微信小程序上传图片功能（附后端代码）

wx.chooseImage({
 count: 1, // 默认9
 sizeType: ['original', 'compressed'], // 可以指定是原图还是压缩图，默认二者都有
 sourceType: ['album', 'camera'], // 可以指定来源是相册还是相机，默认二者都有
 success: function (res) {
 // 返回选定照片的本地文件路径列表，tempFilePath可以作为img标签的src属性显示图片
 var tempFilePaths = res.tempFilePaths
 }
})

wx.chooseImage({
 success: function(res) {
 var tempFilePaths = res.tempFilePaths
 wx.uploadFile({
 url: 'http://example.weixin.qq.com/upload', //仅为示例，非真实的接口地址
 filePath: tempFilePaths[0],
 name: 'file',
 formData:{
 'user': 'test'
 },
 success: function(res){
 var data = res.data
 //do something
 }
 })
 }
})

import constant from '../../common/constant';
Page({
 data: {
 src: "../../image/photo.png", //绑定image组件的src
 //略...
 },
 onLoad: function (options) {
 //略... 
 },
 uploadPhoto() {
 var that = this; 
 wx.chooseImage({
 count: 1, // 默认9
 sizeType: ['compressed'], // 可以指定是原图还是压缩图，默认二者都有
 sourceType: ['album', 'camera'], // 可以指定来源是相册还是相机，默认二者都有
 success: function (res) {
 // 返回选定照片的本地文件路径列表，tempFilePath可以作为img标签的src属性显示图片
 var tempFilePaths = res.tempFilePaths;
 upload(that, tempFilePaths);
 }
 })
 }
})

function upload(page, path) {
 wx.showToast({
 icon: "loading",
 title: "正在上传"
 }),
 wx.uploadFile({
 url: constant.SERVER_URL + "/FileUploadServlet",
 filePath: path[0], 
 name: 'file',
 header: { "Content-Type": "multipart/form-data" },
 formData: {
 //和服务器约定的token, 一般也可以放在header中
 'session_token': wx.getStorageSync('session_token')
 },
 success: function (res) {
 console.log(res);
 if (res.statusCode != 200) { 
  wx.showModal({
  title: '提示',
  content: '上传失败',
  showCancel: false
  })
  return;
 }
 var data = res.data
 page.setData({ //上传成功修改显示头像
  src: path[0]
 })
 },
 fail: function (e) {
 console.log(e);
 wx.showModal({
  title: '提示',
  content: '上传失败',
  showCancel: false
 })
 },
 complete: function () {
 wx.hideToast(); //隐藏Toast
 }
 })
}

public class FileUploadServlet extends HttpServlet {

 private static final long serialVersionUID = 1L;
 private static Logger logger = LoggerFactory.getLogger(FileUploadServlet.class);

 public FileUploadServlet() {
 super();
 }

 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 JsonMessage<Object> message = new JsonMessage<Object>();
 EOSResponse eosResponse = null;
 String sessionToken = null;
 FileItem file = null;
 InputStream in = null;
 ByteArrayOutputStream swapStream1 = null;
 try {
  request.setCharacterEncoding("UTF-8"); 

  //1、创建一个DiskFileItemFactory工厂 
  DiskFileItemFactory factory = new DiskFileItemFactory(); 
  //2、创建一个文件上传解析器 
  ServletFileUpload upload = new ServletFileUpload(factory);

  //解决上传文件名的中文乱码 
  upload.setHeaderEncoding("UTF-8"); 
  // 1. 得到 FileItem 的集合 items 
  List<FileItem> items = upload.parseRequest(request);
  logger.info("items:{}", items.size());
  // 2. 遍历 items: 
  for (FileItem item : items) { 
  String name = item.getFieldName(); 
  logger.info("fieldName:{}", name);
  // 若是一个一般的表单域, 打印信息 
  if (item.isFormField()) { 
   String value = item.getString("utf-8"); 
   if("session_token".equals(name)){
   sessionToken = value;
   }
  }else {
   if("file".equals(name)){
   file = item;
   }
  } 
  }
  //session校验
  if(StringUtils.isEmpty(sessionToken)){
  message.setStatus(StatusCodeConstant.SESSION_TOKEN_TIME_OUT);
  message.setErrorMsg(StatusCodeConstant.SESSION_TOKEN_TIME_OUT_MSG);
  }
  String userId = RedisUtils.hget(sessionToken,"userId");
  logger.info("userId:{}", userId);
  if(StringUtils.isEmpty(userId)){
  message.setStatus(StatusCodeConstant.SESSION_TOKEN_TIME_OUT);
  message.setErrorMsg(StatusCodeConstant.SESSION_TOKEN_TIME_OUT_MSG);
  }
  //上传文件
  if(file == null){
  }else{
  swapStream1 = new ByteArrayOutputStream();

  in = file.getInputStream();
  byte[] buff = new byte[1024];
  int rc = 0;
  while ((rc = in.read(buff)) > 0) {
   swapStream1.write(buff, 0, rc);
  }

  Usr usr = new Usr();
  usr.setObjectId(Integer.parseInt(userId));

  final byte[] bytes = swapStream1.toByteArray();

  eosResponse= ServerProxy.getSharedInstance().saveHeadPortrait(usr, new RequestOperation() {

   @Override
   public void addValueToRequest(EOSRequest request) {
   request.addMedia("head_icon_media", new EOSMediaData(EOSMediaData.MEDIA_TYPE_IMAGE_JPEG, bytes));
   }
  });

  // 请求成功的场合
  if (eosResponse.getCode() == 0) {
   message.setStatus(ConstantUnit.SUCCESS);
  } else {
   message.setStatus(String.valueOf(eosResponse.getCode()));
  }
  }
 } catch (Exception e) {
  e.printStackTrace();
 } finally{
  try {
  if(swapStream1 != null){
   swapStream1.close();
  }
  } catch (IOException e) {
  e.printStackTrace();
  }
  try {
  if(in != null){
   in.close();
  }
  } catch (IOException e) {
  e.printStackTrace();
  }
 }
 PrintWriter out = response.getWriter(); 
 out.write(JSONObject.toJSONString(message)); 
 }

 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 doGet(request, response);
 }

}