java servlet中上传文件的简单实现（基于第三方jar）

这里的案例使用了两种文件上传的组件、分别介绍

1、使用JSPSmartUpload完成上传

package test_servlet_package;

import java.io.File;
import java.io.IOException;
import java.util.Calendar;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.jspsmart.upload.SmartUpload;

public class test_servlet_SmartUpload extends HttpServlet {

    String tempPath = "D:\test";
    String filePath = "D:\filePath";
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setCharacterEncoding("GBK");
        SmartUpload mySmartUpload = new SmartUpload();
        // 初始化
        mySmartUpload.initialize(getServletConfig(), request, response);
        long file_size_max = 4000000;
        String ext = "";
        try {
            mySmartUpload.setAllowedFilesList("jpg,gif,png");
            mySmartUpload.upload();// 上载文件
        } catch (Exception e) {
            response.getWriter().write("<script> alert('只允许上传.jpg和.gif类型图片文件');</script>");
        }
        try {
            com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(0);
            if (!myFile.isMissing()) {
                ext = myFile.getFileExt(); // 取得后缀名
                int file_size = myFile.getSize(); // 取得文件的大小
                String saveurl = "";
                if (file_size < file_size_max) {
                    // 更改文件名，取得当前上传时间的毫秒数值
                    Calendar calendar = Calendar.getInstance();
                    String filename = String.valueOf(calendar.getTimeInMillis());
                    Random r = new Random();
                    String ram = String.valueOf(r.nextInt(1241241241));
                    filename = filename + ram;
                    filename = filename.substring(0, (filename.length() - ext.length() - 1));
                    //saveurl = this.getServletContext().getRealPath("/") + "/uploadFile/" + filename + "." + ext;
                    //System.out.println(saveurl);
                    File uploadFile2 = new File(filePath);
                    if(!uploadFile2.exists()){
                        uploadFile2.mkdirs();
                    }
                    myFile.saveAs(filePath+"/"+filename+"." + ext);
                }
            }
            String name = mySmartUpload.getRequest().getParameter("name");
            request.setAttribute("name", "name");
            request.getSession().setAttribute("name", "name");
            request.getSession().getId();
            System.out.println(name);
        } catch (Exception e) {
            e.printStackTrace();
        }
        request.getRequestDispatcher("/uploadsuccess.jsp").forward(request, response);
    }
}

2、使用commons-fileupload完成文件上传

package test_servlet_package;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
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.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class test_servlet extends HttpServlet {

    String tempPath = "D:\test";
    String filePath = "D:\filePath";
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
        res.setContentType("text/plain;charset=gbk");
        PrintWriter pw = res.getWriter();
        try {
            DiskFileItemFactory diskFactory = new DiskFileItemFactory();
            // threshold 极限、临界值，即硬盘缓存 1M
            diskFactory.setSizeThreshold(4 * 1024);
            // repository 贮藏室，即临时文件目录
            diskFactory.setRepository(new File(tempPath));
            ServletFileUpload upload = new ServletFileUpload(diskFactory);
            // 设置允许上传的最大文件大小 4M
            upload.setSizeMax(4 * 1024 * 1024);
            // 解析HTTP请求消息头
            List<FileItem> fileItems = upload.parseRequest(req);
            Iterator<FileItem> iter = fileItems.iterator();
            while (iter.hasNext()) {
                FileItem item = (FileItem) iter.next();
                if (item.isFormField()) {
                    System.out.println("处理表单内容 ...");
                    processFormField(item, pw);
                } else {
                    System.out.println("处理上传的文件 ...");
                    processUploadFile(item, pw);
                }
            }
            pw.close();
        } catch (Exception e) {
            System.out.println("使用 fileupload 包时发生异常 ...");
            e.printStackTrace();
        }
    }

    // 处理表单内容
    private void processFormField(FileItem item, PrintWriter pw) throws Exception {
        String name = item.getFieldName();
        String value = item.getString();
        pw.println(name + " : " + value + "
");
    }

    // 处理上传的文件
    private void processUploadFile(FileItem item, PrintWriter pw) throws Exception {
        // 此时的文件名包含了完整的路径，得注意加工一下
        String filename = item.getName();
        System.out.println("完整的文件名：" + filename);
        int index = filename.lastIndexOf("\");
        filename = filename.substring(index + 1, filename.length());
        long fileSize = item.getSize();
        if ("".equals(filename) && fileSize == 0) {
            System.out.println("文件名为空 ...");
            return;
        }
        File uploadFile = new File(filePath + "/" + filename);
        File uploadFile2 = new File(filePath);
        if(!uploadFile2.exists()){
            uploadFile2.mkdirs();
        }
        item.write(uploadFile);
        pw.println(filename + " 文件保存完毕 ...");
        pw.println("文件大小为 ：" + fileSize + "
");
    }
}

3、依赖的jar：

<classpath>
    <classpathentry kind="lib" path="base/WEB-INF/lib/commons-fileupload-1.2.2.jar"/>
    <classpathentry kind="lib" path="base/WEB-INF/lib/commons-io-2.0.1.jar"/>
    <classpathentry kind="lib" path="base/WEB-INF/lib/jsmartcom_zh_CN.jar"/>
    <classpathentry kind="lib" path="base/WEB-INF/lib/mysql-connector-java-5.1.21-bin.jar"/>
    <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-compat-1.2.1.jar"/>
    <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-impl-1.2.1.jar"/>
    <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-jstlel-1.2.1.jar"/>
    <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-spec-1.2.1.jar"/>
    <classpathentry kind="output" path="base/WEB-INF/classes"/>
</classpath>