无法从Spring控制器返回JSON响应（也添加了jackson jar）

Question

我尝试将客户列表作为JSON响应发送，但是，它以错误响应返回

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

配置类

@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();
    }

}

客户类

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;
}


}

JARs添加

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4.3.9版本）

仍在回复我的错误回复。

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)

非常感谢任何想法

Answer 1

在项目中添加Jackson依赖项或jar。

像，

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

Answer 2

如果在Spring MVC中进行此操作，则dispatcher-servlet的xml文件必须具有<mvc:annotation-driven />标记才能进行转换。