void onReceiveValue(String s) {
                                //将button显示的文字改成JS返回的字符串
                                (s);
                            }
                        });
                    }
                });
            }
        });
 
        (new WebChromeClient() {
 
            @Override
            public boolean onJsAlert(WebView view, String url, String message, final JsResult result) {
                 b = new ();
                ("alert1");
                (message);
                (, new () {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        ();
                    }
                });
                (false);
                ().show();
                return true;
            }
        });
    }
}