wx.login()返回的code用java代码获取

在Java中获取微信小程序登录的code，可以使用HTTPURLConnection或者OkHttp库来发送HTTP请求，示例代码如下：

使用HTTPURLConnection：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class WeChatLogin {
    public static void main(String[] args) {
        String appId = "your_app_id";
        String secret = "your_secret";
        String jsCode = "your_js_code";
        String url = "https://api.weixin.qq.com/sns/jscode2session?appid=" + appId + "&secret=" + secret + "&js_code=" + jsCode + "&grant_type=authorization_code";
        try {
            URL obj = new URL(url);
            HttpURLConnection con = (HttpURLConnection) obj.openConnection();
            con.setRequestMethod("GET");
            BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
            String inputLine;
            StringBuffer response = new StringBuffer();
            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
            in.close();
            System.out.println(response.toString());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

使用OkHttp：

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
import java.io.IOException;

public class WeChatLogin {
    public static void main(String[] args) {
        String appId = "your_app_id";
        String secret = "your_secret";
        String jsCode = "your_js_code";
        String url = "https://api.weixin.qq.com/sns/jscode2session?appid=" + appId + "&secret=" + secret + "&js_code=" + jsCode + "&grant_type=authorization_code";
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url(url)
                .build();
        try (Response response = client.newCall(request).execute()) {
            System.out.println(response.body().string());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

在这个例子中，你需要将 `your_app_id` 和 `your_secret` 替换成你的小程序的AppID和AppSecret，`your_js_code` 替换成 `wx.login()` 方法返回的code。