springboot中责任链模式之简朴应用

知者何南 · 4 天前

一、简朴需求

在CSDN博客主动阅读器-服务端推送技术SSE之简朴应用一文中，我们实现了个人博客文章的后台推送功能。
初始化推送数据是通过接口来实现的，如今我们盼望实现如下功能优化：

定义多种初始化数据来源，详细而言，有3种方式：①web 接口、②docker映射文件、③本地资源文件
支持初始化数据方式的优先级指定。
不排除将来会添加其他的初始化方式。比方，通过本地接口提交初始化数据。

二、实现过程

下面我们利用责任链模式来实现上述需求。
1、定义接口

import java.util.List;
import com.fly.demo.entity.Article;
/**
* 数据初始化
*/
public interface DataInitor
{
/**
* 执行初始化
*
* @param articles
* @return 是否成功
*/
boolean init(List<Article> articles);
}

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2、定义实现类

1.）web 接口方式初始化类

留意： web 接口方式初始化Webclient不可利用异步，而且需要设置超时时间，避免长时间无相应的情况下导致的无谓的等候。

import java.nio.charset.StandardCharsets;
import java.time.Duration;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.annotation.Order;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import org.springframework.web.reactive.function.client.WebClient;
import com.fly.demo.entity.Article;
import com.fly.demo.entity.BlogData;
import lombok.extern.slf4j.Slf4j;
/**
* 通过WebApi接口初始化
*/
@Slf4j
@Order(1)
@Component
public class WebApiDataInitor implements DataInitor
{
@Autowired
WebClient webClient;
@Override
public boolean init(List<Article> articles)
{
try
{
log.info("start init...");
BlogData blogData = webClient.get()
.uri("https://00fly.online/upload/data.json")
.acceptCharset(StandardCharsets.UTF_8)
.accept(MediaType.APPLICATION_JSON)
.retrieve()
.bodyToMono(BlogData.class)
.timeout(Duration.ofSeconds(10)) // 单独设置超时
.block();
if (blogData != null)
{
articles.addAll(blogData.getData().getList());
}
return !CollectionUtils.isEmpty(articles);
}
catch (Exception e)
{
log.error(e.getMessage(), e);
return false;
}
}
}

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2.）Docker映射文件初始化

import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
import org.apache.commons.io.IOUtils;
import org.springframework.core.annotation.Order;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import com.fly.core.utils.JsonBeanUtils;
import com.fly.demo.entity.Article;
import com.fly.demo.entity.BlogData;
import lombok.extern.slf4j.Slf4j;
/**
* 通过Docker映射文件初始化
*/
@Slf4j
@Order(2)
@Component
public class DockerDataInitor implements DataInitor
{
PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
@Override
public boolean init(List<Article> articles)
{
try
{
log.info("start init...");
Resource[] jsons = resolver.getResources("file:/data/data*.json");
articles.addAll(Arrays.stream(jsons).map(json -> parseToArticles(json)).flatMap(List::stream).distinct().collect(Collectors.toList()));
return !CollectionUtils.isEmpty(articles);
}
catch (IOException e)
{
log.error(e.getMessage(), e);
return false;
}
}
/**
* 解析Resource为List
*
* @param resource
* @return
*/
private List<Article> parseToArticles(Resource resource)
{
try (InputStream input = resource.getInputStream())
{
String jsonData = IOUtils.toString(input, StandardCharsets.UTF_8);
return JsonBeanUtils.jsonToBean(jsonData, BlogData.class, true).getData().getList();
}
catch (IOException e)
{
log.error(e.getMessage(), e);
return Collections.emptyList();
}
}
}

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3.）通过资源文件初始化

import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
import org.apache.commons.io.IOUtils;
import org.springframework.core.annotation.Order;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import com.fly.core.utils.JsonBeanUtils;
import com.fly.demo.entity.Article;
import com.fly.demo.entity.BlogData;
import lombok.extern.slf4j.Slf4j;
/**
* 通过资源文件初始化
*/
@Slf4j
@Order(3)
@Component
public class ResourceDataInitor implements DataInitor
{
PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
@Override
public boolean init(List<Article> articles)
{
try
{
log.info("start init...");
Resource[] jsons = resolver.getResources("classpath:*.json");
articles.addAll(Arrays.stream(jsons).map(json -> parseToArticles(json)).flatMap(List::stream).distinct().collect(Collectors.toList()));
return !CollectionUtils.isEmpty(articles);
}
catch (IOException e)
{
log.error(e.getMessage(), e);
return false;
}
}
/**
* 解析Resource为List
*
* @param resource
* @return
*/
private List<Article> parseToArticles(Resource resource)
{
try (InputStream input = resource.getInputStream())
{
String jsonData = IOUtils.toString(input, StandardCharsets.UTF_8);
return JsonBeanUtils.jsonToBean(jsonData, BlogData.class, true).getData().getList();
}
catch (IOException e)
{
log.error(e.getMessage(), e);
return Collections.emptyList();
}
}
}

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3、编写初始化逻辑

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import com.fly.demo.entity.Article;
import com.fly.demo.service.init.DataInitor;
import lombok.extern.slf4j.Slf4j;
/**
* DataService
*/
@Slf4j
@Service
public class DataService
{
@Autowired
List<DataInitor> dataInitors;
/**
* 获取url数据列表
*
* @return
* @throws IOException
*/
@Cacheable(cacheNames = "data", key = "'articles'", sync = true)
public List<Article> getArticles()
{
AtomicInteger count = new AtomicInteger();
dataInitors.stream().forEach(d -> log.info("{}. {}", count.incrementAndGet(), d));
// 串行流,有一个DataInitor执行init成功就返回
List<Article> articles = new ArrayList<>();
dataInitors.stream()
.peek(d -> log.info("{}", d.getClass().getName())) // debug
.anyMatch(d -> d.init(articles));
log.info("############## articles.size: {} ", articles.size());
return articles;
}
}

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三、单位测试

为了方便演示，我们编写了单位测试代码
1、单位测试代码

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import com.fly.demo.entity.Article;
import com.fly.demo.service.init.DataInitor;
import lombok.extern.slf4j.Slf4j;
@Slf4j
@SpringBootTest(webEnvironment = WebEnvironment.NONE)
public class DataInitTest
{
@Autowired
List<DataInitor> dataInitors;
@BeforeEach
public void before()
{
AtomicInteger count = new AtomicInteger();
dataInitors.stream().forEach(d -> log.info("{}. {}", count.incrementAndGet(), d));
}
@Test
public void testStream()
{
// lambda写法, 串行流至少有一个DataInitor执行init成功
List<Article> articles = new ArrayList<>();
dataInitors.stream()
.peek(d -> log.info("{}", d.getClass().getName())) // debug
.anyMatch(d -> d.init(articles));
log.info("############## articles.size: {} ", articles.size());
}
@Test
public void testCommon()
{
// 传统写法
List<Article> articles = new ArrayList<>();
for (DataInitor dataInitor : dataInitors)
{
log.info("{}", dataInitor.getClass().getName());
if (dataInitor.init(articles))
{
log.info("############## articles.size: {} ", articles.size());
return;
}
}
}
}

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2、运行结果

. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.2.4.RELEASE)
2024-12-22 13:04:16.155 INFO 3144 --- [ main] c.f.DataInitTest : Starting DataInitTest on 7t9lppye5cj7lud with PID 3144 (started by 00fly in D:\Gitcode\csdn-reader)
2024-12-22 13:04:16.162 INFO 3144 --- [ main] c.f.DataInitTest : The following profiles are active: dev
2024-12-22 13:04:18.201 INFO 3144 --- [ main] c.f.c.u.SpringContextUtils : ###### execute setApplicationContext ######
2024-12-22 13:04:19.535 INFO 3144 --- [ main] o.s.s.c.ThreadPoolTaskScheduler : Initializing ExecutorService 'taskScheduler'
2024-12-22 13:04:19.663 INFO 3144 --- [ main] c.f.DataInitTest : Started DataInitTest in 4.551 seconds (JVM running for 10.165)
2024-12-22 13:04:20.366 INFO 3144 --- [ main] c.f.DataInitTest : 1. com.fly.demo.service.init.WebApiDataInitor@2881ad47
2024-12-22 13:04:20.367 INFO 3144 --- [ main] c.f.DataInitTest : 2. com.fly.demo.service.init.DockerDataInitor@37fdfb05
2024-12-22 13:04:20.367 INFO 3144 --- [ main] c.f.DataInitTest : 3. com.fly.demo.service.init.ResourceDataInitor@5e39850
2024-12-22 13:04:20.374 INFO 3144 --- [ main] c.f.DataInitTest : com.fly.demo.service.init.WebApiDataInitor
2024-12-22 13:04:20.374 INFO 3144 --- [ main] c.f.d.s.i.WebApiDataInitor : start init...
2024-12-22 13:04:24.000 INFO 3144 --- [ main] c.f.DataInitTest : ############## articles.size: 126
2024-12-22 13:04:26.082 INFO 3144 --- [extShutdownHook] o.s.s.c.ThreadPoolTaskScheduler : Shutting down ExecutorService 'taskScheduler'

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3、如何控制优先级

细心的同鞋，已经发现了在我们的实现类中利用了@Order 注解，仔细关心上面的日记输出，我们发现order的取值会影响 List<DataInitor> dataInitors的实现类的排列顺序，假如我们需要把Docker映射文件初始化优先级提升，只需要把order改小，改为0或-1均可，大家可以动手尝试！
四、源码放送

https://gitcode.com/00fly/csdn-reader

有任何问题和发起，都可以向我提问讨论,大家一起进步，谢谢!
-over-

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springboot中责任链模式之简朴应用

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