Servlet檔案上傳
阿新 • • 發佈:2019-02-07
兩點要素:
1.表單提交方式必須是post
2.enctype要指定為multipart/form-data。
enctype的預設值是application/x-www-form-urlencoded,
這種編碼格式只支援鍵值對的資料,且只能是字串,無法傳輸檔案。
需要的jar包:
實現:
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import javax.servlet.ServletException;
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;
public class UploadServlet extends HttpServlet {
//資料夾路徑常量
private static String TEMP_PATH = "E:/Learning/temp/170926";
private static final long serialVersionUID = 3364746345428715093 L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
// 判斷內容是否包含檔案
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
// 判斷是否是檔案上傳請求
if (!isMultipart) {
out.println("Error : 表單必須包含 enctype=multipart/form-data");
return;
}
// 用於建立解析檔案上傳的工廠類
DiskFileItemFactory factory = new DiskFileItemFactory();
// 用於從請求中解析出檔案
ServletFileUpload upload = new ServletFileUpload(factory);
try {
// 獲取所有提交過來的檔案(包含表單內容) 這個FileItem叫做一個項,這個項有可能是檔案也有可能是表單引數
List<FileItem> items = upload.parseRequest(request);
// 定義一個輸出流
FileOutputStream fos = null;
//緩衝區
byte [] buf = new byte[8192];
if (items != null && items.size() > 0) { // 不為空且長度大於0則遍歷之
for (FileItem item : items) {
if (item.isFormField()) { // isFormField = true 文字框的值
out.println("使用者名稱: " + item.getString() + "<br />");
} else {
//獲取輸入流
BufferedInputStream bis = new BufferedInputStream(item.getInputStream());
//初始化本地輸出流
fos = new FileOutputStream(new File(TEMP_PATH + "/" + item.getName()));
int len = -1;
while ((len = bis.read(buf)) != -1) {
fos.write(buf , 0 , len);
fos.flush();
}
out.println("檔案: " + item.getName() + "已上傳 <br />");
}
}
}
} catch (FileUploadException e) {
out.println("Error: 檔案解析異常");
}
}
}