java 异步执行代码(先返回结果，后执行代码

业务场景：

        在用户那，角色那变更后，要更新数据，因为更新要比较长时间，需要先返回结果（2:已接收待执行）。更新结束后，再返回值结果。

（执行结果. 0:执行失败 ； 1:执行成功； 2:已接收待执行）

处理1： 简单异步

使用 ExecutorService 异步

    public void onCallback(JSONObject param) {        ExecutorService executor = Executors.newCachedThreadPool();        executor.execute(() -> {            try {                Thread.sleep(1000 * 10);            } catch (InterruptedException e) {                e.printStackTrace();            }            // 这边执行具体的方法            this.syncDealResult(param);        });        executor.shutdown();    }    public JSONObject dealResult(jsONObject params) {        // 先返回结果，然后异步执行        this.onCallback(params);        JSONObject result = new JSONObject();        result.put("excRs", "2");        return result;    }     public void syncDealResult(JSONObject params) {        logger.info("deal abRole param {}", JSON.toJSONString(params));        String logId = MapUtils.getString(params, "logId");        String excRs = "1";        try {            // 具体操作        } catch (Exception e) {            e.printStackTrace();            excRs = "-1";        }        logger.info("update abRole finish callRecordId {}, excRs {}", logId, excRs);        // 处理完后推送结果        JSONObject param = new JSONObject();        param.put("logId", logId);        param.put("excRs", excRs);        // 推送结果    }

加 Thread.sleep(1000 * 10); 就明显看得出差别了。

如果是有多种异步执行，比如：A执行完后，B要做通知；C要入库；D要做统计，这时候要怎么处理呢？

处理2：多个异步执行

IRoleCallback

import com.alibaba.fastjson.JSONObject;import org.apache.commons.lang3.StringUtils;public interface IRoleCallback {        Object call(JSONObject param) throws Exception;        default String name() {        return StringUtils.uncapitalize(getClass().getSimpleName());    }        default double order() {        return 1.0d;    }}

RoleCallbackReGISter

import java.util.*;public class RoleCallbackRegister {    private static final Map CALLBACKS = new HashMap<>();    public static boolean register(IRoleCallback callback) {        if (CALLBACKS.containsKey(callback.name())) {            return false;        }        CALLBACKS.put(callback.name(), callback);        return true;    }    public static List getCallbacks() {        List roleCallbacks = new ArrayList<>(CALLBACKS.values());        roleCallbacks.sort(Comparator.comparingDouble(IRoleCallback::order));        return roleCallbacks;    }}

springUtils

@Componentpublic class SpringUtils implements ApplicationContextAware {    private static ApplicationContext applicationContext;    @Override    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {        SpringUtils.applicationContext = applicationContext;    }    public static Object getBean(String name) {        return applicationContext.getBean(name);    }    public static  T getBean(Class clazz) {        return applicationContext.getBean(clazz);    }}

AbstractRoleCallbackImpl

import com.WEB.work.common.support.SpringUtils;import com.alibaba.fastjson.JSONObject;import org.apache.commons.lang3.StringUtils;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.InitializingBean;public abstract class AbstractRoleCallbackImpl implements IRoleCallback, InitializingBean {    protected final Logger logger = LoggerFactory.getLogger(getClass());    @Override    public Object call(JSONObject param) throws Exception {        return doCall(param);    }    protected abstract Object doCall(JSONObject param) throws Exception;    @Override    public String name() {        return StringUtils.uncapitalize(getClass().getSimpleName());    }    @Override    public void afterPropertiesSet() {        boolean register = RoleCallbackRegister.register(SpringUtils.getBean(this.getClass()));        if (!register) {            logger.error("register role callback name:{} failed.", name());        } else {            logger.info("register role callback name:{} succeed.", name());        }    }}

RoleCallBackService

@Servicepublic class RoleCallBackService implements InitializingBean, DisposableBean {    private final static Logger logger = LoggerFactory.getLogger(RoleCallBackService.class);    private ThreadPoolExecutor pool;    public void onCallback(JSONObject param) {        pool.execute(() -> {            RoleCallbackRegister.getCallbacks().forEach(x -> {                try {                    logger.info("call {}", x.name());                    x.call(param);                } catch (Exception e) {                    logger.error("回调{}接口失败：", x.name(), e);                }            });        });    }    @Override    public void afterPropertiesSet() {        int size = Runtime.getRuntime().availableProcessors() + 1;        pool = new ThreadPoolExecutor(size, size * 2, 300L, TimeUnit.SECONDS, new LinkedBlockingQueue<>(1000),                Executors.defaultThreadFactory(), new ThreadPoolExecutor.CallerRunsPolicy());    }    @Override    public void destroy() throws Exception {        pool.shutdown();    }}

RoleUpdateService

@Servicepublic class RoleUpdateService extends AbstractRoleCallbackImpl {    private final static Logger logger = LoggerFactory.getLogger(RoleUpdateService.class);    @Override    protected Object doCall(JSONObject params) throws Exception {        Thread.sleep(1000 * 10);        logger.info("deal abRole param {}", JSON.toJSONString(params));        String logId = MapUtils.getString(params, "logId");        String excRs = "1";        try {            // 执行更新操作        } catch (Exception e) {            e.printStackTrace();            excRs = "-1";        }        logger.info("update abRole finish callRecordId {}, excRs {}", logId, excRs);        // 处理完后推送结果        JSONObject param = new JSONObject();        param.put("logId", logId);        param.put("excRs", excRs);        logger.info("update role record {}", JSON.toJSONString(param));        // 推送结果        return "";    }}

先返回结果后执行

    @Resource    private RoleCallBackService roleCallBackService;    public JSONObject dealResult(JSONObject params) {        // 先返回结果，然后异步执行        try {            roleCallBackService.onCallback(params);        } catch (Exception e) {            e.printStackTrace();        }        JSONObject result = new JSONObject();        result.put("excRs", "2");        return result;    }

总结：

        要先返回结果，后执行内容，需要使用异步的方式，用ExecutorService进行处理。如果是单个的，就直接调用比较简单。如果是多个的，就先要注册下，然后遍历去调用。 

来源地址：https://blog.csdn.net/qq_35461948/article/details/130762448