Jackson中的序列化注解

2025年3月17日 | 阅读13分钟

当我们将Java对象序列化为Json字符串时，会使用序列化注解。Jackson库提供了几种序列化注解，例如 @JsonSerialize、@JacksonGetter、@JsonAnyGetter等。

让我们通过一个例子来逐一理解它们。

@JsonAnyGetter

@JsonAnyGetter 是最重要的注解之一，用于以与其他属性相同的方式序列化JSON的附加属性。该注解允许getter方法返回一个Map，然后我们将其用于序列化。 JsonAnyGetter注解用于序列化，这意味着它属于 序列化注解 的类别。

让我们看两个例子来理解 @JsonAnyGetter 注解。在第一个例子中，我们将在不使用注解的情况下将Java对象转换为JSON。在第二个例子中，我们通过使用注解来理解 @JsonAnyGetter 注解的用法。

JsonAnyGetterExample1.java

// import required classes and package
import java.io.IOException; 
import java.util.HashMap; 
import java.util.Map;
import java.util.Scanner;

import com.fasterxml.jackson.databind.ObjectMapper; 

// create class JsonAnyGetterExample1
public class JsonAnyGetterExample1 { 
    
    // main() method start
    public static void main(String args[]){
        
        // create instance of ObjectMapper class
        ObjectMapper mapper = new ObjectMapper(); 
        
        // create Scanner class object
        Scanner sc= new Scanner(System.in);
        
        try{
            
            Faculty faculty = new Faculty();
            
            String facId, facname, facEmail;
            
            System.out.println("Enter Faculty Id:");
            facId = sc.nextLine();
            faculty.add("Id", facId);
            
            System.out.println("Enter Faculty Name");
            facname = sc.nextLine();
            faculty.add("Name", facname);
            
            System.out.println("Enter Faculty Email");
            facEmail = sc.nextLine();
            faculty.add("Email", facEmail);
            
            // convert Java type into Json string
            String jsonString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(faculty); 
            System.out.println(jsonString); 
        } 
        catch (IOException e) { 
            e.printStackTrace(); 
        }
        
        // close Scanner class object
        sc.close();
    }
}
class Faculty {
    
    private Map<String, String> facultyData; 
    
    public Faculty(){ 
        facultyData = new HashMap<>(); 
    } 
    public Map<String, String> getFacultyData(){ 
        return facultyData; 
    } 
    public void add(String key, String value){ 
        facultyData.put(key, value); 
    } 
}

输出

JsonAnyGetterExample2.java

// import required classes and package
import java.io.IOException; 
import java.util.HashMap; 
import java.util.Map;
import java.util.Scanner;

import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.databind.ObjectMapper; 

// create class JsonAnyGetterExample2 to understand use of @JsonAnyGetter
public class JsonAnyGetterExample2 { 
    
    // main() method start
    public static void main(String args[]){
        
        // create instance of ObjectMapper class
        ObjectMapper mapper = new ObjectMapper(); 
        
        // create Scanner class object
        Scanner sc= new Scanner(System.in);
        
        try{
            
            Faculty faculty = new Faculty();
            
            String facId, facname, facEmail;
            
            System.out.println("Enter Faculty Id:");
            facId = sc.nextLine();
            faculty.add("Id", facId);
            
            System.out.println("Enter Faculty Name");
            facname = sc.nextLine();
            faculty.add("Name", facname);
            
            System.out.println("Enter Faculty Email");
            facEmail = sc.nextLine();
            faculty.add("Email", facEmail);
            
            // convert Java type into Json string
            String jsonString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(faculty); 
            System.out.println(jsonString); 
        } 
        catch (IOException e) { 
            e.printStackTrace(); 
        }
        
        // close Scanner class object
        sc.close();
    }
}
class Faculty {
    
    private Map<String, String> facultyData; 
    
    public Faculty(){ 
        facultyData = new HashMap<>(); 
    } 
    @JsonAnyGetter
    public Map<String, String> getFacultyData(){ 
        return facultyData; 
    } 
    public void add(String key, String value){ 
        facultyData.put(key, value); 
    } 
}

输出

说明

第一个例子中，输出带有 facultyData 头部，因为我们没有使用 @JsonAnyGetter 注解。在第二个例子中，输出只带有Id、Name和Email值。输出中没有 facultyData 头部，因为我们在那里使用了 @JsonAnyGetter 注解。

@JsonGetter

@JsonGetter 是另一个最重要的注解，用于序列化JSON的附加属性。它类似于 @JsonProperty 注解，允许将特定方法标记为getter方法。 @JsonGetter 注解也用于序列化，所以它属于 序列化注解。

让我们看两个例子来理解 @JsonGetter 注解。在第一个例子中，我们将在不使用注解的情况下将Java对象转换为JSON。在第二个例子中，我们通过使用注解来理解 @JsonGetter 注解的用法。

JsonGetterExample1.java

//import required classes and package
import java.io.IOException;
import java.util.Scanner;
import com.fasterxml.jackson.databind.ObjectMapper; 

//create class JsonGetterExample1
public class JsonGetterExample1 { 
    // main() method start
    public static void main(String args[]){
        // create instance of ObjectMapper class
        ObjectMapper mapper = new ObjectMapper(); 
        // create Scanner class object
        Scanner sc= new Scanner(System.in);
        try{
            String facId, facName, facEmail;
            System.out.println("Enter Faculty Id:");
            facId = sc.nextLine();
            System.out.println("Enter Faculty Name");
            facName = sc.nextLine();
            System.out.println("Enter Faculty Email");
            facEmail = sc.nextLine();
            FacultyNew faculty = new FacultyNew(facId, facName, facEmail);
            // convert Java type into Json string
            String jsonString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(faculty); 
            System.out.println(jsonString); 
        } 
        catch (IOException e) { 
            e.printStackTrace(); 
        }
        // close Scanner class object
        sc.close();
    }
}
class FacultyNew {
    private String facId;
    private String facName;
    private String facEmail;
    public FacultyNew(String id, String name, String email){
        facId = id;
        facName = name;
        facEmail = email;
    }
    public String getId(){
        return facId;
    } 
    public String getName(){
        return facName;
    }
    public String getEmail(){
        return facEmail;
    }
}

输出

JsonGetterExample2.java

//import required classes and package
import java.io.IOException;
import java.util.Scanner;
import com.fasterxml.jackson.annotation.JsonGetter;
import com.fasterxml.jackson.databind.ObjectMapper; 

//create class JsonGetterExample2 to understand the JsonGetter annotation
public class JsonGetterExample2 { 
    // main() method start
    public static void main(String args[]){
        // create instance of ObjectMapper class
        ObjectMapper mapper = new ObjectMapper(); 
        
        // create Scanner class object
        Scanner sc= new Scanner(System.in);
        try{
            String facId, facName, facEmail;
            System.out.println("Enter Faculty Id:");
            facId = sc.nextLine();
            System.out.println("Enter Faculty Name");
            facName = sc.nextLine();
            System.out.println("Enter Faculty Email");
            facEmail = sc.nextLine();
            FacultyNew faculty = new FacultyNew(facId, facName, facEmail);
            // convert Java type into Json string
            String jsonString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(faculty); 
            System.out.println(jsonString); 
        } 
        catch (IOException e) { 
            e.printStackTrace(); 
        }
        // close Scanner class object
        sc.close();
    }
}
class FacultyNew {
    private String id;
    private String name;
    private String email;
    public FacultyNew(String id, String name, String email){
        this.id = id;
        this.name = name;
        this.email = email;
    }
    public String getFacultyId(){
        return id;
    } 
    @JsonGetter("name")
    public String getFacultyName(){
        return name;
    }
    public String getFacultyEmail(){
        return email;
    }
}

输出

说明

在第一个例子中，每个变量名都以faculty前缀开头，因为我们没有使用 @JsonGetter 注解。在第二个例子中，变量名没有前缀(faculty)值。

@JsonPropertyOrder

@JsonPropertyOrder 是Jackson的另一个重要注解。它用于在序列化JSON对象时保留特定的顺序。它也用于序列化，所以它也属于 序列化注解。

让我们看两个例子来理解 @JsonPropertyOrder 注解。两个代码的逻辑和功能相似。它们之间唯一的区别是，在第一个代码中，我们没有使用 @JsonPropertyOrder，而在第二个代码中，我们使用了它。

JsonPropertyOrderExample1.java

import java.io.IOException;
import java.util.Scanner;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

// create JsonPropertyOrderExample1 class to convert Java Object into JSON
public class JsonPropertyOrderExample1 {
    
    // main() method start
    public static void main(String args[]){
        
        // create instance of the ObjectSerialization class
        ObjectMapper obj = new ObjectMapper();
        
        Scanner sc1 = new Scanner(System.in);
        
        try {
            
            Product prod = new Product();
            String prodId, prodName, price;
            
            System.out.println("Enter Product Id:");
            prodId = sc1.nextLine();
            prod.setProId(prodId);
            
            System.out.println("Enter Product Name");
            prodName = sc1.nextLine();
            prod.setProName(prodName);
            
            System.out.println("Enter Product Price:");
            price = sc1.nextLine();
            prod.setPrice(price);
            
            String jsonString = obj
                .writerWithDefaultPrettyPrinter()
                .writeValueAsString(prod);
            System.out.println(jsonString);
            
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
        // close scanner class object
        sc1.close();
    }
}
class Product {  
    
    //Creating properties of Product class  
    private String proId;    
    private String name;    
    private String price;  
    
    //Getter and Setters
    public String getProId() {  
        return proId;  
    }  
    public void setProId(String proId) {  
        this.proId = proId;  
    }  
    public String getName() {  
        return name;  
    }  
    public void setProName(String name) {  
        this.name = name;  
    }  
    public String getPrice() {  
        return price;  
    }  
    public void setPrice(String price) {  
        this.price = price;  
    }  
    @Override    
    public String toString() {    
        // TODO Auto-generated method stub    
        return "\"Product [ProductId "+ proId + ", ProductName = " + name + ", ProductPrice = " + price + "]";    
    }  
}

输出

JsonPropertyOrderExample2.java

import java.io.IOException;
import java.util.Scanner;

import com.fasterxml.jackson.annotation.JsonPropertyOrder;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

// create JsonPropertyOrderExample1 class to convert Java Object into JSON
public class JsonPropertyOrderExample1 {
    
    // main() method start
    public static void main(String args[]){
        
        // create instance of the ObjectSerialization class
        ObjectMapper obj = new ObjectMapper();
        
        Scanner sc1 = new Scanner(System.in);
        
        try {
            
            Product prod = new Product();
            String prodId, prodName, price;
            
            System.out.println("Enter Product Id:");
            prodId = sc1.nextLine();
            prod.setProId(prodId);
            
            System.out.println("Enter Product Name");
            prodName = sc1.nextLine();
            prod.setProName(prodName);
            
            System.out.println("Enter Product Price:");
            price = sc1.nextLine();
            prod.setPrice(price);
            
            String jsonString = obj
                .writerWithDefaultPrettyPrinter()
                .writeValueAsString(prod);
            System.out.println(jsonString);
            
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
        // close scanner class object
        sc1.close();
    }
}
@JsonPropertyOrder({"name", "proId"})
class Product {  
    
    //Creating properties of Product class  
    private String proId;    
    private String name;    
    private String price;  
    
    //Getter and Setters
    public String getProId() {  
        return proId;  
    }  
    public void setProId(String proId) {  
        this.proId = proId;  
    }  
    public String getName() {  
        return name;  
    }  
    public void setProName(String name) {  
        this.name = name;  
    }  
    public String getPrice() {  
        return price;  
    }  
    public void setPrice(String price) {  
        this.price = price;  
    }  
    @Override    
    public String toString() {    
        // TODO Auto-generated method stub    
        return "\"Product [ProductId "+ proId + ", ProductName = " + name + ", ProductPrice = " + price + "]";    
    }  
}  

输出

说明

在第一个例子中，输出带有字段的默认顺序，因为我们没有使用 @JsonPropertyOrder。在第二个例子中，输出带有我们在 @JsonPropertyOrder 中定义的字段的顺序。因此，JsonProprtyOrder注解用于以指定的顺序获取结果字段。

@JsonRawValue

@JsonRawValue 是Jackson的另一个重要注解，用于序列化对象。它用于在不进行转义或任何修饰的情况下序列化文本。它也属于 序列化注解。

让我们看一些例子来理解 @JsonRawValue 注解的用法，我们在这些例子中编写了有和没有 @JsonRawValue 注解的代码。

JsonRawValueExample1.java

import java.io.IOException;
import java.util.Scanner;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

// create JsonRawValueExample1 class to convert Java Object into JSON
public class JsonRawValueExample1 {
    
    // main() method start
    public static void main(String args[]){
        
        // create instance of the ObjectSerialization class
        ObjectMapper obj = new ObjectMapper();
        
        Scanner sc1 = new Scanner(System.in);
        
        try {
            
            Product prod = new Product();
            String prodId, prodName, price;
            
            System.out.println("Enter Product Id:");
            prodId = sc1.nextLine();
            prod.setProId(prodId);
            
            System.out.println("Enter Product Name");
            prodName = sc1.nextLine();
            prod.setProName(prodName);
            
            System.out.println("Enter Product Price:");
            price = sc1.nextLine();
            prod.setPrice(price);
            
            prod.setJson("{\"attr\":false}");
            
            String jsonString = obj
                .writerWithDefaultPrettyPrinter()
                .writeValueAsString(prod);
            System.out.println(jsonString);
            
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
        // close scanner class object
        sc1.close();
    }
}

class Product {  
    
    //Creating properties of Product class  
    private String proId;    
    private String name;    
    private String price;
    private String json;
    
    //Getter and Setters
    public String getProId() {  
        return proId;  
    }  
    public void setProId(String proId) {  
        this.proId = proId;  
    }  
    public String getName() {  
        return name;  
    }  
    public void setProName(String name) {  
        this.name = name;  
    }  
    public String getPrice() {  
        return price;  
    }  
    public void setPrice(String price) {  
        this.price = price;  
    }
    public String getJson() {  
        return json;  
    }  
    public void setJson(String json) {  
        this.json = json;  
    } 
    @Override    
    public String toString() {    
        // TODO Auto-generated method stub    
        return "\"Product [ProductId "+ proId + ", ProductName = " + name + ", ProductPrice = " + price + "]";    
    }  
}

输出

JsonRawValueExample2.java

import java.io.IOException;
import java.util.Scanner;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.annotation.JsonRawValue; 

// create JsonRawValueExample2 class to convert Java Object into JSON
public class JsonRawValueExample2 {
    
    // main() method start
    public static void main(String args[]){
        
        // create instance of the ObjectSerialization class
        ObjectMapper obj = new ObjectMapper();
        
        Scanner sc1 = new Scanner(System.in);
        
        try {
            
            Product prod = new Product();
            String prodId, prodName, price;
            
            System.out.println("Enter Product Id:");
            prodId = sc1.nextLine();
            prod.setProId(prodId);
            
            System.out.println("Enter Product Name");
            prodName = sc1.nextLine();
            prod.setProName(prodName);
            
            System.out.println("Enter Product Price:");
            price = sc1.nextLine();
            prod.setPrice(price);
            
            prod.setJson("{\"attr\":false}");
            
            String jsonString = obj
                .writerWithDefaultPrettyPrinter()
                .writeValueAsString(prod);
            System.out.println(jsonString);
            
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
        // close scanner class object
        sc1.close();
    }
}

class Product {  
    
    //Creating properties of Product class  
    private String proId;    
    private String name;    
    private String price;
    
    @JsonRawValue
    private String json;
    
    //Getter and Setters
    public String getProId() {  
        return proId;  
    }  
    public void setProId(String proId) {  
        this.proId = proId;  
    }  
    public String getName() {  
        return name;  
    }  
    public void setProName(String name) {  
        this.name = name;  
    }  
    public String getPrice() {  
        return price;  
    }  
    public void setPrice(String price) {  
        this.price = price;  
    }
    public String getJson() {  
        return json;  
    }  
    public void setJson(String json) {  
        this.json = json;  
    } 
    @Override    
    public String toString() {    
        // TODO Auto-generated method stub    
        return "\"Product [ProductId "+ proId + ", ProductName = " + name + ", ProductPrice = " + price + "]";    
    }  
}  

输出

说明

在第一个例子中，json字段的值带有修饰，因为我们没有使用 @JsonRawValue 注解。然而，在第二个例子中，json字段的值在没有转义或修饰的情况下出现，因为我们使用了 @JsonRawValue 注解。因此，这些值没有斜杠(/)。

@JsonValue

@JsonValue 是最常用和最重要的注解之一，它用于通过使用其单个方法序列化单个对象。

让我们看一个例子来理解如何使用注解来序列化对象

JsonValueExample1.java

import java.io.IOException;
import java.util.Scanner;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.annotation.JsonValue; 

// create JsonValueExample class to serialize an object using its single method
public class JsonValueExample {
    
    // main() method start
    public static void main(String args[]){
        
        // create instance of the ObjectSerialization class
        ObjectMapper obj = new ObjectMapper();
        
        Scanner sc1 = new Scanner(System.in);
        
        try {
            
            Product prod = new Product();
            String prodId, prodName, price;
            
            System.out.println("Enter Product Id:");
            prodId = sc1.nextLine();
            prod.setProId(prodId);
            
            System.out.println("Enter Product Name");
            prodName = sc1.nextLine();
            prod.setProName(prodName);
            
            System.out.println("Enter Product Price:");
            price = sc1.nextLine();
            prod.setPrice(price);
            
            String jsonString = obj
                .writerWithDefaultPrettyPrinter()
                .writeValueAsString(prod);
            System.out.println(jsonString);
            
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
        // close scanner class object
        sc1.close();
    }
}

class Product {  
    
    //Creating properties of Product class  
    private String proId;    
    private String name;    
    private String price;
    
    //Getter and Setters
    public String getProId() {  
        return proId;  
    }  
    public void setProId(String proId) {  
        this.proId = proId;  
    }  
    public String getName() {  
        return name;  
    }  
    public void setProName(String name) {  
        this.name = name;  
    }  
    public String getPrice() {  
        return price;  
    }  
    public void setPrice(String price) {  
        this.price = price;  
    }
    
    @JsonValue
    public String toString() {    
        // TODO Auto-generated method stub    
        return "{ ProductId = "+ proId + ", ProductName = " + name + ", ProductPrice = " + price + "}";    
    }  
}  

输出

@JsonRootName

@JsonRootName 注解是最重要的注解之一，用于指示应该序列化的POJO的名称。简单来说，它用于包装一个对象，以便使用顶层元素进行序列化。它也属于 序列化注解 的范畴。

我们将名称作为参数传递给注解。我们还使用 "WRAP_ROOT_VALUE"，即SerializationFeature枚举的特性。我们启用它，以便在单个属性JSON对象中包装路由值，其中键是路由名称。

让我们看一个 @JsonRootName 的例子来理解它是如何工作的

JsonRootNameExample.java

import java.io.IOException;
import java.util.Scanner;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.annotation.JsonRootName; 

// create JsonRootNameExample class to serialize an object
public class JsonRootNameExample {
    
    // main() method start
    public static void main(String args[]){
        
        // create instance of the ObjectSerialization class
        ObjectMapper obj = new ObjectMapper();
        
        Scanner sc1 = new Scanner(System.in);
        
        try {
            
            Product prod = new Product();
            String prodId, prodName, price;
            
            System.out.println("Enter Product Id:");
            prodId = sc1.nextLine();
            prod.setProId(prodId);
            
            System.out.println("Enter Product Name");
            prodName = sc1.nextLine();
            prod.setProName(prodName);
            
            System.out.println("Enter Product Price:");
            price = sc1.nextLine();
            prod.setPrice(price);
            
            String jsonString = obj.
                enable(SerializationFeature.WRAP_ROOT_VALUE)
                .writerWithDefaultPrettyPrinter()
                .writeValueAsString(prod);
            System.out.println(jsonString);
            
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
        // close scanner class object
        sc1.close();
    }
}

@JsonRootName(value = "Details")
class Product {  
    
    //Creating properties of Product class  
    private String proId;    
    private String name;    
    private String price;
    
    //Getter and Setters
    public String getProId() {  
        return proId;  
    }  
    public void setProId(String proId) {  
        this.proId = proId;  
    }  
    public String getName() {  
        return name;  
    }  
    public void setProName(String name) {  
        this.name = name;  
    }  
    public String getPrice() {  
        return price;  
    }  
    public void setPrice(String price) {  
        this.price = price;  
    }
    
    @Override    
    public String toString() {    
        // TODO Auto-generated method stub    
        return "\"Product [ProductId "+ proId + ", ProductName = " + name + ", ProductPrice = " + price + "]";    
    }  
}  

输出

@JsonSerialize

@JsonSerialize 是在序列化Java对象时最常用的注解之一。它用于为编组Json对象定义一个自定义序列化器。

让我们看一个例子来理解它如何帮助序列化一个对象。

JsonSerializerExample.java

import java.io.IOException; 
import java.text.ParseException; 
import java.text.SimpleDateFormat; 
import java.util.Date;
import java.util.Scanner;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
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; 

// create class JsonSerializeExample to understand how we can use custom specific serializer
public class JsonSerializeExample {
    //main method start 
    public static void main(String args[]) throws ParseException {
        
        // create instance of the ObjectSerialization class
        ObjectMapper obj = new ObjectMapper();
        
        // create instance of SimpleDateFormat class to format a date
        SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy"); 
        
        Scanner sc1 = new Scanner(System.in);
        
        try {
            
            Product prod = new Product();
            String prodId, prodName, price;
            Date exp;
            
            System.out.println("Enter Product Id:");
            prodId = sc1.nextLine();
            prod.setProId(prodId);
            
            System.out.println("Enter Product Name");
            prodName = sc1.nextLine();
            prod.setProName(prodName);
            
            System.out.println("Enter Product Price:");
            price = sc1.nextLine();
            prod.setPrice(price);
            
            System.out.println("Enter expiry date of product in dd-MM-yyyy format:");
            exp = sdf.parse(sc1.nextLine());
            prod.setDate(exp);
            
            String jsonString = obj
                .writerWithDefaultPrettyPrinter()
                .writeValueAsString(prod);
            System.out.println(jsonString);
            
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } 
    }
}

// create class Product
class Product {  
    
    //Creating properties of Product class  
    private String proId;    
    private String name;    
    private String price;
    
    @JsonSerialize(using = DateSerializer.class)
    private Date expire; 
    
    //Getter and Setters
    public String getProId() {  
        return proId;  
    }  
    public void setProId(String proId) {  
        this.proId = proId;  
    }  
    public String getName() {  
        return name;  
    }  
    public void setProName(String name) {  
        this.name = name;  
    }  
    public String getPrice() {  
        return price;  
    }  
    public void setPrice(String price) {  
        this.price = price;  
    }
    public Date getDate() {  
        return expire;  
    }  
    public void setDate(Date expire) {  
        this.expire = expire;  
    }
} 

// create custom serializer by extending StdSerializer<Date>
class DateSerializer extends StdSerializer<Date> {
    
    // declare and initialize serialVersionUID
    private static final long serialVersionUID = 1L; 
    private static SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
    
    // default and parameterized constructor
    public DateSerializer() { 
        this(null); 
    }
    public DateSerializer(Class<Date> t) { 
        super(t); 
    }
    
    // override serialize method
    @Override 
    public void serialize(Date d1, JsonGenerator jsonGen, SerializerProvider serializer) throws IOException { 
        jsonGen.writeString(sdf.format(d1)); 
    } 
}

输出