JsonFormat注解是一个时间格式化注解，在实际开发过程中，我们需要用到JsonFormat注解来格式化我们的时间。但是却发现jsonformat不起作用，那么今天我们就来给大家讲解一下jsonformat不起作用的相关内容。
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;
}
@Override
public 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>
JsonFormat注解是一个时间格式化注解，作为java人员一定要学会解决JsonFormat的各项问题，最后大家如果想要了解更多json相关知识，敬请关注奇Q工具网。
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