使用Jackson进行XML序列化和反序列化

2025年3月17日 | 阅读11分钟

在本节中，我们将讨论Jackson的另一个重要概念，即XML数据的序列化和反序列化。通过使用Jackson，我们可以轻松地将Java对象序列化为XML数据，或者将其反序列化回Java对象（POJO）。为了使用XML，我们使用Jackson "2.x"。

首先，我们将在POM.xml文件中添加Jackson "2.x"依赖项

<dependency>
	<groupId>com.fasterxml.jackson.dataformat</groupId>
    	<artifactId>jackson-dataformat-xml</artifactId>
    	<version>2.11.1</version>
</dependency>

注意：请添加Jackson-dataformat-xml依赖项的最新版本。

让我们详细了解如何使用Jackson处理XML。

XmlMapper 对象

XmlMapper 是 Jackson "2.x" 中最重要的类之一。它用于XML数据的序列化和反序列化。因此，序列化和反序列化XML数据的第一步是以以下方式创建 XmlMapper 类的实例

将 Java 对象序列化为 XML

ObjectMapper 是 XmlMapper 的父类，用于序列化 JSON 数据。如果我们想对父类进行任何更改，请在父类中添加一些 XML 特定的更改。让我们了解如何使用它来序列化以下 Java 类

College.java

class College {    
	//Creating properties of College class    
	public String name;      
	public String university;   
	public String address; 
	public String rank;   
	
	// default constructor 
	College(){
		
	}
	// parameterized constructor  
	College(String name, String university, String address, String rank){  
		this.name = name;  
		this.university = university;  
		this.address = address;  
		this.rank = rank;  
	}  
	// getters and setters 
}

将 POJO 序列化为 XML 字符串

我们可以通过简单地创建 XmlMapper 类的实例并使用其 writeValueAsString() 方法，轻松地将 POJO 转换为 XML 字符串，方法如下

XmlMapper xmlMap = new XmlMapper();
xmlMap.writeValueAsString(new College());

让我们举个例子来了解如何使用它将 Java 对象序列化为 XML 字符串。

PojoToXMLExample1.java

//import required classes and package if any  
import java.io.IOException;  
import java.util.Scanner;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
//create class PojoToXMLExample1
public class PojoToXMLExample1 {  
	//main() methods start  
	public static void main(String args[]) {  
		// create an instance of XmlMapper class  
		XmlMapper xmlMap = new XmlMapper();  
		// create Scanner class object  
		Scanner sc= new Scanner(System.in);       
		// using try-catch
		try {  
			College colg;  
			String name, university, street, state, city, rank;  
			System.out.println("Enter College Name:");  
			name = sc.nextLine();  
			System.out.println("Enter University Name:");  
			university = sc.nextLine();  

			System.out.println("Enter Street:");  
			street = sc.nextLine();  
			
			System.out.println("Enter City:");  
			city = sc.nextLine();
			
			System.out.println("Enter State:");  
			state = sc.nextLine();
			System.out.println("Enter College Rank:");  
			rank = sc.nextLine();  
			// set values to College object by using constructor  
			colg = new College(name, university, new Address(street, state, city), rank);
			// serialize College using xmlMap  
			String xmlString = xmlMap
					.writeValueAsString(colg);  
			System.out.println(xmlString);  
		} catch (IOException e) {   
			e.printStackTrace();  
		}  
		//close Scanner class object  
		sc.close();  
	}  
}
//create class College
class College {    

	//Creating properties of College class    
	public String name;      
	public String university;   
	public Address address; 
	public String rank;   

	// constructor  
	College(String name, String university, Address address, String rank){  
		this.name = name;  
		this.university = university;  
		this.address = address;  
		this.rank = rank;  
	}  

}
//create class Address 
class Address {  
	public String street;
	public String state;
	public String city;
	
	Address(String street, String state, String city){  
		  this.street = street;
		  this.state = state;
		  this.city = city;
	}         
}

输出

XML Serialization and Deserialization with Jackson

将 POJO 序列化为 XML 文件

为了将 Java 对象序列化为 XML 文件，我们只需创建 XmlMapper 类的实例并使用其 writeValue() 方法。在 writeValue() 方法中，我们传递两个参数，即 XML 文件的位置和 Java 对象的实例，方法如下

XmlMapper xmlMap = new XmlMapper();
xmlMap.writeValue(file_location, java_object)

让我们举个例子来了解如何使用它将 Java 对象序列化为 XML 文件。

PojoToXMLExample2.java

import java.io.File;
//import required classes and package if any  
import java.io.IOException;  
import java.util.Scanner;

import com.fasterxml.jackson.dataformat.xml.XmlMapper;

//create class PojoToXMLExample2
public class PojoToXMLExample2 {  

	//main() methods start  
	public static void main(String args[]) {  

		// create an instance of XmlMapper class  
		XmlMapper xmlMap = new XmlMapper();  

		// create Scanner class object  
		Scanner sc= new Scanner(System.in);       

		// using try-catch
		try {  

			College colg;  

			String name, university, street, state, city, rank;  

			System.out.println("Enter College Name:");  
			name = sc.nextLine();  

			System.out.println("Enter University Name:");  
			university = sc.nextLine();  

			System.out.println("Enter Street:");  
			street = sc.nextLine();  
			
			System.out.println("Enter City:");  
			city = sc.nextLine();
			
			System.out.println("Enter State:");  
			state = sc.nextLine();
			
			System.out.println("Enter College Rank:");  
			rank = sc.nextLine();  

			// set values to College  object by using constructor  
			colg = new College(name, university, new Address(street, state, city), rank);
			
			// serialize College using xmlMap  
			xmlMap.writeValue(new File("C:\\Users\\rastogi ji\\Desktop\\College.xml"), colg);
			
			System.out.println("College object is successfully serialize into College.xml file.");  
	            
		} catch (IOException e) {   
			e.printStackTrace();  
		}  

		//close Scanner class object  
		sc.close();  

	}  
}
//create class College
class College {    

	//Creating properties of College class    
	public String name;      
	public String university;   
	public Address address; 
	public String rank;   

	// constructor  
	College(String name, String university, Address address, String rank){  
		this.name = name;  
		this.university = university;  
		this.address = address;  
		this.rank = rank;  
	}  

}
//create class Address 
class Address {  
	public String street;
	public String state;
	public String city;
	
	Address(String street, String state, String city){  
		  this.street = street;
		  this.state = state;
		  this.city = city;
	}         
}

输出

将 XML 反序列化为 POJO

就像序列化一样，我们可以使用 XmlMapper 类轻松地将 XML 数据反序列化为 POJO。让我们了解如何从 XML 字符串或 XML 文件中逐个反序列化数据。

我们使用 XmlMapper 将以下 XML 反序列化为 POJO

<College>
	<name>ABES</name>
	<university>AKTU</university>
	<address>
		NH-24 GZB UP
	</address>
	<rank>1</rank>
</College>

从 XML 字符串反序列化数据

为了将 XML 字符串反序列化为 POJO，请按照以下步骤操作

1. 按照以下方式创建 XmlMapper 类的实例

2. 使用 XmlMapper 类的 readValue() 方法并传递 XML 字符串和要反序列化 XML 字符串的类的名称。

让我们举个例子来了解如何使用它将 XML 字符串反序列化为 POJO。

XMLToPojoExample1.java

//import required classes and package if any  
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.annotation.JsonProperty;
//create class XMLToPojoExample1
public class XMLToPojoExample1 {  
	//main() methods start  
	public static void main(String args[]) {  
		// create an instance of XmlMapper class  
		XmlMapper xmlMap = new XmlMapper();  
		// xmlString
		String xmlString = "<College><name>ABES</name><university>AKTU</university>"
				+ "<address>NH-24 Highway GZB UP</address><rank>1</rank></College>";
		try {
			College colg = xmlMap.readValue(xmlString, College.class);
			System.out.println(colg.getCollegeName());
			System.out.println(colg.getUniversityName());
			System.out.println(colg.getAddress());
			System.out.println(colg.getRank());			
		} catch (JsonMappingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (JsonProcessingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}  
}
//create class College
class College {    

	//Creating properties of College class 
	@JsonProperty("name")
	private String name;    
	
	@JsonProperty("university")
	private String university;
	private String address;	
	private String rank;   
	public String getCollegeName() {  
		return name;  
	}
	public void setCollegeName(String name) {  
		this.name = name;  
	}
	
	public String getUniversityName() {  
		return university;  
	}
	public void setUniversityName(String university) {  
		this.university = university;
	}
	public String getAddress() {  
		return address;  
	}
	public void setAddress(String address) {  
		this.address = address;  
	}
	public String getRank() {  
		return rank;  
	}
	public void setRank(String rank) {  
		this.rank = rank;  
	}

}

输出

从 XML 文件反序列化数据

为了将 XML 文件的数据反序列化为 POJO，我们使用以下步骤

1. 按照以下方式创建 XmlMapper 类的实例

2. 从 xml 文件中读取数据作为字符串并将其存储在字符串变量中。

3. 使用 XmlMapper 类的 readValue() 方法并传递 XML 字符串和要反序列化 XML 字符串的类的名称。

让我们举个例子来了解如何使用它将 XML 文件的数据反序列化为 POJO。

XMLToPojoExample2.java

//import required classes and package if any  
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import com.fasterxml.jackson.annotation.JsonProperty;
//create class XMLToPojoExample2
public class XMLToPojoExample2 {  
	//main() methods start  
	public static void main(String args[]) throws IOException {  
		// create an instance of XmlMapper class  
		XmlMapper xmlMap = new XmlMapper();  
		// create instance of File
		File file = new File("C:\\Users\\rastogi ji\\Desktop\\College.xml");
		// read data from College.xml and store it into xmlString
		String xmlString;
		InputStream data = new FileInputStream(file);
		StringBuilder builder = new StringBuilder();
	    String line;
	    BufferedReader reader = new BufferedReader(new InputStreamReader(data));
	    while ((line = reader.readLine()) != null) {
	        builder.append(line);
	    }
	    reader.close();
	    xmlString = builder.toString();
	    System.out.println(xmlString);
		try {
			//deserialize xmlString into POJO
			College colg = xmlMap.readValue(xmlString, College.class);	
			System.out.println(colg.getCollegeName());
			System.out.println(colg.getUniversityName());
			System.out.println(colg.getAddress());
			System.out.println(colg.getRank());
			
		} catch (JsonMappingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (JsonProcessingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}  
}
//create class College
class College {    

	//Creating properties of College class 
	@JsonProperty("name")
	private String name;    
	
	@JsonProperty("university")
	private String university;
	
	private String address;
	
	private String rank;   

	public String getCollegeName() {  
		return name;  
	}
	public void setCollegeName(String name) {  
		this.name = name;  
	}
	
	public String getUniversityName() {  
		return university;  
	}
	public void setUniversityName(String university) {  
		this.university = university;
	}
	public String getAddress() {  
		return address;  
	}
	public void setAddress(String address) {  
		this.address = address;  
	}
	public String getRank() {  
		return rank;  
	}
	public void setRank(String rank) {  
		this.rank = rank;  
	}
}

输出

处理大写元素

在本节中，我们将了解如何处理以下情况：我们有带有大写元素的 XML 要反序列化，或者我们需要将 Java 对象序列化为具有一个或多个大写元素的 XML。

让我们通过一个例子逐一了解这两种情况。

从 XML 字符串反序列化数据

我们使用 XmlMapper 将以下 XML 反序列化为 POJO

<College>
	<NAME>ABES</NAME>
	<UNIVERSITY>AKTU</UNIVERSITY>
	<address>
		NH-24 GZB UP
	</address>
	<rank>1</rank>
</College>

HandleCapitalizedElement1.java

//import required classes and package if any  

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.annotation.JsonProperty;

//create class HandleCapitalizedElement1
public class HandleCapitalizedElement1 {  

	//main() methods start  
	public static void main(String args[]) {  

		// create an instance of XmlMapper class  
		XmlMapper xmlMap = new XmlMapper();  

		// xmlString
		String xmlString = "<College><NAME>ABES</NAME><UNIVERSITY>AKTU</UNIVERSITY>"
				+ "<address>NH-24 Highway GZB UP</address><rank>1</rank></College>";
		
		try {
			
			College colg = xmlMap.readValue(xmlString, College.class);
			
			System.out.println(colg.getCollegeName());
			System.out.println(colg.getUniversityName());
			System.out.println(colg.getAddress());
			System.out.println(colg.getRank());
			
		} catch (JsonMappingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (JsonProcessingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}  
}
//create class College
class College {    

	//Creating properties of College class 
	@JsonProperty("NAME")
	private String name;    
	
	@JsonProperty("UNIVERSITY")
	private String university;
	
	private String address;
	
	private String rank;   

	public String getCollegeName() {  
		return name;  
	}
	public void setCollegeName(String name) {  
		this.name = name;  
	}
	
	public String getUniversityName() {  
		return university;  
	}
	public void setUniversityName(String university) {  
		this.university = university;
	}
	public String getAddress() {  
		return address;  
	}
	public void setAddress(String address) {  
		this.address = address;  
	}
	public String getRank() {  
		return rank;  
	}
	public void setRank(String rank) {  
		this.rank = rank;  
	}
}

输出

将 POJO 序列化为 XML 字符串

我们以以下方式将 POJO 序列化为具有一个或多个大写元素的 XML 字符串或 XML 文件

HandleCapitalizedElement2.java

//import required classes and package if any  
import java.io.IOException;  
import java.util.Scanner;

import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;

//create class HandleCapitalizedElement2
public class HandleCapitalizedElement2 {  

	//main() methods start  
	public static void main(String args[]) {  

		// create an instance of XmlMapper class  
		XmlMapper xmlMap = new XmlMapper();  

		// create Scanner class object  
		Scanner sc= new Scanner(System.in);       

		// using try-catch
		try {  

			College colg;  

			String name, university, street, state, city, rank;  

			System.out.println("Enter College Name:");  
			name = sc.nextLine();  

			System.out.println("Enter University Name:");  
			university = sc.nextLine();  

			System.out.println("Enter Street:");  
			street = sc.nextLine();  
			
			System.out.println("Enter City:");  
			city = sc.nextLine();
			
			System.out.println("Enter State:");  
			state = sc.nextLine();
			
			System.out.println("Enter College Rank:");  
			rank = sc.nextLine();  

			// set values to College  object by using constructor  
			colg = new College(name, university, new Address(street, state, city), rank);
			
			// serialize College using xmlMap  
			String xmlString = xmlMap
					.writeValueAsString(colg);  
			System.out.println(xmlString);  
	            
		} catch (IOException e) {   
			e.printStackTrace();  
		}  

		//close Scanner class object  
		sc.close();  

	}  
}
//create class College
class College {    

	//Creating properties of College class  
	@JsonProperty("NAME")
	public String name;
	
	@JsonProperty("UNIVERSITY")
	public String university;   
	public Address address; 
	public String rank;   

	// constructor  
	College(String name, String university, Address address, String rank){  
		this.name = name;  
		this.university = university;  
		this.address = address;  
		this.rank = rank;  
	}  

}
//create class Address 
class Address {  
	public String street;
	public String state;
	public String city;
	
	Address(String street, String state, String city){  
		  this.street = street;
		  this.state = state;
		  this.city = city;
	}         
}

输出

将 List 序列化/反序列化为/从 XML

我们可以使用 XmlMapper 类轻松地将整个 Java bean 序列化为文档。我们将创建一个具有 comName、comEmail、address 和 contacts 等字段的 Company.java 类并将其序列化为 XML。我们使用 @JacksonXmlElementWrapper 注解来序列化列表。

SerializeListToXML.java

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

import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper;

//create class SerializeListToXML
public class SerializeListToXML {  

	//main() methods start  
	public static void main(String args[]) {  

		// create an instance of XmlMapper class  
		XmlMapper xmlMap = new XmlMapper();  

		// create Scanner class object  
		Scanner sc= new Scanner(System.in);       

		// using try-catch
		try {  

			Company company;  

			String name, email, mailingCity, mailingState, mailingStreet, shippingCity, shippingState, shippingStreet, con1, con2;  
			List<String> contacts = new ArrayList<String>();
			List<Address> address = new ArrayList<Address>();
			
			System.out.println("Enter Company Name:");  
			name = sc.nextLine();  

			System.out.println("Enter Company Email:");  
			email = sc.nextLine();  
			
			System.out.println("Enter Mailing Street:");  
			mailingStreet = sc.nextLine();  
			
			System.out.println("Enter Mailing City:");  
			mailingCity = sc.nextLine();
			
			System.out.println("Enter Mailing State:");  
			mailingState = sc.nextLine();
			
			System.out.println("Enter Shipping Street:");  
			shippingStreet = sc.nextLine();  
			
			System.out.println("Enter Shipping City:");  
			shippingCity = sc.nextLine();
			
			System.out.println("Enter Shipping State:");  
			shippingState = sc.nextLine();
			
			System.out.println("Enter Contact 1:");  
			con1 = sc.nextLine();  
			
			System.out.println("Enter Contact 2:");  
			con2 = sc.nextLine();  
			
			contacts.add(con1);
			contacts.add(con2);
			address.add(new Address(mailingStreet, mailingCity, mailingState));
			address.add(new Address(shippingStreet, shippingCity, shippingState));
			
			// set values to company  object by using constructor  
			company = new Company(name, email, address, contacts);
			
			// serialize College using xmlMap  
			String xmlString = xmlMap
					.writeValueAsString(company);  
			System.out.println(xmlString);  
	            
		} catch (IOException e) {   
			e.printStackTrace();  
		}  

		//close Scanner class object  
		sc.close();  

	}  
}
//create class Company
class Company {    

	//Creating properties of Company class  
	public String comName;
	public String comEmail;   
	
	@JacksonXmlElementWrapper(useWrapping = false)
	public List<Address> address; 
	public List<String> contacts;   

	// constructor  
	Company(String comName, String comEmail, List<Address> address, List<String> contacts){  
		this.comName = comName;  
		this.comEmail = comEmail;  
		this.address = address;  
		this.contacts = contacts;  
	}  
}
//create class Address 
class Address {  
	public String street;
	public String state;
	public String city;
	
	Address(String street, String state, String city){  
		  this.street = street;
		  this.state = state;
		  this.city = city;
	}         
}

输出

XMLMapper 类自动反序列化列表 xml 元素，而无需使用任何额外的注解。让我们举个例子来了解我们如何使用 XMLMapper 反序列化具有列表元素的 XML 字符串。

DeserializeListFromXML.java

//import required classes and package if any  
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import java.util.List;

//create class DeserializeListFromXML
public class DeserializeListFromXML {  
	//main() methods start  
	public static void main(String args[]) {  

		// create an instance of XmlMapper class  
		XmlMapper xmlMap = new XmlMapper();  

		// xmlString
		String xmlString = "<Company><comName>javaTpoint</comName><comEmail>javaTpoint@gmail.com</comEmail>"
				+ "<address><address>Sector 18 Noida UP</address><address>Sector 18 Noida UP</address></address>"
				+ "<contacts><contacts>9945238833</contacts><contacts>8975235588</contacts></contacts></Company>";
		
		try {
			
			Company cmp = xmlMap.readValue(xmlString, Company.class);
			
			System.out.println(cmp.getCompanyName());
			System.out.println(cmp.getCompanyEmail());
			System.out.println(cmp.getContacts());
			System.out.println(cmp.getAddress());
			
		} catch (JsonMappingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (JsonProcessingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}  
}
//create class Company
class Company {    

	//Creating properties of Company class  
	public String comName;
	
	public String comEmail;   
	
	public List<String> address;
	
	public List<String> contacts;   

	public String getCompanyName() {  
		return comName;  
	}
	public void setCompanyName(String comName) {  
		this.comName = comName;  
	}
	public String getCompanyEmail() {  
		return comEmail;  
	}
	public void setCompanyEmail(String comEmail) {  
		this.comEmail = comEmail;  
	}
	
	public List<String> getContacts() {  
		return contacts;  
	}
	public void setContacts(List<String> contacts) {  
		this.contacts = contacts;
	}
	public List<String> getAddress() {  
		return address;  
	}
	public void setAddress(List<String> address) {  
		this.address = address;  
	}
	@Override
    public String toString() {
        return "Dataset{" +
                "Name=" + comName +
                ", Email=" + comEmail +
                ", Address=" + address +
                ", Contact=" + contacts +
                '}';
    }
}

输出