Jackson2.0与Spring 3.1

25-02-20 18

对于想了解Jackson2.0与Spring3.1的读者，本文将是一篇不可错过的文章，并且为您提供关于android–使用RoboSpice与Jackson2和Spring、Fastjson、Jack

对于想了解Jackson2.0与Spring 3.1的读者，本文将是一篇不可错过的文章，并且为您提供关于android – 使用RoboSpice与Jackson2和Spring、Fastjson、Jackson与SpringMVC整合的MessageConverter配置、Jackson 2.0 with Spring 3.1、Jackson 与Spring MVC复制嵌套对象不反序列化的有价值信息。

本文目录一览：

Jackson2.0与Spring 3.1
android – 使用RoboSpice与Jackson2和Spring
Fastjson、Jackson与SpringMVC整合的MessageConverter配置
Jackson 2.0 with Spring 3.1
Jackson 与Spring MVC复制嵌套对象不反序列化

Jackson2.0与Spring 3.1

Spring MVC 3.1与Jackson 2.0兼容吗？Spring
MVC在类路径上自动检测Jackson并委托给Jackson以JSON内容类型的请求是否仍然有效？

答案1

小编典典

在Spring 3.2中添加了对Jackson 2的支持，并且已经将其反向移植到Spring
3.1.2（SPR-9507）

android – 使用RoboSpice与Jackson2和Spring

我想将Jackson2与 SpringRoboSpice一起使用.
我的libs文件夹包含以下jar.

> commons-io-1.3.2.jar
> commons-lang3-3.2.1.jar
> jackson-annotations-2.2.3.jar
> jackson-core-2.2.3.jar
> jackson-databind-2.2.3.jar
> robospice-1.4.11.jar
> robospice-cache-1.4.11.jar
> robospice-spring-android-1.4.11.jar
> spring-android-core-1.0.1.RELEASE.jar
> spring-android-rest-template-1.0.1.RELEASE.jar

如果写了here,如果找到jackson2 jar,SpringAndroidSpiceService将切换到jackson2.

应用程序因此异常而崩溃：

java.lang.NoClassDefFoundError: org.codehaus.jackson.map.ObjectMapper
            at org.springframework.http.converter.json.MappingJacksonHttpMessageConverter.<init>(MappingJacksonHttpMessageConverter.java:54)
            at com.octo.android.robospice.JacksonspringAndroidSpiceService.createRestTemplate(JacksonspringAndroidSpiceService.java:33)
            at com.octo.android.robospice.SpringAndroidSpiceService.onCreate(SpringAndroidSpiceService.java:26)
            at android.app.ActivityThread.handleCreateService(ActivityThread.java:2572)
            at android.app.ActivityThread.access$1800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)

我错过了什么？

解决方法

如果你使用Jackson 2,那么你需要使用 Jackson2SpringAndroidSpiceService而不是JacksonspringAndroidSpiceService. 2件事:)

Fastjson、Jackson与SpringMVC整合的MessageConverter配置

1.Jackson

maven依赖

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.7.1</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.dataformat</groupId>
    <artifactId>jackson-dataformat-xml</artifactId>
    <version>2.7.1</version>
</dependency>

springmvc-servlet.xml中配置

<mvc:annotation-driven>
    <mvc:message-converters>
        <bean>
            <constructor-arg value="UTF-8"/>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>

2.FastJson

由于FastJson针对Spring4.2以后进行特殊优化，具体如图

所以FastJson可以分为Spring4.2及以下配置和Spring4.2以上的不同配置

2.1Spring4.2及以下配置

maven依赖

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.7</version>
</dependency>

springmvc-servlet.xml中配置

<mvc:annotation-driven>
        <mvc:message-converters register-defaults="true">
            <bean>
                <property name="supportedMediaTypes">
                    <list>
                        <value>text/html;charset=UTF-8</value>
                        <value>application/json</value>
                        <value>application/xml;charset=UTF-8</value>
                    </list>
                </property>
                <property name="features">
                    <list>
                        <value>WriteMapNullValue</value>
                        <value>QuoteFieldNames</value>
                        <value>WriteDateUseDateFormat</value>
                    </list>
                </property>
            </bean>
        </mvc:message-converters>
</mvc:annotation-driven>

2.2Spring4.2以上配置

maven依赖

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.7</version>
</dependency>

springmvc-servlet.xml中配置

<mvc:annotation-driven validator="validator">
        <mvc:message-converters register-defaults="true">
            <ref bean="stringHttpMessageConverter"/>
            <ref bean="fastJsonHttpMessageConverter"/>
        </mvc:message-converters>
</mvc:annotation-driven>
<!--FastJson(spring4.2x版本以上)-->
<bean id="stringHttpMessageConverter">
        <constructor-arg value="UTF-8" index="0"></constructor-arg>
        <property name="supportedMediaTypes">
            <list>
                <value>text/plain;charset=UTF-8</value>
            </list>
        </property>
</bean>

<bean id="fastJsonHttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/html;charset=UTF-8</value>
                <value>application/json;charset=UTF-8</value>
            </list>
        </property>
        <property name="fastJsonConfig">
            <bean>
                <property name="features">
                    <list>
                        <value>AllowArbitraryCommas</value>
                        <value>AllowUnQuotedFieldNames</value>
                        <value>DisableCircularReferenceDetect</value>
                    </list>
                </property>
                <property name="dateFormat" value="yyyy-MM-dd HH:mm:ss"></property>
            </bean>
        </property>
</bean>

Jackson 2.0 with Spring 3.1

Spring MVC 3.1与Jackson 2.0兼容吗？Spring MVC在类路径上自动检测Jackson并委托给Jackson以JSON内容类型的请求是否仍然有效？

答案1

小编典典

来自spring的Keith Donald前一段时间在Twitter上发布了推文。

Spring MVC对Jackson 2的支持；还可以与Jackson的本机“漂亮打印”功能配合使用https://gist.github.com/2423129

我没有尝试MappingJackson2HttpMessageConverter上面要点中的发现，但是如果不起作用，我会感到惊讶。

Jackson 与Spring MVC复制嵌套对象不反序列化

我正在尝试将以下POJO转换为JSON @RestController：

@Entity@Table(name="user_location")@NamedQuery(name="UserLocation.findAll", query="SELECT u FROM UserLocation u")public class UserLocation implements Serializable {    private static final long serialVersionUID = 1L;    @Id    @GeneratedValue(strategy=GenerationType.IDENTITY)    private int id;    private String addr1;    private String addr2;    private String landmark;    private BigDecimal lat;    private BigDecimal lng;    private String zipcode;    //bi-directional many-to-one association to City    @ManyToOne    private City city;    //bi-directional many-to-one association to State    @ManyToOne    private State state;    public UserLocation() {    }    //Getter - Setters}

嵌套的City.java如下：

@Entity@NamedQuery(name="City.findAll", query="SELECT c FROM City c")@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property="@id", scope = City.class)public class City implements Serializable {    private static final long serialVersionUID = 1L;    @Id    @GeneratedValue(strategy=GenerationType.IDENTITY)    private int id;    private String name;    //bi-directional many-to-one association to State    @ManyToOne    @JsonIgnore    private State state;    //bi-directional many-to-one association to UserLocation    @OneToMany(mappedBy="city")    @JsonIgnore    private List<UserLocation> userLocations;    public City() {    }    public int getId() {        return this.id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return this.name;    }    public void setName(String name) {        this.name = name;    }    @JsonProperty("state")    public State getState() {        return this.state;    }    public void setState(State state) {        this.state = state;    }    public List<UserLocation> getUserLocations() {        return this.userLocations;    }    public void setUserLocations(List<UserLocation> userLocations) {        this.userLocations = userLocations;    }    public UserLocation addUserLocation(UserLocation userLocation) {        getUserLocations().add(userLocation);        userLocation.setCity(this);        return userLocation;    }    public UserLocation removeUserLocation(UserLocation userLocation) {        getUserLocations().remove(userLocation);        userLocation.setCity(null);        return userLocation;    }}

另一个嵌套类State.java如下：

@Entity@NamedQuery(name="State.findAll", query="SELECT s FROM State s")@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property="@id", scope = State.class)public class State implements Serializable {    private static final long serialVersionUID = 1L;    @Id    @GeneratedValue(strategy=GenerationType.IDENTITY)    private int id;    private String name;    //bi-directional many-to-one association to City    @OneToMany(mappedBy="state")    @JsonIgnore    private List<City> cities;    //bi-directional many-to-one association to UserLocation    @OneToMany(mappedBy="state")    @JsonIgnore    private List<UserLocation> userLocations;    public State() {    }    public int getId() {        return this.id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return this.name;    }    public void setName(String name) {        this.name = name;    }    public List<City> getCities() {        return this.cities;    }    public void setCities(List<City> cities) {        this.cities = cities;    }    public City addCity(City city) {        getCities().add(city);        city.setState(this);        return city;    }    public City removeCity(City city) {        getCities().remove(city);        city.setState(null);        return city;    }    public List<UserLocation> getUserLocations() {        return this.userLocations;    }    public void setUserLocations(List<UserLocation> userLocations) {        this.userLocations = userLocations;    }    public UserLocation addUserLocation(UserLocation userLocation) {        getUserLocations().add(userLocation);        userLocation.setState(this);        return userLocation;    }    public UserLocation removeUserLocation(UserLocation userLocation) {        getUserLocations().remove(userLocation);        userLocation.setState(null);        return userLocation;    }}

从UserLocation.java转换的JSON如下：

{    id: 1,    addr1: "11905 Technology",    addr2: "Eden Prairie",    landmark: null,    lat: null,    lng: null,    zipcode: "55344",    city: {        @id: 1,        id: 2,        name: "Westborough",        state: {            @id: 1,            id: 2,            name: "MA"        }    },    state: 1}

如您所见，该State对象作为一个整体进入了内部city。但是外部的state（“ UserLocation is showing justan id ofState object. I need to have a samestate object as that ofcity
”的属性，而不只是ID。

我对JackSon API比较陌生。请建议我应该采取哪种方法来实现此要求。

谢谢

答案1

小编典典

这就是杰克逊设计JsonIdentityInfo批注逻辑的方式。

 * Annotation used for indicating that values of annotated type * or property should be serializing so that instances either * contain additional object identifier (in addition actual object * properties), or as a reference that consists of an object id * that refers to a full serialization. In practice this is done * by serializing the first instance as full object and object * identity, and other references to the object as reference values.

Jackson将第一次运行完整的序列化，只有第二次找到该对象时，才会对ID进行序列化。

因此，有两种解决方法：

1）您可以简单地删除@JsonIdentityInfo批注，Jackson将按您期望的方式序列化对象，但将从响应中删除@id字段。这可能很好，因为您仍然会拥有’id’属性。

2）我觉得您可以简单地重组对象并删除一些引用。我会说还是做这些更改是一件好事。首先，您可以从UserLocation中删除对State的引用。我要说的是，因为State附加在City上，所以没有必要将State放在userLocation类中。这样，您将可以从城市访问州，从而解决了您的问题。另外，我将从City类和State类中删除对userLocations列表的引用。

它看起来像：

UserLocation有城市，没有州。

城市有州，没有用户位置

州没有用户位置，也没有城市。

希望这可以帮助

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