Java-libvirt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
     * bandwidth: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

        <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

        <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();