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/pom.xml

@@ -57,6 +57,11 @@
       <artifactId>mockito-junit-jupiter</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.junit-pioneer</groupId>
+      <artifactId>junit-pioneer</artifactId>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.hibernate.validator</groupId>
       <artifactId>hibernate-validator</artifactId>
@@ -92,6 +97,17 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <configuration>
+          <!-- https://junit-pioneer.org/docs/environment-variables/#warnings-for-reflective-access -->
+          <argLine>
+            --add-opens java.base/java.util=ALL-UNNAMED
+            --add-opens java.base/java.lang=ALL-UNNAMED
+          </argLine>
+        </configuration>
+      </plugin>
     </plugins>
   </build>
 

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

@@ -0,0 +1,61 @@
+package io.github.belgif.rest.problem.jaxrs;
+
+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 I18N helper (and clears it afterward).
+ */
+@PreMatching
+@Provider
+public class I18NAcceptLanguageFilter implements ContainerRequestFilter, ContainerResponseFilter {
+
+    public static final String I18N_FLAG = "io.github.belgif.rest.problem.i18n";
+
+    @Context
+    private ServletContext servletContext;
+
+    private boolean enabled = true;
+
+    @PostConstruct
+    public void initialize() {
+        if (servletContext.getInitParameter(I18N_FLAG) != null) {
+            enabled = Boolean.parseBoolean(servletContext.getInitParameter(I18N_FLAG));
+        } else if (System.getProperty(I18N_FLAG) != null) {
+            enabled = Boolean.parseBoolean(System.getProperty(I18N_FLAG));
+        } else if (System.getenv(I18N_FLAG) != null) {
+            enabled = Boolean.parseBoolean(System.getenv(I18N_FLAG));
+        } else {
+            enabled = true;
+        }
+    }
+
+    @Override
+    public void filter(ContainerRequestContext requestContext) {
+        if (enabled && !requestContext.getAcceptableLanguages().isEmpty()) {
+            I18N.setRequestLocale(requestContext.getAcceptableLanguages().get(0));
+        }
+    }
+
+    @Override
+    public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) {
+        if (enabled) {
+            I18N.clearRequestLocale();
+        }
+    }
+
+    protected void setServletContext(ServletContext servletContext) {
+        this.servletContext = servletContext;
+    }
+
+}

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

@@ -0,0 +1,91 @@
+package io.github.belgif.rest.problem.jaxrs;
+
+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.junitpioneer.jupiter.SetEnvironmentVariable;
+import org.junitpioneer.jupiter.SetSystemProperty;
+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() {
+        I18N.clearRequestLocale();
+    }
+
+    @Test
+    void languageRequested() {
+        when(requestContext.getAcceptableLanguages()).thenReturn(Collections.singletonList(new Locale("nl", "BE")));
+        filter.filter(requestContext);
+        assertThat(I18N.getRequestLocale()).isEqualTo(new Locale("nl", "BE"));
+    }
+
+    @Test
+    void noLanguageRequested() {
+        when(requestContext.getAcceptableLanguages()).thenReturn(Collections.emptyList());
+        filter.filter(requestContext);
+        assertThat(I18N.getRequestLocale()).isEqualTo(new Locale("en"));
+    }
+
+    @Test
+    void clearLocaleAfterResponse() {
+        I18N.setRequestLocale(new Locale("nl", "BE"));
+        filter.filter(requestContext, responseContext);
+        assertThat(I18N.getRequestLocale()).isEqualTo(new Locale("en"));
+    }
+
+    @Test
+    void disabledViaInitParam() {
+        when(servletContext.getInitParameter(I18NAcceptLanguageFilter.I18N_FLAG)).thenReturn("false");
+        filter.initialize();
+        filter.filter(requestContext);
+        verifyNoInteractions(requestContext);
+    }
+
+    @Test
+    @SetSystemProperty(key = I18NAcceptLanguageFilter.I18N_FLAG, value = "false")
+    void disabledViaSystemProperty() {
+        when(servletContext.getInitParameter(I18NAcceptLanguageFilter.I18N_FLAG)).thenReturn(null);
+        filter.initialize();
+        filter.filter(requestContext);
+        verifyNoInteractions(requestContext);
+    }
+
+    @Test
+    @SetEnvironmentVariable(key = I18NAcceptLanguageFilter.I18N_FLAG, value = "false")
+    void disabledViaEnvironmentVariable() {
+        when(servletContext.getInitParameter(I18NAcceptLanguageFilter.I18N_FLAG)).thenReturn(null);
+        filter.initialize();
+        filter.filter(requestContext);
+        verifyNoInteractions(requestContext);
+    }
+
+}

belgif-rest-problem-spring/pom.xml

@@ -40,6 +40,11 @@
       <artifactId>spring-web</artifactId>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>org.springframework</groupId>
+      <artifactId>spring-webmvc</artifactId>
+      <scope>provided</scope>
+    </dependency>
     <dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-webflux</artifactId>

belgif-rest-problem-spring/src/main/java/io/github/belgif/rest/problem/spring/I18NAcceptLanguageFilter.java

@@ -0,0 +1,38 @@
+package io.github.belgif.rest.problem.spring;
+
+import java.io.IOException;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletRequest;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.stereotype.Component;
+import org.springframework.web.servlet.support.RequestContextUtils;
+
+import io.github.belgif.rest.problem.i18n.I18N;
+
+/**
+ * Filter that registers the requested locale, as specified in Accept-Language HTTP header,
+ * with the I18N helper (and clears it afterward).
+ */
+@Component
+@ConditionalOnProperty(prefix = "io.github.belgif.rest.problem", name = "i18n", havingValue = "true",
+        matchIfMissing = true)
+public class I18NAcceptLanguageFilter implements Filter {
+
+    @Override
+    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
+            throws IOException, ServletException {
+        I18N.setRequestLocale(RequestContextUtils.getLocale((HttpServletRequest) servletRequest));
+        try {
+            filterChain.doFilter(servletRequest, servletResponse);
+        } finally {
+            I18N.clearRequestLocale();
+        }
+    }
+
+}

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/test/java/io/github/belgif/rest/problem/spring/I18NAcceptLanguageFilterTest.java

@@ -0,0 +1,63 @@
+package io.github.belgif.rest.problem.spring;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.io.IOException;
+import java.util.Locale;
+import java.util.concurrent.atomic.AtomicReference;
+
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.mock.web.MockHttpServletResponse;
+
+import io.github.belgif.rest.problem.i18n.I18N;
+
+@ExtendWith(MockitoExtension.class)
+class I18NAcceptLanguageFilterTest {
+
+    private final I18NAcceptLanguageFilter filter = new I18NAcceptLanguageFilter();
+
+    @Mock
+    private FilterChain filterChain;
+
+    @Test
+    void languageRequested() throws ServletException, IOException {
+        MockHttpServletRequest servletRequest = new MockHttpServletRequest();
+        MockHttpServletResponse servletResponse = new MockHttpServletResponse();
+        servletRequest.addHeader("Accept-Language", "nl-BE");
+        AtomicReference<Locale> locale = new AtomicReference<>();
+        Mockito.doAnswer(invocationOnMock -> {
+            locale.set(I18N.getRequestLocale());
+            return null;
+        }).when(filterChain).doFilter(servletRequest, servletResponse);
+        filter.doFilter(servletRequest, servletResponse, filterChain);
+        // during the request processing, locale should be nl-BE
+        assertThat(locale).hasValue(new Locale("nl", "BE"));
+        // after the request processing, locale should be restored to default = en
+        assertThat(I18N.getRequestLocale()).isEqualTo(new Locale("en"));
+    }
+
+    @Test
+    void noLanguageRequested() throws ServletException, IOException {
+        MockHttpServletRequest servletRequest = new MockHttpServletRequest();
+        MockHttpServletResponse servletResponse = new MockHttpServletResponse();
+        AtomicReference<Locale> locale = new AtomicReference<>();
+        Mockito.doAnswer(invocationOnMock -> {
+            locale.set(I18N.getRequestLocale());
+            return null;
+        }).when(filterChain).doFilter(servletRequest, servletResponse);
+        filter.doFilter(servletRequest, servletResponse, filterChain);
+        // during the request processing, locale should be default = en
+        assertThat(locale).hasValue(new Locale("en"));
+        // after the request processing, locale should be restored to default = en
+        assertThat(I18N.getRequestLocale()).isEqualTo(new Locale("en"));
+    }
+
+}