java微信自动回复怎么实现

实现微信自动回复需要使用微信公众平台接口进行开发，以下是实现的大致步骤：

1. 注册微信公众平台账号并获取开发者ID和开发者密码。

2. 在微信公众平台中创建公众号，并开启开发模式。

3. 编写Java程序，使用微信公众平台提供的接口实现自动回复功能。

4. 在程序中使用开发者ID和开发者密码进行认证并获取access_token。

5. 根据用户发送的消息类型进行相应的处理并回复消息。

以下是一份Java微信自动回复的示例代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Arrays;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import javax.net.ssl.HttpsURLConnection;

import org.apache.commons.codec.binary.Base64;
import org.json.JSONArray;
import org.json.JSONObject;

public class WeChatAutoReply {
    private static final String APPID = "your_appid";
    private static final String APPSECRET = "your_appsecret";
    private static final String TOKEN = "your_token";

    public static void main(String[] args) {
        try {
            WeChatAutoReply autoReply = new WeChatAutoReply();
            String message = autoReply.getMessage("hello");
            System.out.println(message);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public String getMessage(String content) throws Exception {
        String message = "";
        String accessToken = getAccessToken();
        String url = "https://api.weixin.qq.com/cgi-bin/message/custom/send?access_token=" + accessToken;
        JSONObject json = new JSONObject();
        json.put("touser", "your_openid");
        json.put("msgtype", "text");
        JSONObject text = new JSONObject();
        text.put("content", content);
        json.put("text", text);
        String data = json.toString();
        String result = sendPost(url, data);
        JSONObject resultJson = new JSONObject(result);
        if (resultJson.getInt("errcode") == 0) {
            message = "发送成功";
        } else {
            message = "发送失败";
        }
        return message;
    }

    private String getAccessToken() throws Exception {
        String accessToken = "";
        String url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=" + APPID + "&secret=" + APPSECRET;
        String result = sendGet(url);
        JSONObject resultJson = new JSONObject(result);
        if (resultJson.has("access_token")) {
            accessToken = resultJson.getString("access_token");
        }
        return accessToken;
    }

    private String sendGet(String url) throws Exception {
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();
        con.setRequestMethod("GET");
        con.setRequestProperty("User-Agent", "Mozilla/5.0");
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();
        return response.toString();
    }

    private String sendPost(String url, String data) throws Exception {
        URL obj = new URL(url);
        HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();
        con.setRequestMethod("POST");
        con.setRequestProperty("User-Agent", "Mozilla/5.0");
        con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
        con.setRequestProperty("Content-Type", "application/json");
        con.setRequestProperty("Authorization", "Basic " + getAuthorization());
        String urlParameters = data;
        con.setDoOutput(true);
        con.getOutputStream().write(urlParameters.getBytes("UTF-8"));
        InputStream inputStream = con.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        String line;
        StringBuilder response = new StringBuilder();
        while ((line = reader.readLine()) != null) {
            response.append(line);
        }
        reader.close();
        return response.toString();
    }

    private String getAuthorization() throws Exception {
        String[] keys = new String[] { "grant_type", "appid", "secret" };
        Arrays.sort(keys);
        StringBuilder sb = new StringBuilder();
        for (String key : keys) {
            sb.append(key).append("=").append(URLEncoder.encode(getValue(key), "UTF-8")).append("&");
        }
        sb.deleteCharAt(sb.length() - 1);
        String stringToSign = sb.toString();
        String signature = hmacSha256(stringToSign, APPSECRET);
        return Base64.encodeBase64String((APPID + ":" + signature).getBytes("UTF-8"));
    }

    private String hmacSha256(String message, String secret) throws Exception {
        SecretKeySpec keySpec = new SecretKeySpec(secret.getBytes("UTF-8"), "HmacSHA256");
        Mac mac = Mac.getInstance("HmacSHA256");
        mac.init(keySpec);
        byte[] rawHmac = mac.doFinal(message.getBytes("UTF-8"));
        return Base64.encodeBase64String(rawHmac);
    }

    private String getValue(String key) {
        if ("grant_type".equals(key)) {
            return "client_credential";
        } else if ("appid".equals(key)) {
            return APPID;
        } else if ("secret".equals(key)) {
            return APPSECRET;
        }
        return null;
    }
}

在这段代码中，需要将`your_appid`、`your_appsecret`和`your_openid`替换为你的微信公众平台账号相关信息。同时，需要注意在使用微信公众平台接口时需要遵循微信公众平台开发规范，例如不要频繁调用API接口等。