kvmlibvirt的使用：创建虚拟机与快照

1.创建域(虚拟机)：包括Volume和描述硬件配置的xml

//前端与节点建立连接
Connect conn=new Connect("qemu+ssh://root@192.168.69/system",false);
//根据xml描述创建新虚拟机并启动
SAXReader reader = new SAXReader();
Document docu =reader.read(new File("/domain.xml"));
String xmlDesc=docu.asXML();
Domain domain=conn.domainCreateXML(xmlDesc, 0);
domain.resume();

补：新建域可以直接加载镜像(.img)，但这样镜像只能被一个用户使用。为可以让镜像能被多个用户使用，可使用StorageVol来关联镜像，虚拟机加载该备份即可。

Connect con=new Connect("");
//根据存储池的名字获得StoragePool
StoragePool pool=con.storagePoolLookupByName("default");
SAXReader reader=new SAXReader();
Document docu=reader.read(new File("/volume.xml"));
StorageVol vol=pool.storageVolCreateXML(docu.asXML(), 0);

记录下vol的存储地址，赋值到域的配置文件中即可。

删除vol

StorageVol vol=pool.storageVolLookupByName(volName);
vol.delete(0);

补：StorageVol可以作为镜像的快照，大小很小，只记录了对镜像的修改。
2.迁移/销毁域

//前端与节点建立连接
Connect conn1=new Connect("qemu+ssh://root@192.168.82.70/system",false);
//根据域的uuid-unique id（在生成域时，libvirt自动分配唯一的uuid），返回域。
String uuid="";
Domain domain=conn1.domainLookupByUUIDString(uuid);
Connect conn2=new Connect("qemu+ssh://root@192.168.82.71/system",false);
/*
 * 把域从当前主机迁移到目的主机
 * Domain migrate(Connect dconn, long flags, String dname, String uri, long bandwidth)
 * dconn:目的主机
 * dname:可选，重命名域在目的机的名字
 * uri:可选，目的机ip
 * band迁移带宽，Mbps
 */
domain.migrate(conn2, 1, null, null, 5);
//销毁域
domain.destroy();

补：域的名字、id等信息都在xml配置描述里定义。对于xml文件的操作使用dom4j。

标准domain.xml

<?xml version="1.0" encoding="UTF-8"?>
<domain type='kvm'>
  <name>test</name>
  <memory>524288</memory>
  <currentMemory>524288</currentMemory>
  <vcpu>1</vcpu>
  <os>
    <type arch='x86_64' machine='pc-0.14'>hvm</type>
    <boot dev='hd'/>
    <bootmenu enable='no'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='localtime'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-kvm</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/test.img'/><!--运行的镜像-->
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </disk>
    <interface type='network'>
      <mac address='52:54:00:19:25:7b'/>
      <source network='default'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <input type='tablet' bus='usb'/>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='5910' autoport='no' listen='0.0.0.0'/>
    <sound model='ac97'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </sound>
    <video>
      <model type='cirrus' vram='9216' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </memballoon>
  </devices>
</domain>

标准volume.xml

<?xml version="1.0" encoding="UTF-8"?>
<volume>
  <name></name> 
  <key>/var/lib/libvirt/images/temp.ss</key> 
  <source>
  </source>
  <capacity>8589934592</capacity> 
  <allocation>139264</allocation>
  <target>
    <path>/var/lib/libvirt/images/temp.ss</path> <!--新卷的地址-->
    <format type='qcow2'/> 
    <permissions>
      <mode>0600</mode>
      <owner>0</owner>
      <group>0</group>
    </permissions>
  </target>
   <backingStore>
    <path>/var/lib/libvirt/images/WinXP.img</path><!--关联的镜像-->
    <format type='qcow2'/> 
    <permissions>
      <mode>0600</mode>
      <owner>107</owner>
      <group>107</group>
    </permissions>
  </backingStore>
</volume>

补：dom4j使用示例

SAXReader reader = new SAXReader();
Document docu =	reader.read(new File("/domain.xml"));
//更改元素的属性值
Element graphics=docu.getRootElement().element("devices").element("graphics");
Attribute attrPort=graphics.attribute("port");
attrPort.setText(getPort());
//更改元素值
Element nameEle=docu.getRootElement().element("name");
nameEle.setText("new name");
//以字符串形式返回xml
String docXmlText=docu.asXML();