JsonFormat 标签使用

打算将数据库取出的Date类型的数据改成一定格式的时间，如改成yyyy-MM-dd。然后在属性的get方法上加了@JsonFormat，结果取出时一直是long类型的Date，代码如下：

package soc.entity;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

import com.fasterxml.jackson.annotation.JsonFormat;

//@JsonIgnoreProperties({“hibernateLazyInitializer”, “handler”})
/*@XmlRootElement
@XmlType(name = “user”, propOrder = {
“id”,
“name”,
“salary”,
“birthday”}
)*/
public class User {
private long id;
private String name;

@Min(value=6000,message="最低工资为6000")@Max(value=25000,message="最高工资为25000")private Double salary;private Date birthday;public User() {}public User(long id, String name, Double salary, String birthday) {    super();    this.id = id;    this.name = name;    this.salary = salary;    try {        this.birthday = new SimpleDateFormat("yyyy-MM-dd").parse(birthday);    } catch (ParseException e) {        e.printStackTrace();    }}public User(String name, Double salary, String birthday) {    super();    this.name = name;    this.salary = salary;    try {        this.birthday = new SimpleDateFormat("yyyy-MM-dd").parse(birthday);    } catch (ParseException e) {        e.printStackTrace();    }}public String getName() {    return name;}public void setName(String name) {    this.name = name;}public Double getSalary() {    return salary;}public void setSalary(Double salary) {    this.salary = salary;}

// @XmlJavaTypeAdapter(DateAdapter.class)//这种格式也可以2018-10-15 10:12:15
// @JsonFormat(pattern=”yyyy-MM-dd HH:mm:ss”,timezone = “GMT+8”)//json的返回格式
@JsonFormat(pattern=”yyyy/MM/dd HH:mm:ss”,timezone = “GMT+8”)//json的返回格式
public Date getBirthday() {
return birthday;
}

public void setBirthday(Date birthday) {    this.birthday = birthday;}public long getId() {    return id;}public void setId(long id) {    this.id = id;}@Overridepublic String toString() {    String birthdayS = (new SimpleDateFormat("yyyy-MM-dd")).format(birthday);    return "User : id="+id+", Name="+name+", Salary="+salary+", Birthday="+birthdayS;}

}
配置类如下：

package soc.config;

import org.codehaus.jackson.jaxrs.JacksonJsonProvider;
import org.glassfish.jersey.filter.LoggingFilter;
//import org.glassfish.jersey.jackson.JacksonFeature;
import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.server.spring.scope.RequestContextFilter;

public class ApplicationApi extends ResourceConfig {
public ApplicationApi() {

    // 注册数据转换器    register(JacksonJsonProvider.class);    // 注册日志    register(LoggingFilter.class);    // register application resources    // register(UserResource.class);    packages("soc.resource");    // register filters    register(RequestContextFilter.class);    // register mine exception class ,to find the trace of exception    register(DebugMapperException.class);    // register features    // register(JacksonFeature.class);}

}
经过一番查看，最后发现该配置类里的JacksonJsonProvider是

org.codehaus.jackson.jaxrs.JacksonJsonProvider
而实体User类上的注解@JsonFormat则是

com.fasterxml.jackson.annotation.JsonFormat
两者根本不是同一类型，将JacksonJsonProvider改成

com.fasterxml.jackson.jaxrs.json.JacksonJsonProvider
则问题解决。

综上得出结论，用@JsonFormat注解时，json格式支持的jaxrs的实现类必须与该注解是同一个大类型，即fasterxml,jar包如下：

        <dependency>        <groupId>com.fasterxml.jackson.jaxrs</groupId>        <artifactId>jackson-jaxrs-json-provider</artifactId>        <version>2.5.4</version>    </dependency>

如果json格式支持的jaxrs的实现类是codehaus,则@JsonFormat注解不起作用，即不可以是如下jar包：

    <dependency>      <groupId>org.codehaus.jackson</groupId>      <artifactId>jackson-jaxrs</artifactId>     <version>1.9.13</version>     </dependency>