Add internationalization support

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/java/com/acme/custom/CustomProblem.java

@@ -8,6 +8,7 @@
 
 import io.github.belgif.rest.problem.api.ClientProblem;
 import io.github.belgif.rest.problem.api.ProblemType;
+import io.github.belgif.rest.problem.i18n.I18N;
 
 @ProblemType(CustomProblem.TYPE)
 public class CustomProblem extends ClientProblem {
@@ -24,6 +25,7 @@ public class CustomProblem extends ClientProblem {
     @JsonCreator
     public CustomProblem(@JsonProperty("customField") String customField) {
         super(TYPE_URI, TITLE, STATUS);
+        setDetail(I18N.getLocalizedDetail(CustomProblem.class));
         this.customField = customField;
     }
 

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/java/io/github/belgif/rest/problem/AbstractRestProblemIT.java

@@ -134,6 +134,7 @@ void constraintViolationMissingRequiredQueryParameter() {
                 .get("/beanValidation/queryParameter").then().assertThat()
                 .statusCode(400)
                 .body("type", equalTo("urn:problem-type:belgif:badRequest"))
+                .body("detail", equalTo("The input message is incorrect"))
                 .body("issues[0].type", equalTo("urn:problem-type:belgif:input-validation:schemaViolation"))
                 .body("issues[0].title", equalTo("Input value is invalid with respect to the schema"))
                 .body("issues[0].in", equalTo("query"))
@@ -331,4 +332,39 @@ void constraintViolationBodyInheritance() {
                 .body("issues[1].detail", equalTo("must not be blank"));
     }
 
+    @Test
+    void i18n() {
+        getSpec().when()
+                .header("Accept-Language", "nl-BE")
+                .queryParam("param", -1)
+                .queryParam("other", "TOO_LONG")
+                .get("/beanValidation/queryParameter").then().assertThat()
+                .statusCode(400)
+                .body("type", equalTo("urn:problem-type:belgif:badRequest"))
+                .body("detail", equalTo("Het input bericht is ongeldig"))
+                .body("issues[0].type", equalTo("urn:problem-type:belgif:input-validation:schemaViolation"))
+                .body("issues[0].title", equalTo("Input value is invalid with respect to the schema"))
+                .body("issues[0].detail", equalTo("grootte moet tussen 0 en 5 liggen"))
+                .body("issues[0].in", equalTo("query"))
+                .body("issues[0].name", equalTo("other"))
+                .body("issues[0].value", equalTo("TOO_LONG"))
+                .body("issues[1].type", equalTo("urn:problem-type:belgif:input-validation:schemaViolation"))
+                .body("issues[1].title", equalTo("Input value is invalid with respect to the schema"))
+                .body("issues[1].detail", equalTo("moet groter dan 0 zijn"))
+                .body("issues[1].in", equalTo("query"))
+                .body("issues[1].name", equalTo("param"))
+                .body("issues[1].value", equalTo(-1));
+    }
+
+    @Test
+    void i18nCustom() {
+        getSpec().when()
+                .header("Accept-Language", "nl-BE")
+                .get("/custom").then().assertThat()
+                .statusCode(409)
+                .body("type", equalTo("urn:problem-type:acme:custom"))
+                .body("customField", equalTo("value from frontend"))
+                .body("detail", equalTo("NL detail"));
+    }
+
 }

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/resources/com/acme/custom/Messages.properties

@@ -0,0 +1 @@
+CustomProblem.detail=Custom detail

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/resources/com/acme/custom/Messages_de.properties

@@ -0,0 +1 @@
+CustomProblem.detail=DE detail

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/resources/com/acme/custom/Messages_fr.properties

@@ -0,0 +1 @@
+CustomProblem.detail=FR detail

belgif-rest-problem-it/belgif-rest-problem-it-common/src/main/resources/com/acme/custom/Messages_nl.properties

@@ -0,0 +1 @@
+CustomProblem.detail=NL detail

belgif-rest-problem-java-ee/src/main/java/io/github/belgif/rest/problem/jaxrs/i18n/I18NAcceptLanguageFilter.java

@@ -0,0 +1,51 @@
+package io.github.belgif.rest.problem.jaxrs.i18n;
+
+import javax.annotation.PostConstruct;
+import javax.servlet.ServletContext;
+import javax.ws.rs.container.ContainerRequestContext;
+import javax.ws.rs.container.ContainerRequestFilter;
+import javax.ws.rs.container.ContainerResponseContext;
+import javax.ws.rs.container.ContainerResponseFilter;
+import javax.ws.rs.container.PreMatching;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.ext.Provider;
+
+import io.github.belgif.rest.problem.i18n.I18N;
+
+/**
+ * Filter that registers the requested locale, as specified in Accept-Language HTTP header,
+ * with the {@link ThreadLocalLocaleResolver} (and clears it afterward).
+ */
+@PreMatching
+@Provider
+public class I18NAcceptLanguageFilter implements ContainerRequestFilter, ContainerResponseFilter {
+
+    @Context
+    private ServletContext servletContext;
+
+    @PostConstruct
+    public void initialize() {
+        if (servletContext.getInitParameter(I18N.I18N_FLAG) != null) {
+            I18N.setEnabled(Boolean.parseBoolean(servletContext.getInitParameter(I18N.I18N_FLAG)));
+        }
+    }
+
+    @Override
+    public void filter(ContainerRequestContext requestContext) {
+        if (I18N.isEnabled() && !requestContext.getAcceptableLanguages().isEmpty()) {
+            ThreadLocalLocaleResolver.setLocale(requestContext.getAcceptableLanguages().get(0));
+        }
+    }
+
+    @Override
+    public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) {
+        if (I18N.isEnabled()) {
+            ThreadLocalLocaleResolver.clear();
+        }
+    }
+
+    protected void setServletContext(ServletContext servletContext) {
+        this.servletContext = servletContext;
+    }
+
+}

belgif-rest-problem-java-ee/src/main/java/io/github/belgif/rest/problem/jaxrs/i18n/ThreadLocalLocaleResolver.java

@@ -0,0 +1,48 @@
+package io.github.belgif.rest.problem.jaxrs.i18n;
+
+import java.util.Locale;
+
+import io.github.belgif.rest.problem.i18n.I18N;
+import io.github.belgif.rest.problem.i18n.LocaleResolver;
+
+/**
+ * LocaleResolver implementation that uses a ThreadLocal.
+ */
+public class ThreadLocalLocaleResolver implements LocaleResolver {
+
+    /**
+     * ThreadLocal with the locale of the current request (defaults to English).
+     */
+    private static final ThreadLocal<Locale> LOCALE = new InheritableThreadLocal<Locale>() {
+        @Override
+        protected Locale initialValue() {
+            return I18N.DEFAULT_LOCALE;
+        }
+    };
+
+    @Override
+    public Locale getLocale() {
+        return LOCALE.get();
+    }
+
+    /**
+     * Set the locale of the current request.
+     *
+     * <p>
+     * NOTE: The locale is stored in a ThreadLocal that must be cleaned up with {@link #clear()}.
+     * </p>
+     *
+     * @param locale the locale of the current request.
+     */
+    public static void setLocale(Locale locale) {
+        LOCALE.set(locale);
+    }
+
+    /**
+     * Clear the locale of the current request.
+     */
+    public static void clear() {
+        LOCALE.remove();
+    }
+
+}

belgif-rest-problem-java-ee/src/main/resources/META-INF/services/io.github.belgif.rest.problem.i18n.LocaleResolver

@@ -0,0 +1 @@
+io.github.belgif.rest.problem.jaxrs.i18n.ThreadLocalLocaleResolver

belgif-rest-problem-java-ee/src/test/java/io/github/belgif/rest/problem/jaxrs/i18n/I18NAcceptLanguageFilterTest.java

@@ -0,0 +1,73 @@
+package io.github.belgif.rest.problem.jaxrs.i18n;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.util.Collections;
+import java.util.Locale;
+
+import javax.servlet.ServletContext;
+import javax.ws.rs.container.ContainerRequestContext;
+import javax.ws.rs.container.ContainerResponseContext;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import io.github.belgif.rest.problem.i18n.I18N;
+
+@ExtendWith(MockitoExtension.class)
+class I18NAcceptLanguageFilterTest {
+
+    @InjectMocks
+    private I18NAcceptLanguageFilter filter;
+
+    @Mock
+    private ContainerRequestContext requestContext;
+
+    @Mock
+    private ContainerResponseContext responseContext;
+
+    @Mock
+    private ServletContext servletContext;
+
+    @AfterEach
+    void cleanup() {
+        ThreadLocalLocaleResolver.clear();
+        I18N.setEnabled(true);
+    }
+
+    @Test
+    void languageRequested() {
+        when(requestContext.getAcceptableLanguages())
+                .thenReturn(Collections.singletonList(Locale.forLanguageTag("nl-BE")));
+        filter.filter(requestContext);
+        assertThat(I18N.getRequestLocale()).isEqualTo(Locale.forLanguageTag("nl-BE"));
+    }
+
+    @Test
+    void noLanguageRequested() {
+        when(requestContext.getAcceptableLanguages()).thenReturn(Collections.emptyList());
+        filter.filter(requestContext);
+        assertThat(I18N.getRequestLocale()).isEqualTo(Locale.forLanguageTag("en"));
+    }
+
+    @Test
+    void clearLocaleAfterResponse() {
+        ThreadLocalLocaleResolver.setLocale(Locale.forLanguageTag("nl-BE"));
+        filter.filter(requestContext, responseContext);
+        assertThat(I18N.getRequestLocale()).isEqualTo(Locale.forLanguageTag("en"));
+    }
+
+    @Test
+    void disabledViaInitParam() {
+        when(servletContext.getInitParameter(I18N.I18N_FLAG)).thenReturn("false");
+        filter.initialize();
+        filter.filter(requestContext);
+        verifyNoInteractions(requestContext);
+    }
+
+}

belgif-rest-problem-java-ee/src/test/java/io/github/belgif/rest/problem/jaxrs/i18n/ThreadLocalLocaleResolverTest.java

@@ -0,0 +1,39 @@
+package io.github.belgif.rest.problem.jaxrs.i18n;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.util.Locale;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+class ThreadLocalLocaleResolverTest {
+
+    private final ThreadLocalLocaleResolver resolver = new ThreadLocalLocaleResolver();
+
+    @AfterEach
+    void cleanup() {
+        ThreadLocalLocaleResolver.clear();
+    }
+
+    @Test
+    void defaultLocale() {
+        assertThat(resolver.getLocale()).isEqualTo(Locale.forLanguageTag("en"));
+    }
+
+    @Test
+    void setAndGetLocale() {
+        Locale locale = Locale.forLanguageTag("nl-BE");
+        ThreadLocalLocaleResolver.setLocale(locale);
+        assertThat(resolver.getLocale()).isEqualTo(locale);
+    }
+
+    @Test
+    void clear() {
+        Locale locale = Locale.forLanguageTag("nl-BE");
+        ThreadLocalLocaleResolver.setLocale(locale);
+        ThreadLocalLocaleResolver.clear();
+        assertThat(resolver.getLocale()).isEqualTo(Locale.forLanguageTag("en"));
+    }
+
+}

belgif-rest-problem-spring/pom.xml

@@ -37,7 +37,7 @@
     </dependency>
     <dependency>
       <groupId>org.springframework</groupId>
-      <artifactId>spring-web</artifactId>
+      <artifactId>spring-webmvc</artifactId>
       <scope>provided</scope>
     </dependency>
     <dependency>

belgif-rest-problem-spring/src/main/java/io/github/belgif/rest/problem/spring/ProblemConfigurationProperties.java

@@ -13,6 +13,8 @@ public class ProblemConfigurationProperties {
 
     private List<String> scanAdditionalProblemPackages = new ArrayList<>();
 
+    private boolean i18n = true;
+
     public void setScanAdditionalProblemPackages(List<String> scanAdditionalProblemPackages) {
         this.scanAdditionalProblemPackages = scanAdditionalProblemPackages;
     }
@@ -21,4 +23,12 @@ public List<String> getScanAdditionalProblemPackages() {
         return scanAdditionalProblemPackages;
     }
 
+    public void setI18n(boolean i18n) {
+        this.i18n = i18n;
+    }
+
+    public boolean isI18n() {
+        return i18n;
+    }
+
 }

belgif-rest-problem-spring/src/main/java/io/github/belgif/rest/problem/spring/i18n/I18NConfigurator.java

@@ -0,0 +1,18 @@
+package io.github.belgif.rest.problem.spring.i18n;
+
+import org.springframework.stereotype.Component;
+
+import io.github.belgif.rest.problem.i18n.I18N;
+import io.github.belgif.rest.problem.spring.ProblemConfigurationProperties;
+
+/**
+ * Enables or disables problem I18N support based on configuration property.
+ */
+@Component
+public class I18NConfigurator {
+
+    public I18NConfigurator(ProblemConfigurationProperties configuration) {
+        I18N.setEnabled(configuration.isI18n());
+    }
+
+}

belgif-rest-problem-spring/src/main/java/io/github/belgif/rest/problem/spring/i18n/LocaleContextHolderLocaleResolver.java

@@ -0,0 +1,19 @@
+package io.github.belgif.rest.problem.spring.i18n;
+
+import java.util.Locale;
+
+import org.springframework.context.i18n.LocaleContextHolder;
+
+import io.github.belgif.rest.problem.i18n.LocaleResolver;
+
+/**
+ * Spring LocaleResolver implementation that delegates to {@link LocaleContextHolder#getLocale()}.
+ */
+public class LocaleContextHolderLocaleResolver implements LocaleResolver {
+
+    @Override
+    public Locale getLocale() {
+        return LocaleContextHolder.getLocale();
+    }
+
+}

belgif-rest-problem-spring/src/main/resources/META-INF/services/io.github.belgif.rest.problem.i18n.LocaleResolver

@@ -0,0 +1 @@
+io.github.belgif.rest.problem.spring.i18n.LocaleContextHolderLocaleResolver