Jaxb的优点与用法（bean转xml的插件，简化webservice接口的开发工作量）

一、jaxb是什么

　　JAXB是Java Architecture for XML Binding的缩写。可以将一个Java对象转变成为XML格式，反之亦然。
    　我们把对象与关系数据库之间的映射称为ORM，其实也可以把对象与XML之间的映射称为OXM(Object XML Mapping)。原来JAXB是Java EE的一部分，在JDK1.6中，SUN将其放到了Java SE中，这也是SUN的一贯做法。JDK1.6中自带的这个JAXB版本是2.0，比起1.0(JSR 31)来，JAXB2(JSR 222)用JDK5的新特性Annotation来标识要作绑定的类和属性等，这就极大简化了开发的工作量。

二、jaxb应用模式

　　在JAVA EE 5\6中，jaxb可以很方便的与jax-rs、jax-ws集成，极大的简化了web service接口的开发工作量。

三、jaxb代码举例

　　第一步：需要引入javax.xml.bind.jar
　　第二步：编写java bean;

package com.mkyong.core; import javax.xml.bind.annotation.XmlAttribute;import javax.xml.bind.annotation.XmlElement;import javax.xml.bind.annotation.XmlRootElement; @XmlRootElementpublic class Customer {  String name; int age; int id;  public String getName() {  return name; }  @XmlElement public void setName(String name) {  this.name = name; }  public int getAge() {  return age; }  @XmlElement public void setAge(int age) {  this.age = age; }  public int getId() {  return id; }  @XmlAttribute public void setId(int id) {  this.id = id; } }

　  第三步：main方法把java bean转化为xml字符串

package com.mkyong.core; import java.io.File;import javax.xml.bind.JAXBContext;import javax.xml.bind.JAXBException;import javax.xml.bind.Marshaller; public class JAXBExample { public static void main(String[] args) {    Customer customer = new Customer();   customer.setId(100);   customer.setName("mkyong");   customer.setAge(29);    try {   File file = new File("C:\\file.xml");  JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);  Marshaller jaxbMarshaller = jaxbContext.createMarshaller();   // output pretty printed  jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);   jaxbMarshaller.marshal(customer, file);  jaxbMarshaller.marshal(customer, System.out);        } catch (JAXBException e) {  e.printStackTrace();       }  }}

　 下面是输出：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><customer id="100">    <age>29</age>    <name>mkyong</name></customer>

四、jaxb开发常用

jdk提供了xjc工具可以使xsd自动生成相应的java bean，这大大提高了开发的效率。同时，我们也可以使用trang.jar把xml轻松转化为xsd。下面是使用的举例。

第一步：把数据库表映射为xml

<?xml version="1.0" encoding="UTF-8"?><User u_id="1" u_name="moto" u_email="aaa@XXX.com"  u_mood="今天放假了" u_state="online" u_mobile="12345678901"  u_hometown="山西" u_job="IT软件工程师" u_avatar="w34353453543r53" />

第二步：使用trang.jar转化为xsd文件。在命令行执行：

java -jar D:\lib\trang.jar user.xml user.xsd

下面，是生成的User.java。

//// This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, vJAXB 2.1.10 in JDK 6 // See <a href="http://java.sun.com/xml/jaxb">http://java.sun.com/xml/jaxb</a> // Any modifications to this file will be lost upon recompilation of the source schema. // Generated on: 2011.11.13 at 01:26:07 ���� CST //package com.moto.server.bean;import java.math.BigInteger;import javax.xml.bind.annotation.XmlAccessType;import javax.xml.bind.annotation.XmlAccessorType;import javax.xml.bind.annotation.XmlAttribute;import javax.xml.bind.annotation.XmlRootElement;import javax.xml.bind.annotation.XmlSchemaType;import javax.xml.bind.annotation.XmlType;import javax.xml.bind.annotation.adapters.CollapsedStringAdapter;import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;/** * <p>Java class for anonymous complex type. *  * <p>The following schema fragment specifies the expected content contained within this class. *  * <pre> * <complexType> *   <complexContent> *     <restriction base="{http://www.w3.org/2001/XMLSchema}anyType"> *       <attribute name="u_avatar" use="required" type="{http://www.w3.org/2001/XMLSchema}NCName" /> *       <attribute name="u_email" use="required" type="{http://www.w3.org/2001/XMLSchema}anySimpleType" /> *       <attribute name="u_hometown" use="required" type="{http://www.w3.org/2001/XMLSchema}NCName" /> *       <attribute name="u_id" use="required" type="{http://www.w3.org/2001/XMLSchema}integer" /> *       <attribute name="u_job" use="required" type="{http://www.w3.org/2001/XMLSchema}NCName" /> *       <attribute name="u_mobile" use="required" type="{http://www.w3.org/2001/XMLSchema}integer" /> *       <attribute name="u_mood" use="required" type="{http://www.w3.org/2001/XMLSchema}NCName" /> *       <attribute name="u_name" use="required" type="{http://www.w3.org/2001/XMLSchema}NCName" /> *       <attribute name="u_state" use="required" type="{http://www.w3.org/2001/XMLSchema}NCName" /> *     </restriction> *   </complexContent> * </complexType> * </pre> *  *  */@XmlAccessorType(XmlAccessType.FIELD)@XmlType(name = "")@XmlRootElement(name = "User")public class User {    @XmlAttribute(name = "u_avatar", required = true)    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)    @XmlSchemaType(name = "NCName")    protected String uAvatar;    @XmlAttribute(name = "u_email", required = true)    @XmlSchemaType(name = "anySimpleType")    protected String uEmail;    @XmlAttribute(name = "u_hometown", required = true)    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)    @XmlSchemaType(name = "NCName")    protected String uHometown;    @XmlAttribute(name = "u_id", required = true)    protected BigInteger uId;    @XmlAttribute(name = "u_job", required = true)    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)    @XmlSchemaType(name = "NCName")    protected String uJob;    @XmlAttribute(name = "u_mobile", required = true)    protected BigInteger uMobile;    @XmlAttribute(name = "u_mood", required = true)    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)    @XmlSchemaType(name = "NCName")    protected String uMood;    @XmlAttribute(name = "u_name", required = true)    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)    @XmlSchemaType(name = "NCName")    protected String uName;    @XmlAttribute(name = "u_state", required = true)    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)    @XmlSchemaType(name = "NCName")    protected String uState;    /**     * Gets the value of the uAvatar property.     *      * @return     *     possible object is     *     {@link String }     *          */    public String getUAvatar() {        return uAvatar;    }    /**     * Sets the value of the uAvatar property.     *      * @param value     *     allowed object is     *     {@link String }     *          */    public void setUAvatar(String value) {        this.uAvatar = value;    }    /**     * Gets the value of the uEmail property.     *      * @return     *     possible object is     *     {@link String }     *          */    public String getUEmail() {        return uEmail;    }    /**     * Sets the value of the uEmail property.     *      * @param value     *     allowed object is     *     {@link String }     *          */    public void setUEmail(String value) {        this.uEmail = value;    }    /**     * Gets the value of the uHometown property.     *      * @return     *     possible object is     *     {@link String }     *          */    public String getUHometown() {        return uHometown;    }    /**     * Sets the value of the uHometown property.     *      * @param value     *     allowed object is     *     {@link String }     *          */    public void setUHometown(String value) {        this.uHometown = value;    }    /**     * Gets the value of the uId property.     *      * @return     *     possible object is     *     {@link BigInteger }     *          */    public BigInteger getUId() {        return uId;    }    /**     * Sets the value of the uId property.     *      * @param value     *     allowed object is     *     {@link BigInteger }     *          */    public void setUId(BigInteger value) {        this.uId = value;    }    /**     * Gets the value of the uJob property.     *      * @return     *     possible object is     *     {@link String }     *          */    public String getUJob() {        return uJob;    }    /**     * Sets the value of the uJob property.     *      * @param value     *     allowed object is     *     {@link String }     *          */    public void setUJob(String value) {        this.uJob = value;    }    /**     * Gets the value of the uMobile property.     *      * @return     *     possible object is     *     {@link BigInteger }     *          */    public BigInteger getUMobile() {        return uMobile;    }    /**     * Sets the value of the uMobile property.     *      * @param value     *     allowed object is     *     {@link BigInteger }     *          */    public void setUMobile(BigInteger value) {        this.uMobile = value;    }    /**     * Gets the value of the uMood property.     *      * @return     *     possible object is     *     {@link String }     *          */    public String getUMood() {        return uMood;    }    /**     * Sets the value of the uMood property.     *      * @param value     *     allowed object is     *     {@link String }     *          */    public void setUMood(String value) {        this.uMood = value;    }    /**     * Gets the value of the uName property.     *      * @return     *     possible object is     *     {@link String }     *          */    public String getUName() {        return uName;    }    /**     * Sets the value of the uName property.     *      * @param value     *     allowed object is     *     {@link String }     *          */    public void setUName(String value) {        this.uName = value;    }    /**     * Gets the value of the uState property.     *      * @return     *     possible object is     *     {@link String }     *          */    public String getUState() {        return uState;    }    /**     * Sets the value of the uState property.     *      * @param value     *     allowed object is     *     {@link String }     *          */    public void setUState(String value) {        this.uState = value;    }}

转载自：https://blog.csdn.net/hfrujhv/article/details/83788497