如何使用Jackson ObjectMapper获得字段类型？

Question

Any idea how to retrieve Java type for given json path based on Jackson's ObjectMapper object and particular Class?

Let's say we have

class User {
    String fullName;
    Integer age;
    Boolean active;
    // ...
}
class Account {
    @JsonProperty("accountOwner")
    User owner;
    // ...
}

and Jackson's ObjectMapper I'd like to find a way to deserialize String value to object of type represented by the field on given path (or at least get its type), eg

• given "/accountOwner/age" and "25" get 25 (of type Integer)
• given "/accountOwner/active" and "true" get true (of type Boolean)
• given "/accountOwner/fullName" and "Johny Bravo" get "Johny Bravo" String
• etc ...

Answer 1

I have an example here:

User user = new User();
ObjectMapper mapper = new ObjectMapper();
try {
     user = mapper.readValue(new File("D:\\json.txt"), User.class);
    System.out.println("user : " + user);
} catch (Exception e) {
    e.printStackTrace();
}

My bean:

public class User {
    String fullName;
    Integer age;
    Boolean active;
    /**
     * @return the fullName
     */
    public String getFullName() {
        return fullName;
    }
    /**
     * @param fullName the fullName to set
     */
    public void setFullName(String fullName) {
        this.fullName = fullName;
    }
    /**
     * @return the age
     */
    public Integer getAge() {
        return age;
    }
    /**
     * @param age the age to set
     */
    public void setAge(Integer age) {
        this.age = age;
    }
    /**
     * @return the active
     */
    public Boolean getActive() {
        return active;
    }
    /**
     * @param active the active to set
     */
    public void setActive(Boolean active) {
        this.active = active;
    }

    @Override
    public String toString() {
        return "User [fullName=" + fullName + ", age=" + age + ", " +
                "active=" + active + "]";
    }
}

And finally the Json object (json.txt):

{"fullName":"Pedro Gamarra","age":30,"active":true}

I hope this can help you.