API开放平台接口设计-------基于OAuth2.0协议方式

1，简介OAuth

http://www.ruanyifeng.com/blog/2019/04/oauth_design.html OAuth 是什么？

http://www.ruanyifeng.com/blog/2019/04/oauth-grant-types.html OAuth的四种授权方式

一般用于联合登陆,比如第三方系统，可以用微信快速等速，不需要输入输入用户名，密码，只需一个access token,在没有过期之前，你就有访问的权限了。

2，https://mp.weixin.qq.com/wiki?t=resource/res_main&id=mp1421140842 微信公众技术平台文档里有：

1 第一步：用户同意授权，获取code

2 第二步：通过code换取网页授权access_token

3 第三步：刷新access_token（如果需要）

4 第四步：拉取用户信息(需scope为 snsapi_userinfo)

5 附：检验授权凭证（access_token）是否有效

3，简单的小例子：

package com.zfb.api.controller;

import javax.servlet.http.HttpServletRequest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.alibaba.fastjson.JSONObject;
import com.zfb.base.Response;
import com.zfb.utils.HttpClientUtils;
import com.zfb.utils.WeiXinUtils;

@Controller
public class OauthController extends Response {

    @Autowired
    private WeiXinUtils weiXinUtils;
    private String errorPage = "errorPage";

    // 生成授权链接
    @RequestMapping("/authorizedUrl")
    public String authorizedUrl() {
        return "redirect:" + weiXinUtils.getAuthorizedUrl();
    }

    // 微信授权回调地址
    @RequestMapping("/callback")
    public String callback(String code, HttpServletRequest request) {
        // 1.使用Code 获取 access_token
        String accessTokenUrl = weiXinUtils.getAccessTokenUrl(code);
        JSONObject resultAccessToken = HttpClientUtils.httpGet(accessTokenUrl);
        boolean containsKey = resultAccessToken.containsKey("errcode");

        if (containsKey) {
            request.setAttribute("errorMsg", "系统错误!");
            return errorPage;
        }
        // 2.使用access_token获取用户信息
        String accessToken = resultAccessToken.getString("access_token");
        String openid = resultAccessToken.getString("openid");
        // 3.拉取用户信息(需scope为 snsapi_userinfo)
        String userInfoUrl = weiXinUtils.getUserInfo(accessToken, openid);
        JSONObject userInfoResult = HttpClientUtils.httpGet(userInfoUrl);
        System.out.println("userInfoResult:" + userInfoResult);
        request.setAttribute("nickname", userInfoResult.getString("nickname"));
        request.setAttribute("city", userInfoResult.getString("city"));
        request.setAttribute("headimgurl", userInfoResult.getString("headimgurl"));
        return "info";
    }

}

封装了一些链接，微信提供

@Component
public class WeiXinUtils {
    @Value("${appid}")
    private String appId;
    @Value("${secret}")
    private String secret;
    @Value("${redirecturi}")
    private String redirectUri;
    @Value("${authorizedUrl}")
    private String authorizedUrl;
    @Value("${access_token}")
    private String accessToken;
    @Value("${userinfo}")
    private String userinfo;

    //生成授权链接权
    public String getAuthorizedUrl() {
        return authorizedUrl.replace("APPID", appId).replace("REDIRECT_URI", URLEncoder.encode(redirectUri));
    }
    
    // 生成accessToken
    public String getAccessTokenUrl(String code) {
        return accessToken.replace("APPID", appId).replace("SECRET", secret).replace("CODE", code);
    }

    // 获取用户信息
    public String getUserInfo(String accessToken, String openId) {
        return userinfo.replace("ACCESS_TOKEN", accessToken).replace("OPENID", openId);
    }

}

WeiXinUtils 从配置文件读取链接：

appid: wx5c43fde3c9733d9e
secret: b8b217126c33a5fb7074927d5e72a81a
redirectUri: http://127.0.0.1:8080/callback
### 生成微信授权
authorizedUrl: https://open.weixin.qq.com/connect/oauth2/authorize?appid=APPID&redirect_uri=REDIRECT_URI&response_type=code&scope=snsapi_userinfo&state=STATE#wechat_redirect
###获取code后，请求以下链接获取access_token
access_token: https://api.weixin.qq.com/sns/oauth2/access_token?appid=APPID&secret=SECRET&code=CODE&grant_type=authorization_code
###拉取用户信息(需scope为 snsapi_userinfo)
userinfo: https://api.weixin.qq.com/sns/userinfo?access_token=ACCESS_TOKEN&openid=OPENID&lang=zh_CN