Get the WeChat OpenId

First get the code

Then get the authtoken through the code, take out the openid from the authtoken and give it to the front desk

Don’t forget to set the authorization callback page domain name in the WeChat account

The flow chart is as follows

Main code

Page js code

/* 寫cookie */
function setCookie(name, value) {
  var Days = 30;
  var exp = new Date();
  exp.setTime(exp.getTime() + Days * 24 * 60 * 60 * 1000);
  document.cookie = name + "=" + escape(value) + ";expires=" + exp.toGMTString() + ";path=/";
}
/* 讀cookie */
function getCookie(name) {
  var arr = document.cookie.match(new RegExp("(^| )" + name + "=([^;]*)(;|$)"));
  if (arr != null) {
    return unescape(arr[2]);
  }
  return null;
}
 
/* 獲取URL參數(shù) */
function getUrlParams(name) {
  var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)", "i");
  var r = window.location.search.substr(1).match(reg);
  if (r != null) {
    return unescape(r[2]);
  }
  return null;
}
 
/* 獲取openid */
function getOpenId(url) {
  var openid = getCookie("usropenid");
  if (openid == null) {
    openid = getUrlParams('openid');
    alert("openid="+openid);
    if (openid == null) {
      window.location.href = "wxcode?url=" + url;
    } else {
      setCookie("usropenid", openid);
    }
  }
}

WxCodeServlet code

//訪問微信獲取code
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException {
  String state = req.getParameter("url");
  //WxOpenIdServlet的地址
  String redirect ="http://"+Configure.SITE+"/wxopenid";
  redirect = URLEncoder.encode(redirect, "utf-8");
  StringBuffer url = new StringBuffer("https://open.weixin.qq.com/connect/oauth2/authorize?appid=")
      .append(Configure.APP_ID).append("&redirect_uri=").append(redirect)
      .append("&response_type=code&scope=snsapi_base&state=").append(state).append("#wechat_redirect");
  resp.sendRedirect(url.toString());
}

WxOpenIdServlet code

//訪問微信獲取openid
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException {
  String code = req.getParameter("code");
  String state = req.getParameter("state");
  Result ret = new Result();
  AuthToken token = WXUtil.getAuthToken(code);
  if(null != token.getOpenid()){
    ret.setCode(0);
    log.info("====openid=="+token.getOpenid());
    Map<String,String> map = new HashMap<String,String>();
    map.put("openid", token.getOpenid());
    map.put("state", state);
    ret.setData(map);
  }else{
    ret.setCode(-1);
    ret.setMsg("登錄錯(cuò)誤");
  }
  String redUrl = state+"?openid="+token.getOpenid();
  resp.sendRedirect(redUrl);
}

Get AuthToken (WXUtil.getAuthToken(code)) code

public static AuthToken getAuthToken(String code){
  AuthToken vo = null;
  try {
    String uri = "https://api.weixin.qq.com/sns/oauth2/access_token?";
    StringBuffer url = new StringBuffer(uri);
    url.append("appid=").append(Configure.APP_ID);
    url.append("&secret=").append(Configure.APP_SECRET);
    url.append("&code=").append(code);
    url.append("&grant_type=").append("authorization_code");
    HttpURLConnection conn = HttpClientUtil.CreatePostHttpConnection(url.toString());
    InputStream input = null;
    if (conn.getResponseCode() == 200) {
      input = conn.getInputStream();
    } else {
      input = conn.getErrorStream();
    }
    vo = JSON.parseObject(new String(HttpClientUtil.readInputStream(input),"utf-8"),AuthToken.class);
  } catch (Exception e) {
    log.error("getAuthToken error", e);
  }
  return vo;
}

HttpClientUtil class

package com.huatek.shebao.util;
 
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
 
public class HttpClientUtil {
 
  // 設(shè)置body體
  public static void setBodyParameter(String sb, HttpURLConnection conn)
      throws IOException {
    DataOutputStream out = new DataOutputStream(conn.getOutputStream());
    out.writeBytes(sb);
    out.flush();
    out.close();
  }
 
  // 添加簽名header
  public static HttpURLConnection CreatePostHttpConnection(String uri) throws MalformedURLException,
      IOException, ProtocolException {
    URL url = new URL(uri);
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setUseCaches(false);
    conn.setDoInput(true);
    conn.setDoOutput(true);
    conn.setRequestMethod("POST");
    conn.setInstanceFollowRedirects(true);
    conn.setConnectTimeout(30000);
    conn.setReadTimeout(30000);
    conn.setRequestProperty("Content-Type","application/json");
    conn.setRequestProperty("Accept-Charset", "utf-8");
    conn.setRequestProperty("contentType", "utf-8");
    return conn;
  }
 
  public static byte[] readInputStream(InputStream inStream) throws Exception {
    ByteArrayOutputStream outStream = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int len = 0;
    while ((len = inStream.read(buffer)) != -1) {
      outStream.write(buffer, 0, len);
    }
    byte[] data = outStream.toByteArray();
    outStream.close();
    inStream.close();
    return data;
  }
 
}

The VO class that encapsulates AuthToken

package com.huatek.shebao.wxpay;
 
public class AuthToken {
  private String access_token;
  private Long expires_in;
  private String refresh_token;
  private String openid;
  private String scope;
  private String unionid;
  private Long errcode;
  private String errmsg;
  public String getAccess_token() {
    return access_token;
  }
  public void setAccess_token(String access_token) {
    this.access_token = access_token;
  }
  public Long getExpires_in() {
    return expires_in;
  }
  public void setExpires_in(Long expires_in) {
    this.expires_in = expires_in;
  }
  public String getRefresh_token() {
    return refresh_token;
  }
  public void setRefresh_token(String refresh_token) {
    this.refresh_token = refresh_token;
  }
  public String getOpenid() {
    return openid;
  }
  public void setOpenid(String openid) {
    this.openid = openid;
  }
  public String getScope() {
    return scope;
  }
  public void setScope(String scope) {
    this.scope = scope;
  }
  public String getUnionid() {
    return unionid;
  }
  public void setUnionid(String unionid) {
    this.unionid = unionid;
  }
  public Long getErrcode() {
    return errcode;
  }
  public void setErrcode(Long errcode) {
    this.errcode = errcode;
  }
  public String getErrmsg() {
    return errmsg;
  }
  public void setErrmsg(String errmsg) {
    this.errmsg = errmsg;
  }
}