无法从Spring controler返回JSON响应（也添加了jackson jars）

Question

我试图将客户列表作为JSON响应发送，但是，它返回的错误响应为

 No converter found for return value of type: class java.util.ArrayList

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "net.ifg.spring")
public class AppConfig {

@Bean
public Jackson2ObjectMapperBuilder jackson2ObjectMapperBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
    return builder;
}
}

我的控制器是

@RestController
public class CustomerRestController {

    @Autowired
    private CustomerDAO customerDAO;

    @GetMapping("/customers")
    public List<Customer> getCustomers() {
        return customerDAO.list();
    }

}

public class Customer {

private Long id;
private String firstName;


public Customer(long id, String firstName) {
    this.id = id;
    this.firstName = firstName;     
}

public Customer() {
}

public Long getId() {
    return id;
}

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

public String getFirstName() {
    return firstName;
}

public void setFirstName(String firstName) {
    this.firstName = firstName;
}


}

commons-logging-1.2.jar,jackson-core-asl-1.9.13.jar,jackson-mapper-asl-1.9.13.jar,jackson-databind-2.9.0.jar,spring-aop,spring-core,spring-beans,spring-context,spring-expression,spring-web,spring-webmvc（全部4.3.9版本）

仍然返回me错误响应。

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.IllegalArgumentException: No converter found for return value of type: class java.util.ArrayList
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

任何想法都将不胜感激

Answer 1

在项目中添加Jackson依赖项或jar。

就像，

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>VERSION</version></dependency>