上传文件时表单enctype属性必须要更改为<enctype='multipart/form-data'>；采用post提交表单，元素需要有name属性；
利用第三方jar包（commons-fileupload-1.2.1.jar commons-io-1.3.2.jar ）进行普通数据获取和文件上传；普通文本需要用getString（"编码格式"）方法获取，否则汉字会出现乱码，最开始我一直用的getString（）获取，发现传到数据的数据全是乱码，查看流浪器的里面的请求和响应全是正常的，百度了半天也没找到真正的解决方法，无意间发现第三方包里面的FileItem还有一个重载的getString（String args）方法，但是不晓得参数传什么；后来发现这个getString（String args）方法会抛一个
UnsupportedEncodingException异常，英语也不好，百度单词的意思吧，什么不支持的编码异常，到此终于发现这个是设置编码的方法；
所以呢，写方法；写类；写变量；写参数时，能让人见文知意是多么重要；要是这个方法直接这样写的getString（String charset）一看就知道是设置编码格式的方法了把。
添加商品的Servlet：
package ni.jun.yang.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import ni.jun.yang.service.KindService;
@WebServlet("/AddGoodsServlet")
public class AddGoodsServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public AddGoodsServlet() {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//响应编码格式
response.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
//遍历类型的集合，得到下拉框选项
List<String> list = new ArrayList<>();
String sql = "Select * from kind";
list = new KindService().select(sql);
out.println("<html><head><meta charset='utf-8'><title>添加商品</title>");
out.println("</head>");
out.println("<body>");
//上传文件的提交方式
out.println("<form action='AddResultServlet' method='post' enctype='multipart/form-data'>");
out.println("<table>");
out.println("<tr>");
out.println("<td>名称：</td>");
out.println("<td><input type='text' name='mingzi'></td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td></td>");
out.println("<td><input type='file' name='filename'></td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>介绍：</td>");
out.println("<td><input type='text' name='jieshao'></td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>售价：</td>");
out.println("<td><input type='text' name='shoujia'></td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td>分类：</td>");
out.println("<td>");
out.println("<select name='fenlei'>");
//遍历类型的集合，得到下拉框选项
for (int i = 0;i<list.size();i++) {
out.println("<option value="+(i+1)+">");
out.println(list.get(i));
out.println("</option>");
}
out.println("</select>");
out.println("</td>");
out.println("</tr>");
out.println("<tr>");
out.println("<td> </td>");
out.println("<td><input type='submit' value='添加'></td>");
out.println("</tr>");
out.println("</table>");
out.println("</form>");
out.println("</body>");
out.println("</html>");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
处理提交数据的Servlet：
package ni.jun.yang.servlet;
import java.io.File;
import java.io.IOException;
import java.util.Date;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import ni.jun.yang.bean.Goods;
import ni.jun.yang.service.GoodsService;
@WebServlet("/AddResultServlet")
public class AddResultServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public AddResultServlet() {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
DiskFileItemFactory factory = new DiskFileItemFactory();
factory.setSizeThreshold(1024*1024*5);
ServletFileUpload upload = new ServletFileUpload(factory);
List<FileItem> fileItems = null;
Goods goods = new Goods();
try {
//请求数据返回FileItem类型的数组
fileItems = upload.parseRequest(request);
} catch (FileUploadException e) {
e.printStackTrace();
}
//上传的文件存放路径
String path = getServletContext().getRealPath("/image");
File f = new File(path);
//没有此路径就创建
if(!f.exists()){
f.mkdirs();
}
//遍历请求数据的集合进行数据的获取和文件的上传
for (FileItem x : fileItems) {
try {
uploading(x, goods, path);
} catch (Exception e) {
e.printStackTrace();
}
}
//普通数据存入数据库，页面跳转
if(new GoodsService().add(goods)){
request.getRequestDispatcher("success.html").forward(request, response);
}else{
response.sendRedirect("lose.html");
}
}
/**
* 数据的获取和文件上传
* @param fileItem
* @param goods 待添加的商品
* @param path 上传的路径
* @throws Exception
*/
private void uploading (FileItem fileItem,Goods goods,String path) throws Exception{
//普通文本数据
//只能获取字符串，其他的数据需要通过包装类的方法转化得到
if(fileItem.isFormField()){
if(fileItem.getFieldName().equals("mingzi")){
//获取普通的文本数据利用getString("utf-8")，设置编码格式。否则会出现汉字乱码
goods.setName(fileItem.getString("utf-8"));
}else if(fileItem.getFieldName().equals("jieshao")){
goods.setExplain(fileItem.getString("utf-8"));
}else if(fileItem.getFieldName().equals("shoujia")){
//字符串转Double
goods.setPrice(Double.parseDouble(fileItem.getString()));
}else if(fileItem.getFieldName().equals("fenlei")){
String type = fileItem.getString();
goods.setType(Integer.parseInt(type));
}
}else{
// 文件类型
String fileName = fileItem.getName();
// System.out.println(fileName);
//设置上传的文件名字，利用时间返回毫秒数，保证上传的文件不重名
String path1 = new Date().getTime()+"_"+fileName;
String fileName2= path+"\"+ path1;
File file = new File(fileName2);
//数据只存放文件名字
goods.setPhoto(path1);
// System.out.println(fileName2);
try {
fileItem.write(file);
} catch (Exception e) {
e.printStackTrace();
}
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
效果图：
完整项目网盘地址：http://pan.baidu.com/s/1boWm05T 密码：blqh