一个注解，一个拦截器，还有一个中转html页（来源网上，稍微修改），原理看拦截器的类注解。
三个文件的下载链接https://pan.baidu.com/s/1Gt07PVtiKrG1uh2SVJKqSQ
package com.xxx.admin.interceptor;
import com.xxx.core.annotation.GetOpenId;
import com.jfinal.aop.Interceptor;
import com.jfinal.aop.Invocation;
import com.jfinal.weixin.sdk.api.SnsAccessToken;
import com.jfinal.weixin.sdk.api.SnsAccessTokenApi;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.net.URLEncoder;
/**
* 模板
* 多域名获取openid 样例DEMO
* B.getOpenid(一般是充值页面路由) -->A.GETWXCODE.html-->weixin--> A.GETWXCODE.html?redirect_uri=B.getOpenid&code=XXX --(redirect_uri)--> B.getOpenid?code=XXX
* http://有页面回调权限的项目域名/GETWXCODE.html?appid=APPID&response_type=code&redirect_uri=Encode(GETWXCODE.html?redirect_uri=当前请求地址)&scope=snsapi_base&state=wx#wechat_redirect
* 当前请求参数不要用?a=1&b=1传参数,用jfinal的/a-b-c形式传参
*
* 获得的openId被存在会话session中，后续接口可以直接获取
* @author WesleyOne
* @create 2018/8/19
*/
public class _GetOpenidInterceptor implements Interceptor {
private static final Logger LOG = LoggerFactory.getLogger(_GetOpenidInterceptor.class);
@Override
public void intercept(Invocation inv) {
GetOpenId getOpenId = inv.getMethod().getAnnotation(GetOpenId.class);
if (getOpenId == null) {
inv.invoke();
return;
}
//会话中已经存在openId就不获取
if (inv.getController().getSessionAttr("wxopenid")!=null){
inv.invoke();
return;
}
//不在微信浏览器的也不获取
String userAgent = inv.getController().getHeader("user-agent");
boolean isWx = false;
if (userAgent!=null){
userAgent = userAgent.toLowerCase();
if (userAgent.indexOf("micromessenger") > -1){
isWx = true;
}
}
inv.getController().setAttr("isWx",isWx);
if (!isWx){
inv.invoke();
return;
}
// 当前是跳转页面业务逻辑先处理，再获取openId
inv.invoke();
String code = inv.getController().getPara("code");
StringBuffer requestURL = inv.getController().getRequest().getRequestURL();
// TODO 你的配置项
String wxAppId = "你的微信APPID";
String wxAppSecret = "你的微信APPSECRET";
String domain = "有页面回调权限的项目域名";
if (code == null){
LOG.info("获取code url={}",requestURL);
//拼接当前路由作为回调地址，请求回调中转页
String redirectdomain = "http://"+domain+"/GETWXCODE.html";
// 当前路由全名
String url = redirectdomain+"?appid="+wxAppId+"&scope=snsapi_base&state=STATE&redirect_uri="+URLEncoder.encode(redirectdomain+"?redirect_uri="+requestURL.toString());
inv.getController().redirect(url,true);
return;
}else {
//获取到了code，以获取openid
LOG.info("获取到code={} url={}",code,requestURL);
SnsAccessToken snsAccessToken = SnsAccessTokenApi.getSnsAccessToken(wxAppId, wxAppSecret, code);
if (snsAccessToken == null||snsAccessToken.getOpenid()==null){
inv.getController().renderText("非法操作");
return;
}
inv.getController().setSessionAttr("wxopenid",snsAccessToken.getOpenid());
}
}
}package com.xxx.core.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* 获取openId
*/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface GetOpenId {
}<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>微信登陆</title>
</head>
<body>
<script>
function getUrlParams(key) {
var args = {};
var pairs = location.search.substring(1).split('&');
for (var i = 0; i < pairs.length; i++) {
var pos = pairs[i].indexOf('=');
if (pos === -1) {
continue;
}
args[pairs[i].substring(0, pos)] = decodeURIComponent(pairs[i].substring(pos + 1));
}
return args[key];
}
function appendParams(params, url) {
var baseWithSearch = url.split('#')[0];
var hash = url.split('#')[1];
for (var i = 0; i < params.length; i++) {
if (params[i].value !== undefined) {
var newParam = params[i].key + "=" + params[i].value;
if (baseWithSearch.indexOf('?') > 0) {
var oldParamReg = new RegExp(params[i].key + '=[-\\w]{0,40}', 'g');
if (oldParamReg.test(baseWithSearch)) {
baseWithSearch = baseWithSearch.replace(oldParamReg, newParam);
} else {
baseWithSearch += "&" + newParam;
}
} else {
baseWithSearch += "?" + newParam;
}
}
}
if (hash) {
url = baseWithSearch + '#' + hash;
} else {
url = baseWithSearch;
}
return url;
}
var code = getUrlParams('code');
var appId = getUrlParams('appid');
var scope = getUrlParams('scope') || 'snsapi_base';
var state = getUrlParams('state');
var redirectUrl;
if (!code) {
redirectUrl = appendParams([{
key: 'appid',
value: appId
}, {
key: 'redirect_uri',
value: encodeURIComponent(location.href)
}, {
key: 'response_type',
value: 'code'
}, {
key: 'scope',
value: scope
}, {
key: 'state',
value: state
}], 'https://open.weixin.qq.com/connect/oauth2/authorize#wechat_redirect');
} else {
redirectUrl = appendParams([{key: 'code', value: code},{
key: 'state',
value: state
}], getUrlParams('redirect_uri'));
}
location.href = redirectUrl;
</script>
</body>
</html>
贴代码有个专用按钮，可以贴出来 html、xml、java 等常见代码格式，注意看可视化编辑器上方的 icon，鼠标停留时会显示功能提示
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