仿微信中加载网页时带线行进度条的WebView的实现

finddreams：/article/1515096.html

为了仿微信中加载网页时带进度条的WebView的实现，首先我们来看一下微信中的效果是什么样的：

明确需求之后，我们来开始动手做，首先我们来自定义一个带进度条的WebView,名字为ProgressWebView：

/**
* @Description:带进度条的WebView
* @author http://blog.csdn.net/finddreams */
@SuppressWarnings("deprecation")
public class ProgressWebView extends WebView {

private ProgressBar progressbar;

public ProgressWebView(Context context, AttributeSet attrs) {
super(context, attrs);
progressbar = new ProgressBar(context, null,
android.R.attr.progressBarStyleHorizontal);
progressbar.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
10, 0, 0));

Drawable drawable = context.getResources().getDrawable(R.drawable.progress_bar_states);
progressbar.setProgressDrawable(drawable);
addView(progressbar);
// setWebViewClient(new WebViewClient(){});
setWebChromeClient(new WebChromeClient());
//是否可以缩放
getSettings().setSupportZoom(true);
getSettings().setBuiltInZoomControls(true);
}

public class WebChromeClient extends android.webkit.WebChromeClient {
@Override
public void onProgressChanged(WebView view, int newProgress) {
if (newProgress == 100) {
progressbar.setVisibility(GONE);
} else {
if (progressbar.getVisibility() == GONE)
progressbar.setVisibility(VISIBLE);
progressbar.setProgress(newProgress);
}
super.onProgressChanged(view, newProgress);
}

}

@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
LayoutParams lp = (LayoutParams) progressbar.getLayoutParams();
lp.x = l;
lp.y = t;
progressbar.setLayoutParams(lp);
super.onScrollChanged(l, t, oldl, oldt);
}
}

[/code]

从这个类中可以看出，我们在自定义的WebView中加入了一个水平方向的progressbar，然后为这个progressbar设置progressDrawable,这是一个很关键的地方：

<span style="font-size:14px;"><code class="hljs avrasm has-numbering"></code></span><pre name="code" class="java"> Drawable drawable = context.getResources().getDrawable(R.drawable.progress_bar_states);
progressbar.setProgressDrawable(drawable);

下面我们来看一下drawable目录下的progress_bar_states.xml是如何写的：

<?xml version="1.0" encoding="utf-8"?>
<!-- 层叠 -->
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >

<item android:id="@android:id/background">
<shape>
<corners android:radius="2dp" />

<gradient
android:angle="270"
android:centerColor="#E3E3E3"
android:endColor="#E6E6E6"
android:startColor="#C8C8C8" />
</shape>
</item>
<item android:id="@android:id/progress">
<clip>
<shape>
<corners android:radius="2dp" />

<gradient
android:centerColor="#4AEA2F"
android:endColor="#31CE15"
android:startColor="#5FEC46" />
</shape>
</clip>
</item>

</layer-list>

[/code]

<layer-list>这个标签可能我们不是很熟悉，因为我们一般常用的就是<shape>和<selector>这两个，layer-list是将多个图片或上面两种效果按照顺序层叠起来，layer就像photoshop中的图层一样。
其中有个<clip>标签，是可以用来剪载图片显示，例如，可以通过它来做进度度。你可以选择是从水平或垂直方向剪载。
自定义好ProgressWebView之后，我们只需要在xml布局文件中声明就可以使用了：

<span style="font-size:14px;"><code class="hljs xml has-numbering">
</code></span><pre name="code" class="html">   <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<com.finddreams.progresswebview.ProgressWebView
android:id="@+id/baseweb_webview"
android:layout_width="match_parent"
android:layout_height="match_parent"/>

</LinearLayout>

接着我们定义一个BaseWebActivity来显示我们自定义的WebView：

<span style="font-size:14px;"><code class="hljs java has-numbering"><span class="hljs-javadoc">/**
*<span class="hljs-javadoctag"> @Description</span>:WebActivity
*<span class="hljs-javadoctag"> @author</span> http://blog.csdn.net/finddreams */</span>
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">BaseWebActivity</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">Activity</span> {</span>

<span class="hljs-comment">// private View mLoadingView;</span>
<span class="hljs-keyword">protected</span> ProgressWebView mWebView;
<span class="hljs-keyword">private</span> ProgressBar web_progressbar;

<span class="hljs-annotation">@Override</span>
<span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onCreate</span>(Bundle savedInstanceState) {
<span class="hljs-comment">// TODO Auto-generated method stub</span>
<span class="hljs-keyword">super</span>.onCreate(savedInstanceState);
setContentView(R.layout.activity_baseweb);
<span class="hljs-comment">// mLoadingView = findViewById(R.id.baseweb_loading_indicator);</span>
mWebView = (ProgressWebView) findViewById(R.id.baseweb_webview);
mWebView.getSettings().setJavaScriptEnabled(<span class="hljs-keyword">true</span>);
initData();
}

<span class="hljs-keyword">private</span> <span class="hljs-keyword">void</span> <span class="hljs-title">initData</span>() {
Intent intent = getIntent();

String url = intent.getStringExtra(<span class="hljs-string">"url"</span>);
<span class="hljs-keyword">if</span>(url!=<span class="hljs-keyword">null</span>){
mWebView.loadUrl(url);
}
}

}</code>

</span>

然后调用这个Activity即可，例如：

<span style="font-size:14px;"><code class="hljs java has-numbering"><span class="hljs-javadoc">/**
*<span class="hljs-javadoctag"> @Description</span>:
*<span class="hljs-javadoctag"> @author</span> http://blog.csdn.net/finddreams */</span>
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">MainActivity</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">Activity</span> {</span>

<span class="hljs-annotation">@Override</span>
<span class="hljs-keyword">protected</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onCreate</span>(Bundle savedInstanceState) {
<span class="hljs-keyword">super</span>.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">openUrl</span>(View v){
Intent intent =<span class="hljs-keyword">new</span> Intent(<span class="hljs-keyword">this</span>,BaseWebActivity.class);
intent.putExtra(<span class="hljs-string">"url"</span>, <span class="hljs-string">"http://blog.csdn.net/finddreams/article/details/43486527"</span>);
<span class="hljs-comment">//  intent.putExtra("url", "http://www.baidu.com");</span>
startActivity(intent);
}
}</code></span>

好吧，到这里你应该学会怎么做带线行进度条的WebView了吧！