Android 最简单的js交互

public class Main3Activity extends AppCompatActivity {

    private View button;
    private WebView web;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main3);
        button = findViewById(R.id.button);
        web = findViewById(R.id.webview);

        web.setWebViewClient(new WebViewClient());
        web.setWebChromeClient(new WebChromeClient());
        WebSettings settings = web.getSettings();
        settings.setJavaScriptCanOpenWindowsAutomatically(true);
        settings.setJavaScriptEnabled(true);
        //加载本地html
        web.loadUrl("file:///android_asset/about.html");
        //调用
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                    web.evaluateJavascript("calljs()", null);
                }
            }
        });
    }

}