Java后端实现微信JS-SDK图片上传与下载完整流程

配置wx.config与获取Ticket

<code class="hljs cs">wx.config({
  debug: true, // 开启调试模式,调用的所有api的返回值会在客户端alert出来，若要查看传入的参数，可以在pc端打开，参数信息会通过log打出，仅在pc端时才会打印。
  appId: '', // 必填，公众号的唯一标识
  timestamp: , // 必填，生成签名的时间戳
  nonceStr: '', // 必填，生成签名的随机串
  signature: '',// 必填，签名，见附录1
  jsApiList: [] // 必填，需要使用的JS接口列表，所有JS接口列表见附录2
});</code>

<code class="hljs avrasm">import java.util.UUID;
import java.util.Map;
import java.util.HashMap;
import java.util.Formatter;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.io.UnsupportedEncodingException;
 
public class WxConfig {
  public static void main(String[] args) {
    String jsapi_ticket = "jsapi_ticket";
 
    // 注意 URL 一定要动态获取，不能 hardcode
    String url = "http://example.com";
    Map<string, string=""> ret = sign(jsapi_ticket, url);
    for (Map.Entry entry : ret.entrySet()) {
      System.out.println(entry.getKey() + ", " + entry.getValue());
    }
  };
 
  public static Map<string, string=""> sign(String jsapi_ticket, String url) {
    Map<string, string=""> ret = new HashMap<string, string="">();
    String nonce_str = create_nonce_str();
    String timestamp = create_timestamp();
    String string1;
    String signature = "";
 
    //注意这里参数名必须全部小写，且必须有序
    string1 = "jsapi_ticket=" + jsapi_ticket +
        "&noncestr=" + nonce_str +
        "×tamp=" + timestamp +
        "&url=" + url;
    System.out.println(string1);
 
    try
    {
      MessageDigest crypt = MessageDigest.getInstance("SHA-1");
      crypt.reset();
      crypt.update(string1.getBytes("UTF-8"));
      signature = byteToHex(crypt.digest());
    }
    catch (NoSuchAlgorithmException e)
    {
      e.printStackTrace();
    }
    catch (UnsupportedEncodingException e)
    {
      e.printStackTrace();
    }
 
    ret.put("url", url);
    ret.put("jsapi_ticket", jsapi_ticket);
    ret.put("nonceStr", nonce_str);
    ret.put("timestamp", timestamp);
    ret.put("signature", signature);
 
    return ret;
  }
 
  private static String byteToHex(final byte[] hash) {
    Formatter formatter = new Formatter();
    for (byte b : hash)
    {
      formatter.format("%02x", b);
    }
    String result = formatter.toString();
    formatter.close();
    return result;
  }
 
  private static String create_nonce_str() {
    return UUID.randomUUID().toString();
  }
 
  private static String create_timestamp() {
    return Long.toString(System.currentTimeMillis() / 1000);
  }
}
</string,></string,></string,></string,></code>

<code class="hljs cs">public static String getTicket(String accessToken) throws ParseException, IOException {
    public final static String sign_ticket_create_url = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token=ACCESS_TOKEN&type=jsapi";
    JSONObject jsonObject = new JSONObject();
    JSONObject postjson=new JSONObject();
    String ticket =null;
    String url = sign_ticket_create_url.replace("ACCESS_TOKEN",accessToken);
    System.out.print("url="+url);
    String ticketurl ="";
    try {
      jsonObject = WeixinUtil.httpsRequest(url, "POST",postjson.toString());
      ticket= jsonObject.getString("ticket");
      System.out.println("ticket:"+ticket);
    }catch (Exception e) {
      e.printStackTrace();
    }
    return ticket;
  };</code>

前端图片选择与上传实现

<code class="hljs javascript">wx.ready(function(){
    //拍照或从手机相册中选图接口
    wx.chooseImage({
      count: 1, // 最多能选择多少张图片，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) {
        var localIds = res.localIds; // 返回选定照片的本地ID列表，localId可以作为img标签的src属性显示图片
        //上传图片接口
        wx.uploadImage({
          localId: localIds.toString(), // 需要上传的图片的本地ID，由chooseImage接口获得
          isShowProgressTips: 1, // 默认为1，显示进度提示
          success: function (res) {
            var serverId = res.serverId; // 返回图片的服务器端ID
          }
        });
      }
    });
  });</code>

后端下载媒体文件至本地

<code class="hljs java">import org.apache.log4j.Level;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;
import org.apache.log4j.Priority;
import org.springframework.util.StringUtils;
 
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
 
public class DloadImgUtil {
 /**
  * 根据内容类型判断文件扩展名
  *
  * @param contentType 内容类型
  * @return
  */
 public static String getFileexpandedName(String contentType) {
  String fileEndWitsh = "";
  if ("image/jpeg".equals(contentType))
   fileEndWitsh = ".jpg";
  else if ("audio/mpeg".equals(contentType))
   fileEndWitsh = ".mp3";
  else if ("audio/amr".equals(contentType))
   fileEndWitsh = ".amr";
  else if ("video/mp4".equals(contentType))
   fileEndWitsh = ".mp4";
  else if ("video/mpeg4".equals(contentType))
   fileEndWitsh = ".mp4";
  return fileEndWitsh;
 }
 /**
  * 获取媒体文件
  * @param accessToken 接口访问凭证
  * @param mediaId 媒体文件id
  * @param savePath 文件在本地服务器上的存储路径
  * */
 public static String downloadMedia(String accessToken, String mediaId, String savePath) {
  try {
   accessToken = WeixinUtil.getAccessToken1().getToken();
  } catch (IOException e) {
   e.printStackTrace();
  }
  String filePath = null;
  // 拼接请求地址
  String requestUrl = "http://file.api.weixin.qq.com/cgi-bin/media/get?access_token=ACCESS_TOKEN&media_id=MEDIA_ID";
  requestUrl = requestUrl.replace("ACCESS_TOKEN", accessToken).replace("MEDIA_ID", mediaId);
  try {
   URL url = new URL(requestUrl);
   HttpURLConnection conn = (HttpURLConnection) url.openConnection();
   conn.setDoInput(true);
   conn.setRequestMethod("GET");
 
   if (!savePath.endsWith("/")) {
    savePath += "/";
   }
   // 根据内容类型获取扩展名
   String fileExt = DloadImgUtil .getFileexpandedName(conn.getHeaderField("Content-Type"));
   // 将mediaId作为文件名
   filePath = savePath + mediaId + fileExt;
   BufferedInputStream bis = new BufferedInputStream(conn.getInputStream());
   FileOutputStream fos = new FileOutputStream(new File(filePath));
   byte[] buf = new byte[8096];
   int size = 0;
   while ((size = bis.read(buf)) != -1)
    fos.write(buf, 0, size);
   fos.close();
   bis.close();
 
   conn.disconnect();
   String info = String.format("下载媒体文件成功，filePath=" + filePath);
   System.out.println(info);
  } catch (Exception e) {
   filePath = null;
   String error = String.format("下载媒体文件失败：%s", e);
   System.out.println(error);
  }
  return filePath;
 }
}
</code>