1：@RestController

那麼這個註解和@Controller有什麼區別？ 嗯哼，事情開始變得有意思起來了

1. Controller, RestController的共同點

     都是用來表示spring某個類的是否可以接收HTTP請求

2.  Controller, RestController的不同點

     @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。

下面是@RestController的原始碼，看了之後你會更清晰的看出來他們之間的區別

 * Copyright 2002-2016 the original author or authors.

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.
 *
 * <p><b>NOTE:</b> {@code @RestController} is processed if an appropriate
 * {@code HandlerMapping}-{@code HandlerAdapter} pair is configured such as the
 * {@code RequestMappingHandlerMapping}-{@code RequestMappingHandlerAdapter}
 * pair which are the default in the MVC Java config and the MVC namespace.
 * In particular {@code @RestController} is not supported with the
 * {@code DefaultAnnotationHandlerMapping}-{@code AnnotationMethodHandlerAdapter}
 * pair both of which are also deprecated.
 *
 * @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 "";

}
 

這裡需要注意一點：當你在springboot中使用模板模式返回一個字串去匹配對應的頁面的時候，方法所在的類是不能使用@RestController而應該使用@Controller，為什麼？看上面。當然，如果http請求是通過ajax傳送到服務端，還是要使用@RestController註解的。