It demonstrate how to call JavaScript function in HTML from Android Java code (the EditText), call Android Java methods with @JavascriptInterface from HTML JavaScript (the first "Say hello" and "Open Dialog" buttons).
For applications targeted to API level JELLY_BEAN_MR1 and above, only public methods that are annotated with JavascriptInterface can be accessed from JavaScript. For applications targeted to API level JELLY_BEAN or below, all public methods (including the inherited ones) can be accessed. This example also show Android Java method without @JavascriptInterface (called from the second "Say hello" button), and non-public method (called from second "Open Dialog" button) cannot be accessed from Javascript.
Create a Android Project using Project Wizard in Android-Eclipse, to generate a default MainActivity extends ActionBarActivity. Implement MyJavaScriptInterface class, its public method with @JavascriptInterface can be called from Javascript. Modify the onCreateView() method of PlaceholderFragment() class to embed our HTML.
MainActivity.java
package com.example.androidbrowser;
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.app.AlertDialog;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.JavascriptInterface;
import android.webkit.WebView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
WebView myBrowser;
EditText Msg;
Button btnSendMsg;
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
//
myBrowser = (WebView) rootView.findViewById(R.id.mybrowser);
final MyJavaScriptInterface myJavaScriptInterface =
new MyJavaScriptInterface(getActivity());
myBrowser.addJavascriptInterface(myJavaScriptInterface,
"AndroidFunction");
myBrowser.getSettings().setJavaScriptEnabled(true);
myBrowser.loadUrl("file:///android_asset/mypage.html");
Msg = (EditText) rootView.findViewById(R.id.msg);
btnSendMsg = (Button) rootView.findViewById(R.id.sendmsg);
btnSendMsg.setOnClickListener(new Button.OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
String msgToSend = Msg.getText().toString();
myBrowser.loadUrl("javascript:callFromActivity(\""
+ msgToSend + "\")");
}
});
//
return rootView;
}
public class MyJavaScriptInterface {
Context mContext;
MyJavaScriptInterface(Context c) {
mContext = c;
}
@JavascriptInterface
public void showToast(String toast) {
Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
}
@JavascriptInterface
public void openAndroidDialog() {
AlertDialog.Builder myDialog = new AlertDialog.Builder(mContext);
myDialog.setTitle("DANGER!");
myDialog.setMessage("You can do what you want!");
myDialog.setPositiveButton("ON", null);
myDialog.show();
}
/*
* The following methods have no @JavascriptInterface
* It cannot be accessed
*/
public void showToast2(String toast) {
Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
}
/*
* The following methods not public
* It cannot be accessed
*/
@JavascriptInterface
void openAndroidDialog2() {
AlertDialog.Builder myDialog = new AlertDialog.Builder(mContext);
myDialog.setTitle("DANGER!");
myDialog.setMessage("You can do what you want!");
myDialog.setPositiveButton("ON", null);
myDialog.show();
}
}
}
}
/res/layout/fragment_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:autoLink="web"
android:text="http://arteluzevida.blogspot.com/"
android:textStyle="bold" />
<EditText
android:id="@+id/msg"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<Button
android:id="@+id/sendmsg"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Msg to JavaScript" />
<WebView
android:id="@+id/mybrowser"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</LinearLayout>
/assets/mypage.html, it will be loaded in WebView.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width; user-scalable=0;" />
<title>My HTML</title>
</head>
<body>
<h1>MyHTML</h1>
<p id="mytext">Hello!</p>
<input type="button" value="Say hello" onClick="showAndroidToast('Hello Android!')" />
<input type="button" value="Open Dialog" onClick="openAndroidDialog()" />
<br/>
<p>Call Java method Without @JavascriptInterface</p>
<input type="button" value="Say hello" onClick="showAndroidToast2('Hello Android!')" />
<br/>
<p>Call Java method not public</p>
<input type="button" value="Open Dialog" onClick="openAndroidDialog2()" />
<br/>
<script language="javascript">
function showAndroidToast(toast) {
AndroidFunction.showToast(toast);
}
function openAndroidDialog() {
AndroidFunction.openAndroidDialog();
}
function showAndroidToast2(toast) {
AndroidFunction.showToast2(toast);
}
function openAndroidDialog2() {
AndroidFunction.openAndroidDialog2();
}
function callFromActivity(msg){
document.getElementById("mytext").innerHTML = msg;
}
</script>
</body>
</html>
Download the files.