java开发微信小程序——二维码生成-即速应用

https://blog.csdn.net/persistencegoing/article/details/84376427

工具类：
public class TwoCode {

   /*
* 获取 token
　　　* 普通的 get 可获 token
*/
public static String getToken() {
try {

Map<String, String> map = new LinkedHashMap<String, String>();
map.put("grant_type", "client_credential");
map.put("appid", Contants.appId);//改成自己的appid
map.put("secret", Contants.secret);

String rt = UrlUtil.sendPost("https://api.weixin.qq.com/cgi-bin/token", map);

System.out.println("what is:"+rt);
JSONObject json = JSONObject.parseObject(rt);

if (json.getString("access_token") != null || json.getString("access_token") != "") {
return json.getString("access_token");
} else {
return null;
}
} catch (Exception e) {

e.printStackTrace();
return null;
}

}

/*
* 获取二维码图片
　　 *
*/
public static String getminiqrQr( String accessToken,HttpServletRequest request) {
   String p=request.getSession().getServletContext().getRealPath("/");
   String codeUrl=p+"/twoCode.png";
   String twoCodeUrl="twoCode.png";
   try
{
URL url = new URL("https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token="+accessToken);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");// 提交模式
// conn.setConnectTimeout(10000);//连接超时单位毫秒
// conn.setReadTimeout(2000);//读取超时单位毫秒
// 发送POST请求必须设置如下两行
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
// 获取URLConnection对象对应的输出流
PrintWriter printWriter = new PrintWriter(httpURLConnection.getOutputStream());
// 发送请求参数
JSONObject paramJson = new JSONObject();
paramJson.put("scene", "1234567890");
paramJson.put("path", "pages/index?query=1");
paramJson.put("width", 430);
paramJson.put("is_hyaline", true);
paramJson.put("auto_color", true);
/**
* line_color生效
* paramJson.put("auto_color", false);
* JSONObject lineColor = new JSONObject();
* lineColor.put("r", 0);
* lineColor.put("g", 0);
* lineColor.put("b", 0);
* paramJson.put("line_color", lineColor);
* */

printWriter.write(paramJson.toString());
// flush输出流的缓冲
printWriter.flush();
//开始获取数据
BufferedInputStream bis = new BufferedInputStream(httpURLConnection.getInputStream());
OutputStream os = new FileOutputStream(new File(codeUrl));
int len;
byte[] arr = new byte[1024];
while ((len = bis.read(arr)) != -1)
{
os.write(arr, 0, len);
os.flush();
}
os.close();
}
catch (Exception e)
{
e.printStackTrace();
}
       return twoCodeUrl;
}
}
2.controller层：

/**
   * 接收二维码
   * @param request
   * @return
   * @throws IOException
   */
   @RequestMapping(value="/twoCode",method=RequestMethod.POST,produces="text/html;charset=utf-8")
   @ResponseBody
   public Object twoCode(HttpServletRequest request) throws IOException{
       JSONObject data=new JSONObject();
       String accessToken = TwoCode.getToken();
       System.out.println("accessToken;"+accessToken);
       String twoCodeUrl = TwoCode.getminiqrQr(accessToken,request);
       data.put("twoCodeUrl", twoCodeUrl);
       return data;

   }
3.http工具：
public class UrlUtil {
   /**
   * 向指定 URL 发送POST方法的请求
   *
   * @param url 发送请求的 URL
   * @param param 请求参数
   * @return 所代表远程资源的响应结果
   */
   public static String sendPost(String url, Map<String, ?> paramMap) {
   PrintWriter out = null;
   BufferedReader in = null;
   String result = "";

   String param = "";
   Iterator<String> it = paramMap.keySet().iterator();

   while(it.hasNext()) {
   String key = it.next();
   param += key + "=" + paramMap.get(key) + "&";
   }

   try {
   URL realUrl = new URL(url);
   // 打开和URL之间的连接
   URLConnection conn = realUrl.openConnection();
   // 设置通用的请求属性
   conn.setRequestProperty("accept", "*/*");
   conn.setRequestProperty("connection", "Keep-Alive");
   conn.setRequestProperty("Accept-Charset", "utf-8");
   conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
   // 发送POST请求必须设置如下两行
   conn.setDoOutput(true);
   conn.setDoInput(true);
   // 获取URLConnection对象对应的输出流
   out = new PrintWriter(conn.getOutputStream());
   // 发送请求参数
   out.print(param);
   // flush输出流的缓冲
   out.flush();
   // 定义BufferedReader输入流来读取URL的响应
   in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
   String line;
   while ((line = in.readLine()) != null) {
   result += line;
   }
   } catch (Exception e) {
   System.out.println(e);
   }
   //使用finally块来关闭输出流、输入流
   finally{
   try{
   if(out!=null){
   out.close();
   }
   if(in!=null){
   in.close();
   }
   }
   catch(IOException ex){
   ex.printStackTrace();
   }
   }
   return result;
   }
}