Java接入微信開放平台登入

1.通過微信開放平台https://open.weixin.qq.com注冊應用并通過稽核，拿到APPID和SECRET

2.通過請求微信登入，跳轉後進行處理

https://open.weixin.qq.com/connect/qrconnect?appid=APPID&redirect_uri=REDIRECT_URI&response_type=code&scope=SCOPE&state=STATE#wechat_redirect
授權成功傳回：
   redirect_uri?code=CODE&state=STATE
授權失敗傳回：
   redirect_uri?state=STATE
獲得code後擷取access_token      

import cn.xishan.oftenporter.porter.core.base.WObject;
import com.alibaba.fastjson.JSONObject;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;

/**
 * Created by YangJi on 2017/5/23.
 */
public class WeiXinLogin {
    private final String APPID = "";
    private final String SECRET = "";

    /**
     *  通過請求微信登入，跳轉後進行處理
     https://open.weixin.qq.com/connect/qrconnect?appid=APPID&redirect_uri=REDIRECT_URI&response_type=code&scope=SCOPE&state=STATE#wechat_redirect
     授權成功傳回：
        redirect_uri?code=CODE&state=STATE
     授權失敗傳回：
        redirect_uri?state=STATE
     獲得code後擷取access_token
     *
      */
    public void redirect(){
        if(wObject.getRequest().getParameter("code")!=null){
            String code = (String) wObject.getRequest().getParameter("code");
            String accessToken = getAccessToken(code);

            if(accessToken!=null){
                JSONObject returnObj = JSONObject.parseObject(accessToken);
                if (returnObj!=null){
                    String access_token = returnObj.getString("access_token");
                    String openId = returnObj.getString("openid");

                    String userInfo = getUserInfo(access_token,openId);
                    System.out.println(userInfo);
                }
            }

        }
    }

    /**
     * 獲得code後擷取access_token
         {
         "access_token":"ACCESS_TOKEN",
         "expires_in":7200,
         "refresh_token":"REFRESH_TOKEN",
         "openid":"OPENID",
         "scope":"SCOPE"
         }
     * @param code
     */
    public String getAccessToken(String code){
        // https://api.weixin.qq.com/sns/oauth2/access_token?appid=APPID&secret=SECRET&code=CODE&grant_type=authorization_code
        try{
            String url = "https://api.weixin.qq.com/sns/oauth2/access_token";
            String param = "appid="+APPID+"&secret="+SECRET+"&code="+code+"&grant_type=authorization_code";
            return sendGet(url,param);
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 擷取微信使用者資訊
        https://api.weixin.qq.com/sns/userinfo?access_token=ACCESS_TOKEN&openid=OPENID
         {
         "openid":"OPENID",
         "nickname":"NICKNAME",
         "sex":1,
         "province":"PROVINCE",
         "city":"CITY",
         "country":"COUNTRY",
         "headimgurl": "http://wx.qlogo.cn/mmopen/g3MonUZtNHkdmzicIlibx6iaFqAc56vxLSUfpb6n5WKSYVY0ChQKkiaJSgQ1dZuTOgvLLrhJbERQQ4eMsv84eavHiaiceqxibJxCfHe/0",
         "privilege":[
         "PRIVILEGE1",
         "PRIVILEGE2"
         ],
         "unionid": " o6_bmasdasdsad6_2sgVt7hMZOPfL"

         }
     * @param access_token
     * @param openId
     * @return
     */
    public String getUserInfo(String access_token,String openId){
        return sendGet("https://api.weixin.qq.com/sns/userinfo","access_token="+access_token+"&openid="+openId);
    }


    /**
     * 發送GET請求
     * @param url
     * @param param
     * @return
     */
    public static String sendGet(String url, String param) {
        String result = "";
        BufferedReader in = null;
        try {
            String urlNameString = url + "?" + param;
            URL realUrl = new URL(urlNameString);
            URLConnection connection = realUrl.openConnection();
            connection.setRequestProperty("accept", "*/*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            connection.connect();
            Map<String, List<String>> map = connection.getHeaderFields();
            for (String key : map.keySet()) {
                System.out.println(key + "--->" + map.get(key));
            }
            in = new BufferedReader(new InputStreamReader(
                    connection.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return result;
    }


}