add read one article

src/main/java/io/spring/JacksonCustomizations.java

@@ -0,0 +1,44 @@
+package io.spring;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.Module;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.module.SimpleModule;
+import com.fasterxml.jackson.databind.ser.std.StdSerializer;
+import org.joda.time.DateTime;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import java.io.IOException;
+
+@Configuration
+public class JacksonCustomizations {
+
+    @Bean
+    public Module realWorldModules() {
+        return new RealWorldModules();
+    }
+
+    public static class RealWorldModules extends SimpleModule {
+        public RealWorldModules() {
+            addSerializer(DateTime.class, new DateTimeSerializer());
+        }
+    }
+
+    public static class DateTimeSerializer extends StdSerializer<DateTime> {
+
+        protected DateTimeSerializer() {
+            super(DateTime.class);
+        }
+
+        @Override
+        public void serialize(DateTime value, JsonGenerator gen, SerializerProvider provider) throws IOException {
+            if (value == null) {
+                gen.writeNull();
+            } else {
+                gen.writeString(value.toString());
+            }
+        }
+    }
+
+}

src/main/java/io/spring/api/ArticleApi.java

@@ -0,0 +1,30 @@
+package io.spring.api;
+
+import io.spring.api.exception.ResourceNotFoundException;
+import io.spring.application.article.ArticleData;
+import io.spring.application.article.ArticleQueryService;
+import io.spring.core.user.User;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping(path = "/articles/{slug}")
+public class ArticleApi {
+    private ArticleQueryService articleQueryService;
+
+    @Autowired
+    public ArticleApi(ArticleQueryService articleQueryService) {
+        this.articleQueryService = articleQueryService;
+    }
+
+    @GetMapping
+    public ResponseEntity<ArticleData> article(@PathVariable("slug") String slug,
+                                               @AuthenticationPrincipal User user) {
+        return articleQueryService.findBySlug(slug, user).map(ResponseEntity::ok).orElseThrow(ResourceNotFoundException::new);
+    }
+}

src/main/java/io/spring/api/exception/ResourceNotFoundException.java

@@ -0,0 +1,8 @@
+package io.spring.api.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(value = HttpStatus.NOT_FOUND)
+public class ResourceNotFoundException extends RuntimeException {
+}

src/main/java/io/spring/api/security/WebSecurityConfig.java

@@ -26,6 +26,7 @@ public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
             .sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS).and()
             .authorizeRequests()
             .antMatchers(HttpMethod.POST, "/users", "/users/login").permitAll()
+            .antMatchers(HttpMethod.GET, "/articles/**").permitAll()
             .anyRequest().authenticated();
 
         http.addFilterBefore(jwtTokenFilter(), UsernamePasswordAuthenticationFilter.class);

src/main/java/io/spring/application/article/ArticleQueryService.java

@@ -23,17 +23,35 @@ public class ArticleQueryService {
     }
 
     public Optional<ArticleData> findById(String id, User user) {
-        ArticleData articleData = articleReadService.ofId(id);
+        ArticleData articleData = articleReadService.findById(id);
         if (articleData == null) {
             return Optional.empty();
         } else {
-            articleData.setFavorited(articleFavoritesQueryService.isUserFavorite(user.getId(), id));
-            articleData.setFavoritesCount(articleFavoritesQueryService.articleFavoriteCount(id));
-            articleData.getProfileData().setFollowing(
-                userRelationshipQueryService.isUserFollowing(
-                    user.getId(),
-                    articleData.getProfileData().getId()));
+            if (user != null) {
+                fillExtraInfo(id, user, articleData);
+            }
             return Optional.of(articleData);
         }
     }
+
+    public Optional<ArticleData> findBySlug(String slug, User user) {
+        ArticleData articleData = articleReadService.findBySlug(slug);
+        if (articleData == null) {
+            return Optional.empty();
+        } else {
+            if (user != null) {
+                fillExtraInfo(articleData.getId(), user, articleData);
+            }
+            return Optional.of(articleData);
+        }
+    }
+
+    private void fillExtraInfo(String id, User user, ArticleData articleData) {
+        articleData.setFavorited(articleFavoritesQueryService.isUserFavorite(user.getId(), id));
+        articleData.setFavoritesCount(articleFavoritesQueryService.articleFavoriteCount(id));
+        articleData.getProfileData().setFollowing(
+            userRelationshipQueryService.isUserFollowing(
+                user.getId(),
+                articleData.getProfileData().getId()));
+    }
 }

src/main/java/io/spring/application/article/ArticleReadService.java

@@ -7,5 +7,7 @@ import org.springframework.stereotype.Component;
 @Component
 @Mapper
 public interface ArticleReadService {
-    ArticleData ofId(@Param("id") String id);
+    ArticleData findById(@Param("id") String id);
+
+    ArticleData findBySlug(@Param("slug") String slug);
 }