Spring MVC中OrderList对象XML序列化无转换器问题求助

在Spring MVC应用中返回OrderList类型对象作为XML格式HTTP响应时，收到如下警告：

WARN 21264 --- [nio-8080-exec-2] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class com.gcu.model.OrderList] with preset Content-Type 'null']

OrderList是标注了JAXB注解的POJO，用于XML序列化，内部包含OrderModel列表，代码如下：

package com.gcu.model;

import jakarta.xml.bind.annotation.XmlElement;
import jakarta.xml.bind.annotation.XmlRootElement;

import java.util.ArrayList;
import java.util.List;

@XmlRootElement(name = "orders")
public class OrderList {

    private List<OrderModel> orders = new ArrayList<OrderModel>();

    public void setOrders(List<OrderModel> orders) {
        this.orders = orders;
    }

    @XmlElement(name = "order")
    public List<OrderModel> getOrders() {
        return orders;
    }

}

当前相关依赖：

<dependency>
    <groupId>jakarta.xml.bind</groupId>
    <artifactId>jakarta.xml.bind-api</artifactId>
    <version>3.0.0</version>
</dependency>
<dependency>
    <groupId>com.sun.xml.bind</groupId>
    <artifactId>jaxb-impl</artifactId>
    <version>2.3.3</version>
    <scope>runtime</scope>
</dependency>

REST服务实现代码：

package com.gcu.business;

import org.springframework.web.bind.annotation.RestController;

import com.gcu.model.OrderList;
import com.gcu.model.OrderModel;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

@RestController
@RequestMapping("/service")
public class OrdersRestService {

    @Autowired
    private OrdersBusinessInterface service;

    @GetMapping(path = "/getjson", produces = { MediaType.APPLICATION_JSON_VALUE })
    public List<OrderModel> getOrdersAsJson() {
        return service.getOrders();
    }

    @GetMapping(path="/getorder/{id}", produces = { MediaType.APPLICATION_JSON_VALUE })
    public ResponseEntity<?> getOrder(@PathVariable("id") String id)
    {
        try
        {
            OrderModel order = service.getOrder(id);
            if (order == null)
            {
                return new ResponseEntity<>(HttpStatus.NOT_FOUND);
            }
            else
            {
                return new ResponseEntity<>(order, HttpStatus.OK);
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
            return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

    @GetMapping(path = "/getxml", produces = { MediaType.APPLICATION_XML_VALUE })
    public OrderList getOrdersAsXml() {
        OrderList orders = new OrderList();
        orders.setOrders(service.getOrders());
        return orders;
    }
}

解决方案 #

1. 修复JAXB依赖版本不兼容问题

你使用的jakarta.xml.bind-api:3.0.0属于Jakarta EE 9规范（包名从javax.xml.bind改为jakarta.xml.bind），但配套的实现jaxb-impl:2.3.3是Java EE 8版本，两者不兼容，导致Spring无法找到正确的XML转换器。

将依赖替换为Jakarta EE 9兼容的JAXB实现：

<!-- Jakarta XML Binding API -->
<dependency>
    <groupId>jakarta.xml.bind</groupId>
    <artifactId>jakarta.xml.bind-api</artifactId>
    <version>3.0.2</version>
</dependency>
<!-- Jakarta XML Binding 实现 -->
<dependency>
    <groupId>com.sun.xml.bind</groupId>
    <artifactId>jaxb-impl</artifactId>
    <version>3.0.2</version>
    <scope>runtime</scope>
</dependency>
<!-- 可选：JAXB运行时核心依赖 -->
<dependency>
    <groupId>com.sun.xml.bind</groupId>
    <artifactId>jaxb-core</artifactId>
    <version>3.0.2</version>
    <scope>runtime</scope>
</dependency>

2. 确保OrderModel类正确标注JAXB注解

OrderList包含OrderModel列表，必须确保OrderModel也添加了JAXB序列化注解，否则XML转换器无法处理嵌套对象：

package com.gcu.model;

import jakarta.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "order")
public class OrderModel {
    private String id;
    private String productName;

    // getter和setter方法
    public String getId() { return id; }
    public void setId(String id) { this.id = id; }
    public String getProductName() { return productName; }
    public void setProductName(String productName) { this.productName = productName; }
}

3. 手动配置JAXB消息转换器（自动配置失效时使用）

如果Spring Boot没有自动注册Jaxb2RootElementHttpMessageConverter，可以手动创建配置类添加转换器：

package com.gcu.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.util.List;

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(new Jaxb2RootElementHttpMessageConverter());
    }
}

完成以上步骤后，重启应用，访问/service/getxml接口即可正常返回XML格式的OrderList响应。

内容的提问来源于stack exchange，提问作者Isaac Luth