微信公众号第三方登录，简单易懂

1.准备工作

1）登录微信公众号接口测试平台设置信息，地址：http://mp.weixin.qq.com/debug/cgi-bin/sandbox?t=sandbox/login
登录成功后可以看到测试用的appid和appsecret，这个在代码里面会用到。

2）需要设置网页授权

这边需要填域名，如果没有域名，可以用内网穿透动态解析一个域名。这边用的是NATAPP，没有账号可以注册一个：https://natapp.cn/register
注册完毕后实名认证，选择免费通道，具体操作手册可参考：https://natapp.cn/article/minecraft

根据操作手册就是这样：

然后设置域名，这边要注意的是这个地址，只需要域名部分，下图是我映射好的地址，一定不能填错，不然在微信授权登录会一直报redirect_url错误

另外后面回调地址用微信访问的时候，使用的微信得先扫一下这个二维码关注一下才可以

2.代码部分

1）请求微信接口的工具类

package com.example.demo.util;import net.sf.json.JSONObject;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;import java.io.IOException;public class AuthUtil {public static final String APPID = "wxca86e04bc4065918";public static final String APPSECRET = "cb44b8fa1791d5f2ea4e8c9eb4d2b963";//回调地址public static final String backUrl="http://mt4ynq.natappfree.cc/callBack";public static JSONObject doGetJson(String url) throws ClientProtocolException, IOException {JSONObject jsonObject = null;//首先初始化HttpClient对象DefaultHttpClient client = new DefaultHttpClient();//通过get方式进行提交HttpGet httpGet = new HttpGet(url);//通过HTTPclient的execute方法进行发送请求HttpResponse response = client.execute(httpGet);//从response里面拿自己想要的结果HttpEntity entity = response.getEntity();if(entity != null){String result = EntityUtils.toString(entity,"UTF-8");jsonObject = jsonObject.fromObject(result);}//把链接释放掉httpGet.releaseConnection();return jsonObject;}
}

2）controller类（版本1）

package com.example.demo.controller.wx;import com.example.demo.util.AuthUtil;
import net.sf.json.JSONObject;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.websocket.server.PathParam;
import java.io.IOException;
import java.net.URLEncoder;@RestController
@RequestMapping("/front/auth")
public class WxAuthorizeController {/*** Tea微信登录接口* @throws IOException*/@RequestMapping("/wx_login")public void wxLogin(HttpServletResponse response) throws IOException {//域名(暂时写死的)String sym = "http://mt4ynq.natappfree.cc";//这里是回调的urlString redirect_uri = URLEncoder.encode(sym + "/front/auth/callBack", "UTF-8");String url = "https://open.weixin.qq.com/connect/oauth2/authorize?" +"appid=APPID" +"&redirect_uri=REDIRECT_URI" +"&response_type=code" +"&scope=SCOPE" +"&state=123#wechat_redirect";response.sendRedirect(url.replace("APPID", "wxca86e04bc4065918").replace("REDIRECT_URI", redirect_uri).replace("SCOPE", "snsapi_userinfo"));}/*** Tea微信授权成功的回调函数** @param request* @param response* @throws IOException*/@RequestMapping("/callBack")protected void deGet(HttpServletRequest request, HttpServletResponse response)throws Exception {//获取回调地址中的codeString code = request.getParameter("code");//拼接url  ！！！！！！！！！！根据code获取openId和access_tokenString url = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=" + "wxca86e04bc4065918" + "&secret="+ "cb44b8fa1791d5f2ea4e8c9eb4d2b963" + "&code=" + code + "&grant_type=authorization_code";JSONObject jsonObject = AuthUtil.doGetJson(url);//1.获取微信用户的openidString openid = jsonObject.getString("openid");//2.获取获取access_tokenString access_token = jsonObject.getString("access_token");//！！！！！！！！！！！再根据access_token获取用户信息String infoUrl = "https://api.weixin.qq.com/sns/userinfo?access_token=" + access_token + "&openid=" + openid+ "&lang=zh_CN";//3.获取微信用户信息JSONObject userInfo = AuthUtil.doGetJson(infoUrl);//至此拿到了微信用户的所有信息,剩下的就是业务逻辑处理部分了//保存openid和access_token到sessionrequest.getSession().setAttribute("openid", openid);request.getSession().setAttribute("access_token", access_token);//去数据库查询此微信是否绑定过手机
//        UserVo user = userService.queryByOpenId(openid);
//        String mobile=user==null?"":user.getMobile();//        if(null == mobile || "".equals(mobile)){//            //如果无手机信息,则跳转手机绑定页面String wareName1=URLEncoder.encode(userInfo.get("nickname").toString(), "UTF-8");response.sendRedirect("/front/auth/loginSucess?name="+wareName1);
//        }else{//            //否则直接跳转首页
//            response.sendRedirect("/front/index.html");
//        }}@RequestMapping("/loginSucess")public String loginSucess(@PathParam("name")String name){return "wechat login sucesss "+name;}}

版本2的代码步骤说明更详细

版本2

package com.example.demo.controller.wx;import com.example.demo.dao.UserMapper;
import com.example.demo.entity.User;
import com.example.demo.util.AuthUtil;
import net.sf.json.JSONObject;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;import javax.annotation.Resource;
import javax.jws.soap.SOAPBinding;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;@RestController
public class WxV2Controller {@Resourceprivate UserMapper userMapper;@RequestMapping(value="/wxlogin")public void wx(HttpServletRequest request, HttpServletResponse response) throws IOException {//第一步：引导用户进入授权页面同意授权，获取codeStringBuilder builder = new StringBuilder("https://open.weixin.qq.com/connect/oauth2/authorize?appid=");builder.append(AuthUtil.APPID);builder.append("&redirect_uri=");builder.append(URLEncoder.encode(AuthUtil.backUrl));//开发文档要求转换builder.append("&response_type=code");builder.append("&scope=snsapi_userinfo");builder.append("&state=STATE#wechat_redirect");//授权页面地址//将StringBuilder转换成StringString url=builder.toString();//重定向到授权页面response.sendRedirect(url);}@RequestMapping(value="/callBack")public String wxcallback(@RequestParam("code") String code, Model model)throws IOException {System.out.println("code:" + code);//获取code后，请求以下链接获取access_tokenStringBuilder builder = new StringBuilder("https://api.weixin.qq.com/sns/oauth2/access_token?appid=");builder.append(AuthUtil.APPID);builder.append("&secret=");builder.append(AuthUtil.APPSECRET);builder.append("&code=");builder.append(code);builder.append("&grant_type=authorization_code");//通过网络请求方法来请求上面这个接口//将StringBuilder转换成StringString url=builder.toString();JSONObject jsonObject = AuthUtil.doGetJson(url);System.out.println("==========================jsonObject" + jsonObject);//从返回的JSON数据中取出access_token和openid，拉取用户信息时用String token = jsonObject.getString("access_token");String openid = jsonObject.getString("openid");// 第三步：刷新access_token（如果需要）// 第四步：拉取用户信息(需scope为 snsapi_userinfo)StringBuilder builder1 = new StringBuilder("https://api.weixin.qq.com/sns/userinfo?access_token=");builder1.append(token);builder1.append("&openid=");builder1.append(openid);builder1.append("&lang=zh_CN");//通过网络请求方法来请求上面这个接口//将StringBuilder转换成StringString infoUrl=builder1.toString();JSONObject userInfo = AuthUtil.doGetJson(infoUrl);System.out.println("userInfo=======" + userInfo);//第1种情况：使用微信用户信息直接登录，无需注册和绑定
//        model.addAttribute("info",userInfo);
//        return "wx/wxtest1";
////第2种情况：查看数据库是否存在相对应用户try {User wxuser = userMapper.findNameByopenId(openid);if (wxuser != null) {//已绑定model.addAttribute("info",userInfo);model.addAttribute("name", wxuser.getUsername());return "wx/wxtest2";} else {//未绑定model.addAttribute("openid", openid);return "wx/wxtest3";}} catch (Exception e) {e.printStackTrace();}return "wx/fail";   //跳转到登录失败页面}
}

3.测试

以版本1的controller为例，可浏览器请求：
（1）http://mt4ynq.natappfree.cc/front/auth/wxLogin获取code，并根据代码里面的重定向转发请求给callback接口；
（2）callback这里面根据code请求了微信接口获取openId和access_token；
（3）再根据获取的openid和access_token获取用户信息。