Android 基礎控件的使用二 WebView

1.webview的功能

1.加載h5顯示

2.可以實現多媒體文本編輯器

 

2.webivew的使用優化

1.由於顯示的h5在服務端需要從服務端加載數據了本地才能顯示，因此需要對h5做緩存處理

2.webview加載一次以後會常駐內存因此實例webview的activity會被一直引用，需要通過application進行實例化，通過動態設置layoutparames的寬和高加到view中間去，並且實例的activity最好做到複用。

3.webview的cookie和原生app同步

public class WebViewCookieHandler implements CookieJar {
//    CookieManager cookieManager = CookieManager.getInstance();

    @Override
    public void saveFromResponse(HttpUrl url, List<Cookie> cookies) {
        String urlString = url.toString();
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
            CookieSyncManager.createInstance(RiceApp.getAppContext());
        }
        for (Cookie cookie : cookies) {
            CookieManager.getInstance().setCookie(urlString, cookie.toString());
        }

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            android.webkit.CookieManager.getInstance().flush();
        } else {
            //noinspection deprecation
            CookieSyncManager.createInstance(RiceApp.getAppContext());
            CookieSyncManager.getInstance().sync();
        }
    }

    @Override
    public List<Cookie> loadForRequest(HttpUrl url) {
        String urlString = url.toString();
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
            CookieSyncManager.createInstance(RiceApp.getAppContext());
        }
        String cookiesString = CookieManager.getInstance().getCookie(urlString);
        if (cookiesString != null && !cookiesString.isEmpty()) {
            //We can split on the ';' char as the cookie manager only returns cookies
            //that match the url and haven't expired, so the cookie attributes aren't included
            String[] cookieHeaders = cookiesString.split(";");
            List<Cookie> cookies = new ArrayList<>(cookieHeaders.length);
            for (String header : cookieHeaders) {
                cookies.add(Cookie.parse(url, header));
            }
            return cookies;
        }
        return Collections.emptyList();
    }
}

 

4.通過動態代理給webview設置原生方法

    /**
     * call javascript method with giving class's methods
     * @param nativeToJSInterface
     * @param <T>
     * @return
     */
    @SuppressWarnings("unchecked")
    public <T> T jsService(Class<T> nativeToJSInterface){

        /**
         * using Proxy to invoke method call from input interface
         */
        return (T) Proxy.newProxyInstance(nativeToJSInterface.getClassLoader(), new Class[]{nativeToJSInterface}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                String methodName = method.getName();
                StringBuilder callStringBuilder = new StringBuilder();
                callStringBuilder.append(methodName).append("(");
                if(args != null && args.length > 0){
                    for(int i = 0; i < args.length; i++){
                        Object arg = args[i];
                        if(arg.getClass() == boolean.class || arg.getClass() == Boolean.class){
                            callStringBuilder.append(((Boolean) arg) ? "true" : "false");
                        }else if(arg.getClass().isPrimitive()) {
                            callStringBuilder.append(arg + "");
                        }else if(CharSequence.class.isAssignableFrom(arg.getClass())){
                            callStringBuilder.append("\"").append(arg.toString()).append("\"");
                        }else{
                            callStringBuilder.append(arg);
                        }
                        if(i != args.length - 1) callStringBuilder.append(",");
                    }
                }

                callStringBuilder.append(");");

                if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT){
                    evaluateJavascript(callStringBuilder.toString(), null);
                }else{
                    loadUrl(callStringBuilder.insert(0, "javascript:").toString());
                }
                return null;
            }
        });
    }