Spring Boot Web 响应处理

1. 方法标注 @ResponseBody

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

spring-boot-starter-web 里有 spring-boot-starter-json(默认是 jackson)

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-json</artifactId>
</dependency>

1.1 示例

@Controller
public class ResponseController {

    @ResponseBody
    @GetMapping("/get/user")
    public User getUser() {
        User user = new User();
        user.setName("tinyspot");
        return user;
    }
}

1. DispatcherServlet#doDispatch
2. 返回值解析器 RequestMappingHandlerAdapter#invokeHandlerMethod
3. ServletInvocableHandlerMethod#invokeAndHandle
4. 寻找返回值处理器 HandlerMethodReturnValueHandlerComposite#selectHandler

image.png

2. Spring MVC 支持的返回值类型

• ModelAndViewMethodReturnValueHandler
• ModelMethodProcessor
• ViewMethodReturnValueHandler
• RequestResponseBodyMethodProcessor

2.1 RequestResponseBodyMethodProcessor

• 处理 @ResponseBody 注解
• MessageConverter 将数据写为 JSON

2.2 HttpMessageConverter

• ByteArrayHttpMessageConverter
• StringHttpMessageConverter
• ResourceHttpMessageConverter
• MappingJackson2HttpMessageConverter