I've come into contact with some relatively new things recently. Record them

First post the official API address of wechat and feel the charm of wechat...

https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=9_6

After learning some notes about wechat download bill, we will officially start

The following is the specific implementation:

Paste the main method first, and other tool classes will have specific instructions:

	public static void main(String[] args) throws Exception {
//		downloadBill();
	}  

    public static void downloadBill() throws Exception {
        //The MyConfig tool class here is some of its own encapsulated configurations. To facilitate your own use, you can skip this step
		MyConfig myConfig = new MyConfig();  
		SortedMap<Object,Object> parameters =new TreeMap<Object,Object>();
        //The value value in this can be configured according to the wechat merchant parameters
		parameters.put("appid", myConfig.getAppID());//appid
		parameters.put("mch_id", myConfig.getMchID());//Merchant No
		parameters.put("nonce_str", CreateNoncestr());//Random string
		parameters.put("bill_date", "20180125");//Statement date
		parameters.put("bill_type", "ALL");//Statement type
        //Call the method here to generate the signature required by wechat (this is a pit. When making a wechat refund, I was stuck for a day because the signature did not meet the specification)
		String sign = createSign("utf-8", parameters);//autograph
		parameters.put("sign", sign);

        //The getRequestXml method here is a tool method to transfer xml, which I will post below
		String reuqestXml = getRequestXml(parameters); 
        /**
          * CommonUtil here is an https general tool class, which I will post below
          * download_bill_url It is the download address of wechat official statement
          * download_bill_url = "https://api.mch.weixin.qq.com/pay/downloadbill"
          */
		String result=CommonUtil.httpsRequest(myConfig.download_bill_url, "POST", reuqestXml);
		//The generation time of wechat statement is after 9:00 of the next day, so when the query date is the same day, the error message indicates that the date is invalid
        if(result.startsWith("<xml>")){
            System.out.println(result);
            System.out.println("No order");
        }else {  
            String tradeMsg =  result.substring(result.indexOf("`"));
        	String tradeInfo = tradeMsg.substring(0, tradeMsg.indexOf("total")).replace("`", "");// Remove summary data and '`'
           String tradeInfo =  tradeMsg.substring(0,tradeMsg.indexOf("total"));
           String tradeTotalMsg =tradeMsg.substring(tradeMsg.indexOf("total"));
           String tradeTotalInfo =tradeTotalMsg.substring(tradeTotalMsg.indexOf("`"));
          
           
           System.out.println("result----->"+result);
           System.out.println("tradeMsg----->"+tradeMsg);
           System.out.println("tradeInfo----->"+tradeInfo);
           System.out.println("tradeTotalMsg----->"+tradeTotalMsg);
           System.out.println("tradeTotalInfo----->"+tradeTotalInfo);
           
           //The last column is the rate, which ends with% as the cutting target to facilitate the operation and storage of the database
           String[] tradeArray = tradeInfo.split("%");
           List<Map<String, Object>> resultList = new ArrayList<>();
           
           for(int i = 0;i < tradeArray.length;i++) {
        	   String[] tradeDetailArray = tradeArray[i].split(",");
        	   Map<String, Object> map = new HashMap<>();
        	   
               /**
                 * Here I take several fields that are more useful to me
                 * For detailed fields, you can refer to here or see the print results of the console
                 * https://www.cnblogs.com/mgqy/articles/7657483.html
                 */
        	   map.put("readeTime", tradeDetailArray[0]);//Transaction time
        	   map.put("appid", tradeDetailArray[1]);//The official account ID
        	   map.put("mchId", tradeDetailArray[2]);//Merchant No
        	   map.put("transactionId", tradeDetailArray[5]);//Wechat Order No
        	   map.put("outTradeNo", tradeDetailArray[6]);//Merchant order number
        	   map.put("openid", tradeDetailArray[7]);//User ID (openid)
        	   map.put("tradeState", tradeDetailArray[9]);// Transaction status
        	   map.put("tradeBank", tradeDetailArray[10]);// paying bank
        	   map.put("totalFee", tradeDetailArray[12]);//Total amount
        	   map.put("refundFee", tradeDetailArray[16]);//refund amount 
        	   map.put("tradeName", tradeDetailArray[20]);// Commodity name
        	   map.put("poundage", tradeDetailArray[22]);//Service Charge
        	   resultList.add(map);
           }
           System.out.println("resultList--->"+resultList);
       }
	}

Here are some tool classes and methods used:

1. Random string generation method

	/**
	 * Random string
	 * @return
	 */
    public static String CreateNoncestr() {  
        String chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";  
        String res = "";  
        for (int i = 0; i < 16; i++) {  
            Random rd = new Random();  
            res += chars.charAt(rd.nextInt(chars.length() - 1));  
        }  
        return res;  
     } 

2. Write signature method

    /**
     * Write signature
     * @param charSet
     * @param parameters
     * @return
     * @throws Exception 
     */
     public static String createSign(String charSet,SortedMap<Object,Object> parameters) throws Exception{  
    	MyConfig myconfig = new MyConfig();
        StringBuffer sb = new StringBuffer();  
        Set es = parameters.entrySet();  
        Iterator it = es.iterator();  
        while(it.hasNext()) {  
            Map.Entry entry = (Map.Entry)it.next();  
            String k = (String)entry.getKey();  
            Object v = entry.getValue();  
            if(null != v && !"".equals(v)  
                    && !"sign".equals(k) && !"key".equals(k)) {  
                sb.append(k + "=" + v + "&");  
            }  
        }  
        sb.append("key=" + myconfig.getKey());  
//        String sign = MD5Util.MD5Encode(sb.toString(), charSet).toUpperCase();  
        String sign = MD5Util.MD5Encode(sb.toString(), charSet).toUpperCase();  
//        String sign = MD5.MD5Encode(sb.toString(), charSet).toUpperCase();  
        return sign;  
      }  

3. Transfer to xml format

    /**
      * Convert to xml format
      * @param parameters
      * @return
      */
     public static String getRequestXml(SortedMap<Object,Object> parameters){  
         StringBuffer sb = new StringBuffer();  
         sb.append("<xml>");  
         Set es = parameters.entrySet();  
         Iterator it = es.iterator();  
         while(it.hasNext()) {  
           Map.Entry entry = (Map.Entry)it.next();  
           String k = (String)entry.getKey();  
           String v = (String)entry.getValue();  
           if ("attach".equalsIgnoreCase(k)||"body".equalsIgnoreCase(k)||"sign".equalsIgnoreCase(k)) {  
               sb.append("<"+k+">"+"<![CDATA["+v+"]]></"+k+">");  
           }else {  
               sb.append("<"+k+">"+v+"</"+k+">");  
           }  
         }  
         sb.append("</xml>");  
         return sb.toString();  
     }  

4. https general tool class

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.ConnectException;
import java.net.URL;

import javax.net.ssl.HttpsURLConnection;

import org.apache.log4j.Logger;

import net.sf.json.JSONObject;

/**
 * https General tools
 */
public class CommonUtil {
    
    private static Logger log = Logger.getLogger(CommonUtil.class);
    public static JSONObject httpsRequestToJsonObject(String requestUrl, String requestMethod, String outputStr) {
        JSONObject jsonObject = null;
        try {
             String buffer = httpsRequest(requestUrl, requestMethod, outputStr);
            jsonObject = JSONObject.fromObject(buffer.toString());
        } catch (Exception e) {
            log.error("https Request exception:"+e.getMessage());
        }
        return jsonObject;
    }
    
    
    public static String httpsRequest(String requestUrl, String requestMethod, String outputStr){
        try {
            URL url = new URL(requestUrl);
            HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.setUseCaches(false);
            // Set request mode (GET/POST)
            conn.setRequestMethod(requestMethod);
            conn.setRequestProperty("content-type", "application/x-www-form-urlencoded");
            // Write data to output stream when outputStr is not null
            if (null != outputStr) {
                OutputStream outputStream = conn.getOutputStream();
                // Pay attention to the coding format
                outputStream.write(outputStr.getBytes("UTF-8"));
                outputStream.close();
            }
            // Read return content from input stream
            InputStream inputStream = conn.getInputStream();
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String str = null;
            StringBuffer buffer = new StringBuffer();
            while ((str = bufferedReader.readLine()) != null) {
                buffer.append(str);
            }
            // Release resources
            bufferedReader.close();
            inputStreamReader.close();
            inputStream.close();
            inputStream = null;
            conn.disconnect();
            return buffer.toString();
        } catch (ConnectException ce) {
            System.out.println("Connection timeout:{}");
        } catch (Exception e) {
            System.out.println("https Request exception:{}");
        }
        return null;
    }
 }

Here, wechat download statement function is realized

Please forgive and give your comments on the bad code. 937017870@qq.com