pojo

问题 In my project I have a small data structure Key . public class Key implements Serializable { private static final long serialVersionUID = 1L; public String db; public String ref; public Object id; protected Key() { } public Key(String db, String ref, Object id) { this.db = db; this.ref = ref; this.id = id; } } Yes this class is simple and every field is publicly accessible. But someone has suggested I use POJO style classes instead but when I asked why they were unable to tell me. In my

问题 I want to know if there is any Java API available to convert a POJO object to a JSON object and vice versa. 回答1: Take a look at https://www.json.org [edited] Imagine that you have a simple Java class like this: public class Person { private String name; private Integer age; public String getName() { return this.name; } public void setName( String name ) { this.name = name; } public Integer getAge() { return this.age; } public void setAge( Integer age ) { this.age = age; } } So, to transform

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Difference between DTO, VO, POJO, JavaBeans? Hi please don\'t say my question is duplicate :-) I saw all questions but didn\'t understand the exact difference. Can someone explain what is POJO , Bean , Normal Class in easy language? 回答1: Normal Class : A Java class Java Beans : All properties private (use getters/setters) A public no-argument constructor Implements Serializable. Pojo : Plain Old Java Object is a

问题 I am having a question with Jackson that I think should be simple to solve, but it is killing me. Let\'s say I have a java POJO class that looks like this (assume Getters and Setters for me): class User { private String name; private Integer age; } And I want to deserialize JSON that looks like this into a User object: { \"user\": { \"name\":\"Sam Smith\", \"age\":1 } } Jackson is giving me issues because the User is not the first-level object in the JSON. I could obviously make a UserWrapper

问题 I have a Spring Data repository method with a native query @Query(value = \"SELECT g.*, gm.* FROM group g LEFT JOIN group_members gm ON g.group_id = gm.group_id and gm.user_id = :userId WHERE g.group_id = :groupId\", nativeQuery = true) GroupDetails getGroupDetails(@Param(\"userId\") Integer userId, @Param(\"groupId\") Integer groupId); and I\'d like to map the result to Non-Entity POJO GroupDetails . Is it possible and if so, could you please provide an example ? 回答1: Assuming GroupDetails

问题 Have seen some similar questions: What is the difference between a JavaBean and a POJO? What is the Difference Between POJO (Plain Old Java Object) and DTO (Data Transfer Object)? Can you also please tell me the contexts in which they are used? Or the purpose of them? 回答1: JavaBeans A JavaBean is a class that follows the JavaBeans conventions as defined by Sun. Wikipedia has a pretty good summary of what JavaBeans are: JavaBeans are reusable software components for Java that can be

问题 I\'m not sure about the difference. I\'m using Hibernate and, in some books, they use JavaBean and POJO as an interchangeable term. I want to know if there is a difference, not just in the Hibernate context, but as general concepts. 回答1: A JavaBean follows certain conventions. Getter/setter naming, having a public default constructor, being serialisable etc. See JavaBeans Conventions for more details. A POJO (plain-old-Java-object) isn't rigorously defined. It's a Java object that doesn't

问题 When referring to internal private variables of Java POJOs that have getters/setters, I\'ve used the following terms: field variable attribute property Is there any difference between the above? If so, what is the correct term to use? Is there a different term to use when this entity is persisted? 回答1: From here: http://docs.oracle.com/javase/tutorial/information/glossary.html field A data member of a class. Unless specified otherwise, a field is not static. property Characteristics of an

问题 Recently I\'ve started hearing about \"POJOs\" (Plain Old Java Objects). I googled it, but still don\'t understand the concept well. Can anyone give me a clear description of a POJO? Consider a class \"Person\" with variables \"id, name, address, salary\" -- how would I create a POJO for this scenario? Is the code below a POJO? public class Person { //variables People people = new People(); private int id; private String name; private String address; private int salary; public int getId() {

问题 I\'ve been looking at Jackson, but is seems I would have to convert the Map to JSON, and then the resulting JSON to the POJO. Is there a way to convert a Map directly to a POJO? 回答1: Well, you can achieve that with Jackson, too. (and it seems to be more comfortable since you were considering using jackson). Use ObjectMapper 's convertValue method: final ObjectMapper mapper = new ObjectMapper(); // jackson's objectmapper final MyPojo pojo = mapper.convertValue(map, MyPojo.class); No need to