Move samples from spring-cloud-stream

source/src/main/java/demo/DateFormat.java

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package demo;
+
+import static java.lang.annotation.ElementType.*;
+import static java.lang.annotation.RetentionPolicy.*;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import java.text.SimpleDateFormat;
+
+import javax.validation.Constraint;
+import javax.validation.ConstraintValidator;
+import javax.validation.ConstraintValidatorContext;
+import javax.validation.Payload;
+
+/**
+ * The annotated String must be a valid {@link java.text.SimpleDateFormat} pattern.
+ *
+ * @author Eric Bottard
+ */
+@Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER})
+@Retention(RUNTIME)
+@Documented
+@Constraint(validatedBy = {DateFormat.DateFormatValidator.class})
+public @interface DateFormat {
+
+	String DEFAULT_MESSAGE = "";
+
+	String message() default DEFAULT_MESSAGE;
+
+	Class<?>[] groups() default {};
+
+	Class<? extends Payload>[] payload() default {};
+
+
+	/**
+	 * Defines several {@link DateFormat} annotations on the same element.
+	 *
+	 * @see DateFormat
+	 */
+	@Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER})
+	@Retention(RUNTIME)
+	@Documented
+	@interface List {
+
+		DateFormat[] value();
+	}
+
+	public static class DateFormatValidator implements ConstraintValidator<DateFormat, CharSequence> {
+
+		private String message;
+
+		@Override
+		public void initialize(DateFormat constraintAnnotation) {
+			this.message = constraintAnnotation.message();
+		}
+
+		@Override
+		public boolean isValid(CharSequence value, ConstraintValidatorContext context) {
+			if (value == null) {
+				return true;
+			}
+			try {
+				new SimpleDateFormat(value.toString());
+			}
+			catch (IllegalArgumentException e) {
+				if (DEFAULT_MESSAGE.equals(this.message)) {
+					context.disableDefaultConstraintViolation();
+					context.buildConstraintViolationWithTemplate(e.getMessage()).addConstraintViolation();
+				}
+				return false;
+			}
+			return true;
+		}
+	}
+
+}