using System;  
    using System.Collections.Generic;  
    using System.ComponentModel;  
    using System.Data;  
    using System.Drawing;  
    using System.IO;  
    using System.Linq;  
    using System.Net;  
    using System.Text;  
    using System.Threading;  
    using System.Threading.Tasks;  
    using System.Windows.Forms;  
    using Newtonsoft.Json;  
    using Newtonsoft.Json.Linq;  
      
    namespace 图片下载器 {  
        public partial class Form1 : Form {  
            private string dir;  
            public Form1() {  
                Control.CheckForIllegalCrossThreadCalls = false;//这种方法不推荐使用，即不检查跨线程操作，应该使用委托的  
                InitializeComponent();  
            }  
      
            private void butSelect_Click(object sender , EventArgs e) {  
                FolderBrowserDialog dlg = new FolderBrowserDialog();  
                if (dlg.ShowDialog() == System.Windows.Forms.DialogResult.OK) {  
                    textDir.Text = dlg.SelectedPath;  
      
                }  
            }  
            public static int pagecount = 1;  
            private void Showpages() {  
                this.textShow.AppendText("目前正在下载第" + pagecount + "页\n");  
            }  
            private void butStart_Click(object sender , EventArgs e) {  
                string key = textKeyWords.Text;  
                if (string.IsNullOrEmpty(key)) {//检测关键字  
                    MessageBox.Show("请输入关键词！");  
                    return;  
                }  
                if (string.IsNullOrEmpty(textDir.Text)) {//检测路径  
                    MessageBox.Show("请选择路径！");  
                    return;  
                }  
                dir = textDir.Text;  
                if (!dir.EndsWith("\\")) {  
                    dir = dir + "\\";  
                }  
                Thread thread = new Thread(() => {//启动一个新线程  
                    process(key);  
                });  
                thread.Start();//线程启动  
            }  
      
            private void process(string key) {  
                int count = (int)numericUpDown.Value;//请求的页面数量  
                for (int i = 0 ; i < count ; i++) {  
                    pagecount = i + 1;  
                    Showpages();  
                    HttpWebRequest req = (HttpWebRequest)WebRequest.Create("http://image.baidu.com/search/avatarjson?tn=resultjsonavatarnew&ie=utf-8&word=" + Uri.EscapeUriString(key) + "&cg=girl&pn=" + (i + 1) * 60 + "&rn=60&itg=0&z=0&fr=&width=&height=&lm=-1&ic=0&s=0&st=-1&gsm=360600003c");  
                    using (HttpWebResponse res = (HttpWebResponse)req.GetResponse()) {  
                        if (res.StatusCode == HttpStatusCode.OK) {  
                            using (Stream stream = res.GetResponseStream()) {  
                                try {  
                                    download(stream);  
                                } catch (Exception e) {  
                                    textShow.BeginInvoke(new Action(() => {  
                                        textShow.AppendText(e.Message + Environment.NewLine);  
                                    }));  
                                }  
                            }  
                        } else {  
                            MessageBox.Show("获取第" + i + "页失败！" + res.StatusCode);  
                        }  
                    }  
                }  
            }  
      
            private void download(Stream stream) {  
                using (StreamReader reader = new StreamReader(stream)) {  
                    string json = reader.ReadToEnd();  
                    JObject objRoot = (JObject)JsonConvert.DeserializeObject(json);  
                    JArray imgs = (JArray)objRoot["imgs"];  
                    for (int j = 0 ; j < imgs.Count ; j++) {  
                        JObject img = (JObject)imgs[j];  
                        string objUrl = (string)img["objURL"];//http://hibiadu....../1.jpg  
                        // textShow.AppendText(objUrl + Environment.NewLine);  
                        //保存的路径是：destDir；  
                        try {  
                            DownloadImage(objUrl);//避免一个方法中的代码过于复杂  
                        } catch (Exception ex) {  
                            //子线程的代码中操作界面控件要使用BeginInvoke  
                            textShow.BeginInvoke(new Action(() => {  
                                textShow.AppendText(ex.Message + Environment.NewLine);  
                            }));  
                        }  
                    }  
                }  
            }  
            private void DownloadImage(string objUrl) {  
                //得到保存的路径  
                string path = Path.Combine(dir , Path.GetFileName(objUrl));  
                HttpWebRequest req = (HttpWebRequest)WebRequest.Create(objUrl);  
                req.Referer = "http://image.baidu.com/";//欺骗网站服务器这是从百度图片发出的  
                using (HttpWebResponse res = (HttpWebResponse)req.GetResponse()) {  
                    if (res.StatusCode == HttpStatusCode.OK) {  
                        using (Stream stream = res.GetResponseStream())  
                        using (Stream filestream = new FileStream(path , FileMode.Create)) {  
                            stream.CopyTo(filestream);  
                        }  
                    } else {  
                        throw new Exception("下载失败" + res.StatusCode);  
                    }  
                }  
            }  
        }  
    }  

百度网盘下载： http://pan.baidu.com/s/1kT3YzXl密码: gafi

来自：http://blog.csdn.net/jtahstu/article/details/48109555