webview应用程序中的按钮调用html页面的js事件

public class MethodMutual extends Activity {

private WebView mWebView;
private Handler mHandler = new Handler();
private static final String LOG_TAG = "WebViewDemo";

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
loadAssetHtml();
}

public void loadAssetHtml() {
mWebView = (WebView) findViewById(R.id.webview);
WebSettings webSettings = mWebView.getSettings();
webSettings.setSavePassword(false);
webSettings.setSaveFormData(false);
webSettings.setJavaScriptEnabled(true);
webSettings.setSupportZoom(false);
mWebView.setWebChromeClient(new MyWebChromeClient());
// 将一个java对象绑定到一个javascript对象中,javascript对象名就是interfaceName,作用域是Global.
mWebView.addJavascriptInterface(new DemoJavaScriptInterface(), "demo");
mWebView.loadUrl("file:///android_asset/demo.html");
// 通过应用中按钮点击触发JS函数响应
Button mCallJS = (Button) findViewById(R.id.mCallJS);
mCallJS.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mWebView.loadUrl("javascript:wave()");
}
});
}

private int i = 0;

final class DemoJavaScriptInterface {
DemoJavaScriptInterface() {
}
/**
* This is not called on the UI thread. Post a runnable to invoke
* loadUrl on the UI thread.
*/
public void callAndroid() {
mHandler.post(new Runnable() {
public void run() {
if (i % 2 == 0) {
mWebView.loadUrl("javascript:wave()");
} else {
mWebView.loadUrl("javascript:waveBack()");
}
i++;
}
});
}
}

/**
* Provides a hook for calling "alert" from javascript. Useful for debugging
* your javascript.
*/
final class MyWebChromeClient extends WebChromeClient {
@Override
public boolean onJsAlert(WebView view, String url, String message,
JsResult result) {
Log.d(LOG_TAG, message);
result.confirm();
return true;
}
}
}