java运用jaxb操纵xml示例【XML教程】,java jaxb xml

起首定义两个示例类ClassA,ClassB，用于后续的示例演示

package cn.lzrabbit;
public class ClassA {
    private int classAId;
    private String classAName;
    private ClassB classB;
    public int getClassAId() {
        return classAId;
    }
    public void setClassAId(int classAId) {
        this.classAId = classAId;
    }
    public String getClassAName() {
        return classAName;
    }
    public void setClassAName(String classAName) {
        this.classAName = classAName;
    }
    public ClassB getClassB() {
        return classB;
    }
    public void setClassB(ClassB classB) {
        this.classB = classB;
    }
}
ClassA

package cn.lzrabbit;
public class ClassB {
    private int classBId;
    private String classBName;
    public int getClassBId() {
        return classBId;
    }
    public void setClassBId(int classBId) {
        this.classBId = classBId;
    }
    public String getClassBName() {
        return classBName;
    }
    public void setClassBName(String classBName) {
        this.classBName = classBName;
    }
}
ClassB

用于序列化的XmlUtil

package cn.lzrabbit;
import java.io.StringReader;
import java.io.StringWriter;
import javax.xml.bind.*;
public class XmlUtil {
    public static String toXML(Object obj) {
        try {
            JAXBContext context = JAXBContext.newInstance(obj.getClass());
            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");// //编码花样
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);// 是不是花样化生成的xml串
            marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);// 是不是省略xm头声明信息
            StringWriter writer = new StringWriter();
            marshaller.marshal(obj, writer);
            return writer.toString();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
    @SuppressWarnings("unchecked")
    public static <T> T fromXML(String xml, Class<T> valueType) {
        try {
            JAXBContext context = JAXBContext.newInstance(valueType);
            Unmarshaller unmarshaller = context.createUnmarshaller();
            return (T) unmarshaller.unmarshal(new StringReader(xml));
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }
    }
}
XmlUtil

挪用以下：

package cn.lzrabbit;

public class MainRun {
    /**
     * @param args
     */
    public static void main(String[] args) {
        ClassB classB = new ClassB();
        classB.setClassBId(22);
        classB.setClassBName("B2");
        ClassA classA = new ClassA();
        classA.setClassAId(11);
        classA.setClassAName("A1");
        classA.setClassB(classB);
        System.out.println(XmlUtil.toXML(classA));
    }
}
MainRun

输出效果以下：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<classA>
    <classAId>11</classAId>
    <classAName>A1</classAName>
    <classB>
        <classBId>22</classBId>
        <classBName>B2</classBName>
    </classB>
</classA>

这里要注意以下几点

1要序列化的类加上 @XmlRootElement注解，不然会报错(毛病提醒很清楚，这里就不贴出来了)

2JAXB序列化XML时 默许序列化getter和setter，且getter和setter必需成对涌现才会被序列化

3属性称号，默许序列化出来的类和属性称号默许是首字母转换为小写，若须要掌握属性称号须要在getter或setter上运用 @XmlElement(name="ClassAId") 指定称号，这里要注意的是@XmlElement安排在getter或setter上都行，但只能放一个，也就是说不能同时在getter和setter上运用@XmlElement注解

4怎样掌握根节点称号？
运用@XmlRootElement指定name属性即可，如@XmlRootElement(name="ClassA")

5怎样增加定名空间
运用@XmlRootElement(namespace="cn.lzrabbit") 指定namespace属性

6怎样准确掌握每一个属性称号
JAXB自动转化为首字母小写会致使不可预感的属性称号涌现， 不嫌贫苦的话为每一个属性设置@XmlElement(name="")，想费事的话运用Field

7怎样完成序列化时运用Field字段而不是运用setter和getter
在要运用的类上面加上@XmlAccessorType(XmlAccessType.FIELD)注解，并指定为XmlAccessType.FIELD，这里强烈推荐运用@XmlAccessorType(XmlAccessType.FIELD)注解，由于如许你能够准确的掌握每一个元素的称号，而不须要为每一个属性去设置@XmlElement(name="")注解，固然也能够在Field上运用@XmlElement注解

下面给出运用了运用如上注解后的代码示例

@XmlRootElement(namespace="cn.lzrabbit")
@XmlAccessorType(XmlAccessType.FIELD)
public class ClassA {
    private int classAId;
    
    @XmlElement(name="ClassAName")
    private String classAName;
    private ClassB classB;
    public int getClassAId() {
        return classAId;
    }
    public void setClassAId(int classAId) {
        this.classAId = classAId;
    }
    public String getClassAName() {
        return classAName;
    }
    public void setClassAName(String classAName) {
        this.classAName = classAName;
    }
    public ClassB getClassB() {
        return classB;
    }
    public void setClassB(ClassB classB) {
        this.classB = classB;
    }
}
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class ClassB {
    private int ClassBId;
    private String ClassBName;
    public int getClassBId() {
        return ClassBId;
    }
    public void setClassBId(int classBId) {
        this.ClassBId = classBId;
    }
    public String getClassBName() {
        return ClassBName;
    }
    public void setClassBName(String classBName) {
        this.ClassBName = classBName;
    }
}

输出xml为

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns2:classA xmlns:ns2="cn.lzrabbit">
    <classAId>11</classAId>
    <ClassAName>A1</ClassAName>
    <classB>
        <ClassBId>22</ClassBId>
        <ClassBName>B2</ClassBName>
    </classB>
</ns2:classA>

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