JAXB的XML和Object的自动转换

JAXB可以实现XML和Object的自动转换，这样我们就不用再自己写xml的解析了。

1、从xml文件读取自动转换成Object

2、从xml字符串读取自动转换成Object

3、把对象转化成xml输出到控制台

4、把对象转化成xml输出到文件

5、把对象转化成xml字符串

 

vdi.xml

<?xml version="1.0" encoding="UTF-8"?>
<vdis size="2" batch_number="20141212123456" errmsg="">
    <vdi>
        <id>1</id>
        <uuid>6524552158933218</uuid>
        <name>disk1</name>
        <disk_size>20</disk_size>
    </vdi>
    <vdi>
        <id>2</id>
        <uuid>6524552158933123</uuid>
        <name>disk2</name>
        <disk_size>40</disk_size>
    </vdi>
</vdis>

Vdis.java

package com.chinac.jaxb.parsexml;

import java.util.ArrayList;
import java.util.List;
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;

@XmlRootElement(name = "vdis")
@XmlAccessorType(XmlAccessType.FIELD)
public class Vdis extends ArrayList<Vdi>{
    
    @XmlAttribute(name = "size")
    private int size;
    @XmlAttribute(name = "batch_number")
    private Long batchNumber;
    @XmlAttribute(name = "errmsg")
    private String errmsg;
    
    @XmlElement(name = "vdi")
    private List<Vdi> getVdis(){
        return this;
    }
    
    
    public int getSize() {
        return size;
    }

    public void setSize(int size) {
        this.size = size;
    }

    public Long getBatchNumber() {
        return batchNumber;
    }

    public void setBatchNumber(Long batchNumber) {
        this.batchNumber = batchNumber;
    }

    public String getErrmsg() {
        return errmsg;
    }

    public void setErrmsg(String errmsg) {
        this.errmsg = errmsg;
    }
    
    
    @Override
    public String toString() {
        return "size:"+size
                + ",batchNumber:"+batchNumber
                + ",errmsg:"+errmsg
                + "";
    }    
}

Vdi.java

package com.chinac.jaxb.parsexml;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;

@XmlAccessorType(XmlAccessType.FIELD)
public class Vdi {
    @XmlElement(name = "id")
    private int id;
    @XmlElement(name = "uuid")
    private String uuid;
    @XmlElement(name = "name")
    private String name;
    @XmlElement(name = "disk_size")
    private int diskSize;
    


    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUuid() {
        return uuid;
    }

    public void setUuid(String uuid) {
        this.uuid = uuid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getDiskSize() {
        return diskSize;
    }

    public void setDiskSize(int diskSize) {
        this.diskSize = diskSize;
    }
    
    @Override
    public String toString() {
        return "id:"+id
                + ",uuid:"+uuid
                + ",name:"+name
                + ",diskSize:"+diskSize;
    }
}

Test.java

package com.chinac.jaxb.test;

import java.io.File;
import java.io.StringReader;
import java.io.StringWriter;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import javax.xml.transform.stream.StreamSource;
import com.chinac.jaxb.parsexml.Vdi;
import com.chinac.jaxb.parsexml.Vdis;

@SuppressWarnings("unchecked")
public class Test {

    //从xml文件读取
    public static <T> T readFromFile(Class<T> clazz , String filePath) throws JAXBException{
        JAXBContext jc = JAXBContext.newInstance(clazz);
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        return (T) unmarshaller.unmarshal(new File(filePath));
    }
    
    //从xml字符串读取
    public static <T> T readFromString(Class<T> clazz , StringBuffer xmlStr) throws JAXBException{
        JAXBContext jc = JAXBContext.newInstance(clazz);
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        return (T) unmarshaller.unmarshal(new StreamSource(new StringReader(xmlStr.toString())));
    }
    
    //把对象转化成xml输出到控制台
    public static <T> void writeToConsole(Class<T> clazz , T t) throws JAXBException{
        JAXBContext cxt = JAXBContext.newInstance(clazz);  
        Marshaller marshaller = cxt.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");// 编码格式  
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);// 是否格式化生成的xml串  
        marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);// 默认false表示xml指令存在
        marshaller.marshal(t, System.out);
    }
    
    //把对象转化成xml输出到文件
    public static <T> void writeToFile(Class<T> clazz , T t , String filePath) throws JAXBException{
        JAXBContext cxt = JAXBContext.newInstance(clazz);  
        Marshaller marshaller = cxt.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");// 编码格式  
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);// 是否格式化生成的xml串  
        marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);// 默认false表示xml指令存在
        marshaller.marshal(t, new File(filePath));
    }
    
    //把对象转化成xml字符串
    public static <T> String writeToString(Class<T> clazz , T t) throws JAXBException{
        JAXBContext cxt = JAXBContext.newInstance(clazz);  
        Marshaller marshaller = cxt.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");// 编码格式  
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);// 是否格式化生成的xml串  
        marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);// 默认false表示xml指令存在
        
        StringWriter writer = new StringWriter();
        marshaller.marshal(t, writer);
        return writer.toString();
    }
    
    public static void main(String[] args) throws JAXBException {
        //从xml文件读取
        String filePath = "./src/vdi.xml";
        Vdis vdis1 = Test.readFromFile(Vdis.class, filePath);
        System.out.println(vdis1.toString());
        for(Vdi vdi : vdis1){
            System.out.println(vdi);
        }
        
        //从xml字符串读取
        StringBuffer xmlStr = new StringBuffer("<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
                + "<vdis size=\"2\" batch_number=\"20141212123456\" errmsg=\"\">"
                    + "<vdi>"
                        + "<id>1</id>"
                        + "<uuid>6524552158933218</uuid>"
                        + "<name>disk1</name>"
                        + "<disk_size>20</disk_size>"
                    + "</vdi>"
                    + "<vdi>"
                        + "<id>2</id>"
                        + "<uuid>6524552158933123</uuid>"
                        + "<name>disk2</name>"
                        + "<disk_size>40</disk_size>"
                        + "</vdi>"
                    + "</vdis>");
        Vdis vdis2 = Test.readFromString(Vdis.class, xmlStr);
        System.out.println(vdis2.toString());
        for(Vdi vdi : vdis2){
            System.out.println(vdi);
        }
        
        //把对象转化成xml输出到控制台
        
        Test.writeToConsole(Vdis.class, vdis2);
        
        //把对象转化成xml输出到文件
        String filePath2 = "./src/test.xml";
        Test.writeToFile(Vdis.class, vdis2, filePath2);
        
        //把对象转化成xml字符串
        String xmlStr2 = Test.writeToString(Vdis.class, vdis2);
        System.out.println(xmlStr2);
    }
}

注意：

用了@XmlAccessorType(XmlAccessType.FIELD)、@XmlElement、@XmlAttribute注解后，属性自己的getter/setter方法就会被忽略，去掉这些主键使用属性自己的getter/setter方法一样可以。

简洁版：

Vdis.java

package com.chinac.jaxb.parsexml;

import java.util.ArrayList;
import java.util.List;
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;

@XmlRootElement(name = "vdis")
@XmlAccessorType(XmlAccessType.FIELD)
public class Vdis extends ArrayList<Vdi>{
    
    @XmlAttribute(name = "size")
    private int size;
    @XmlAttribute(name = "batch_number")
    private Long batchNumber;
    @XmlAttribute(name = "errmsg")
    private String errmsg;
    
    @XmlElement(name = "vdi")
    private List<Vdi> getVdis(){
        return this;
    }
    
    @Override
    public String toString() {
        return "size:"+size
                + ",batchNumber:"+batchNumber
                + ",errmsg:"+errmsg
                + "";
    }    
}

Vdi.java

package com.chinac.jaxb.parsexml;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;

@XmlAccessorType(XmlAccessType.FIELD)
public class Vdi {
    @XmlElement(name = "id")
    private int id;
    @XmlElement(name = "uuid")
    private String uuid;
    @XmlElement(name = "name")
    private String name;
    @XmlElement(name = "disk_size")
    private int diskSize;
        
    @Override
    public String toString() {
        return "id:"+id
                + ",uuid:"+uuid
                + ",name:"+name
                + ",diskSize:"+diskSize;
    }
}

自主版：

Vdis.java

package com.chinac.jaxb.parsexml;

import java.util.ArrayList;
import java.util.List;
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;

@XmlRootElement(name = "vdis")
@XmlAccessorType(XmlAccessType.FIELD)
public class Vdis extends ArrayList<Vdi>{

    private int size;
    private Long batchNumber;
    private String errmsg;
    private List<Vdi> getVdis(){
        return this;
    }
    
    
    public int getSize() {
       System.out.println("aaa");
        return size;
    }

    public void setSize(int size) {
       System.out.println("bbb");
        this.size = size;
    }

    public Long getBatchNumber() {
        return batchNumber;
    }

    public void setBatchNumber(Long batchNumber) {
        this.batchNumber = batchNumber;
    }

    public String getErrmsg() {
        return errmsg;
    }

    public void setErrmsg(String errmsg) {
        this.errmsg = errmsg;
    }
    
    
    @Override
    public String toString() {
        return "size:"+size
                + ",batchNumber:"+batchNumber
                + ",errmsg:"+errmsg
                + "";
    }    
}

Vdi.java

package com.chinac.jaxb.parsexml;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;

public class Vdi {
    private int id;
    private String uuid;
    private String name;
    private int diskSize;

    public int getId() {
       System.out.println("ccc");
        return id;
    }

    public void setId(int id) {
        System.out.println("ddd");
       this.id = id;
    }

    public String getUuid() {
        return uuid;
    }

    public void setUuid(String uuid) {
        this.uuid = uuid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getDiskSize() {
        return diskSize;
    }

    public void setDiskSize(int diskSize) {
        this.diskSize = diskSize;
    }
    
    @Override
    public String toString() {
        return "id:"+id
                + ",uuid:"+uuid
                + ",name:"+name
                + ",diskSize:"+diskSize;
    }
}