如何实现JSP文件上传功能？

JSP上传源码通常包括HTML表单、Servlet处理文件上传和存储逻辑。以下是一个简单的示例：，，1. 创建HTML表单（upload.jsp）：，“html，，，，文件上传，，，，选择文件：，，，，，，`，，2. 创建Servlet处理文件上传（UploadServlet.java）：，`

java，import java.io.*;，import javax.servlet.*;，import javax.servlet.annotation.*;，import javax.servlet.http.*;，import org.apache.commons.fileupload.*;，import org.apache.commons.fileupload.disk.*;，import org.apache.commons.fileupload.util.*;，，@WebServlet("/uploadServlet")，public class UploadServlet extends HttpServlet {，    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {，        response.setContentType("text/html;charset=UTF8");，        PrintWriter out = response.getWriter();，，        try {，            FileItemFactory factory = new DiskFileItemFactory();，            ServletFileUpload upload = new ServletFileUpload(factory);，            List items = upload.parseRequest(request);，，            for (FileItem item : items) {，                if (!item.isFormField()) {，                    String fileName = item.getName();，                    InputStream inputStream = item.getInputStream();，                    FileOutputStream outputStream = new FileOutputStream(new File("上传目录", fileName));，                    int len;，                    byte[] buffer = new byte[1024];，                    while ((len = inputStream.read(buffer)) != 1) {，                        outputStream.write(buffer, 0, len);，                    }，                    inputStream.close();，                    outputStream.close();，                    out.println("文件 " + fileName + " 上传成功！");，                }，            }，        } catch (Exception e) {，            out.println("文件上传失败：" + e.getMessage());，        } finally {，            out.close();，        }，    }，}，

`，，3. 在web.xml中配置Servlet：，`xml，，UploadServlet，UploadServlet，，，UploadServlet，/uploadServlet，，“，，这个示例使用了Apache Commons FileUpload库来处理文件上传。请确保在项目中添加该库的依赖。

在JSP中实现文件上传功能，首先需要引入相关的jar包，如Apache的commonsfileupload和commonsio库，创建一个前端页面，例如upload.jsp，用于用户选择要上传的文件，编写一个Servlet类，如UploadServlet，用于处理文件上传请求，配置web.xml文件，将请求映射到UploadServlet。

以下是一个简单的示例：

1、引入jar包

commonsfileupload1.2.2.jar

commonsio2.0.1.jar

2、创建upload.jsp文件

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF8">
    <title>文件上传</title>
</head>
<body>
    <form action="upload" method="post" enctype="multipart/formdata">
        <input type="file" name="file" />
        <input type="submit" value="上传" />
    </form>
</body>
</html>

3、创建UploadServlet.java文件

package com.example;
import java.io.File;
import java.io.IOException;
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.DiskFileItemFactory;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class UploadServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        DiskFileItemFactory factory = new DiskFileItemFactory();
        ServletFileUpload upload = new ServletFileUpload(factory);
        try {
            List<FileItem> items = upload.parseRequest(request);
            for (FileItem item : items) {
                if (!item.isFormField()) {
                    String fileName = item.getName();
                    File file = new File("D:/upload/" + fileName);
                    item.write(file);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

4、配置web.xml文件

<webapp>
    <servlet>
        <servletname>UploadServlet</servletname>
        <servletclass>com.example.UploadServlet</servletclass>
    </servlet>
    <servletmapping>
        <servletname>UploadServlet</servletname>
        <urlpattern>/upload</urlpattern>
    </servletmapping>
</webapp>

这样，当用户访问upload.jsp页面并选择一个文件后，点击上传按钮，文件将被上传到服务器的D:upload目录下。