Spring编程：@ResponseBody 注解

悠悠 2021-11-22 09:34 361阅读 0赞

### 1.定义 ###

@ResponseBody 注解是一个标识型注解，无需设置任何参数值。该注解的作用是：将 Controller 方法返回的对象，转换为 JSON 格式，通过 response 对象返回给客户端。

### 2.源代码 ###

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;
    
    /**
     * Annotation that indicates a method return value should be bound to the web
     * response body. Supported for annotated handler methods in Servlet environments.
     *
     * <p>As of version 4.0 this annotation can also be added on the type level in
     * which case it is inherited and does not need to be added on the method level.
     *
     * @author Arjen Poutsma
     * @since 3.0
     * @see RequestBody
     * @see RestController
     */
    @Target({ElementType.TYPE, ElementType.METHOD})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface ResponseBody {
    
    }

> 该注解指示方法的返回值应该被绑定到 web 响应体中。仅在 servlet 环境中可注解的方法上使用。从 4.0 开始，该注解可以被添加的类级别上，该类中的方法会继承类上的注解，无需单独的为类中方法添加注解。

### 3.代码示例 ###

产品 Controller 类

package org.learn.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    
    @Controller
    @RequestMapping("/product")
    public class ProductController {
    
        @ResponseBody
        @RequestMapping("/detail")
        public ProductDO getUser(){
            ProductDO productDO = new ProductDO();
            productDO.setName("华为手机Mate20");
            productDO.setDescription("华为手机");
            return productDO;
        }
    }

产品类：

package org.learn.controller;
    
    import java.io.Serializable;
    
    /**
     * 产品类
     *
     * @author zhibo
     * @date 2019-07-25 10:39
     */
    public class ProductDO implements Serializable {
        private static final long serialVersionUID = 6550342067524547999L;
        private String name;
        private String description;
    
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getDescription() {
            return description;
        }
        public void setDescription(String description) {
            this.description = description;
        }
    }

运行代码，执行结果如下图所示：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly96aGliby5ibG9nLmNzZG4ubmV0_size_16_color_FFFFFF_t_70]

### 4.@RestController注解 ###

@RestController 注解作用于类上，等于 @Controller 与 @ResponseBody 同时作用于类。

@RestController
    @RequestMapping("/product")
    public class ProductController {
        @RequestMapping("/detail")
        public ProductDO getUser(){
            ProductDO productDO = new ProductDO();
            productDO.setName("华为手机Mate20");
            productDO.setDescription("华为手机");
            return productDO;
        }
    }

等同于

@Controller
    @ResponseBody
    @RequestMapping("/product")
    public class ProductController {
        @RequestMapping("/detail")
        public ProductDO getUser(){
            ProductDO productDO = new ProductDO();
            productDO.setName("华为手机Mate20");
            productDO.setDescription("华为手机");
            return productDO;
        }
    }

本文内容适合于初学 springmvc 的同学。文章内容仅代表个人观点，如有不正之处，欢迎批评指正，谢谢大家。

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