摘要：转百度图片下载器

// 声明一个异步委托去处理图片下载操作
            Action downloadAction = new Action(() =>
            {
                ProcessDownload(keyword);
            });
            // 声明一个下载完成后的回调函数
            AsyncCallback callBack = new AsyncCallback(asyncResult =>
            {
                downloadAction.EndInvoke(asyncResult);
                progressBar.BeginInvoke(new Action(() =>
                {
                    progressBar.Value = progressBar.Maximum;
                }));
                txtLogs.BeginInvoke(new Action(() =>
                {
                    txtLogs.AppendText("下载图片操作结束！" + Environment.NewLine);
                }));
                btnStart.BeginInvoke(new Action(() =>
                {
                    btnStart.Enabled = true;
                }));
            });
            // 执行该异步委托
            IAsyncResult result = downloadAction.BeginInvoke(callBack, null);
            // 主线程继续干自己的事儿
            txtLogs.AppendText("正在下载图片中..." + Environment.NewLine);

private void ProcessDownload(string keyword)
        {
            int pageCount = (int)numPageCount.Value;
            sumCount = pageCount * 60;
            for (int i = 0; i < pageCount; i++)
            {
                HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("http://image.baidu.com/i?tn=resultjsonavatarnew&ie=utf-8&word=" + Uri.EscapeDataString(keyword) + "&pn=" + pageCount * 60 + "&cg=girl&rn=60&itg=0&lm=-1&ic=0&s=0");
                using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
                {
                    if (response.StatusCode == HttpStatusCode.OK)
                    {
                        using (Stream stream = response.GetResponseStream())
                        {
                            try
                            {
                                // 下载指定页的所有图片
                                DownloadPage(stream);
                            }
                            catch (Exception ex)
                            {
                                // 跨线程访问UI线程的txtLogs
                                txtLogs.BeginInvoke(new Action(() =>
                                    {
                                        txtLogs.AppendText(ex.Message + Environment.NewLine);
                                    }));
                            }
                        }
                    }
                    else
                    {
                        MessageBox.Show("获取第" + pageCount + "页失败：" + response.StatusCode);
                    }
                }
            }
        }

private void DownloadPage(Stream stream)
        {
            using (StreamReader reader = new StreamReader(stream))
            {
                string jsonData = reader.ReadToEnd();
                // 解析JSON，分析JSON
                JObject objectRoot = JsonConvert.DeserializeObject(jsonData) as JObject;
                JArray imgsArray = objectRoot["imgs"] as JArray;
                for (int i = 0; i < imgsArray.Count; i++)
                {
                    JObject img = imgsArray[i] as JObject;
                    string objUrl = (string)img["objURL"];
                    //txtLogs.AppendText(objUrl + Environment.NewLine); // 测试获取图片路径
                    try
                    {
                        // 下载具体的某一张图片
                        DownloadImage(objUrl);
                        // 更新进度条
                        progressBar.BeginInvoke(new Action(() =>
                            {
                                progressBar.Value = i * 100 / sumCount;
                            }));
                        // 更新文本框
                        txtLogs.BeginInvoke(new Action(() =>
                            {
                                txtLogs.AppendText("已下载：" + objUrl + Environment.NewLine);
                            }));
                    }
                    catch (Exception ex)
                    {
                        // 跨线程访问UI线程的txtLogs控件
                        txtLogs.BeginInvoke(new Action(() =>
                            {
                                txtLogs.AppendText("【异常：" + ex.Message + "】" + Environment.NewLine);
                            }));
                    }
                }
            }
        }

private void DownloadImage(string objUrl)
        {
            string destFileName = Path.Combine(destDir, Path.GetFileName(objUrl));
            HttpWebRequest request =
                (HttpWebRequest)HttpWebRequest.Create(objUrl);
            // 欺骗服务器判断URLReferer
            request.Referer = "http://image.baidu.com";
            using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    using (Stream stream = response.GetResponseStream())
                    {
                        using (FileStream fileStream = new FileStream(destFileName, FileMode.Create))
                        {
                            stream.CopyTo(fileStream);
                        }
                    }
                }
                else
                {
                    throw new Exception("下载" + objUrl + "失败，错误码：" + response.StatusCode);
                }
            }
        }

转自： http://www.cnblogs.com/edisonchou/p/4175190.html