Jackson_annotations注解使用

news/2025/1/11 14:53:40/

1、@JsonIdentityInfo 英文说明:

1、@JsonIdentityInfo is used when objects have parent child relationship. @JsonIdentityInfo is used to indicate that object identity will be used during serialization/de-serialization.

2、中文翻译：@JsonIdentityInfo 在对象具有父子关系时使用。@JsonIdentityInfo 用于指示在序列化/反序列化期间将使用对象标识。

import java.io.IOException;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.List;import com.fasterxml.jackson.annotation.JsonIdentityInfo;
import com.fasterxml.jackson.annotation.ObjectIdGenerators;
import com.fasterxml.jackson.databind.ObjectMapper;public class JacksonTester {public static void main(String args[]) throws IOException, ParseException{ObjectMapper mapper = new ObjectMapper();     Student student = new Student(1,13, "Mark");Book book1 = new Book(1,"Learn HTML", student);Book book2 = new Book(2,"Learn JAVA", student);student.addBook(book1);student.addBook(book2);String jsonString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(book1);System.out.println(jsonString);}
}
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,property = "id")
class Student { public int id;public int rollNo;public String name;public List<Book> books;Student(int id, int rollNo, String name){this.id = id;this.rollNo = rollNo;this.name = name;this.books = new ArrayList<Book>();}public void addBook(Book book){books.add(book);}
}
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,property = "id")
class Book{public int id;public String name;Book(int id, String name, Student owner){this.id = id;this.name = name;this.owner = owner;}public Student owner;
}输出: 
{
"id" : 1,
"name" : "Learn HTML",
"owner" : {
"id" : 1,
"rollNo" : 13,
"name" : "Mark",
"books" : [
1, {
"id" : 2,
"name" : "Learn JAVA",
"owner" : 1
}
]
}
}

2、@JsonAnyGetter

1、英文
allows a getter method to return Map which is then used to serialize the additional properties of JSON in the similar fashion as other properties.

2、翻译
允许一个 getter 方法返回 Map 然后用于以与其他属性类似的方式序列化 JSON 的其他属性。

  • 没有@JsonAnyGetter 的示例
import java.io.IOException; 
import java.util.HashMap; 
import java.util.Map; 
import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester { public static void main(String args[]){ObjectMapper mapper = new ObjectMapper(); try{Student student = new Student(); student.add("Name", "Mark"); student.add("RollNo", "1"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); }   }
}
class Student {private Map<String, String> properties; public Student(){ properties = new HashMap<>(); } public Map<String, String> getProperties(){ return properties; } public void add(String property, String value){ properties.put(property, value); } 
}
  • 输出结果
{"properties" : {"RollNo" : "1","Name" : "Mark"} 
}
  • @JsonAnyGetter 示例
import java.io.IOException; 
import java.util.HashMap; 
import java.util.Map; 
import com.fasterxml.jackson.annotation.JsonAnyGetter; 
import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester {public static void main(String args[]){ObjectMapper mapper = new ObjectMapper();try{Student student = new Student(); student.add("Name", "Mark"); student.add("RollNo", "1"); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); }catch (IOException e) {e.printStackTrace();} }
}
class Student {private Map<String, String> properties;public Student(){properties = new HashMap<>();}@JsonAnyGetterpublic Map<String, String> getProperties(){return properties;}public void add(String property, String value){properties.put(property, value);}
}
  • 输出
    {
    “RollNo” : “1”,
    “Name” : “Mark”
    }

3、@JsonGetter

  • 英文：
    @JsonGetter allows a specific method to be marked as getter method.
  • 翻译：
    @JsonGetter允许将特定方法标记为 getter 方法。
  • 没有@JsonGetter 的示例
import java.io.IOException; 
import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester {public static void main(String args[]){ObjectMapper mapper = new ObjectMapper();try {Student student = new Student("Mark", 1);String jsonString = mapper .writerWithDefaultPrettyPrinter().writeValueAsString(student);System.out.println(jsonString);}catch (IOException e) {e.printStackTrace();}}
}
class Student {private String name;private int rollNo;public Student(String name, int rollNo){this.name = name;this.rollNo = rollNo;}  public String getStudentName(){return name;} public int getRollNo(){return rollNo;}
}
  • 输出
{
"studentName" : "Mark",
"rollNo" : 1
}
  • @JsonGetter 的示例
import java.io.IOException;
import com.fasterxml.jackson.databind.ObjectMapper; 
import com.fasterxml.jackson.annotation.JsonGetter; public class JacksonTester {public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try {Student student = new Student("Mark", 1);    String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace();  }   }
}
class Student {private String name;private int rollNo;public Student(String name, int rollNo){this.name = name;this.rollNo = rollNo;}@JsonGetterpublic String getStudentName(){return name;}public int getRollNo(){return rollNo;}
}
  • 输出
{
"name" : "Mark",
"rollNo" : 1
}

4、@JsonPropertyOrder

  • 英文：allows a specific order to be preserved while serializing a JSON object.
  • 翻译：允许在序列化 JSON 对象时保留特定顺序。
  • 没有@JsonPropertyOrder 的示例
import java.io.IOException;
import com.fasterxml.jackson.databind.ObjectMapper;public class JacksonTester {public static void main(String args[]){ObjectMapper mapper = new ObjectMapper();try {Student student = new Student("Mark", 1);String jsonString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(student);System.out.println(jsonString);}catch (IOException e) {e.printStackTrace();}}
}
class Student {private String name;private int rollNo;public Student(String name, int rollNo) {this.name = name;this.rollNo = rollNo;}public String getName(){return name;}public int getRollNo(){return rollNo; }
}
  • 输出
{
"name" : "Mark",
"rollNo" : 1
}
  • 示例@JsonPropertyOrder
import java.io.IOException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;public class JacksonTester {public static void main(String args[]){ObjectMapper mapper = new ObjectMapper();try {Student student = new Student("Mark", 1);String jsonString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(student);System.out.println(jsonString);}catch (IOException e) {e.printStackTrace();}}
}
@JsonPropertyOrder({ "rollNo", "name" })
class Student {private String name; private int rollNo; public Student(String name, int rollNo){ this.name = name; this.rollNo = rollNo; }  public String getName(){ return name; } public int getRollNo(){ return rollNo; }  
}
  • 输出
{
"name" : "Mark",
"rollNo" : 1
}

5、@JsonRawValue

  • 英文：@JsonRawValue allows to serialize a text without escaping or without any decoration.
  • 翻译：允许在不转义或不进行任何修饰的情况下序列化文本。
  • 没有@JsonRawValue 的示例
import java.io.IOException; 
import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester {public static void main(String args[]){ObjectMapper mapper = new ObjectMapper();try {Student student = new Student("Mark", 1, "{\"attr\":false}");    String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); }catch (IOException e) { e.printStackTrace(); }   }
}
class Student { private String name; private int rollNo; private String json;  public Student(String name, int rollNo, String json){this.name = name; this.rollNo = rollNo; this.json = json; }  public String getName(){ return name; } public int getRollNo(){ return rollNo; } public String getJson(){ return json; }  
}
  • 输出
{
"name" : "Mark",
"rollNo" : 1,
"json" : {\"attr\":false}
}
  • @JsonRawValue 示例
import java.io.IOException; 
import com.fasterxml.jackson.databind.ObjectMapper; 
import com.fasterxml.jackson.annotation.JsonRawValue; public class JacksonTester {public static void main(String args[]){ObjectMapper mapper = new ObjectMapper(); try {Student student = new Student("Mark", 1, "{\"attr\":false}");    String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); }catch (IOException e) { e.printStackTrace(); }   }
}
class Student { private String name; private int rollNo;@JsonRawValue  private String json;  public Student(String name, int rollNo, String json) {this.name = name; this.rollNo = rollNo; this.json = json; }  public String getName(){ return name; } public int getRollNo(){ return rollNo; } public String getJson(){ return json; }  
}
  • 输出
{
"name" : "Mark",
"rollNo" : 1,
"json" : {"attr":false}
}
  • 6、@JsonValue
  • 英文: @JsonValue allows to serialize an entire object using its single method.
  • 翻译: @JsonValue允许使用其单一方法序列化整个对象
  • 示例@JsonValue
import java.io.IOException; 
import com.fasterxml.jackson.annotation.JsonValue; 
import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonTester {public static void main(String args[]){ObjectMapper mapper = new ObjectMapper(); try { Student student = new Student("Mark", 1);    String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); }catch (IOException e) { e.printStackTrace(); }   }
}
class Student {private String name;private int rollNo;public Student(String name, int rollNo){this.name = name;this.rollNo = rollNo;}public String getName(){return name;} public int getRollNo(){return rollNo;}@JsonValuepublic String toString(){return "{ name : " + name + " }";}
  • 输出：
"{ name : Mark }"

7、JsonRootName

  • 英文：@JsonRootName allows to have a root node specified over the JSON. We need to enable wrap root value as well.
  • 翻译: @JsonRootName允许在 JSON 上指定一个根节点。我们还需要启用包装根值。
  • Example @JsonRootName
import java.io.IOException; 
import com.fasterxml.jackson.annotation.JsonRootName; 
import com.fasterxml.jackson.databind.ObjectMapper; 
import com.fasterxml.jackson.databind.SerializationFeature; public class JacksonTester {public static void main(String args[]){ ObjectMapper mapper = new ObjectMapper(); try {Student student = new Student("Mark", 1);  mapper.enable(SerializationFeature.WRAP_ROOT_VALUE); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); }catch (IOException e) { e.printStackTrace(); }   }
}
@JsonRootName(value = "student") 
class Student {private String name; private int rollNo; public Student(String name, int rollNo){ this.name = name; this.rollNo = rollNo; }  public String getName(){ return name; } public int getRollNo(){ return rollNo; }  
}
  • 输出
{
"student" : {
"name" : "Mark",
"rollNo" : 1
}
}

8、@JsonSerialize

  • 英文: @JsonSerialize is used to specify custom serializer to marshall the json object.
  • 翻译: @JsonSerialize用于指定自定义序列化程序来编组 json 对象。
  • @JsonSerialize 示例
import java.io.IOException; 
import java.text.ParseException; 
import java.text.SimpleDateFormat; 
import java.util.Date; import com.fasterxml.jackson.core.JsonGenerator; 
import com.fasterxml.jackson.databind.ObjectMapper; 
import com.fasterxml.jackson.databind.SerializerProvider; 
import com.fasterxml.jackson.databind.annotation.JsonSerialize; 
import com.fasterxml.jackson.databind.ser.std.StdSerializer; public class JacksonTester {public static void main(String args[]) throws ParseException {ObjectMapper mapper = new ObjectMapper(); SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy"); try {Student student = new Student("Mark", 1, dateFormat.parse("20-11-1984")); String jsonString = mapper .writerWithDefaultPrettyPrinter() .writeValueAsString(student); System.out.println(jsonString); } catch (IOException e) { e.printStackTrace(); }   }
}
class Student {private String name; private int rollNo; @JsonSerialize(using = CustomDateSerializer.class) private Date dateOfBirth; public Student(String name, int rollNo, Date dob){ this.name = name; this.rollNo = rollNo; this.dateOfBirth = dob; }public String getName(){return name;}public int getRollNo(){return rollNo; }public Date getDateOfBirth(){ return dateOfBirth; }
}
class CustomDateSerializer extends StdSerializer<Date> {private static final long serialVersionUID = 1L; private static SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy");public CustomDateSerializer() { this(null); } public CustomDateSerializer(Class<Date> t) { super(t); } @Override public void serialize(Date value, JsonGenerator generator, SerializerProvider arg2) throws IOException { generator.writeString(formatter.format(value)); } 
}
  • 输出
{
"name" : "Mark",
"rollNo" : 1,
"dateOfBirth" : "20-11-1984"
}

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