获取微信OpenId

• 先获取code
• 再通过code获取authtoken，从authtoken中取出openid给前台
• 微信端一定不要忘记设定网页账号中的授权回调页面域名

流程图如下

image

主要代码

页面js代码

/* 写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=/";
}
/* 读cookie */
function getCookie(name) {
    var arr = document.cookie.match(new RegExp("(^| )" + name + "=([^;]*)(;|$)"));
    if (arr != null) {
        return unescape(arr[2]);
    }
    return null;
}

/* 获取URL参数 */
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;
}

/* 获取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代码

//访问微信获取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代码

//访问微信获取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("登录错误");
    }
    String redUrl = state+"?openid="+token.getOpenid();
    resp.sendRedirect(redUrl);
}

获取AuthToken（WXUtil.getAuthToken(code)）代码

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类

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 {

    // 设置body体
    public static void setBodyParameter(String sb, HttpURLConnection conn)
            throws IOException {
        DataOutputStream out = new DataOutputStream(conn.getOutputStream());
        out.writeBytes(sb);
        out.flush();
        out.close();
    }

    // 添加签名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;
    }

}

封装AuthToken的VO类

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;
    }
}

有不明白的同学欢迎留言！