javascript python 爬虫(使用CefSharp和Javascript实现网络爬虫-Javascript和C)
javascript python 爬虫(使用CefSharp和Javascript实现网络爬虫-Javascript和C)async function sendMsg(type msg){await CefSharp.BindObjectAsync('boundAsync');var result = await boundAsync. ReceivMsg(type msg);};sendMsg (1 'hello C#'); myBrowser.JavascriptObjectRepository.ResolveObject = (_sender _e) =>{ var repo = _e.ObjectRepository;if (_e.ObjectName == "boundAsync"){repo.Register("boundAsync" new AsyncJavascriptBindingClass() isAsyn
欢迎浏览“使用CefSharp和Javascript实现网络爬虫”,本篇是第3篇。
在爬虫实现过程中,采用Javascript的DOM操作来抓取目标数据,并通过CefSharp提供的Javascript和C#交互方法,把目标数据传递给C#代码进行处理。上一篇介绍了采用Javascript的DOM操作来抓取目标数据,这一篇介绍CefSharp中Javascript和C#之间的调用和交互,以及使用C#委托实现回调处理。
一、CefSharp中Javascript和C#之间的调用和交互
1、C#调用Javascript
private ChromiumWebBrowser myBrowser;
myBrowser.GetBrowser().MainFrame.ExecuteJavaScriptAsync("console.log('helloworld');");
2、Javascript调用C#,实现数据上报
(1)C#暴露接口定义
public class AsyncJavascriptBindingClass{
public int Receivemsg (int nType string msg){
Console.WriteLine("AsyncJavascriptBindingClass. ReceiveMsg: " nType " " msg);
}
}
(2)C#暴露接口注册
myBrowser.JavascriptObjectRepository.ResolveObject = (_sender _e) =>{
var repo = _e.ObjectRepository;
if (_e.ObjectName == "boundAsync"){
repo.Register("boundAsync" new AsyncJavascriptBindingClass() isAsync: true);
}
};
(3)在Javascript中调用
async function sendMsg(type msg){
await CefSharp.BindObjectAsync('boundAsync');
var result = await boundAsync. ReceivMsg(type msg);
};
sendMsg (1 'hello C#');
二、C#委托使用
当C#代码接收到Javascript传递的目标数据后,常常需要通知其他处理线程进行后续处理,例如通知主界面线程改变当前访问的URL地址等,这里介绍我在实现爬虫过程中使用C#委托实现回调机制。
(1)定义委托类
public delegate void callbackDelegate(string msg);
(2)在AsyncJavascriptBindingClass中触发回调函数
public class AsyncJavascriptBindingClass{
public CallBackDelegate callBack;
public AsyncJavascriptBindingClass(CallBackDelegate _callBack){
this.callBack = _callBack;
}
public int ReceivMsg (int nType string msg){
callback(msg); //todo
}
}
(3)在主界面对象WindowForm中实现回调函数
private void CallBack(string msg){
//your code
}
myBrowser.JavascriptObjectRepository.ResolveObject = (_sender _e) =>{
var repo = _e.ObjectRepository;
if (_e.ObjectName == "boundAsync"){
repo.Register("boundAsync" new AsyncJavascriptBindingClass(CallBack) isAsync: true);
}
};
现在我把“使用CefSharp和Javascript实现网络爬虫”的主要知识点进行了记录和分享,供往后查阅。