Spring 和 JAXB 集成

术语 JAXB 代表用于 XML 绑定的Java体系结构。 Java程序员可以使用它将Java类转换为 XML 表示。可以使用 JAXB 将Java对象编组为 XML，反之亦然。 Sun 提供了一个 OXM（对象 XML 映射）或 O/M 框架。

Note: The biggest and only advantage of JAXB is as there’s no need to develop callback methods or create a SAX or DOM parser.

实现： Spring 和 JAXB 集成（将Java对象编组为 XML）

项目结构如下所示：  

我们使用 Jaxb2Marshaller 实例构建 Marshaller 和 Unmarshaller 实例。在 Jaxb2Marshaller 中，将 jaxb.formatted.output 属性设置为 true 以获得良好的打印效果。要将 XML 标记和属性映射到Java对象，我们需要构造一个带有映射到 XML 标记和属性的属性的Java bean。使用 javax.xml.bind 注释属性。例如，XmlAttribute 和 XmlElement 是将 XML 属性和元素链接到Java bean 属性的注释。

Remember: To run the application, we need the following software as listed: 

1. Java 7
2. Gradle
3. Eclipse
4. Spring-Oxm:4.1.5.RELEASE

Spring OXM 和 Spring Boot Starter 的 Gradle 文件

第 1 步：找到 spring OXM 和 spring Boot Starter 的 Gradle 文件。

文件：构建.xml

XML

apply plugin: 'java'
apply plugin: 'eclipse'
archivesBaseName = 'geeksforgeeks'
version = '1'
repositories {
    mavenCentral()
}
dependencies {
    compile 'org.springframework.boot:spring-boot-starter:1.2.2.RELEASE'
    compile 'org.springframework:spring-oxm:4.1.5.RELEASE'
}

Jaxb2Marshaller 和 Pretty Print 的基于注释的配置文件

Spring OXM 中的 Jaxb2Marshaller 实例用于构造 Marshaller 和 Unmarshaller 实例。

第 2 步：在 Jaxb2Marshaller 中，我们可以配置漂亮的 XML 打印、编码等设置。要制作精美的印刷品，请按照以下说明进行操作。

map.put("jaxb.formatted.output", true);
jaxb2Marshaller.setMarshallerProperties(map); 

文件：应用配置。Java

Java

// Java Program to Illustrate Configuration Class
 
package com.geeksforgeeks;
 
// Importing required classes
import java.util.HashMap;
import java.util.Map;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.oxm.jaxb.Jaxb2Marshaller;
 
// Annotation
@Configuration
// Class
public class AppConfig {
 
    // Method
    @Bean public Processor getHandler()
    {
        Processor handler = new Processor();
        handler.setMarshaller(getCastorMarshaller());
        handler.setUnmarshaller(getCastorMarshaller());
 
        return handler;
    }
 
    // Method
    @Bean public Jaxb2Marshaller getCastorMarshaller()
    {
        Jaxb2Marshaller jaxb2Marshaller
            = new Jaxb2Marshaller();
        jaxb2Marshaller.setPackagesToScan(
            "com.geeksforgeeks.bean");
        Map map
            = new HashMap();
        map.put("jaxb.formatted.output", true);
        jaxb2Marshaller.setMarshallerProperties(map);
 
        return jaxb2Marshaller;
    }
}

Java支持许多用于 XML 和Java对象映射的注解，包括 @XmlRootElement、@XmlAccessorType、@XmlAttribute 和 @XmlElement。

第三步：使用@XmlAttribute 获取Java属性作为XML 属性，并在属性上使用@XmlElement 注解来检索XML 子标签。

档案：公司。Java

Java

// Java Program to Illustrate Bean for XML Mapping
 
package com.geeksforgeeks.bean;
 
// Importing required classes
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
 
// Annotation
@XmlRootElement(name = "company-info",
                namespace = "com.geeksforgeeks")
@XmlAccessorType(XmlAccessType.NONE)
 
// Class
public class Company {
 
    // Class data members
    @XmlAttribute(name = "id") private Integer id;
    @XmlElement(name = "company-name")
    private String companyName;
   
    @XmlElement(name = "ceo-name") private String ceoName;
    @XmlElement(name = "no-emp") private Integer noEmp;
 
    // Getters and setters
    public Integer getId() { return id; }
    public void setId(Integer id)
    {
        // this keyword refers to current itself
        this.id = id;
    }
 
    // Getter and Setter
    public String getCompanyName() { return companyName; }
    public void setCompanyName(String companyName)
    {
        this.companyName = companyName;
    }
 
    // Getter and Setter
    public String getCeoName() { return ceoName; }
    public void setCeoName(String ceoName)
    {
        this.ceoName = ceoName;
    }
 
    // Getter and Setter
    public Integer getNoEmp() { return noEmp; }
    public void setNoEmp(Integer noEmp)
    {
        this.noEmp = noEmp;
    }
}

为 Marshaller 和 Unmarshaller 定义方法

第 4 步：找到一个实用方法，我们在其中调用 Marshaller 和 Unmarshaller。

文件：处理器。Java

Java

// Java Program Defining Method for
// Marshaller and Unmarshaller
 
package com.geeksforgeeks;
 
// Importing required classes
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
 
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
 
import org.springframework.oxm.Marshaller;
import org.springframework.oxm.Unmarshaller;
 
// Class
public class Processor {
   
    // Class data members
    private Marshaller marshaller;
    private Unmarshaller unmarshaller;
 
     // Setter
    public void setMarshaller(Marshaller marshaller) {
        this.marshaller = marshaller;
    }
 
    public void setUnmarshaller(Unmarshaller unmarshaller) {
        this.unmarshaller = unmarshaller;
    }
    // Converting Object to XML file
    public void objectToXML(String fileName, Object graph) throws IOException {
        FileOutputStream fos = null;
       
      // Try block to check for exceptions
      try {
            fos = new FileOutputStream(fileName);
            marshaller.marshal(graph, new StreamResult(fos));
        }
       
      // finally block that will execute for sure
      finally {
         
          // Closing the connections
            fos.close();
        }
    }
     // Method
    // To Convert XML to Java Object
    public Object xmlToObject(String fileName) throws IOException {
         
      FileInputStream fis = null;
       
      // Try block to check for exceptions
      try {
            fis = new FileInputStream(fileName);
            return unmarshaller.unmarshal(new StreamSource(fis));
        }
       
       // finally block that will execute for sure
      finally {
         
        // Closing the connections
            fis.close();
        }
    }
}

第 5 步：运行应用程序

现在为了测试程序，我们可以创建一个 bean 对象，将其转换为 XML，然后将该 XML 转换回Java对象。

文件：运行应用程序。Java

Java

// Java Program to Illustrate Application Class
 
package com.geeksforgeeks;
 
// Importing required classes
import com.geeksforgeeks.bean.Company;
import java.io.IOException;
import org.springframework.beans.BeansException;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 
// Application/Main Class
public class RunApplication {
 
    // Main driver method
    public static void main(String[] args)
        throws IOException
    {
 
        // Try block to check for exceptions
        try (AnnotationConfigApplicationContext ctx
             = new AnnotationConfigApplicationContext()) {
            ctx.register(AppConfig.class);
            ctx.refresh();
            Processor processor
                = ctx.getBean(Processor.class);
 
            // Perform Marshaling
            Company company = new Company();
            company.setId(1000);
            company.setCompanyName("XYZ");
            company.setCeoName("ABCD");
            company.setNoEmp(100);
            processor.objectToXML("country.xml", company);
 
            // Display message only
            System.out.println("Marshaling performed");
 
            // Perform UnMarshaling
            company = (Company)processor.xmlToObject(
                "country.xml");
 
            // Display message only
            System.out.println(
                "After UnMarshaling Data is: id:"
                + company.getId() + ", CountryName:"
                + company.getCompanyName());
        }
 
        // Catch block to handle exceptions
        catch (BeansException | IllegalStateException e) {
 
            // Display exceptions along with line number
            // using printStackTrace() method
            e.printStackTrace();
        }
    }
}

输出： Java对象转XML如下：

   XYZ
   ABCD
   100

输出： XML 到Java对象如下：