在使用WebView加载网页的时候，有一些固定的资源文件如js的jQuery包，css,图片等资源会比较大，如果直接从网络加载会导致页面加载的比较慢，而且会消耗比较多的流量。所以这些文件应该放在assets里面同app打包。

要解决这个问题需要用到API 11（HONEYCOMB）提供的shouldInterceptRequest(WebView view, String url) 函数来加载本地资源。在API 21又将这个方法弃用了，是重载一个新的shouldInterceptRequest，需要的参数中将url替换成了成了request。

比如有一个图片icon.png，这个图片已经放在了assets中，现在加载了一个外部html，就需要直接把assets里面的图片拿出来加载而不需要重新从网络获取。当然可以在html里面将图片链接换成file:///android_asset/icon.png,但是这样这个html就不能在Android ,iOS,WAP中公用了。

实现代码：

[java] view plain copy

print ?

1. webView.setWebViewClient(new WebViewClient() {  
2.   
3.             @Override  
4.             public WebResourceResponse shouldInterceptRequest(WebView view, String url) {  
5.                 WebResourceResponse response = null;  
6.                 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB){  
7.                     response = super.shouldInterceptRequest(view,url);  
8.                     if (url.contains(“icon.png”)){  
9.                         try {  
10.                             response = new WebResourceResponse(“image/png”,“UTF-8”,getAssets().open(“icon.png”));  
11.                         } catch (IOException e) {  
12.                             e.printStackTrace();  
13.                         }  
14.                     }  
15.                 }  
16. //                return super.shouldInterceptRequest(view, url);  
17.                 return  response;  
18.             }  
19.   
20.             @TargetApi(Build.VERSION_CODES.LOLLIPOP)  
21.             @Override  
22.             public WebResourceResponse shouldInterceptRequest(WebView view, WebResourceRequest request) {  
23.                 WebResourceResponse response = null;  
24.                 response =  super.shouldInterceptRequest(view, request);  
25.                 if (url.contains(“icon.png”)){  
26.                     try {  
27.                         response = new WebResourceResponse(“image/png”,“UTF-8”,getAssets().open(“icon.png”));  
28.                     } catch (IOException e) {  
29.                         e.printStackTrace();  
30.                     }  
31.                 }  
32.                 return response;  
33.             }  
34. }  

webView.setWebViewClient(new WebViewClient() {

            @Override
            public WebResourceResponse shouldInterceptRequest(WebView view, String url) {
                WebResourceResponse response = null;
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB){
                    response = super.shouldInterceptRequest(view,url);
                    if (url.contains("icon.png")){
                        try {
                            response = new WebResourceResponse("image/png","UTF-8",getAssets().open("icon.png"));
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
//                return super.shouldInterceptRequest(view, url);
                return  response;
            }

            @TargetApi(Build.VERSION_CODES.LOLLIPOP)
            @Override
            public WebResourceResponse shouldInterceptRequest(WebView view, WebResourceRequest request) {
                WebResourceResponse response = null;
                response =  super.shouldInterceptRequest(view, request);
                if (url.contains("icon.png")){
                    try {
                        response = new WebResourceResponse("image/png","UTF-8",getAssets().open("icon.png"));
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                return response;
            }
}