method invoking formatter as a convenience

org.springframework.context/src/main/java/org/springframework/ui/format/support/MethodInvokingFormatter.java

+/*
+ * Copyright 2002-2009 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 org.springframework.ui.format.support;
+
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.Locale;
+
+import org.springframework.ui.format.Formatter;
+import org.springframework.util.ReflectionUtils;
+
+/**
+ * A generic Formatter that reflectively invokes methods on a class to carry out format and parse operations.
+ * The format method should be a public member method that returns a String and either accepts no arguments or a single Locale argument.
+ * The parse method should be a declared public static method that returns the formattedObjectType and either accepts a single String argument or String and Locale arguments.
+ * Throws an {@link IllegalArgumentException} if either the format method or parse method could not be resolved.
+ * Useful for invoking existing Formatter logic on a formattable type without needing a dedicated Formatter class.
+ *  
+ * @author Keith Donald
+ */
+public class MethodInvokingFormatter implements Formatter {
+
+	private Class<?> formattedObjectType;
+
+	private Method formatMethod;
+
+	private boolean formatMethodLocaleArgumentPresent;
+
+	private Method parseMethod;
+
+	private boolean parseMethodLocaleArgumentPresent;
+
+	/**
+	 * Creates a new reflective method invoking formatter.
+	 * @param formattedObjectType the object type that contains format and parse methods
+	 * @param formatMethodName the format method name e.g. "toString"
+	 * @param parseMethodName the parse method name e.g. "valueOf"
+	 */
+	public MethodInvokingFormatter(Class<?> formattedObjectType, String formatMethodName, String parseMethodName) {
+		this.formattedObjectType = formattedObjectType;
+		resolveFormatMethod(formatMethodName);
+		resolveParseMethod(parseMethodName);
+	}
+
+	public String format(Object object, Locale locale) {
+		if (this.formatMethodLocaleArgumentPresent) {
+			return (String) ReflectionUtils.invokeMethod(this.formatMethod, object, locale);
+		} else {
+			return (String) ReflectionUtils.invokeMethod(this.formatMethod, object);
+		}
+	}
+
+	public Object parse(String formatted, Locale locale) {
+		if (this.parseMethodLocaleArgumentPresent) {
+			return ReflectionUtils.invokeMethod(this.parseMethod, null, formatted, locale);
+		} else {
+			return ReflectionUtils.invokeMethod(this.parseMethod, null, formatted);
+		}
+	}
+
+	private void resolveFormatMethod(String methodName) {
+		Method[] methods = this.formattedObjectType.getMethods();
+		for (Method method : methods) {
+			if (method.getName().equals(methodName) && method.getReturnType().equals(String.class)) {
+				if (method.getParameterTypes().length == 0) {
+					this.formatMethod = method;
+				} else if (method.getParameterTypes().length == 1 && method.getParameterTypes()[0].equals(Locale.class)) {
+					this.formatMethod = method;
+					this.formatMethodLocaleArgumentPresent = true;
+				}
+			}
+		}
+		if (this.formatMethod == null) {
+			throw new IllegalArgumentException("Unable to resolve format method '" + methodName + "' on class ["
+					+ this.formattedObjectType.getName()
+					+ "] method should have signature [public String <methodName>()] "
+					+ "or [public String <methodName>(Locale)]");
+		}
+	}
+
+	private void resolveParseMethod(String methodName) {
+		Method[] methods = this.formattedObjectType.getDeclaredMethods();
+		for (Method method : methods) {
+			if (method.getName().equals(methodName) && method.getReturnType().equals(this.formattedObjectType)
+					&& Modifier.isPublic(method.getModifiers()) && Modifier.isStatic(method.getModifiers())) {
+				if (method.getParameterTypes().length == 1 && method.getParameterTypes()[0].equals(String.class)) {
+					this.parseMethod = method;
+				} else if (method.getParameterTypes().length == 2 && method.getParameterTypes()[0].equals(String.class)
+						&& method.getParameterTypes()[1].equals(Locale.class)) {
+					this.parseMethod = method;
+					this.parseMethodLocaleArgumentPresent = true;
+				}
+			}
+		}
+		if (this.parseMethod == null) {
+			throw new IllegalArgumentException("Unable to resolve parse method '" + methodName + "' on class ["
+					+ this.formattedObjectType.getName()
+					+ "]; method should have signature [public static T <methodName>(String)] "
+					+ "or [public static T <methodName>(String, Locale)]");
+		}
+	}
+}

org.springframework.context/src/test/java/org/springframework/ui/format/GenericFormatterRegistryTests.java → org.springframework.context/src/test/java/org/springframework/ui/format/support/GenericFormatterRegistryTests.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.ui.format;
+package org.springframework.ui.format.support;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
@@ -33,6 +33,9 @@ import org.junit.Test;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.core.style.ToStringCreator;
+import org.springframework.ui.format.AnnotationFormatterFactory;
+import org.springframework.ui.format.Formatted;
+import org.springframework.ui.format.Formatter;
 import org.springframework.ui.format.number.CurrencyFormatter;
 import org.springframework.ui.format.number.IntegerFormatter;
 import org.springframework.ui.format.support.GenericFormatterRegistry;

org.springframework.context/src/test/java/org/springframework/ui/format/support/MethodInvokingFormatterTests.java

+package org.springframework.ui.format.support;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Locale;
+
+import org.junit.Test;
+import org.springframework.ui.format.support.MethodInvokingFormatter;
+
+public class MethodInvokingFormatterTests {
+
+	private MethodInvokingFormatter formatter = new MethodInvokingFormatter(AccountNumber.class, "getFormatted",
+			"valueOf");
+
+	private MethodInvokingFormatter formatter2 = new MethodInvokingFormatter(I8nAccountNumber.class, "getFormatted",
+			"valueOf");
+
+	@Test
+	public void testFormat() {
+		assertEquals("123456789", formatter.format(new AccountNumber(123456789L), null));
+	}
+
+	@Test
+	public void testParse() {
+		assertEquals(new Long(123456789), ((AccountNumber) formatter.parse("123456789", null)).number);
+	}
+
+	@Test
+	public void testFormatI18n() {
+		assertEquals("123456789", formatter2.format(new I8nAccountNumber(123456789L), Locale.GERMAN));
+	}
+
+	@Test
+	public void testParseI18n() {
+		assertEquals(new Long(123456789), ((I8nAccountNumber) formatter2.parse("123456789", Locale.GERMAN)).number);
+	}
+
+	public static class AccountNumber {
+
+		private Long number;
+
+		public AccountNumber(Long number) {
+			this.number = number;
+		}
+
+		public String getFormatted() {
+			return number.toString();
+		}
+
+		public static AccountNumber valueOf(String str) {
+			return new AccountNumber(Long.valueOf(str));
+		}
+
+	}
+
+	public static class I8nAccountNumber {
+
+		private Long number;
+
+		public I8nAccountNumber(Long number) {
+			this.number = number;
+		}
+
+		public String getFormatted(Locale locale) {
+			assertEquals(Locale.GERMAN, locale);
+			return number.toString();
+		}
+
+		public static I8nAccountNumber valueOf(String str, Locale locale) {
+			assertEquals(Locale.GERMAN, locale);
+			return new I8nAccountNumber(Long.valueOf(str));
+		}
+
+	}
+}