使用 Jackson 反序列化到集合/数组

17 Mar 2025 | 4 分钟阅读

当我们在 Java 中使用 API 时，将 JSON 数组反序列化为 Java 数组或集合是最重要的任务之一。我们可以使用 Jackson 轻松地将 JSON 数组反序列化为 Java 数组或集合。

让我们了解如何逐个将 JSON 数组反序列化为 Java 数组和集合

将 JSON 数组反序列化为 Java 数组

我们可以通过使用 ObjectMapper 类的 readValue() 方法轻松地将 JSON 数组反序列化为 Java 数组。在 readValue() 方法中，我们传递两个参数，即 jsonString 和 Student[].class。

让我们举一个例子来了解如何使用 ObjectMapper 类将 JSON 数组反序列化为 Java 数组

DeserializeJSONArrayToJavaArrayExample.java

// import required classes and package if any
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class DeserializeJSONArrayToJavaArrayExample {
	
	//main() method start()
	public static void main(String args []) throws JsonProcessingException {
	
		int n;
		
		// create an instance of ObjectMapper class
		ObjectMapper mapper = new ObjectMapper();
		
		// create Scanner class object
		Scanner sc = new Scanner(System.in);
		
		// create an empty list of Student
		List<Student> students = new ArrayList<Student>();
		
		// take input from user and get student records from user
		System.out.println("How many student records you have?");
		n = Integer.valueOf(sc.nextLine());
		
		// use for loop to fill Student ArrayList
		for(int i = 0; i < n; i++) {
			
			String id, name, status;
			Boolean passed = false, fail = false;
			
			System.out.println("Enter id of "+(i+1)+" Student");
			id = sc.nextLine();
			System.out.println("Enter name of "+(i+1)+" Student");
			name = sc.nextLine();
			
			System.out.println("Is "+name+ " pass in exams(Yes/No)?: ");
			status = sc.nextLine();
			
			if(status.equals("Yes")) {
				passed = true;
			}
			
			if(status.equals("No")) {
				fail = false;
			}
			students.add(new Student(id, name, passed, fail));
		}
		// close Scanner class object
		sc.close();
		// serialize students into JSONArray
		String jsonArray = mapper.writeValueAsString(students);
		
		// deserialize JSON array into Java Array
		Student[] data = mapper.readValue(jsonArray, Student[].class);
		
		// use for each to iterate Student array
		for(Student std : data) {
			System.out.println("Student Id: "+std.getStdId());
			System.out.println("Student Name: "+std.getStdName());
			System.out.println("Is "+std.getStdName()+ "pass in exams(Yes/No)?: "+std.getPassed());
		}
		
	}
	
	
}

// create class Student
class Student {

	private String stdId;
	private String stdName;
	private Boolean passed;
	private Boolean fail;
	
	public Student() {
		this.stdId = null;
		this.stdName = null;
		this.passed = null;
		this.fail = null;
	}

	public Student(String stdId, String stdName, Boolean passed, Boolean fail) {
		this.stdId = stdId;
		this.stdName = stdName;
		this.passed = passed;
		this.fail = fail;
	}

	public String getStdId() {
		return stdId;
	}

	public String getStdName() {
		return stdName;
	}

	public Boolean getPassed() {
		return passed;
	}

	public Boolean getFail() {
		return fail;
	}

}

输出

Deserialize to Collection/Array in Jackson

将 JSON 数组反序列化为集合

就像 Java 数组一样，我们也可以通过使用 ObjectMapper 类的 readValue() 方法将 JSON 数组反序列化为 Java 集合。

让我们举一个例子来了解如何使用 Jackson 将 JSON 数组反序列化为 Java 集合

DeserializeJSONArrayToJavaCollectionExample.java

//import required classes and package, if any
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

// create class DeserializeJSONArrayToJavaArrayExample to deserialize JSONArray to Java Collection
public class DeserializeJSONArrayToJavaCollectionExample {
	
	//main() method start()
	public static void main(String args []) throws JsonProcessingException {
	
		int n;
		
		// create an instance of ObjectMapper class
		ObjectMapper mapper = new ObjectMapper();
		
		// create Scanner class object
		Scanner sc = new Scanner(System.in);
		
		// create an empty list of Student
		List<Student> students = new ArrayList<Student>();
		
		// take input from user and get student records from user
		System.out.println("How many student records you have?");
		n = Integer.valueOf(sc.nextLine());
		
		// use for loop to fill Student ArrayList
		for(int i = 0; i < n; i++) {
			
			String id, name, status;
			Boolean passed = false, fail = false;
			
			System.out.println("Enter id of "+(i+1)+" Student");
			id = sc.nextLine();
			System.out.println("Enter name of "+(i+1)+" Student");
			name = sc.nextLine();
			
			System.out.println("Is "+name+ " pass in exams(Yes/No)?: ");
			status = sc.nextLine();
			
			if(status.equals("Yes")) {
				passed = true;
			}
			
			if(status.equals("No")) {
				fail = false;
			}
			
			students.add(new Student(id, name, passed, fail));
			
		}
		
		// close Scanner class object
		sc.close();
		
		// serialize students into JSONArray
		String jsonArray = mapper.writeValueAsString(students);
		
		// deserialize JSON array into Java Array
		@SuppressWarnings("unchecked")
		List<Student> data = mapper.readValue(jsonArray, List.class);
		
		// use for each to iterate Student array
		for(int i = 0; i < data.size(); i++) {
			System.out.println("JSONArray after deserialize "+(Object) data.get(i));
		}
		
	}
	
	
}

//create class Student
class Student {

	private String stdId;
	private String stdName;
	private Boolean passed;
	private Boolean fail;
	
	public Student() {
		this.stdId = null;
		this.stdName = null;
		this.passed = null;
		this.fail = null;
	}

	public Student(String stdId, String stdName, Boolean passed, Boolean fail) {
		this.stdId = stdId;
		this.stdName = stdName;
		this.passed = passed;
		this.fail = fail;
	}

	public String getStdId() {
		return stdId;
	}

	public String getStdName() {
		return stdName;
	}

	public Boolean getPassed() {
		return passed;
	}

	public Boolean getFail() {
		return fail;
	}

}

输出

下一主题使用 Jackson 比较 JSON 对象

使用 Jackson 反序列化到集合/数组

将 JSON 数组反序列化为 Java 数组

将 JSON 数组反序列化为集合

联系信息

关注我们

教程

面试题

在线编译器

Python

Java

.Net Framework

AI, ML and Data Science

Cloud Technology

B.Tech and MCA

Web Technology

PHP

Software Testing

Technical Interview

Java Interview

Python

Web Interview

Database Interview

B.Tech / MCA

Important Interview

Software Testing Interview

Company Interviews

Online Compilers

Multiple Choice Questions

Jackson 教程

Jackson 注解

序列化/反序列化

高级编组

使用 Jackson 反序列化到集合/数组

将 JSON 数组反序列化为 Java 数组

将 JSON 数组反序列化为集合

相关帖子

Map 序列化和反序列化

使用 Jackson 比较 JSON 对象

序列化和反序列化枚举

Jackson 日期

基于自定义标准序列化字段

Jackson JSON 视图

将布尔值序列化和反序列化为整数

订阅 Tpoint Tech

联系信息

关注我们

教程

面试题

在线编译器