这篇博客详细记录了在开发中如何实现文件下载功能，包括后台Java代码配置文件路径和文件类型，以及前端HTML中如何添加下载链接，实现点击下载的交互操作。
在开发工作中遇到文件下载内容，记录下来
后台代码：
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.math.BigDecimal;
import java.text.SimpleDateFormat;
import java.util.Base64;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.web.util.WebUtils;
@RestController
@Transactional
@RequestMapping("/upload")
public class UploadController {
@Autowired
public UploadService service;
@Autowired
public FileType fileType;
@Value("${upload.path:{#/opt/data/upload}}")
private String basepath;
@Value("${file.endstr}")
private String endstr;
private IIdentityService ident = AdapterFactory.getIdentityService();
@RequestMapping(value = "/test", method = RequestMethod.GET)
public String test() {
return "1234567890";
}
@RequestMapping(value = "/upload", method = { RequestMethod.GET, RequestMethod.POST })
// @PathVariable("tableName")String tableName,@RequestParam("file")
// MultipartFile file
public Map<String, Object> upload(HttpServletRequest request) {
OutputStream out = null;
InputStream is = null;
Map<String, Object> result = new HashMap<String, Object>();
String tableName = request.getParameter("tableName");
String id = request.getParameter("pkVal");
String name = request.getParameter("colName");
String fileTypes = request.getParameter("fileType");
String contentType = request.getContentType();
if (contentType == null || !contentType.toLowerCase().startsWith("multipart/")) {
result.put("code", 500);
result.put("msg", "文件不存在或者文件内容为空");
return result;
}
MultipartHttpServletRequest multipartRequest = WebUtils.getNativeRequest(request,
MultipartHttpServletRequest.class);
MultipartFile file = multipartRequest.getFile("file");
// 判断文件是否存在
if (file.isEmpty()) {
result.put("code", 500);
result.put("msg", "文件不存在");
return result;
}
String fileName = file.getOriginalFilename();
String substring = fileName.substring(fileName.indexOf(".") + 1, fileName.length());
// 自定义路径
SimpleDateFormat fm = new SimpleDateFormat("yyyyMMdd");
SimpleDateFormat fm2 = new SimpleDateFormat("yyyyMMddHHmmss");
String filePath = File.separator + "upload" + File.separator + fm.format(new Date()) + File.separator
+ fm2.format(new Date()) + "." + substring;
File dest = new File(basepath + filePath);
if (!dest.getParentFile().exists()) {
dest.getParentFile().mkdirs();
}
try {
byte[] bytes = file.getBytes();
out = new FileOutputStream(dest);
is = new ByteArrayInputStream(bytes);
byte[] buff = new byte[1024];
int len = 0;
while ((len = is.read(buff)) != -1) {
out.write(buff, 0, len);
}
is.close();
out.close();
// 验证文件类型
fileType.getAllFileType();//加载文件类型
String fileType = FileType.getFileType(dest);
if (checkType(fileType.substring(fileType.indexOf("+") + 1))) {
if (dest.delete()) {
result.put("msg2", "文件删除成功");
}
;
result.put("code", 500);
result.put("msg", "文件类型不符");
return result;
}
// 保存上传信息
UploadFileInformation infor = new UploadFileInformation();
infor.setMain_table(tableName);// 主记录表名
infor.setMain_id(id);// 主记录id
infor.setFile_name(fileName);// 文件名称
infor.setFile_id(filePath);// 文件标识路径
infor.setSmall_id(filePath);// 缩略图标识路径
infor.setMain_field(name);// 主记录字段名称
infor.setFile_type(fileTypes == null ? "图片" : fileTypes);// 文件类型
infor.setReg_date(new Date());// 登记时间
double size = file.getSize();
double kilobytes = (size / 1024);
double megabytes = (kilobytes / 1024);
infor.setAtt_size(new BigDecimal(String.format("%.2f", megabytes)));// 文件大小
// 人员信息 TODO
String reg_staff_id = null;
String reg_staff_name = null;
String iscUserId = null;
if (iscUserId == null) {
iscUserId = (String) request.getAttribute("user_id");
}
if (null == iscUserId || ("").equals(iscUserId) || iscUserId.equals("null")) {
reg_staff_id = "1";
reg_staff_name = "2";
} else {
String userinfo[] = iscUserId.split(":");
List<User> users = ident.getUserByIds(new String[] { userinfo[0] });
reg_staff_name = users.get(0).getName();
reg_staff_id = users.get(0).getId();
}
infor.setReg_staff_id(reg_staff_id);
infor.setReg_staff_name(reg_staff_name);
// infor.setATT_FILE(new Byte("99"));//数据库存储功能的存储字段
service.uploadFileInformation(infor);
result.put("code", 200);
result.put("msg", "文件上传成功");
return result;
} catch (Exception e) {
e.printStackTrace();
result.put("code", 500);
result.put("msg", "文件上传失败");
return result;
}
}
private boolean checkType(String substring) {
boolean open = false;
if("null".equals(substring)){
open = true;
}
return open;
}
@RequestMapping(value = "/download", method = RequestMethod.GET)
public Map<String, Object> download(HttpServletRequest request, HttpServletResponse response,
@RequestParam("tableName") String tableName, @RequestParam("pkVal") String pkVal,
@RequestParam("colName") String colName) {
UploadFileInformation infor = new UploadFileInformation();
infor.setMain_table(tableName);
infor.setMain_id(pkVal);
infor.setMain_field(colName);
Map<String, Object> result = new HashMap<String, Object>();
result.put("code", 500);
result.put("result", "");
result.put("msg", "下载失败");
infor = service.findOneByTABLE_NAMEAndPK_VALAndCOL_NAME(infor);
if (infor == null) {
return result;
}
String fileName = infor.getFile_name();
result.put("fileName", fileName);
File file = new File(basepath + infor.getFile_id());
FileInputStream inputFile = null;
String base64 = null;
try {
inputFile = new FileInputStream(file);
byte[] buffer = new byte[(int) file.length()];
byte[] bytes = new byte[inputFile.available()];
int length = inputFile.read(bytes);
base64 = Base64.getEncoder().encodeToString(bytes);
result.put("code", 200);
result.put("result", "data:text/xml;base64," + base64);
result.put("msg", "");
return result;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (inputFile != null) {
inputFile.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
result.put("msg", "下载失败。。。");
return result;
}
@RequestMapping(value = "/show", method = RequestMethod.GET)
public Map<String, Object> show(HttpServletRequest request, HttpServletResponse response,
@RequestParam("tableName") String tableName, @RequestParam("pkVal") String pkVal,
@RequestParam("colName") String colName) {
UploadFileInformation infor = new UploadFileInformation();
infor.setMain_table(tableName);
infor.setMain_id(pkVal);
infor.setMain_field(colName);
Map<String, Object> result = new HashMap<String, Object>();
result.put("code", 500);
result.put("result", "");
result.put("msg", "预览错误");
infor = service.findOneByTABLE_NAMEAndPK_VALAndCOL_NAME(infor);
if (infor == null) {
return result;
}
String fileName = infor.getFile_name();
File file = new File(basepath + infor.getFile_id());
FileInputStream inputFile = null;
String base64 = null;
try {
inputFile = new FileInputStream(file);
byte[] buffer = new byte[(int) file.length()];
byte[] bytes = new byte[inputFile.available()];
int length = inputFile.read(bytes);
base64 = Base64.getEncoder().encodeToString(bytes);
result.put("code", 200);
result.put("result", "data:text/xml;base64," + base64);
result.put("msg", "");
return result;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (inputFile != null) {
inputFile.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
result.put("msg", "预览错误。。。");
return result;
}
/**
* 根据id 类型 返回所有信息
* @param mainId id
* @param type 文件类型
* @param isReturnFile 是否返回64 1 ：返回
* @return
*/
@RequestMapping(value = "/findbymainidandtype", method = RequestMethod.GET)
public Map<String, Object> findbymainidandtype(
@RequestParam("mainId") String mainId,
@RequestParam("type") String type,
@RequestParam("isReturnFile") String isReturnFile
) {
List<UploadFileInformation> data = service.findbymainid(mainId,type);
if("1".equals(isReturnFile)){
for (UploadFileInformation uploadFileInformation : data) {
String base64 = toBase64(uploadFileInformation);
uploadFileInformation.setImg_base64(base64);
}
}
Map<String, Object> result = new HashMap<String, Object>();
result.put("code", 200);
result.put("data", data);
result.put("msg", "");
return result;
}
/**
* 根据 主记录ID 查询所有的信息
*
* @param mainId
* @return
*/
@RequestMapping(value = "/findbymainid", method = RequestMethod.GET)
public Map<String, Object> findbymainid(
@RequestParam("mainId") String mainId) {
List<UploadFileInformation> data = service.findbymainid(mainId,null);
for (UploadFileInformation uploadFileInformation : data) {
String base64 = toBase64(uploadFileInformation);
uploadFileInformation.setImg_base64(base64);
}
Map<String, Object> result = new HashMap<String, Object>();
result.put("code", 200);
result.put("data", data);
result.put("msg", "");
return result;
}
private String toBase64 (UploadFileInformation infor){
File file = new File(basepath + infor.getFile_id());
FileInputStream inputFile = null;
String base64 = null;
try {
inputFile = new FileInputStream(file);
byte[] buffer = new byte[(int) file.length()];
byte[] bytes = new byte[inputFile.available()];
int length = inputFile.read(bytes);
base64 = Base64.getEncoder().encodeToString(bytes);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (inputFile != null) {
inputFile.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return "data:text/xml;base64,"+base64;
}
}
FileType：
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.math.BigDecimal;
import java.text.SimpleDateFormat;
import java.util.Base64;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.web.util.WebUtils;
@RestController
@Transactional
@RequestMapping("/upload")
public class UploadController {
@Autowired
public UploadService service;
@Autowired
public FileType fileType;
@Value("${upload.path:{#/opt/data/upload}}")
private String basepath;
@Value("${file.endstr}")
private String endstr;
private IIdentityService ident = AdapterFactory.getIdentityService();
@RequestMapping(value = "/test", method = RequestMethod.GET)
public String test() {
return "1234567890";
}
@RequestMapping(value = "/upload", method = { RequestMethod.GET, RequestMethod.POST })
// @PathVariable("tableName")String tableName,@RequestParam("file")
// MultipartFile file
public Map<String, Object> upload(HttpServletRequest request) {
OutputStream out = null;
InputStream is = null;
Map<String, Object> result = new HashMap<String, Object>();
String tableName = request.getParameter("tableName");
String id = request.getParameter("pkVal");
String name = request.getParameter("colName");
String fileTypes = request.getParameter("fileType");
String contentType = request.getContentType();
if (contentType == null || !contentType.toLowerCase().startsWith("multipart/")) {
result.put("code", 500);
result.put("msg", "文件不存在或者文件内容为空");
return result;
}
MultipartHttpServletRequest multipartRequest = WebUtils.getNativeRequest(request,
MultipartHttpServletRequest.class);
MultipartFile file = multipartRequest.getFile("file");
// 判断文件是否存在
if (file.isEmpty()) {
result.put("code", 500);
result.put("msg", "文件不存在");
return result;
}
String fileName = file.getOriginalFilename();
String substring = fileName.substring(fileName.indexOf(".") + 1, fileName.length());
// 自定义路径
SimpleDateFormat fm = new SimpleDateFormat("yyyyMMdd");
SimpleDateFormat fm2 = new SimpleDateFormat("yyyyMMddHHmmss");
String filePath = File.separator + "upload" + File.separator + fm.format(new Date()) + File.separator
+ fm2.format(new Date()) + "." + substring;
File dest = new File(basepath + filePath);
if (!dest.getParentFile().exists()) {
dest.getParentFile().mkdirs();
}
try {
byte[] bytes = file.getBytes();
out = new FileOutputStream(dest);
is = new ByteArrayInputStream(bytes);
byte[] buff = new byte[1024];
int len = 0;
while ((len = is.read(buff)) != -1) {
out.write(buff, 0, len);
}
is.close();
out.close();
// 验证文件类型
fileType.getAllFileType();//加载文件类型
String fileType = FileType.getFileType(dest);
if (checkType(fileType.substring(fileType.indexOf("+") + 1))) {
if (dest.delete()) {
result.put("msg2", "文件删除成功");
}
;
result.put("code", 500);
result.put("msg", "文件类型不符");
return result;
}
// 保存上传信息
UploadFileInformation infor = new UploadFileInformation();
infor.setMain_table(tableName);// 主记录表名
infor.setMain_id(id);// 主记录id
infor.setFile_name(fileName);// 文件名称
infor.setFile_id(filePath);// 文件标识路径
infor.setSmall_id(filePath);// 缩略图标识路径
infor.setMain_field(name);// 主记录字段名称
infor.setFile_type(fileTypes == null ? "图片" : fileTypes);// 文件类型
infor.setReg_date(new Date());// 登记时间
double size = file.getSize();
double kilobytes = (size / 1024);
double megabytes = (kilobytes / 1024);
infor.setAtt_size(new BigDecimal(String.format("%.2f", megabytes)));// 文件大小
// 人员信息 TODO
String reg_staff_id = null;
String reg_staff_name = null;
String iscUserId = null;
if (iscUserId == null) {
iscUserId = (String) request.getAttribute("user_id");
}
if (null == iscUserId || ("").equals(iscUserId) || iscUserId.equals("null")) {
reg_staff_id = "1";
reg_staff_name = "2";
} else {
String userinfo[] = iscUserId.split(":");
List<User> users = ident.getUserByIds(new String[] { userinfo[0] });
reg_staff_name = users.get(0).getName();
reg_staff_id = users.get(0).getId();
}
infor.setReg_staff_id(reg_staff_id);
infor.setReg_staff_name(reg_staff_name);
// infor.setATT_FILE(new Byte("99"));//数据库存储功能的存储字段
service.uploadFileInformation(infor);
result.put("code", 200);
result.put("msg", "文件上传成功");
return result;
} catch (Exception e) {
e.printStackTrace();
result.put("code", 500);
result.put("msg", "文件上传失败");
return result;
}
}
private boolean checkType(String substring) {
boolean open = false;
if("null".equals(substring)){
open = true;
}
return open;
}
@RequestMapping(value = "/download", method = RequestMethod.GET)
public Map<String, Object> download(HttpServletRequest request, HttpServletResponse response,
@RequestParam("tableName") String tableName, @RequestParam("pkVal") String pkVal,
@RequestParam("colName") String colName) {
UploadFileInformation infor = new UploadFileInformation();
infor.setMain_table(tableName);
infor.setMain_id(pkVal);
infor.setMain_field(colName);
Map<String, Object> result = new HashMap<String, Object>();
result.put("code", 500);
result.put("result", "");
result.put("msg", "下载失败");
infor = service.findOneByTABLE_NAMEAndPK_VALAndCOL_NAME(infor);
if (infor == null) {
return result;
}
String fileName = infor.getFile_name();
result.put("fileName", fileName);
File file = new File(basepath + infor.getFile_id());
FileInputStream inputFile = null;
String base64 = null;
try {
inputFile = new FileInputStream(file);
byte[] buffer = new byte[(int) file.length()];
byte[] bytes = new byte[inputFile.available()];
int length = inputFile.read(bytes);
base64 = Base64.getEncoder().encodeToString(bytes);
result.put("code", 200);
result.put("result", "data:text/xml;base64," + base64);
result.put("msg", "");
return result;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (inputFile != null) {
inputFile.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
result.put("msg", "下载失败。。。");
return result;
}
@RequestMapping(value = "/show", method = RequestMethod.GET)
public Map<String, Object> show(HttpServletRequest request, HttpServletResponse response,
@RequestParam("tableName") String tableName, @RequestParam("pkVal") String pkVal,
@RequestParam("colName") String colName) {
UploadFileInformation infor = new UploadFileInformation();
infor.setMain_table(tableName);
infor.setMain_id(pkVal);
infor.setMain_field(colName);
Map<String, Object> result = new HashMap<String, Object>();
result.put("code", 500);
result.put("result", "");
result.put("msg", "预览错误");
infor = service.findOneByTABLE_NAMEAndPK_VALAndCOL_NAME(infor);
if (infor == null) {
return result;
}
String fileName = infor.getFile_name();
File file = new File(basepath + infor.getFile_id());
FileInputStream inputFile = null;
String base64 = null;
try {
inputFile = new FileInputStream(file);
byte[] buffer = new byte[(int) file.length()];
byte[] bytes = new byte[inputFile.available()];
int length = inputFile.read(bytes);
base64 = Base64.getEncoder().encodeToString(bytes);
result.put("code", 200);
result.put("result", "data:text/xml;base64," + base64);
result.put("msg", "");
return result;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (inputFile != null) {
inputFile.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
result.put("msg", "预览错误。。。");
return result;
}
/**
* 根据id 类型 返回所有信息
* @param mainId id
* @param type 文件类型
* @param isReturnFile 是否返回64 1 ：返回
* @return
*/
@RequestMapping(value = "/findbymainidandtype", method = RequestMethod.GET)
public Map<String, Object> findbymainidandtype(
@RequestParam("mainId") String mainId,
@RequestParam("type") String type,
@RequestParam("isReturnFile") String isReturnFile
) {
List<UploadFileInformation> data = service.findbymainid(mainId,type);
if("1".equals(isReturnFile)){
for (UploadFileInformation uploadFileInformation : data) {
String base64 = toBase64(uploadFileInformation);
uploadFileInformation.setImg_base64(base64);
}
}
Map<String, Object> result = new HashMap<String, Object>();
result.put("code", 200);
result.put("data", data);
result.put("msg", "");
return result;
}
/**
* 根据 主记录ID 查询所有的信息
*
* @param mainId
* @return
*/
@RequestMapping(value = "/findbymainid", method = RequestMethod.GET)
public Map<String, Object> findbymainid(
@RequestParam("mainId") String mainId) {
List<UploadFileInformation> data = service.findbymainid(mainId,null);
for (UploadFileInformation uploadFileInformation : data) {
String base64 = toBase64(uploadFileInformation);
uploadFileInformation.setImg_base64(base64);
}
Map<String, Object> result = new HashMap<String, Object>();
result.put("code", 200);
result.put("data", data);
result.put("msg", "");
return result;
}
private String toBase64 (UploadFileInformation infor){
File file = new File(basepath + infor.getFile_id());
FileInputStream inputFile = null;
String base64 = null;
try {
inputFile = new FileInputStream(file);
byte[] buffer = new byte[(int) file.length()];
byte[] bytes = new byte[inputFile.available()];
int length = inputFile.read(bytes);
base64 = Base64.getEncoder().encodeToString(bytes);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (inputFile != null) {
inputFile.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}di
return "data:text/xml;base64,"+base64;
}
}
在yml中定义文件的路径：
在yml中定义文件类型：
前端代码：
在操作列中加入文件下载，点击下载，调用函数
self.customOperations = [ {
caption : "下载",
click : function(item) {
var restClient = new RESTClient();
var requestUrl = cube.gatewayURL
+ `/upload/download?tableName=${item.main_Table}&pkVal=${item.main_Id}&colName=${item.main_Field}`;
restClient.get(requestUrl, function(data) {
if (data.code == 200) {
const blob = data.result;
// 自定义js的a标签
const a = document.createElement("a");
// 将a标签隐藏
a.style.display = "none";
// 获取下载文件的base64路径
a.href = data.result;
// 文件名
a.download = data.fileName;
// 将a标签增加到页面上
document.body.appendChild(a);
// 点击事件
a.click();
// 使用完毕移除a标签
document.body.removeChild(a);
} else {
alert("下载失败");
}
});
console.log(item)
}
} ]
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