Jaxb2 转换XML文档

Jaxb2 转换XML文档

package com.hoo.test;

import java.io.IOException;

import java.io.StringReader;

import java.io.StringWriter;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.xml.bind.JAXBContext;

import javax.xml.bind.JAXBException;

import javax.xml.bind.Marshaller;

import javax.xml.bind.Unmarshaller;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

import com.hoo.entity.Account;

import com.hoo.entity.AccountBean;

import com.hoo.entity.Birthday;

import com.hoo.entity.ListBean;

import com.hoo.entity.MapBean;

/**

* function:Jaxb2 完成Java和XML的编组、解组

* @author hoojo

* @createDate 2011-4-25 上午11:54:06

* @file Jaxb2Test.java

* @package com.hoo.test

* @project WebHttpUtils

* @blog http://blog.csdn.net/IBM_hoojo

* @email [e-mail]

* @version 1.0

*/

public class Jaxb2Test {

private JAXBContext context = null;

private StringWriter writer = null;

private StringReader reader = null;

private AccountBean bean = null;

@Before

public void init() {

bean = new AccountBean();

bean.setAddress("北京");

bean.setEmail("email");

bean.setId(1);

bean.setName("jack");

Birthday day = new Birthday();

day.setBirthday("2010-11-22");

bean.setBirthday(day);

try {

context = JAXBContext.newInstance(AccountBean.class);

} catch (Exception e) {

e.printStackTrace();

}

}

@After

public void destory() {

context = null;

bean = null;

try {

if (writer != null) {

writer.flush();

writer.close();

}

if (reader != null) {

reader.close();

}

} catch (IOException e) {

e.printStackTrace();

}

System.gc();

}

public void fail(Object o) {

System.out.println(o);

}

public void failRed(Object o) {

System.err.println(o);

}

}

通过JAXBContext的newInstance方法，传递一个class就可以获得一个上下文。 newInstance方法也可以传递一个xml的文件的path。通过xml文件，对class的描述进行转换。然后，就可以通过这个上下文的来创建一 个Marshaller，通过Marshaller对象的marshal方法就可以转换JavaBean对象到xml。同样JAXBContext也可以 创建一个Unmarshall的unmarshal方法可以进行xml到Java对象的解组。

二、 对Java编组、XML解组

1、 JavaBean和XML的相互转换

代码如下：

@Test

public void testBean2XML() {

try {

//下面代码演示将对象转变为xml

Marshaller mar = context.createMarshaller();

writer = new StringWriter();

mar.marshal(bean, writer);

fail(writer);

//下面代码演示将上面生成的xml转换为对象

reader = new StringReader(writer.toString());

Unmarshaller unmar = context.createUnmarshaller();

bean = (AccountBean)unmar.unmarshal(reader);

fail(bean);

} catch (JAXBException e) {

e.printStackTrace();

}

}

上面的context是在init方法中创建的，它传递了一个AccountBean的class，这个AccountBean不是一般的普通的bean。除了它带有getter、setter方法外，还有Annotation注解。下面我们就看看这个bean的代码。

package com.hoo.entity;

import javax.xml.bind.annotation.XmlAttribute;

import javax.xml.bind.annotation.XmlRootElement;

import com.sun.xml.internal.txw2.annotation.XmlElement;

@XmlRootElement(name = "account")

public class AccountBean {

private int id;

private String name;

private String email;

private String address;

private Birthday birthday;

@XmlElement

public Birthday getBirthday() {

return birthday;

}

public void setBirthday(Birthday birthday) {

this.birthday = birthday;

}

@XmlAttribute(name = "number")

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

@XmlElement

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

@XmlElement

public String getEmail() {

return email;

}

public void setEmail(String email) {

this.email = email;

}

@XmlElement

public String getAddress() {

return address;

}

public void setAddress(String address) {

this.address = address;

}

@Override

public String toString() {

return this.name + "#" + this.id + "#" + this.address + "#" + this.birthday + "#" + this.email;

}

}

上面的XmlRootElement是设置当前对象转换成xml后的根节点，name的值是设置根节点的名称。在getter方法上设置 XmlElement表示这个方法对应的属性是一个xml元素，如果这个注解还设置了name，那么这个name就是转换后xml的名称。在一个属性上设 置XmlAttribute，表示这个方法对应的属性在转换xml后是父元素的一个属性。XmlAttribute的name就是转换后xml的属性的 name。

运行后，结果如下：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><account number="1"><address>北京</address>

<birthday><birthday>2010-11-22</birthday></birthday><email>email</email><name>jack</name></account>

jack#1#北京#2010-11-22#email

把转换后的xml和上面的AccountBean对应看看

2、 对List类型对象，进行编组、解组

@Test

public void testList2XML() {

ListBean listBean = new ListBean();

listBean.setName("list to xml");

List<Object> list = new ArrayList<Object>();

list.add(bean);

bean = new AccountBean();

bean.setAddress("china");

bean.setEmail("[e-mail]");

bean.setId(2);

bean.setName("tom");

Birthday day = new Birthday("2010-11-22");

bean.setBirthday(day);

Account acc = new Account();

acc.setAddress("china");

acc.setEmail("[e-mail]");

acc.setId(2);

acc.setName("tom");

day = new Birthday("2010-11-22");

acc.setBirthday(day);

list.add(bean);

list.add(acc);

listBean.setList(list);

try {

context = JAXBContext.newInstance(ListBean.class);

//下面代码演示将对象转变为xml

Marshaller mar = context.createMarshaller();

writer = new StringWriter();

mar.marshal(listBean, writer);

fail(writer);

//下面代码演示将上面生成的xml转换为对象

reader = new StringReader(writer.toString());

Unmarshaller unmar = context.createUnmarshaller();

listBean = (ListBean)unmar.unmarshal(reader);

fail(listBean.getList().get(0));

fail(listBean.getList().get(1));

fail(listBean.getList().get(2));

} catch (JAXBException e) {

e.printStackTrace();

}

}

你不能直接new 一个List，然后将对象放到List中。进行编组、解组，这样会出现异常情况的。你需要构建一个JavaBean，在bean中创建一个List的属 性。然后在这个属性的getter方法上进行Annotation注解。下面我们看看ListBean的代码：

package com.hoo.entity;

import java.util.List;

import javax.xml.bind.annotation.XmlAttribute;

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlElements;

import javax.xml.bind.annotation.XmlRootElement;

@SuppressWarnings("unchecked")

@XmlRootElement(name = "list-bean")

public class ListBean {

private String name;

private List list;

@XmlElements({

@XmlElement(name = "account", type = Account.class),

@XmlElement(name = "bean", type = AccountBean.class)

})

public List getList() {

return list;

}

public void setList(List list) {

this.list = list;

}

@XmlAttribute

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

}

XmlElements表示是一个集合类型，然后注解在集合中存放上面类型的对象。

XmlElement表示在集合中存放的一个对象类型和元素名称。

转换后结果如下：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<list-bean name="list to xml">

<bean number="1"><address>北京</address><birthday><birthday>2010-11-22</birthday></birthday>

<email>email</email><name>jack</name></bean>

<bean number="2"><address>china</address><birthday><birthday>2010-11-22</birthday></birthday>

<email>[e-mail]</email><name>tom</name></bean>

<account><address>china</address><birthday><birthday>2010-11-22</birthday></birthday>

<email>[e-mail]</email><id>2</id><name>tom</name></account>

</list-bean>

jack#1#北京#2010-11-22#email

tom#2#china#2010-11-22#[e-mail]

2#tom#[e-mail]#china#2010-11-22

转换后的XML和Bean的注解的描述是一样的吧。

2、 对Map集合进行解组、编组

/**

* <b>function:</b>Map需要自己实现，可以构造一个简单的Map对象实现

* http://metro.1045641.n5.nabble.com/Does-JAXB-2-0-support-Map-td1058084.html

* @author hoojo

* @createDate 2010-12-1 上午10:23:26

*/

@Test

public void testMap2XML() {

MapBean mapBean = new MapBean();

HashMap<String, AccountBean> map = new HashMap<String, AccountBean>();

map.put("NO1", bean);

bean = new AccountBean();

bean.setAddress("china");

bean.setEmail("[e-mail]");

bean.setId(2);

bean.setName("tom");

Birthday day = new Birthday("2010-11-22");

bean.setBirthday(day);

map.put("NO2", bean);

mapBean.setMap(map);

try {

context = JAXBContext.newInstance(MapBean.class);

//下面代码演示将对象转变为xml

Marshaller mar = context.createMarshaller();

writer = new StringWriter();

mar.marshal(mapBean, writer);

fail(writer);

//下面代码演示将上面生成的xml转换为对象

reader = new StringReader(writer.toString());

Unmarshaller unmar = context.createUnmarshaller();

mapBean = (MapBean)unmar.unmarshal(reader);

fail(mapBean.getMap());

} catch (JAXBException e) {

e.printStackTrace();

}

}

下面看看MapBean的代码

package com.hoo.entity;

import java.util.HashMap;

import javax.xml.bind.annotation.XmlRootElement;

import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

import com.hoo.util.MapAdapter;

@XmlRootElement

public class MapBean {

private HashMap<String, AccountBean> map;

@XmlJavaTypeAdapter(MapAdapter.class)

public HashMap<String, AccountBean> getMap() {

return map;

}

public void setMap(HashMap<String, AccountBean> map) {

this.map = map;

}

}

上面的map集合的getter方法有一个XmlJavaTypeAdapter，需要传递一个Adapter的类型。

下面看看MyAdapter的代码

package com.hoo.util;

import java.util.HashMap;

import java.util.Map;

import javax.xml.bind.annotation.adapters.XmlAdapter;

import com.hoo.entity.AccountBean;

/**

* <b>function:</b>AccountBean 编组、解组的XmlAdapter

* @author hoojo

* @createDate 2011-4-25 下午05:03:18

* @file MyAdetper.java

* @package com.hoo.util

* @project WebHttpUtils

* @blog http://blog.csdn.net/IBM_hoojo

* @email [e-mail]

* @version 1.0

*/

public class MapAdapter extends XmlAdapter<MapElements[], Map<String, AccountBean>> {

public MapElements[] marshal(Map<String, AccountBean> arg0) throws Exception {

MapElements[] mapElements = new MapElements[arg0.size()];

int i = 0;

for (Map.Entry<String, AccountBean> entry : arg0.entrySet())

mapElements[i++] = new MapElements(entry.getKey(), entry.getValue());

return mapElements;

}

public Map<String, AccountBean> unmarshal(MapElements[] arg0) throws Exception {

Map<String, AccountBean> r = new HashMap<String, AccountBean>();

for (MapElements mapelement : arg0)

r.put(mapelement.key, mapelement.value);

return r;

}

}

MapElements

package com.hoo.util;

import javax.xml.bind.annotation.XmlElement;

import com.hoo.entity.AccountBean;

/**

* <b>function:</b> MapElements

* @author hoojo

* @createDate 2011-4-25 下午05:04:04

* @file MyElements.java

* @package com.hoo.util

* @project WebHttpUtils

* @blog http://blog.csdn.net/IBM_hoojo

* @email [e-mail]

* @version 1.0

*/

public class MapElements {

@XmlElement

public String key;

@XmlElement

public AccountBean value;

@SuppressWarnings("unused")

private MapElements() {

} // Required by JAXB

public MapElements(String key, AccountBean value) {

this.key = key;

this.value = value;

}

}

运行结果如下：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><mapBean><map><item><key>NO2</key><value number="2"><address>china</address>

<birthday><birthday>2010-11-22</birthday></birthday><email>[e-mail]</email><name>tom</name></value></item>

<item><key>NO1</key><value number="1"><address>北京</address><birthday><birthday>2010-11-22</birthday></birthday>

<email>email</email><name>jack</name></value></item></map></mapBean>

{NO2=tom#2#china#2010-11-22#[e-mail], NO1=jack#1#北京#2010-11-22#email}