上一版需求做了微信公众号开发，秀了一波操作，也遇到了很多坑。现在把微信公众号一些基本的操作记录一下。
微信公众号获取access_token官方文档地址
access_token是公众号的全局唯一接口调用凭据，我们和微信服务器进行交互，服务器通过access_token判断我们是谁(哪个公众号服务的请求)。所以 我们在开发过程中服务端拿到的access_token是一定不能显式暴露给外部，否则将导致数据安全问题。别人拿到你的accessToken操作你的公众号。access_token的有效期目前为2个小时，过期需要再次获取。
下面是一种获取access_token方式
1.项目添加httpclient相关依赖，示例使用httpclient请求微信服务器，获取微信返回结果。
<!-- /artifact/org.apache.httpcomponents/httpclient --><dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpclient</artifactId><version>4.5.3</version></dependency><!-- /artifact/org.apache.httpcomponents/httpcore --><dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpcore</artifactId><version>4.4.6</version></dependency>
2.httpClientUtil类，网上随手找的 试了一下本例的doget方法 没有问题，其他的 暂不考虑
public class HttpClientUtil {public static String doGet(String url, Map<String, String> param) {// 创建Httpclient对象CloseableHttpClient httpclient = HttpClients.createDefault();String resultString = "";CloseableHttpResponse response = null;try {// 创建uriURIBuilder builder = new URIBuilder(url);if (param != null) {for (String key : param.keySet()) {builder.addParameter(key, param.get(key));}}URI uri = builder.build();// 创建http GET请求HttpGet httpGet = new HttpGet(uri);// 执行请求response = httpclient.execute(httpGet);// 判断返回状态是否为200if (response.getStatusLine().getStatusCode() == 200) {resultString = EntityUtils.toString(response.getEntity(), "UTF-8");}} catch (Exception e) {e.printStackTrace();} finally {try {if (response != null) {response.close();}httpclient.close();} catch (IOException e) {e.printStackTrace();}}return resultString;}public static String doGet(String url) {return doGet(url, null);}public static String doPost(String url, Map<String, String> param) {// 创建Httpclient对象CloseableHttpClient httpClient = HttpClients.createDefault();CloseableHttpResponse response = null;String resultString = "";try {// 创建Http Post请求HttpPost httpPost = new HttpPost(url);// 创建参数列表if (param != null) {List<NameValuePair> paramList = new ArrayList<>();for (String key : param.keySet()) {paramList.add(new BasicNameValuePair(key, param.get(key)));}// 模拟表单UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList,"utf-8");httpPost.setEntity(entity);}// 执行http请求response = httpClient.execute(httpPost);resultString = EntityUtils.toString(response.getEntity(), "utf-8");} catch (Exception e) {e.printStackTrace();} finally {try {response.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}return resultString;}public static String doPost(String url) {return doPost(url, null);}public static String doPostJson(String url, String json) {// 创建Httpclient对象CloseableHttpClient httpClient = HttpClients.createDefault();CloseableHttpResponse response = null;String resultString = "";try {// 创建Http Post请求HttpPost httpPost = new HttpPost(url);// 创建请求内容StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);httpPost.setEntity(entity);// 执行http请求response = httpClient.execute(httpPost);resultString = EntityUtils.toString(response.getEntity(), "utf-8");} catch (Exception e) {e.printStackTrace();} finally {try {response.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}return resultString;}}
3.第三步就是简单的测试代码了
public class WeChatAccessTokenTest {public static void main(String[] args) {Map<String, String> params = new HashMap<>();// TODO: /11/16 *号改成真实appidparams.put("appid", "******");// TODO: /11/16 *号改成真实secretparams.put("secret", "******");params.put("grant_type", "client_credential");String response = HttpClientUtil.doGet("https://api./cgi-bin/token", params);JSONObject accessTokenObject = JSONObject.parseObject(response);String accessToken = accessTokenObject.getString("access_token");Long expire = accessTokenObject.getLong("expires_in");System.out.println(accessToken);}}
以上就是微信公众号基础却比较重要的获取access_token操作了！
