SpringBoot 返回JSON一直报错问题

SpringBoot 返回Json一直报错问题

错误如下

1603178643723.png

我的错误原因是重写了 WebMvcConfigurationSupport 配置类，开始配置类是为了解决乱码问题而重写的，但是没注意到JSON问题

@Configuration
public class CharsetConfig extends WebMvcConfigurationSupport {

    @Bean
    public HttpMessageConverter<String> responseBodyConverter() {
        StringHttpMessageConverter converter = new StringHttpMessageConverter(
                Charset.forName("UTF-8"));
        return converter;
    }
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        //错误代码
        //super.configureMessageConverters(converters);
        //converters.add(responseBodyConverter());
        //修改后代码
        GsonHttpMessageConverter gsonHttpMessageConverter=new GsonHttpMessageConverter();
        converters.add(gsonHttpMessageConverter);
    }
    @Override
    public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
        configurer.favorPathExtension(false);
    }

}

默认Json转换器的使用步骤

1、在pom.xml中添加meaven依赖

 <dependency>
      <scope>compile</scope>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
      <version>2.3.4.RELEASE</version>
    </dependency>

此依赖默认加入jackjson-databinding作为JSON处理器，此时不需要额外的处理器就能返回一段JSON了

2、新建实体类

package com.hwp.pojo;

public class User {
    private int id;
    private String username;
    private String password;



    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

3、创建UserController实现类返回User对象即可

@RestController
public class UserController {
    @GetMapping("/user123")
    public User user123(){
        User user=new User();
        user.setId(1);
        user.setPassword("1222");
        user.setUsername("111");
        return   user;
    }
}

运行后浏览器输入

1603179276718.png