java调用微信发消息

要调用微信发送消息，可以使用微信开放平台提供的API接口。以下是使用Java调用微信API发送消息的基本步骤：

1.注册微信开发者账号，并创建自己的应用程序，获取应用程序的AppID和AppSecret。

2.通过Java代码获取微信的Access Token，使用Access Token可以调用微信API。

3.构造消息内容，包括消息类型、接收者、内容等信息。

4.使用Java的HttpURLConnection或HttpClient等工具发送POST请求，将消息发送给微信API。

5.解析微信API返回的结果，判断消息是否发送成功。

以下是Java代码示例，用于发送文本消息：

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

public class WeChatAPIUtil {
    
    // 获取Access Token的URL
    private static final String ACCESS_TOKEN_URL = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=APPID&secret=APPSECRET";
    
    // 发送消息的URL
    private static final String SEND_MESSAGE_URL = "https://api.weixin.qq.com/cgi-bin/message/custom/send?access_token=ACCESS_TOKEN";
    
    /**
     * 获取Access Token
     * @param appId 应用程序的AppID
     * @param appSecret 应用程序的AppSecret
     * @return Access Token
     */
    public static String getAccessToken(String appId, String appSecret) {
        String accessToken = null;
        String url = ACCESS_TOKEN_URL.replace("APPID", appId).replace("APPSECRET", appSecret);
        try {
            URL accessTokenUrl = new URL(url);
            HttpURLConnection connection = (HttpURLConnection) accessTokenUrl.openConnection();
            connection.setRequestMethod("GET");
            connection.setConnectTimeout(5000);
            connection.setReadTimeout(5000);
            connection.connect();
            InputStream inputStream = connection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            StringBuilder responseBuilder = new StringBuilder();
            String line = null;
            while ((line = bufferedReader.readLine()) != null) {
                responseBuilder.append(line);
            }
            String response = responseBuilder.toString();
            accessToken = response.substring(response.indexOf("access_token") + 15, response.indexOf(",", response.indexOf("access_token")) - 1);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return accessToken;
    }
    
    /**
     * 发送消息
     * @param accessToken Access Token
     * @param openId 接收者的OpenID
     * @param content 消息内容
     * @return 是否发送成功
     */
    public static boolean sendMessage(String accessToken, String openId, String content) {
        boolean result = false;
        String url = SEND_MESSAGE_URL.replace("ACCESS_TOKEN", accessToken);
        String message = "{\"touser\":\"" + openId + "\",\"msgtype\":\"text\",\"text\":{\"content\":\"" + content + "\"}}";
        try {
            URL sendMessageUrl = new URL(url);
            HttpURLConnection connection = (HttpURLConnection) sendMessageUrl.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setDoInput(true);
            connection.setUseCaches(false);
            connection.setRequestProperty("Content-Type", "application/json;charset=utf-8");
            connection.connect();
            OutputStream outputStream = connection.getOutputStream();
            outputStream.write(message.getBytes("UTF-8"));
            outputStream.flush();
            outputStream.close();
            InputStream inputStream = connection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            StringBuilder responseBuilder = new StringBuilder();
            String line = null;
            while ((line = bufferedReader.readLine()) != null) {
                responseBuilder.append(line);
            }
            String response = responseBuilder.toString();
            if (response.indexOf("errcode") == -1) {
                result = true;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result;
    }
}

使用示例：

public class Test {
    
    public static void main(String[] args) {
        
        // 公众号的AppID和AppSecret
        String appId = "your app id";
        String appSecret = "your app secret";
        
        // 接收者的OpenID
        String openId = "receiver's open id";
        
        // 获取Access Token
        String accessToken = WeChatAPIUtil.getAccessToken(appId, appSecret);
        
        // 发送消息
        boolean result = WeChatAPIUtil.sendMessage(accessToken, openId, "Hello, World!");
        
        // 判断是否发送成功
        if (result) {
            System.out.println("消息发送成功！");
        } else {
            System.out.println("消息发送失败！");
        }
    }
}