# Spring REST JSON 响应示例 > 原文： [https://howtodoinjava.com/spring-restful/spring-rest-hello-world-json-example/](https://howtodoinjava.com/spring-restful/spring-rest-hello-world-json-example/) 在 **Spring REST JSON 示例**中，我们将学习编写能够返回资源的 JSON 表示形式的[ RESTful Web 服务](https://howtodoinjava.com/restful-web-service/)。 我们将使用`MappingJackson2JsonView`将视图解析为 JSON 正文。 > 阅读更多： [Spring REST XML 教程](https://howtodoinjava.com/spring/spring-restful/spring-rest-hello-world-xml-example/) ## 1\. Spring REST JSON – `@ResponseBody`注解 此**首要技术**简单易行。 我们只需要在应用程序的类路径中包含 **jackson** 依赖项，spring 就会自动将`Jackson2JsonMessageConverter`类注册到上下文中。 每当我们从 REST API 请求资源并提供 http 标头`accept: application/json`时，我们都将取回资源的 json 表示形式。 #### 1.1. JSON 运行时依赖 `pom.xml` ```java <!-- Jackson JSON Processor --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.4.1</version> </dependency> ``` #### 1.2. `@ResponseBody`支持 > 这里`@RestController = @Controller + @ResponseBody` `EmployeeRESTController.java` ```java @RestController public class EmployeeRESTController { @RequestMapping(value = "/employees") public EmployeeListVO getAllEmployees() { EmployeeListVO employees = new EmployeeListVO(); EmployeeVO empOne = new EmployeeVO(1,"Lokesh","Gupta","howtodoinjava@gmail.com"); EmployeeVO empTwo = new EmployeeVO(2,"Amit","Singhal","asinghal@yahoo.com"); EmployeeVO empThree = new EmployeeVO(3,"Kirti","Mishra","kmishra@gmail.com"); employees.getEmployees().add(empOne); employees.getEmployees().add(empTwo); employees.getEmployees().add(empThree); return employees; } @RequestMapping(value = "/employees/{id}") public ResponseEntity<EmployeeVO> getEmployeeById (@PathVariable("id") int id) { if (id <= 3) { EmployeeVO employee = new EmployeeVO(1,"Lokesh","Gupta","howtodoinjava@gmail.com"); return new ResponseEntity<EmployeeVO>(employee, HttpStatus.OK); } return new ResponseEntity(HttpStatus.NOT_FOUND); } } ``` ## 2\. Spring REST JSON – `MappingJackson2JsonView`支持 这是**第二技术**。 `MappingJackson2JsonView`类还取决于类路径中 **Jackson** JSON 处理器库的存在，因此您无需添加任何其他内容。 完整的`pom.xml`看起来像这样。 #### 2.1. Maven 依赖 `pom.xml` ```java <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.howtodoinjava.demo</groupId> <artifactId>springrestexample</artifactId> <packaging>war</packaging> <version>0.0.1-SNAPSHOT</version> <name>springrestexample Maven Webapp</name> <url>http://maven.apache.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> <!-- Spring MVC support --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>4.1.4.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>4.1.4.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>4.1.4.RELEASE</version> </dependency> <!-- Jackson JSON Processor --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.4.1</version> </dependency> </dependencies> <build> <finalName>springrestexample</finalName> </build> </project> ``` #### 2.2. 添加`MappingJackson2JsonView`视图 使用`MappingJackson2JsonView`类时，您将需要返回`MappingJackson2JsonView`类型的视图名称。 因此，您将需要更改两个位置。 ##### 2.2.1. 控制器变更 您将需要从控制器方法返回视图名称。在我们的例子中，视图名称是`jsonTemplate`。 ```java package com.howtodoinjava.demo.controller; import org.springframework.http.HttpStatus; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import com.howtodoinjava.demo.model.EmployeeListVO; import com.howtodoinjava.demo.model.EmployeeVO; @Controller public class EmployeeRESTController { private EmployeeListVO getEmployeesCollection() { EmployeeListVO employees = new EmployeeListVO(); EmployeeVO empOne = new EmployeeVO(1,"Lokesh","Gupta","howtodoinjava@gmail.com"); EmployeeVO empTwo = new EmployeeVO(2,"Amit","Singhal","asinghal@yahoo.com"); EmployeeVO empThree = new EmployeeVO(3,"Kirti","Mishra","kmishra@gmail.com"); employees.getEmployees().add(empOne); employees.getEmployees().add(empTwo); employees.getEmployees().add(empThree); return employees; } @RequestMapping(value = "/employees") public String getAllEmployeesJSON(Model model) { model.addAttribute("employees", getEmployeesCollection()); return "jsonTemplate"; } } ``` ##### 2.2.2. 配置变更 您将需要将视图名称`jsonTemplate`配置为类型为`MappingJackson2JsonView`的 bean。 并且您将需要配置类型为`BeanNameViewResolver`的视图解析器。 这样，视图名称`jsonTemplate`将与`MappingJackson2JsonView`匹配，并且将已解析的 JSON 响应返回给客户端。 `RESTConfiguration.java` ```java @Configuration public class RESTConfiguration { @Bean public View jsonTemplate() { MappingJackson2JsonView view = new MappingJackson2JsonView(); view.setPrettyPrint(true); return view; } @Bean public ViewResolver viewResolver() { return new BeanNameViewResolver(); } } ``` 与上述 java 配置等效的 XML 配置如下。 `spring-servlet.xml` ```java <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context/ http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <context:component-scan base-package="com.howtodoinjava.demo" /> <mvc:annotation-driven /> <!-- JSON Support --> <bean name="viewResolver" class="org.springframework.web.servlet.view.BeanNameViewResolver"/> <bean name="jsonTemplate" class="org.springframework.web.servlet.view.json.MappingJackson2JsonView"/> </beans> ``` **3\. Spring REST JSON 示例 – 演示** 现在，当您点击 URL：`http://localhost:8080/springrestexample/employees`时，您将得到此结果。  Spring REST JSON 示例 ## 4\. Spring REST JSON 示例 – 项目结构  Spring REST JSON 示例 – 项目结构 这就是带有 spring mvc 的 **spring restful web 服务 json** 简单示例的全部内容。 将您的问题留在我的评论中。 学习愉快！