下载附件

1、设置setContentType为application/x-msdownload
2、设置Content-Disposition为附件形式并指定文件名称attachment;filename=contact.csv
3、根据文件路径创建输入流，response获取输出流
4、写入到输出流
5、删除缓存文件
6、关闭流

@RequestMapping(value = "/exportContact", method = RequestMethod.GET)
private void exportContact(HttpServletRequest request, HttpServletResponse response) {

    DBObject query = new BasicDBObject();
    String loginEmail = null;
    DataOutputStream os = null;
    InputStream is = null;
    String contactPath = null;
    try {
        //TODO:登录人信息，目前从配置文件中读取登陆人邮箱
        loginEmail = PropertyUtil.getMailProperties().getProperty("mail.email");
        query.put("emailAccount", loginEmail);

        //取得收件箱所有数据
        List<DBObject> list = wmPerService.getData(WmPerConstant.MONGODB_COLLECTION_CONTACT, query);

        List<String[]> contacts = new ArrayList<String[]>();
        for (DBObject entity : list) {
            String json = entity.toString();
            WmPerInfoDTO wmPerInfo = com.alibaba.fastjson.JSON.parseObject(json, WmPerInfoDTO.class);
            String[] contact =
                    {
                            wmPerInfo.getPerName(),
                            wmPerInfo.getPerEmail(),
                            wmPerInfo.getPerPhone(),
                            wmPerInfo.getPerProvinceName(),
                            wmPerInfo.getPerCityName(),
                            wmPerInfo.getPerCountyName(),
                            wmPerInfo.getPerStreetName(),
                            wmPerInfo.getPerDetailAddrss(),
                            wmPerInfo.getPerRemark()
                    };
//            {"姓名", "邮箱地址", "手机号码", "省", "市", "县/区", "乡镇/街道", "详细地址", "备注"};
            contacts.add(contact);
        }
        contactPath = CVSUtils.writeCsv(loginEmail, contacts);

        response.setContentType("application/x-msdownload");
        response.setHeader("Content-Disposition", "attachment;filename=contact.csv");
        is = new BufferedInputStream(new FileInputStream(contactPath));
        if (null != is){
            os = new DataOutputStream(response.getOutputStream());
            IOUtils.copy(is, os);
            os.flush();
        }
    } catch (Exception e) {
        logger.error("当前下载的附件不存在，或者下载附件错误", e);
    }
    finally {
        IOUtils.closeQuietly(is);
        IOUtils.closeQuietly(os);
        File file = new File(contactPath);
        file.delete();
    }

}

CSVUtils.java

/**
 * CSV文件导出工具类
 */
public class CVSUtils {
    public static final String FILE_EXTENSIONS = ".csv";
    public static final String CONTACT_FOLDER = "contact";
    public static final String CONTACT_PATH = CVSUtils.class.getClassLoader().getResource("/").getPath();
    public static final String[] heads = {"姓名", "邮箱地址", "手机号码", "省", "市", "县/区", "乡镇/街道", "详细地址", "备注"};

    //读取csv文件
    public static List<String[]> readCsv(String filePath) throws Exception {
        List<String[]> csvList = new ArrayList<String[]>();
        if (isCsv(filePath)) {
            CsvReader reader = new CsvReader(filePath, ',', Charset.forName("GBK"));

            while (reader.readRecord()) { //逐行读入除表头的数据
                csvList.add(reader.getValues());
            }
            reader.close();
        } else {
            System.out.println("此文件不是CSV文件！");
            throw new RuntimeException("此文件不是CSV文件！");
        }
        return csvList;
    }

    //判断是否是csv文件
    private static boolean isCsv(String fileName) {
        return fileName.matches("^.+\\.(?i)(csv)$");
    }

    //写入csv文件并返回文件路径
    public static String writeCsv(String fileName, List<String[]> contents) {
        try {
            String filePath = CONTACT_PATH.substring(0, CONTACT_PATH.length() - 8);
            String fileNameTemp = System.currentTimeMillis() + fileName + FILE_EXTENSIONS;
            String fileQualifiedName = filePath + CONTACT_FOLDER + File.separator + fileNameTemp;
            File csvFile = new File(fileQualifiedName);
            File parent = csvFile.getParentFile();//得到父目录
            if (parent != null && !parent.exists()) {
                parent.mkdirs();//创建文件夹
            }
            csvFile.createNewFile();//创建具体的文件

            CsvWriter wr = new CsvWriter(fileQualifiedName, ',', Charset.forName("GBK"));
            wr.writeRecord(heads);
            if (contents != null && contents.size() > 0) {
                for (String[] content : contents) {
                    wr.writeRecord(content);
                }
            }
            wr.close();
            return fileQualifiedName;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

//    public static void writeCsv(Class<?> clazz) {
//        // Get all the declared fields
//        Field[] fields = clazz.getDeclaredFields();
//        LinkedList<Field> fieldList = new LinkedList<Field>();
//        int length = fields.length;
//        for (int i = -1; ++i < length; ) {
//            boolean isStaticField = Modifier.isStatic(fields[i].getModifiers());
//            if (isStaticField)
//                continue;
//            boolean isTransientField = Modifier.isTransient(fields[i].getModifiers());
//            if (isTransientField)
//                continue;
//            fieldList.add(fields[i]);
//        }
//        System.out.println(clazz.getName());
//    }
}

所需jar包

<dependency>
    <groupId>org.jumpmind.symmetric</groupId>
    <artifactId>symmetric-csv</artifactId>
    <version>3.5.19</version>
</dependency>