接受/返回 XML/JSON 请求和响应 - Spring MVC

Question

我需要编写一个 rest 服务，它接受 XML/JSON 作为输入（POST 方法）和 XML/JSON 作为输出（基于输入格式）。我尝试了以下方法来实现这一目标，但没有帮助。终结点方法同时接受 XML/JSON，但在响应时，它始终根据 @RequestMapping -produces 中指定的顺序提供 JSON 或 XML。任何帮助将不胜感激。

我的endpoint方法：

@RequestMapping(value = "/getxmljson", method = RequestMethod.POST,produces={"application/json","application/xml"},
        consumes={"application/json", "application/xml"})
public @ResponseBody Student processXMLJsonRequest(@RequestBody Student student)
        throws Exception {
    System.out.println("*************Inside Controller");
    return student;
}

POJO班：学生.java

import java.io.Serializable;
import java.util.ArrayList;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;

@XmlRootElement(name = "student")
@XmlType(propOrder = {"id", "name", "graduationTime", "courses"})
@JsonPropertyOrder({"id", "name", "graduationTime", "courses"})
public class Student implements Serializable {
    private static final long serialVersionUID = 1L;

    private int id;
    private String name;
    private String graduationTime;
    private ArrayList<Course> courses = new ArrayList<Course>();

    @XmlElement
    public int getId() { return id; }
    @XmlElement
    public String getName() { return name; }
    @XmlElement
    public String getGraduationTime() { return graduationTime; }
    @XmlElement
    public ArrayList<Course> getCourses() { return courses; }

    public void setId(int value) { this.id = value; }
    public void setName(String value) { this.name = value; }
    public void setGraduationTime(String value) { this.graduationTime = value; }
    public void setCourses(ArrayList<Course> value) { this.courses = value; }

    @JsonIgnore
    public String toString() {
        return this.name + " - "
                + graduationTime == null? "Unknown" : graduationTime.toString();
    }

    public Student() {}
    public Student(int id, String name, String graduationTime) {
        this.id = id;
        this.name = name;
        this.graduationTime = graduationTime;
    }
}

POJO类：Course.java

import java.io.Serializable;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

import com.fasterxml.jackson.annotation.JsonPropertyOrder;

@XmlRootElement(name = "course")
@XmlType(propOrder = {"courseName", "score"})
@JsonPropertyOrder({"courseName", "score"})
public class Course implements Serializable {
    private static final long serialVersionUID = 1L;

    private String courseName;
    private Integer score;

    public @XmlElement String getCourseName() { return courseName; }
    public @XmlElement Integer getScore() { return score; }

    public void setCourseName(String value) { courseName = value; }
    public void setScore(Integer value) { score = value; }

    public Course() {}
    public Course(String courseName, Integer score) {
        this.courseName = courseName;
        this.score = score;
    }
}

spring-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:sws="http://www.springframework.org/schema/web-services"
    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:oxm="http://www.springframework.org/schema/oxm"
    xmlns:util="http://www.springframework.org/schema/util"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
            http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/web-services
        http://www.springframework.org/schema/web-services/web-services-2.0.xsd
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
            http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.0.xsd
       http://www.springframework.org/schema/oxm http://www.springframework.org/schema/oxm/spring-oxm-4.0.xsd
       http://www.springframework.org/schema/util
            http://www.springframework.org/schema/util/spring-util-2.5.xsd">

    <!-- DispatcherServlet Context: defines this servlet's request-processing 
        infrastructure -->

    <!-- Enables the Spring MVC @Controller programming model -->
    <annotation-driven />

    <!-- Handles HTTP GET requests for /resources/** by efficiently serving 
        up static resources in the ${webappRoot}/resources directory -->
    <resources mapping="/resources/**" location="/resources/" />

    <!-- Configure to plugin JSON as request and response in method handler -->
    <beans:bean
        class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
        <beans:property name="messageConverters">
            <beans:list>
                <beans:ref bean="jsonMessageConverter" />
                <beans:ref bean="xmlMessageConverter" />
            </beans:list>
        </beans:property>
    </beans:bean>

    <!-- Configure bean to convert JSON to POJO and vice versa -->
    <beans:bean id="jsonMessageConverter"
        class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
    </beans:bean>

    <beans:bean id="xmlMessageConverter"
        class="org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter">
    </beans:bean>

    <beans:bean id="restTemplate" class="org.springframework.web.client.RestTemplate">

    </beans:bean>

    <beans:bean id="objectMapper" class="com.fasterxml.jackson.databind.ObjectMapper" />
    <context:component-scan base-package="com.test" />

</beans:beans>

Json输入:

{
"id":2014,
"name":"test",
"graduationtime":"09/05/2014",
"courses":[
{
"courseName":"Math",
"score":150
},
{
"courseName":"Che",
"score":150
}
]
}

XML输入：

<?xml version="1.0" encoding="UTF-8" ?>
<student>
<id>2014</id>
<name>test</name>
<graduationTime>09/05/2014</graduationTime>
<courses>
    <courseName>Math</courseName>
    <score>150</score>
</courses>
<courses>
    <courseName>Che</courseName>
    <score>150</score>
</courses>
</student>

Answer 1

注册一个拦截每个请求的过滤器，将HttpServletRequest扭曲为HttpServletRequest estWrapper的实现，并返回接受标头的Content-Type值。例如，您可以注册一个名为SameInSameOutFilter的过滤器，如下所示：

@Component
public class SameInSameOutFilter extends GenericFilterBean {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        SameInSameOutRequest wrappedRequest = new SameInSameOutRequest((HttpServletRequest) request);
        chain.doFilter(wrappedRequest, response);
    }
}

它将当前请求包装在＜code＞SameInSameOutRequest＜code＞中：

public class SameInSameOutRequest extends HttpServletRequestWrapper {
    public SameInSameOutRequest(HttpServletRequest request) {
        super(request);
    }

    @Override
    public String getHeader(String name) {
        if (name.equalsIgnoreCase("accept")) {
            return getContentType();
        }

        return super.getHeader(name);
    }
}

这个包装器告诉spring mvc根据请求的< code>Content-Type值选择一个< code > HttpMessageConverter 。如果请求正文的< code>Content-Type是< code>application/xml，则响应将是< code>XML。否则，响应将是< code>JSON。

另一种解决方案是在每个请求中手动设置接受标头以及Content-Type并避免所有这些黑客攻击。

Answer 2

补充Manish上面的回答，如果你不想使用基于xml的配置，请使用基于java的配置

@Bean
public ViewResolver contentNegotiatingViewResolver() {
    ContentNegotiatingViewResolver resolver =
            new ContentNegotiatingViewResolver();

    List<View> views = new ArrayList<>();
    views.add(new MappingJackson2XmlView());
    views.add(new MappingJackson2JsonView());

    resolver.setDefaultViews(views);
    return resolver;
}

Answer 3

使用同一个控制器处理不同数据格式的最佳实践是让框架完成确定编组和解编组机制的所有工作。

步骤1：使用最小控制器配置

@RequestMapping(value = "/getxmljson", method = RequestMethod.POST)
@ResponseBody
public Student processXMLJsonRequest(@RequestBody Student student) {
  return student;
}

这里不需要指定消耗和产生。例如，考虑到您可能希望将来使用相同的方法来处理其他格式，例如Google协议缓冲区、EDI等。使控制器免于消耗和产生将允许您通过全局配置添加数据格式，而不必修改控制器代码。

步骤 2：使用 ContentNegotiatingViewResolver 而不是 RequestMappingHandlerAdapter

  <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
    <property name="defaultViews">
      <list>
        <bean class="org.springframework.web.servlet.view.json.MappingJackson2JsonView"/>
      </list>
    </property>
  </bean>

让视图解析器决定如何读取传入的数据以及如何写回。

步骤 3：使用接受和内容类型 HTTP 标头

用正确的HTTP头值访问您的控制器将强制< code > contentnegotiatingviewrolver 使用适当的数据表示自动封送和解封送数据。

如果您想以JSON格式交换数据，请将两个头设置为＜code＞application/JSON＜/code＞。如果希望使用XML，请将两者设置为＜code＞application/XML＜/code＞。

如果您不想使用HTTP头(理想情况下您应该使用)，您可以简单地添加< code >。json或< code >。xml转换为URL，而< code > contentnegotiatingviewrolver 将完成剩下的工作。

您可以查看我使用您的代码片段创建的示例应用程序，这些代码片段适用于JSON和XML。