1 /*
2 * Copyright 2002-2014 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.springframework.web.servlet.mvc.method.annotation;
18
19 import org.springframework.core.MethodParameter;
20 import org.springframework.util.PatternMatchUtils;
21 import org.springframework.web.context.request.NativeWebRequest;
22 import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
23 import org.springframework.web.method.support.ModelAndViewContainer;
24 import org.springframework.web.servlet.RequestToViewNameTranslator;
25
26 /**
27 * Handles return values of types {@code void} and {@code String} interpreting
28 * them as view name reference.
29 *
30 * <p>A {@code null} return value, either due to a {@code void} return type or
31 * as the actual return value is left as-is allowing the configured
32 * {@link RequestToViewNameTranslator} to select a view name by convention.
33 *
34 * <p>A String return value can be interpreted in more than one ways depending
35 * on the presence of annotations like {@code @ModelAttribute} or
36 * {@code @ResponseBody}. Therefore this handler should be configured after
37 * the handlers that support these annotations.
38 *
39 * @author Rossen Stoyanchev
40 * @since 3.1
41 */
42 public class ViewNameMethodReturnValueHandler implements HandlerMethodReturnValueHandler {
43
44 private String[] redirectPatterns;
45
46
47 /**
48 * Configure one more simple patterns (as described in
49 * {@link PatternMatchUtils#simpleMatch}) to use in order to recognize
50 * custom redirect prefixes in addition to "redirect:".
51 * <p>Note that simply configuring this property will not make a custom
52 * redirect prefix work. There must be a custom View that recognizes the
53 * prefix as well.
54 * @since 4.1
55 */
56 public void setRedirectPatterns(String... redirectPatterns) {
57 this.redirectPatterns = redirectPatterns;
58 }
59
60 /**
61 * The configured redirect patterns, if any.
62 */
63 public String[] getRedirectPatterns() {
64 return this.redirectPatterns;
65 }
66
67
68 @Override
69 public boolean supportsReturnType(MethodParameter returnType) {
70 Class<?> paramType = returnType.getParameterType();
71 return (void.class.equals(paramType) || String.class.equals(paramType));
72 }
73
74 @Override
75 public void handleReturnValue(Object returnValue, MethodParameter returnType,
76 ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
77
78 if (returnValue == null) {
79 return;
80 }
81 else if (returnValue instanceof String) {
82 String viewName = (String) returnValue;
83 mavContainer.setViewName(viewName);
84 if (isRedirectViewName(viewName)) {
85 mavContainer.setRedirectModelScenario(true);
86 }
87 }
88 else {
89 // should not happen
90 throw new UnsupportedOperationException("Unexpected return type: " +
91 returnType.getParameterType().getName() + " in method: " + returnType.getMethod());
92 }
93 }
94
95 /**
96 * Whether the given view name is a redirect view reference.
97 * The default implementation checks the configured redirect patterns and
98 * also if the view name starts with the "redirect:" prefix.
99 * @param viewName the view name to check, never {@code null}
100 * @return "true" if the given view name is recognized as a redirect view
101 * reference; "false" otherwise.
102 */
103 protected boolean isRedirectViewName(String viewName) {
104 if (PatternMatchUtils.simpleMatch(this.redirectPatterns, viewName)) {
105 return true;
106 }
107 return viewName.startsWith("redirect:");
108 }
109
110 }