微信公众号授权登陆

工具类：

package com.wx.auth.util;

import java.io.IOException;

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 net.sf.json.JSONObject;

public class AuthUtil {
	public static final String APPID="wxc232cd9ce5bc6b19";
	public static final String APPSECR="xxxxxxx";
	public static JSONObject doGetJson(String url) throws ClientProtocolException, IOException{
		JSONObject jsonObject =null;
		DefaultHttpClient client=new DefaultHttpClient();
		HttpGet httpGet=new HttpGet(url);
		HttpResponse response=client.execute(httpGet);
		HttpEntity entity=response.getEntity();
		if(entity!=null){
			String result=EntityUtils.toString(entity, "UTF-8");
			jsonObject=JSONObject.fromObject(result);
		}
		return jsonObject;
	}
}

LoginServlet(用户请求):

package com.wx.auth.servlet;

import java.io.IOException;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.http.client.utils.URLEncodedUtils;

import com.wx.auth.util.AuthUtil;

public class LoginServlet extends HttpServlet {
	
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//公众号的唯一标识
		String APPID=AuthUtil.APPID;
		//授权后重定向的回调链接地址， 请使用 urlEncode 对链接进行处理
		String REDIRECT_URI=URLEncoder.encode("http://jrqaea.natappfree.cc/WxAuth/CallBackServlet2");
//		System.out.println(REDIRECT_URI);
		//返回类型，请填写code
		String code="code";
		//应用授权作用域，snsapi_base （不弹出授权页面，直接跳转，只能获取用户openid），snsapi_userinfo （弹出授权页面，可通过openid拿到昵称、性别、所在地。并且， 即使在未关注的情况下，只要用户授权，也能获取其信息 ）
		String SCOPE="snsapi_userinfo";
		//重定向后会带上state参数，开发者可以填写a-zA-Z0-9的参数值，最多128字节
		String STATE="STATE";
//		System.out.println(SCOPE);
		//跳转地址
		String url="https://open.weixin.qq.com/connect/oauth2/authorize?"
				+ "appid="+APPID
				+ "&redirect_uri="+REDIRECT_URI
				+ "&response_type=code"
				+ "&scope="+SCOPE
				+ "&state=STATE#wechat_redirect";
//		System.out.println(url);
		resp.sendRedirect(url);
	}
	
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		this.doGet(req, resp);
	}
}

CallBackServlet(回调页面):

/**
 * 直接获取用户信息不保存在数据库中
 */
package com.wx.auth.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.Set;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.wx.auth.util.AuthUtil;
import net.sf.json.JSONObject;

public class CallBackServlet extends HttpServlet{
	
	String codeFlag=null;
	JSONObject userInfo1=null;
	
	protected  void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String code=req.getParameter("code");
		//判断code是否已经使用
		if(code.equals(codeFlag)){
			System.out.println("code失效");
		}else{
			System.out.println("code有效效");
			codeFlag=code;
			//公众号的唯一标识
			String APPID=AuthUtil.APPID;
			//公众号的appsecret
			String SECRET=AuthUtil.APPSECR;
			//填写第一步获取的code参数
			String CODE=code;
			String url="https://api.weixin.qq.com/sns/oauth2/access_token?"
					+ "appid="+APPID
					+ "&secret="+SECRET
					+ "&code="+CODE
					+ "&grant_type=authorization_code";
			
			JSONObject jsonObject=AuthUtil.doGetJson(url);
			System.out.println(jsonObject);
	
			String openid=jsonObject.getString("openid");
			String token=jsonObject.getString("access_token");
			
			String infoUrl="https://api.weixin.qq.com/sns/userinfo?"
					+ "access_token="+token
					+ "&openid="+openid
					+ "&lang=+zh_CN";
			JSONObject userInfo=AuthUtil.doGetJson(infoUrl);
			//未知原因会重复请求
			userInfo1=userInfo;
			System.out.println(userInfo);
		}
		Set info=userInfo1.keySet();
		Iterator it=info.iterator();
		while(it.hasNext()){
			String key=(String) it.next();
			req.setAttribute(key, userInfo1.getString(key));
		}
		System.out.println("重定向1");
		req.getRequestDispatcher("/index1.jsp").forward(req, resp);
	}
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		this.doGet(req, resp);
	}
}