Controller 與 RestController 區別

官方文檔：

A convenience annotation that is itself annotated with @Controller and @ResponseBody.

意思是：
@RestController註解相當於@ResponseBody ＋ @Controller合在一起的作用。 

1. 共同點

都是用來表示Spring某個類的是否可以接收HTTP請求

2. 不同點

•      @Controller標識一個Spring類是Spring MVC controller處理器
•      @RestController：@RestController是@Controller和@ResponseBody的結合體，兩個標註合併起來的作用。

@Controller  
@ResponseBody  
public class MyController { }  
  
@RestController  
public class MyRestController { }

 1）如果只是使用@RestController註解Controller，則Controller中的方法無法返回jsp頁面，配置的視圖解析器InternalResourceViewResolver則不起作用，返回的內容就是Return 裏的內容（String/JSON）。
例如：本來應該到success.jsp頁面的，則其顯示success.

@RequestMapping(value = "/test")
public String test(HttpServletRequest request, HttpServletResponse response){
     return "success";
}

2）如果使用@RestController註解Controller，需要返回到指定頁面，則需要配置視圖解析器InternalResourceViewResolver，可以利用ModelAndView返回試圖。

@RequestMapping(value = "/test")
public String test(HttpServletRequest request, HttpServletResponse response){
     return newModelAndView("success");
}

3）如果使用@Controller註解Controller，如果需要返回JSON，XML或自定義mediaType內容到頁面，則需要在對應的方法上加上@ResponseBody註解。

@ResponseBody
@RequestMapping(value = "/test")
public String test(HttpServletRequest request, HttpServletResponse response){
     return "success";
}

最後貼上Spring4.x的RestController和Controller源碼，以供學習和理解。

RestController源碼：

/*
 * Copyright 2002-2014 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.web.bind.annotation;
 
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
 
import org.springframework.stereotype.Controller;
 
/**
 * A convenience annotation that is itself annotated with {@link Controller @Controller}
 * and {@link ResponseBody @ResponseBody}.
 * <p>
 * Types that carry this annotation are treated as controllers where
 * {@link RequestMapping @RequestMapping} methods assume
 * {@link ResponseBody @ResponseBody} semantics by default.
 *
 * @author Rossen Stoyanchev
 * @author Sam Brannen
 * @since 4.0
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Controller
@ResponseBody
public @interface RestController {
 
	/**
	 * The value may indicate a suggestion for a logical component name,
	 * to be turned into a Spring bean in case of an autodetected component.
	 * @return the suggested component name, if any
	 * @since 4.0.1
	 */
	String value() default "";
 
}

Controller源碼：

/*
 * Copyright 2002-2007 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.stereotype;
 
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
 
/**
 * Indicates that an annotated class is a "Controller" (e.g. a web controller).
 *
 * <p>This annotation serves as a specialization of {@link Component @Component},
 * allowing for implementation classes to be autodetected through classpath scanning.
 * It is typically used in combination with annotated handler methods based on the
 * {@link org.springframework.web.bind.annotation.RequestMapping} annotation.
 *
 * @author Arjen Poutsma
 * @author Juergen Hoeller
 * @since 2.5
 * @see Component
 * @see org.springframework.web.bind.annotation.RequestMapping
 * @see org.springframework.context.annotation.ClassPathBeanDefinitionScanner
 */
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Controller {
 
	/**
	 * The value may indicate a suggestion for a logical component name,
	 * to be turned into a Spring bean in case of an autodetected component.
	 * @return the suggested component name, if any
	 */
	String value() default "";
 
}