Spring MVC配置+ Jackson + Guava多图

Question

我正在努力解决这个问题:

我们有一个带有Guava多重映射的Table类(简化代码,基本上是1个成员,2个构造函数,多重映射的getter和setter):

public class Table {

    private LinkedHashMultimap<String,Field> fields;

    public Table(){
        this.fields = LinkedHashMultimap.create();
    };

    public Table (LinkedHashMultimap<String, Field> fields){
        this.fields= fields;
    }

    public LinkedHashMultimap<String, Field> getFields() {
        return fields;
    }

    public void setFields(LinkedHashMultimap<String, Field> fields) {
        this.fields = fields;
    }
}

我想使用Jackson 2.4.3使用Spring MVC 3.2.11将其序列化.

POM相关的依赖关系是:

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-core</artifactId>
  <version>2.4.3</version>
  <scope>compile</scope>
</dependency>
<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.4.3</version>
  <scope>compile</scope>
</dependency>
<dependency>
  <groupId>com.fasterxml.jackson.datatype</groupId>
  <artifactId>jackson-datatype-guava</artifactId>
  <version>2.4.3</version>
  <scope>compile</scope>
</dependency>
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-context</artifactId>
  <version>3.2.11.RELEASE</version>
  <scope>compile</scope>
</dependency>
<dependency>
  <groupId>org.springframework</groupId>
  <artifactId>spring-webmvc</artifactId>
  <version>3.2.11.RELEASE</version>
  <scope>compile</scope>
</dependency>
<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>servlet-api</artifactId>
  <version>2.5</version>
  <scope>provided</scope>
</dependency>

我的spring.xml 现在看起来像这样(按照这个例子)

<bean id="abstractJacksonObjectMapper"
      class="org.springframework.beans.factory.config.MethodInvokingFactoryBean"
      p:targetMethod="registerModule">
    <property name="targetObject">
        <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean"
              p:indentOutput="true">
            <!--<property name="featuresToDisable">-->
                <!--<util:constant static-field="com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES" />-->
            <!--</property>-->
        </bean>
    </property>
    <property name="arguments">
        <list>
            <bean class="com.fasterxml.jackson.datatype.guava.GuavaModule" />
        </list>
    </property>
</bean>

<bean id="abstractMappingJacksonHttpMessageConverter"
      class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"
      abstract="true"/>

<bean id="abstractMappingJacksonJsonView"
      class="org.springframework.web.servlet.view.json.MappingJackson2JsonView"
      abstract="true"
      p:extractValueFromSingleKeyModel="true"/>

<bean id="jacksonObjectMapper" parent="abstractJacksonObjectMapper" />

<bean id="mappingJacksonHttpMessageConverter"
      parent="abstractMappingJacksonHttpMessageConverter"
      p:objectMapper-ref="jacksonObjectMapper"
      p:supportedMediaTypes="application/json" />

<bean id="mappingJacksonJsonView"
      parent="abstractMappingJacksonJsonView"
      p:objectMapper-ref="jacksonObjectMapper"
      p:contentType="application/json" />

我还使用扩展的Jackson2ObjectMapperFactoryBean 尝试了另一种方法:

<!-- Json rendering configuration-->
<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
    <property name="order" value="1" />
    <property name="mediaTypes">
        <map>
            <entry key="json" value="application/json" />
            <entry key="xml" value="application/xml" />
        </map>
    </property>
    <property name="defaultViews">
        <list>
            <bean class="org.springframework.web.servlet.view.json.MappingJackson2JsonView">
                <property name="objectMapper">
                    <bean class="my.package.Jackson2ObjectMapperFactoryBean"/>
                </property>
            </bean>
        </list>
    </property>
    <property name="ignoreAcceptHeader" value="true" />
</bean>

然后FactoryBean看起来像这样:

package my.package;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.guava.GuavaModule;

public class Jackson2ObjectMapperFactoryBean extends org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean{

public ObjectMapper getObject(){

    ObjectMapper objectMapper =super.getObject();
    objectMapper.registerModule(new GuavaModule());

    return objectMapper;
}

}

我有一个工作正常的Test类,根本不使用Spring(只测试Table.class + Jackson + guava)简化:

Table study = getTable();

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new GuavaModule());

String tableString = mapper.writeValueAsString(table);

它正确地序列化:

{
  "fields":{
    "Field1":[
      {
        "index":0,
        "header":"Field1",
        "fieldType":"fieldtype",
        "description":null,
        "cleanHeader":null
      }
    ],
    "Field2":[
      {
        "index":1,
        "header":"Field2",
        "fieldType":"fieldtype",
        "description":null,
        "cleanHeader":null
      }
    ]
  }
}

使用spring(2种方法中的任何一种)我得到:

{
  "fields":{
    "empty": false
  }
}

我的控制器有一个@ResponseBody注释,它返回一个表.

编辑:我正在深入调试春季课程(第一次,;-))和org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor正在处理请求.这与我的问题有关......我的spring xml是否与@ResponseBody注释有些矛盾？

我有什么想法我做错了吗？

注意:我需要Multimap,不能是标准的Java集合.

Answer 1

毕竟我发现 @ResponseBody 注释强制使用不同的“viewResolver”，即使用 Jackson，但没有 Guava 模块。

因此，为了解决这个问题，我删除了 Controller 方法中的 @ResponseBody 注释：

<!-- language: java -->
@ResponseBody
@RequestMapping("table")
public Table getTable() {

不幸的是，返回的是：{Table:{...}}，并且是 ValueHandlder (ModelAttributeMethodProcessor) 引入的人工制品。

最后，现在正在做的事情是：

1.- 恢复@ResponseBody 2.- 在默认情况下与@ResponseBody 处理程序一起提供的MappingJackson2HttpMessageConverter 中注册Guava 模块。

这就是 spring xml 的样子： 更加干净和简单：

<!-- JSON parser configuration-->
<bean id="guavaObjectMapper" class="com.fasterxml.jackson.databind.ObjectMapper"/>

<bean class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetObject"><ref local="guavaObjectMapper" /></property>
    <property name="targetMethod"><value>registerModule</value></property>
    <property name="arguments">
        <list>
            <bean id="guavaModule" class="com.fasterxml.jackson.datatype.guava.GuavaModule"/>
        </list>
    </property>
</bean>


<mvc:annotation-driven>
    <mvc:message-converters register-defaults="true">
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="objectMapper">
                <ref  local="guavaObjectMapper"/>
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>