Hystrix 简单请求合并_resttemplate 合并请求

频繁的调用provider接太浪费了， 就有了将多个请求合并为一个请求的方式。
首先在provider中提供一个请求合并的接口：

@RestController
public class UserController {
    /**【既可以处理多个，也可以处理单个请求】
    *单个请求的话，List中只有一项数据
    *假设 consumer 传过来的多个id格式是 1,2,3,4....*/
    @GetMapping("/user/{ids}")
    public List<User> getUserByIds(@PathVariable String ids){
        System.out.println(ids);
        String[] split = ids.split(",");
        List<User> user = new ArrayList<>();
        for(String s : split){
            User user1 = new User();
            user1.setId(Integer.parseInt(s));
            user.add(user1);
        }
        return user;
    }
}
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然后在Hystrix中定义UserService：

@Service
public class UserService {

    @Autowired
    RestTemplate restTemplate;
    

    public List<User> getUsersByIds(List<Integer> ids){
        User[] users = restTemplate.getForObject("http://provider/user/{1}", User[].class, StringUtils.join(ids, ","));
        return Arrays.asList(users);
    }
}
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接下来定义 UserBatchCommand ，相当于我们之前的 HelloCommand：

public class UserBatchCommand extends HystrixCommand<List<User>> {
    private List<Integer> ids;
    private UserService userService;

    public UserBatchCommand(List<Integer> ids, UserService userService) {
        super(HystrixCommand.Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("batchCmd")).andCommandKey(HystrixCommandKey.Factory.asKey("batchKey")));
        this.ids = ids;
        this.userService = userService;
    }

    @Override
    protected List<User> run() throws Exception {
        return userService.getUsersByIds(ids);
    }
}

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一、最后定请求合并方法，【继承方式，做为了解】：

public class UserCollapseCommand extends HystrixCollapser<List<User>, User, Integer> {
    private UserService userService;
    private Integer id;

    public UserCollapseCommand(UserService userService, Integer id) {
        super(HystrixCollapser.Setter.withCollapserKey(HystrixCollapserKey.Factory.asKey("UserCollapseCommand")).andCollapserPropertiesDefaults(HystrixCollapserProperties.Setter().withTimerDelayInMilliseconds(200)));
        this.userService = userService;
        this.id = id;
    }

    /**
     * 请求参数
     *
     * @return
     */
    @Override
    public Integer getRequestArgument() {
        return id;
    }

    /**
     * 请求合并的方法
     *
     * @param collection
     * @return
     */
    @Override
    protected HystrixCommand<List<User>> createCommand(Collection<CollapsedRequest<User, Integer>> collection) {
        List<Integer> ids = new ArrayList<>(collection.size());
        for (CollapsedRequest<User, Integer> userIntegerCollapsedRequest : collection) {
            ids.add(userIntegerCollapsedRequest.getArgument());
        }
        return new UserBatchCommand(ids, userService);
    }

    /**
     * 请求结果分发
     *
     * @param users
     * @param collection
     */
    @Override
    protected void mapResponseToRequests(List<User> users, Collection<CollapsedRequest<User, Integer>> collection) {
        int count = 0;
        for (CollapsedRequest<User, Integer> request : collection) {
            request.setResponse(users.get(count++));
        }
    }
}
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然后测试调用：

@GetMapping("/hello5")
    public void hello5() throws ExecutionException,InterruptedException{
        HystrixRequestContext ctx = HystrixRequestContext.initializeContext();
        UserCollapseCommand cmd1 = new UserCollapseCommand(userService, 99);
        UserCollapseCommand cmd2 = new UserCollapseCommand(userService, 98);
        UserCollapseCommand cmd3 = new UserCollapseCommand(userService, 97);

        Future<User> q1 = cmd1.queue();
        Future<User> q2 = cmd2.queue();
        Future<User> q3 = cmd3.queue();

        User u1 = q1.get();
        User u2 = q2.get();
        User u3 = q3.get();

        System.out.println(u1);
        System.out.println(u2);
        System.out.println(u3);
        Thread.sleep(2000);//睡2秒就变成两次请求，
        UserCollapseCommand cmd4 = new UserCollapseCommand(userService, 96);
        Future<User> q4 = cmd4.queue();
        User u4 = q4.get();
        System.out.println(u4);
        ctx.close();

    }
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二、通过注解实现请求合并【掌握】：

@Service
public class UserService {

    @Autowired
    RestTemplate restTemplate;

    /**
     * 注解方式实现请求合并
     * @param id
     * @return HystrixCollapse
     *【重要：@HystrixCollapser 注解指定批处理方法】
     */
    @HystrixCollapser(batchMethod = "getUsersByIds",collapserProperties = {@HystrixProperty(name = "timerDelayInMilliseconds",value = "200")})
    public Future<User> getUserById(Integer id) {
        return null;
    }

    @HystrixCommand
    public List<User> getUsersByIds(List<Integer> ids){
        User[] users = restTemplate.getForObject("http://provider/user/{1}", User[].class, StringUtils.join(ids, ","));
        return Arrays.asList(users);
    }
}
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测试方法：

    /**
     * 注解方式实现请求合并 测试方法
     * @throws ExecutionException
     * @throws InterruptedException
     */
    @GetMapping("/hello6")
    public void hello6() throws ExecutionException, InterruptedException {
        HystrixRequestContext ctx = HystrixRequestContext.initializeContext();
        Future<User> q1 = userService.getUserById(99);
        Future<User> q2 = userService.getUserById(98);
        Future<User> q3 = userService.getUserById(97);
        User u1 = q1.get();
        User u2 = q2.get();
        User u3 = q3.get();
        System.out.println(u1);
        System.out.println(u2);
        System.out.println(u3);
        Thread.sleep(2000);
        Future<User> q4 = userService.getUserById(96);
        User u4 = q4.get();
        System.out.println(u4);
        ctx.close();
    }
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小结 ：@HystrixCollapser(batchMethod = “getUserByIds”,collapserProperties = {@HystrixProperty(name = “timerDelayInMilliseconds”,value = “200”)})

@HystrixCommand

代码地址：https://github.com/astronger/springcloud-simple-samples