获取二维码流程如下，重新整理总结：（java）

1.后台向微信发送请求，返回的为图片流

2.将微信返回的图片保存到服务器

3.将图片的地址返回到前台

4.前台处理就相当于处理 获取服务器的普通图片文件

如果图片有文件

可能是token失效(2个小时) ，参数传递失败等

HttpClientConnectionManager 自定义工具类

 package cn.edu.hbcf.plugin.wx.utils;import java.io.BufferedReader;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.net.URL;import java.net.URLConnection;import java.net.URLEncoder;import java.util.List;import java.util.Map;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.client.methods.HttpPost;import org.apache.http.entity.StringEntity;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.message.BasicHeader;import org.apache.http.protocol.HTTP; public class HttpClientConnectionManager {    /**     * @param reqUrl     *            基础的url地址     * @param params     *            查询参数     * @return 构建好的url     */                  public static String httpPostWithJSON(String url, String json,String id)            throws Exception {        String result = null;        // 将JSON进行UTF-8编码,以便传输中文        String encoderJson = URLEncoder.encode(json, HTTP.UTF_8);         DefaultHttpClient httpClient = new DefaultHttpClient();        HttpPost httpPost = new HttpPost(url);        httpPost.addHeader(HTTP.CONTENT_TYPE, "application/json");          StringEntity se = new StringEntity(json);        se.setContentType("application/json");        se.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE,"UTF-8"));        httpPost.setEntity(se);        // httpClient.execute(httpPost);        HttpResponse response = httpClient.execute(httpPost);        if (response != null) {            HttpEntity resEntity = response.getEntity();            if (resEntity != null) {                InputStream instreams = resEntity.getContent();                // ResourceBundle systemConfig = ResourceBundle.getBundle("config/system", Locale.getDefault());              //  String uploadSysUrl = systemConfig.getString("agentImgUrl")+id+"/";              //  File saveFile = new File(uploadSysUrl+id+".jpg");                String uploadSysUrl = "D:\upload"+"/";                File saveFile = new File(uploadSysUrl+id+".jpg");                   // 判断这个文件（saveFile）是否存在                   if (!saveFile.getParentFile().exists()) {                       // 如果不存在就创建这个文件夹                       saveFile.getParentFile().mkdirs();                   }                saveToImgByInputStream(instreams, uploadSysUrl, id+".jpg");            }        }        return result;    }          /* @param instreams 二进制流    * @param imgPath 图片的保存路径    * @param imgName 图片的名称    * @return    *      1：保存正常    *      0：保存失败    */   public static int saveToImgByInputStream(InputStream instreams,String imgPath,String imgName) throws FileNotFoundException{         int stateInt = 1;       File file=new File(imgPath,imgName);//可以是任何图片格式.jpg,.png等       FileOutputStream fos=new FileOutputStream(file);       if(instreams != null){           try {                                                byte[] b = new byte[1024];               int nRead = 0;               while ((nRead = instreams.read(b)) != -1) {                   fos.write(b, 0, nRead);               }                                         } catch (Exception e) {               stateInt = 0;               e.printStackTrace();           } finally {                          try {               fos.flush();   fos.close();} catch (IOException e) {e.printStackTrace();}            }       }       return stateInt;   }         public static boolean exists(String imgPath){       File saveFile = new File(imgPath);       if (!saveFile.getParentFile().exists()) {           return false;       }else{           //如果存在判断这个文件的大小           if(saveFile.length()0){               System.out.println("--------------------------------"+saveFile.length());               return true;           }else{               return false;           }       }        }         /**    * 向指定URL发送GET方法的请求    *     * @param url    *            发送请求的URL    * @param param    *            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。    * @return URL 所代表远程资源的响应结果    */   public static String sendGet(String url, String param) {       String result = "";       BufferedReader in = null;       try {           String urlNameString = url + "?" + param;           System.out.println(urlNameString+"........");           URL realUrl = new URL(urlNameString);           // 打开和URL之间的连接           URLConnection connection = realUrl.openConnection();           // 设置通用的请求属性           connection.setRequestProperty("accept", "*/*");           connection.setRequestProperty("connection", "Keep-Alive");           connection.setRequestProperty("user-agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");           // 建立实际的连接           connection.connect();           // 获取所有响应头字段           MapString, ListString map = connection.getHeaderFields();           // 遍历所有的响应头字段           for (String key : map.keySet()) {               System.out.println(key + "---" + map.get(key));           }           // 定义 BufferedReader输入流来读取URL的响应           in = new BufferedReader(new InputStreamReader(                   connection.getInputStream()));           String line;           while ((line = in.readLine()) != null) {               result += line;           }       } catch (Exception e) {           System.out.println("发送GET请求出现异常！" + e);           e.printStackTrace();       }       // 使用finally块来关闭输入流       finally {           try {               if (in != null) {                   in.close();               }           } catch (Exception e2) {               e2.printStackTrace();           }       }       return result;   }          public static Object httpPostWithJSON2(String url, String json,String id)           throws Exception {       // 将JSON进行UTF-8编码,以便传输中文   InputStream instreams = null;       String encoderJson = URLEncoder.encode(json, HTTP.UTF_8);        DefaultHttpClient httpClient = new DefaultHttpClient();       HttpPost httpPost = new HttpPost(url);       httpPost.addHeader(HTTP.CONTENT_TYPE, "application/json");         StringEntity se = new StringEntity(json);       se.setContentType("application/json");       se.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE,"UTF-8"));       httpPost.setEntity(se);       // httpClient.execute(httpPost);       HttpResponse response = httpClient.execute(httpPost);       if (response != null) {           HttpEntity resEntity = response.getEntity();           if (resEntity != null) {                instreams = resEntity.getContent();                         }       }       return instreams;   }    }

调用工具类中的方法 获取图片  参数需要前台传给

/** *  获取微信二维码 * @param path * @param width 二维码的宽度 * @param access_token  * @return */@RequestMapping(value = "/createwxaqrcode")@ResponseBodypublic Object  createwxaqrcode(String access_token,String path,String width, String id ){AgentDTO agentDTO = new AgentDTO();String URL = "https://api.weixin.qq.com/cgi-bin/wxaapp/createwxaqrcode";  //二维码图片位置String agentImgDownloadUrl = "D:\upload";        try {          AgentReqView agentResView = new AgentReqView();        MapString, Object map = new HashMapString, Object();        map.put("path", path);        map.put("width", width);            JSONObject json = JSONObject.fromObject(map);            HttpClientConnectionManager.httpPostWithJSON(URL+"?access_token="+ access_token, json.toString(),id );            String downloadUrl = agentImgDownloadUrl+ id+  "/";            //返回给前端的后台服务器文件下载路径            String downloadfileUrl = downloadUrl + id + ".jpg";            agentResView.setDownloadfileUrl(downloadfileUrl);            agentDTO.setResultCode("200");            agentDTO.setDesc("成功");            agentDTO.setBody(agentResView);        } catch (Exception e) {              e.printStackTrace();          }        return agentDTO;}

import java.util.List;public class AgentDTO {private String resultCode;private String desc;private AgentReqView body;public AgentDTO (){}public AgentDTO (String resultCode,String desc){this.setResultCode(resultCode);this.setDesc(desc);}public String getResultCode() {return resultCode;}public void setResultCode(String resultCode) {this.resultCode = resultCode;}public String getDesc() {return desc;}public void setDesc(String desc) {this.desc = desc;}public AgentReqView getBody() {return body;}public void setBody(AgentReqView body) {this.body = body;}}

public class AgentReqView {private String downloadfileUrl;public String getDownloadfileUrl() {return downloadfileUrl;}public void setDownloadfileUrl(String downloadfileUrl) {this.downloadfileUrl = downloadfileUrl;}}