为什么写这篇博客？
领导要求公众号自动回复需要支持图片（之前的版本只支持文本和图文），而支持图片就需要先把图片上传到微信素材库，于是我就开始读文档，查资料，发现还真不好找。尤其是步骤2中上传的参数问题——我试着把前端的MultipartFile转为InputStream再转InputStreamBody，但是失败了。如果直接转File再转FileBody的话，可以上传，但是就比较复杂，微信必须先把MultipartFile保存为本地的File，然后再把这个File读取出来，这就有点恶心了。于是我又找到了一种两全的办法MultipartFile转InputStream再转byte[]，这样就方便了很多。话说多了......直接上源码----》》》
1.Controller层（从前端接收要上传的文件）
package com.wxpub.controller.enterprise;import com.youliantong.wxpub.config.Resources;import lombok.extern.slf4j.Slf4j;import net.sf.json.JSONObject;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.*;import org.springframework.web.multipart.MultipartFile;import java.io.IOException;import java.util.Arrays;/*** @Description 图片上传controller* @Author BigBird* @Date /11/27 19:15**/@RestController("fileController")@RequestMapping("/enterprise")@Slf4jpublic class FileController {// 上传微信永久素材的urlprivate static final String UPLOAD_FOREVER_MEDIA_URL = "https://api./cgi-bin/material/add_material?access_token=ACCESS_TOKEN&type=TYPE";private static final long MAX_SIZE = 1024 * 1024 * 2;private static final String SUPPORTED_FORMAT = "bmp,png,jpeg,jpg,gif";/*** 上传素材到微信素材库* @param file*/@RequestMapping(value = "uploadMediaToWechat", method = RequestMethod.POST)@ResponseBodypublic String uploadMediaToWechat(@RequestParam("media") @ApiParam(name = "media", value = "待上传素材图片文件", required = true) MultipartFile file) throws Exception{String[] split = file.getOriginalFilename().split("\\.");String suffixName = split[split.length-1];boolean validPic = this.isValidPic(file.getSize(), suffixName);if (!validPic) {return "上传失败";}// 获取access_token,如果你不会获取，那么这篇博客不适合你。 // 这步在你的IDE上会提示报错，请修改为你自己获取access_token的方式String token = TokenUtil.getToken(account);String replacedUrl = UPLOAD_FOREVER_MEDIA_URL.replace("ACCESS_TOKEN", token).replace("TYPE", "image");JSONObject jsonObject = CommonUtil.uploadFile(replacedUrl, file.getResource().getInputStream(),file.getOriginalFilename());log.info("微信素材上传结果：[{}]", jsonObject.toString());if (jsonObject != null && jsonObject.containsKey("media_id")) {return jsonObject.getString("media_id") ;}return "素材图片上传失败";}/*** 图片是否符合微信规范* @param size* @param suffixName* @return*/public Boolean isValidPic(long size, String suffixName) {if (size > MAX_SIZE) {log.info("文件太大，文件的大小最大为2M，请重新上传!");return false;}if (!Arrays.asList(SUPPORTED_FORMAT.split(",")).contains(suffixName)) {log.info("图片格式不支持，请选择bmp/png/jpeg/jpg/gif的任意一种!");return false;}return true;}}
2.把文件上传到微信服务器
package com.wxpub.util;import net.sf.json.JSONObject;import org.apache.http.HttpEntity;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.config.RequestConfig;import org.apache.http.client.methods.CloseableHttpResponse;import org.apache.http.client.methods.HttpPost;import org.apache.http.entity.ContentType;import org.apache.http.entity.mime.MultipartEntityBuilder;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.util.EntityUtils;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import .ssl.HttpsURLConnection;import .ssl.SSLContext;import .ssl.SSLSocketFactory;import .ssl.TrustManager;import java.io.*;import .ConnectException;import .URL;/*** http通用工具类**/public class CommonUtil {private static Logger log = LoggerFactory.getLogger(CommonUtil.class);/*** 把文件上传到指定url上去* @param url 上传地址* @param file 待上传文件*/public static JSONObject uploadFile(String url, InputStream file,String fileName) throws IOException{CloseableHttpClient httpclient = HttpClients.createDefault();try {HttpPost httppost = new HttpPost(url);RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(200000).setSocketTimeout(200000).build();httppost.setConfig(requestConfig);/*** 这一步最关键：*调用addBinaryBody("media",input2byte(file),ContentType.DEFAULT_BINARY, fileName),* fileName可以为任意值，但不能为null，如果为null则上传失败。* input2byte(file)：把inputstream转为byte[]，* 如果直接调用addPart用FileBody做参数，则MultifilePart不好转换；* 如果直接调用addPart用InpustreamBody做参数，则因为没有fileName会造成上传失败*/HttpEntity reqEntity = MultipartEntityBuilder.create().addBinaryBody("media", input2byte(file), ContentType.DEFAULT_BINARY, fileName).build();httppost.setEntity(reqEntity);CloseableHttpResponse response = httpclient.execute(httppost);try {System.out.println(response.getStatusLine());HttpEntity resEntity = response.getEntity();if (resEntity != null) {String responseEntityStr = EntityUtils.toString(response.getEntity());log.info("responseEntityStr=[{}]",responseEntityStr);return JSONObject.fromObject(responseEntityStr);}EntityUtils.consume(resEntity);} finally {response.close();}} catch (ClientProtocolException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {try {httpclient.close();} catch (IOException e) {e.printStackTrace();}}return null;}private static final byte[] input2byte(InputStream inStream)throws IOException {ByteArrayOutputStream swapStream = new ByteArrayOutputStream();byte[] buff = new byte[100];int rc = 0;while ((rc = inStream.read(buff, 0, 100)) > 0) {swapStream.write(buff, 0, rc);}byte[] in2b = swapStream.toByteArray();return in2b;}}
