WebView性能优化（1）全局webview预加载

参考链接：https://blog.csdn.net/zgx19910405/article/details/87623697

第一步：
创建工具类来实现WebView的实例化和资源释放

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public class WebViewPools {
//AtomicReference提供了以无锁方式访问共享资源的能力
private static WebViewPools mWebPools = null;

/**
 * 引用类型的原子类
 **/
private static final AtomicReference<WebViewPools> mAtomicReference = new AtomicReference<>();

private final Queue<WebView> mWebViews;

private Object lock = new Object();

private WebViewPools() {
    mWebViews = new LinkedBlockingQueue<>();
}

public static WebViewPools getInstance() {
    for (; ; ) {
        if (mWebPools != null)
            return mWebPools;
        if (mAtomicReference.compareAndSet(null, new WebViewPools()))
            return mWebPools = mAtomicReference.get();
    }
}

/**
 * 页面销毁
 * （1）去除WebView的上下文，避免内存泄漏
 * （2）加入缓存
 **/
public void recycle(WebView webView) {
    recycleInternal(webView);
}

/**
 * 页面加入浏览器
 * （1）缓存没有，则新建webView
 **/
public WebView acquireWebView(Activity activity) {
    return acquireWebViewInternal(activity);
}


private WebView acquireWebViewInternal(Activity activity) {

    WebView mWebView = mWebViews.poll();

    if (mWebView == null) {
        synchronized (lock) {
            return new WebView(new MutableContextWrapper(activity));
        }
    } else {
        MutableContextWrapper mMutableContextWrapper = (MutableContextWrapper) mWebView.getContext();
        mMutableContextWrapper.setBaseContext(activity);
        return mWebView;
    }
}


private void recycleInternal(WebView webView) {
    try {
        if (webView.getContext() instanceof MutableContextWrapper) {
            MutableContextWrapper mContext = (MutableContextWrapper) webView.getContext();
            mContext.setBaseContext(mContext.getApplicationContext());
            mWebViews.offer(webView);
        }
        if (webView.getContext() instanceof Activity) {
            throw new RuntimeException("leaked");
        }

    } catch (Exception e) {
        e.printStackTrace();
    }


}

}

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第二步：

在Application或者主页预先加载一个WebView并释放资源

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    //long l = System.currentTimeMillis();
    WebView webView = WebViewPools.getInstance().acquireWebView(this);
    //LogUtil.logD("第一次初始化：" + (System.currentTimeMillis() - l));
    WebViewPools.getInstance().recycle(webView);

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第三步：

在需要使用的地方通过WebViewPools取出WebView进行使用

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    LinearLayout ll_webview = findViewById(R.id.ll_webview);
    WebView x5Webview = WebViewPools.getInstance().acquireWebView(this);
    ll_webview.addView(x5Webview, new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));

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第四步：

页面销毁时记得释放资源

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@Override
protected void onDestroy() {
    super.onDestroy();
    ll_webview.removeAllViews();
    WebViewPools.getInstance().recycle(x5Webview);
}

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