A Custom WebView Helper for interface JS, and some common use function integrated.

CustomWebView.java

package com.kirin.ui;

import java.io.IOException;
import java.io.InputStream;


import android.content.Context;
import android.content.res.AssetManager;
import android.graphics.Bitmap;
import android.util.AttributeSet;
import android.util.Log;
import android.view.Gravity;
import android.view.KeyEvent;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.FrameLayout;

public class CustomWebView extends WebView{

	private final String TAG = "CUSTOMWEBVIEW";

	/** custom view created by the browser (a video player for example) */
	private View mCustomView;
	private WebChromeClient.CustomViewCallback mCustomViewCallback;
	
	private String js = "";
	
	private JavaScriptInterface javaInterface;

	static final FrameLayout.LayoutParams COVER_SCREEN_GRAVITY_CENTER =
			new FrameLayout.LayoutParams(
					ViewGroup.LayoutParams.MATCH_PARENT,
					ViewGroup.LayoutParams.MATCH_PARENT,
					Gravity.CENTER);

	public CustomWebView(Context context) {
		super(context);
	}
	public CustomWebView(Context context, AttributeSet attrs) {
		super(context, attrs);
	}
	public CustomWebView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
	}

	public void init(){
		js = getAssetsFileToString(getContext(), "jsInterface.js");
		webviewSetting(this, new CustomWebViewChromeClient(), new CustomWebViewClient(), null);
	}
	
	/**
	 * after init() function 
	 */
	public void setWebChromeClient(WebChromeClient myWebChromeClient){
		this.setWebChromeClient(myWebChromeClient);
	}
	/**
	 * after init() function 
	 */
	public void setWebViewclient(WebViewClient mWebViewClient){
		this.setWebViewClient(mWebViewClient);
	}
	
	/**
	 * setup webview setup
	 * @param w = webview 
	 */
	public void webviewSetting(WebView w , WebChromeClient myWebChromeClient, WebViewClient wvc ,JavaScriptInterface mJS ){
		
		w.setWebViewClient(wvc);
		w.setWebChromeClient(myWebChromeClient);
		w.setInitialScale(0);
		
		WebSettings setting = w.getSettings();
		setting.setUseWideViewPort(true);
		setting.setLoadWithOverviewMode(true);
		setting.setJavaScriptEnabled(true);		//--- JavaScript 
		setting.setGeolocationEnabled(true);
		setting.setJavaScriptCanOpenWindowsAutomatically(true); 
		setting.setLoadsImagesAutomatically(true);
		setting.setPluginsEnabled(true);
		setting.setLightTouchEnabled(true); 
		setting.setSupportZoom(true);
		setting.setBuiltInZoomControls(true);

		//--- HTML5 Database
		setting.setDatabaseEnabled(true);		//--- HTML5 Database 
		//--- Database WebChromeClient.onExceededDatabaseQuota(~) 
		setting.setDatabasePath("/data/data/" + w.getContext().getPackageName() + "/database");

		//--- HTML5DOM Storage
		setting.setDomStorageEnabled(true);		//--- HTML5 DOM Storage 

		//--- HTML5 Cache 
		//--- DatabaseWebChromeClient.onReachedMaxAppCacheSize(~) 
		setting.setAppCacheMaxSize(1024 * 1024 * 8);	//--- Default Cache Size 8 MB
		setting.setAppCachePath("/data/data/" + w.getContext().getPackageName() + "/cache");
		setting.setAppCacheEnabled(true);
		setting.setAllowFileAccess(true);
		setting.setCacheMode(WebSettings.LOAD_DEFAULT);
		
		if(mJS == null){
			if(javaInterface == null)
				javaInterface = new JavaScriptInterface();
		}else{
			javaInterface = mJS;
		}
		
		w.addJavascriptInterface(javaInterface, "_custom_js_controller");		
	}
	
	public class CustomWebViewChromeClient extends WebChromeClient{

		@Override
		public void onConsoleMessage(String message, int lineNumber,
				String sourceID) {
			super.onConsoleMessage(message, lineNumber, sourceID);
			l("MyApplication " + message + " -- From line " 
					+ lineNumber + " of "
					+ sourceID );
		}
	};
	public class JavaScriptInterface {
		public void request(String jsResult) {
			
		}
	}
		
	public class CustomWebViewClient extends WebViewClient{
		
		@Override
		public void onPageStarted(WebView view, String url, Bitmap favicon) {
			l("CustomWebViewClient onPageStarted : " + url);
			super.onPageStarted(view, url, favicon);			
		}

		@Override
		public void onPageFinished(WebView view, String url) {
			l("CustomWebViewClient onPageFinished");			
			loadSepcialResourceOnPageFinished(view , js);	
		}

		@Override
		public boolean shouldOverrideUrlLoading(WebView view, String url) {
			l("CustomWebViewClient shouldOverrideUrlLoading : " + url);
			view.loadUrl(url);			
			return true ; 
		}
		
		@Override
		public void onReceivedError(WebView view, int errorCod,String description, String failingUrl) {
			l("CustomWebViewClient shouldOverrideUrlLoading : " + errorCod + " , des : " + description + " failingurl : " + failingUrl);
        }
	}
	
	public void showCustomView(View view, WebChromeClient.CustomViewCallback callback) {
		// This code is adapted from the original Android Browser code, licensed under the Apache License, Version 2.0
		l("showing Custom View");
		// if a view already exists then immediately terminate the new one
		if (mCustomView != null) {
			callback.onCustomViewHidden();
			return;
		}

		// Store the view and its callback for later (to kill it properly)
		mCustomView = view;
		mCustomViewCallback = callback;

		// Add the custom view to its container.
		ViewGroup parent = (ViewGroup) this.getParent();
		parent.addView(view, COVER_SCREEN_GRAVITY_CENTER);

		// Hide the content view.
		this.setVisibility(View.GONE);

		// Finally show the custom view container.
		parent.setVisibility(View.VISIBLE);
		parent.bringToFront();
	}

	public void hideCustomView() {
		// This code is adapted from the original Android Browser code, licensed under the Apache License, Version 2.0
		l("Hidding Custom View");
		if (mCustomView == null) return;

		// Hide the custom view.
		mCustomView.setVisibility(View.GONE);

		// Remove the custom view from its container.
		ViewGroup parent = (ViewGroup) this.getParent();
		parent.removeView(mCustomView);
		mCustomView = null;
		mCustomViewCallback.onCustomViewHidden();

		// Show the content view.
		this.setVisibility(View.VISIBLE);
	}

	/**
	 * if the video overlay is showing then we need to know 
	 * as it effects back button handling
	 * 
	 * @return
	 */
	public boolean isCustomViewShowing() {
		return mCustomView != null;
	}

	@Override
	public boolean onKeyUp(int keyCode, KeyEvent event)
	{
		// If back key
		if (keyCode == KeyEvent.KEYCODE_BACK) {
			// A custom view is currently displayed  (e.g. playing a video)
			if(mCustomView != null) {
				this.hideCustomView();
			} 
		}

		//Does webkit change this behavior?
		return super.onKeyUp(keyCode, event);
	}

	
	/**
	 * load special resources - js to current webpage
	 * @param wv
	 * @param res
	 */
	private void loadSepcialResourceOnPageFinished(WebView wv , String res){
		wv.loadUrl("javascript: " + res  );
	}
	
	private String getAssetsFileToString(Context context , String path){
		String xmlString = null;
		AssetManager am = context.getAssets();
		try {
			InputStream is = am.open(path);
			int length = is.available();
			byte[] data = new byte[length];
			is.read(data);
			xmlString = new String(data);
		} catch (IOException e1) {
			l("getAssets file error");
			e1.printStackTrace();
		}
		return xmlString;
	}
	
	/**
	 * LogCat Helper
	 * @param str
	 */
	private void l(String str){
		Log.d(TAG, "" + str);
	}

}