POST https://oapi.dingtalk.com/robot/send?access_token=ACCESS_TOKEN

{
  "at":{
    "isAtAll":"false",
    "atUserIds":["user001","user002"],
    "atMobiles":["15xxx","18xxx"]
  },
    //链接消息
  "link":{
    "messageUrl":"1",
    "picUrl":"1",
    "text":"1",
    "title":"1"
  },
    //markdown消息
  "markdown":{
    "text":"1",
    "title":"1"
  },
    //feedCard消息
  "feedCard":{
    "links":{
      "picURL":"1",
      "messageURL":"1",
      "title":"1"
    }
  },
    //文本消息
  "text":{
    "content":"123"
  },
  "msgtype":"text",
    //actionCard消息
  "actionCard":{
    "hideAvatar":"1",
    "btnOrientation":"1",
    "singleTitle":"1",
    "btns":[{
      "actionURL":"1",
      "title":"1"
    }],
    "text":"1",
    "singleURL":"1",
    "title":"1"
  }
}

<dependency>
    <groupId>com.aliyun</groupId>
    <artifactId>alibaba-dingtalk-service-sdk</artifactId>
    <version>2.0.0</version>
</dependency>
<dependency>
    <groupId>com.aliyun</groupId>
    <artifactId>dingtalk</artifactId>
    <version>2.0.18</version>
</dependency>

import com.dingtalk.api.DefaultDingTalkClient;
import com.dingtalk.api.DingTalkClient;
import com.dingtalk.api.request.OapiRobotSendRequest;
import com.dingtalk.api.response.OapiRobotSendResponse;
import com.taobao.api.ApiException;
import java.util.Arrays;
public class DingTalk {
    public static void main(String[] args) {
        try {
            // 1-初始化API调用Client
            DingTalkClient client = new DefaultDingTalkClient("https://oapi.dingtalk.com/robot/send?access_token=87b520af3e0b6aacc137d1525e4d9b21f61c901f1c8ac4f05a17bc12a8e7f737");
            // 2-初始化请求参数
            OapiRobotSendRequest req = new OapiRobotSendRequest();
            // 2-1 设置消息类型
            req.setMsgtype("text");
            // 2-2 设置消息@人
            OapiRobotSendRequest.At at = new OapiRobotSendRequest.At();
            at.setAtMobiles(Arrays.asList("17600477102"));
            req.setAt(at);
            // 2-3 设置消息内容(必须匹配关键词)，工作中这里就对应error日志
            OapiRobotSendRequest.Text text = new OapiRobotSendRequest.Text();
            text.setContent("[告警]测试java代码消息");
            req.setText(text);
            // 3 消息发送
            OapiRobotSendResponse rsp = client.execute(req, "");
            System.out.println(rsp.getBody());
        } catch (ApiException e) {
            e.printStackTrace();
        }
    }
}