Spring Boot响应实体不返回JSON

Question

当我从RestController返回POJO时，它在JSON对象中转换。但是当我尝试返回new responseEntity<>（“success”,HttpStatus.created）；controller返回纯文本。怎么了？

我的RestController：

    @RequestMapping(value = "/register", method = RequestMethod.POST,consumes = "application/json", produces="application/json")
public ResponseEntity<?>  registerUser(@RequestBody User user) throws MessagingException {
    if(registrationService.canRegister(user.getEmail())){
        registrationService.registerUser(user);
        logger.info("Registered user "+user.getEmail());
        return new ResponseEntity<>("success", HttpStatus.CREATED);
    }
    return new ResponseEntity<>(HttpStatus.CONFLICT);
}

    <dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-java8</artifactId>
        <version>5.0.1.Final</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-jwt</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-config</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.7.2</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-oauth2</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-mail</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

Answer 1

“success”作为字符串不能强制转换为JSON格式。因此，spring controller返回plain/text。通常，对于要强制转换为JSON的任何对象，它必须是键值对的格式，因此所有POJO都可以转换为相应的键值对，其中key是属性名，value是属性的值。您可以查看此页面以验证什么构成有效的JSON。https://jsonformatter.curiousconcept.com/