Question

我阅读了这些文档，看起来您需要使用slimerjs http://docs.casperjs.org/en/latest/events-filters.html才能从package main import ( "context" "fmt" "time" ) func interruptable_call(sleep time.Duration) <-chan time.Time { fmt.Println("sleeping for ", sleep*time.Second) time.Sleep(sleep * time.Second) return time.After(0 * time.Second) } func A(ctx context.Context) int { for { select { case <-ctx.Done(): fmt.Println("func done") return 1 case <-interruptable_call(2): fmt.Println("blocking") case <-interruptable_call(3): fmt.Println("blocking") case <-interruptable_call(4): fmt.Println("blocking") case <-interruptable_call(5): fmt.Println("blocking") } } return 0 } func main() { ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second) defer cancel() fmt.Println("go A") go A(ctx) fmt.Println("go A done") select { case <-ctx.Done(): fmt.Println("main done") break } }事件中获取responseData.body。

我的用例是在页面加载时下载图像，所以我不做另外的往返：获取资源JSON，下载并保存任何图像文件，重新加载文件以检查图像尺寸和如果太小（图标） - ＆gt;消除。

我想知道是否有更好的方法来做到这一点。事实上，我可以去page.resource.received evaluate选择器，但有些网站会使用img css，这很棘手。

Answer 1

评估可能很棘手，但这是一种可行的方法：（ PhantomJS Only ）

这个例子有可能

存储符合特定条件的clipRects图像这些元素的后page.render()到屏幕截图文件中。
存储匹配资源的URL以供后续下载请求
捕获内部网址＆＃39; src＆＃39;属性或背景图像＆＃39; css属性，试图获得宽度＆amp;标准匹配和捕获目的的高度。

var page = require('webpage').create();
page.onConsoleMessage = function(msg) {console.log(msg);};
console.log('[#] I M A G E · N I N J A');
page.open('http://cartawifi.com', function(status) {
  var clipRectList = page.evaluate(function(pagex) {
    // .: Captured Images : In-Memory Reference Storage :.
    const IMAGES = {
        'src':{'indxs':[],'ref':[]},
        'background-image':{'indxs':[],'ref':[]},
        'selectors':[]
    }; 
    var clipRects = []; // maybe you want to take page screenshots of specific elements containing matching images
    var capturedImages = 0; var totalElements = 0;
    // .: Define Image Capture : Min/Max Width/Height :.
    const minWidth = 1; const minHeight = 1;
    const maxWidth = 9999;  const maxHeight = 9999;
    const regxp = new RegExp('url');
    $('*').each(function(index, el) { var ignore=false;
        // search for elements with 'background-image' css property
        if($(el).css('background-image')!=null!=null){
            var wu = $(this).css('width');
            var width = parseFloat(wu.replace('px',''));
            var hu = $(this).css('height');
            var height = parseFloat(wu.replace('px',''));
            var src = $(el).css('background-image');
            var group = "background-image"
            if(!src.match(regxp)){ignore=true;}else{
                //remove the keep the contents inside the 'url()' string'
                src = (($(el).css('background-image')).slice(4));
                src = src.substring(0, src.length - 1);
            }
        }
        // search for elements with 'src' html attribute
        else if($(el).attr('src')!=null){
            var width = $(this).get(0).naturalWidth; 
            var height = $(this).get(0).naturalHeight;
            var group = "src" 
            var src = $(el).attr('src');
        }
        //---------------------------------------------------------
        if(width>=minWidth&&height>=minWidth&&
           width<=maxWidth&&height<=maxWidth&&
           !ignore){
                IMAGES[group].indxs.push(index); 
                IMAGES[group].ref.push(src); 
                IMAGES.selectors.push(this); 
                capturedImages++;
                console.log("  [captured] :",group,width,height,src);
                //:store clipRect for this element
                var clipR = $.extend({},$(el).offset(),{width: $(el).offsetWidth,height: $(el).offsetHeight});
                console.log("    (clipRect)",JSON.stringify(clipR));
                clipRects.push(clipR);
        }
        totalElements++;
    });
    // report information :
    console.log('[i] Total Elements Parsed : ',totalElements);
    console.log('[*] Total Images Captured : ',capturedImages);
    console.log('     >              [src] : ',IMAGES['src'].indxs.length);
    console.log('     > [background-image] : ',IMAGES['background-image'].indxs.length);
  });
  console.log('[!] TO-DO : STORE CAPTURED IMAGES AS FILES');
  phantom.exit();
});

使用casperjs下载资源图像文件

1 个答案: