介绍完libvirt Java API的部署工作：
《Windows下Libvirt Java API使用教程(一)- 开发环境部署》
接下来我们就介绍一下接口的使用和代码样例。
libvirt的管理单位是单个主机，所以探测和监控接口所能获取的信息的最大范围也是主机。所以先从主机入手，验证libvirt接口。主机（libvirt所在管理节点）探测相关接口验证代码如下：
- @Before
- public void init() {
- System.setProperty("jna.library.path",
- "D:/Git-Repo/git/libvirt-java/libvirt-java/src/test/java/kubi/coder/");
- try {
- xenConn = new Connect("xen+tcp://10.4.55.203/");
- // system代表拥有系统权限/session是用户权限
- kvmConn = new Connect("qemu+tcp://10.4.54.10/system");
- } catch (LibvirtException e) {
- e.printStackTrace();
- }
- }
- /**
- * 主机信息探测接口验证，验证可以获取的主机属性和监控指标，分别考虑Xen环境和KVM环境
- *
- *
- * @author lihzh
- * @date 2012-5-15 下午1:28:00
- */
- @Test
- public void testDetectHost() {
- // KVM
- doDetectHost(kvmConn);
- // XEN
- doDetectHost(xenConn);
- }
- /**
- * 执行探测主机测试函数
- *
- * @param conn
- * @author lihzh
- * @date 2012-5-15 下午1:37:37
- */
- private void doDetectHost(Connect conn) {
- try {
- // Returns the free memory for the connection
- // System.out.println("FreeMemory: " + conn.getFreeMemory());// 不支持
- // Returns the system hostname on which the hypervisor is running.
- // (the result of the gethostname(2) system call)
- // If we are connected to a remote system,
- // then this returns the hostname of the remote system
- System.out.println("Host name: " + conn.getHostName());
- // Gets the name of the Hypervisor software used.
- System.out.println("Type: " + conn.getType());
- // Gets the version level of the Hypervisor running. This may work
- // only with hypervisor call, i.e. with priviledged access to the
- // hypervisor, not with a Read-Only connection. If the version can't
- // be extracted by lack of capacities returns 0.
- // Returns:
- // major * 1,000,000 + minor * 1,000 + release
- System.out.println(conn.getVersion());
- NodeInfo nodeInfo = conn.nodeInfo();
- System.out.println("the number of active CPUs: " + nodeInfo.cpus);
- System.out.println("number of core per socket: " + nodeInfo.cores);
- System.out.println("memory size in kilobytes: " + nodeInfo.memory);
- System.out.println("expected CPU frequency: " + nodeInfo.mhz);
- System.out.println("string indicating the CPU model: "
- + nodeInfo.model);
- System.out.println("the number of NUMA cell, 1 for uniform: "
- + nodeInfo.nodes);
- System.out.println("number of CPU socket per node: "
- + nodeInfo.sockets);
- System.out.println("number of threads per core: "
- + nodeInfo.threads);
- System.out
- .println("the total number of CPUs supported but not necessarily active in the host.: "
- + nodeInfo.maxCpus());
- // for (String interName : conn.listInterfaces()) {
- // System.out.println(interName);
- // } 不支持
- // Provides the list of names of defined interfaces on this host
- // for (String interName : conn.listDefinedInterfaces()) {
- // System.out.println(interName);
- // } // 不支持
- // Lists the active networks.
- for (String networkName : conn.listNetworks()) {
- System.out.println("Network name: " + networkName);
- }
- // Lists the names of the network filters
- for (String networkFilterName : conn.listNetworkFilters()) {
- System.out.println("Network filter name: " + networkFilterName);
- }
- System.out.println(conn.getCapabilities());
- } catch (LibvirtException e) {
- e.printStackTrace();
- }
- }
分别在KVM和XEN环境下测试了libvirt接口，测试结果如下：
|
Host name: s5410
Type: QEMU
9001
the number of active CPUs: 64
number of core per socket: 8
memory size in kilobytes: 49444896
expected CPU frequency: 2131
string indicating the CPU model: x86_64
the number of NUMA cell, 1 for uniform: 1
number of CPU socket per node: 4
number of threads per core: 2
the total number of CPUs supported but not necessarily active in the host.: 64
Network name: hello
Network name: default
Network filter name: no-other-l2-traffic
Network filter name: allow-dhcp
...
...
...
Host name: s55203
Type: Xen
3001000
the number of active CPUs: 32
number of core per socket: 8
memory size in kilobytes: 50276352
expected CPU frequency: 1995
string indicating the CPU model: x86_64
the number of NUMA cell, 1 for uniform: 1
number of CPU socket per node: 2
number of threads per core: 2
the total number of CPUs supported but not necessarily active in the host.: 32
Network name: default
Network filter name: allow-dhcp-server
Network filter name: qemu-announce-self-rarp
...
...
|
说明：
注1：标注不支持的，是在当前环境当前libvirt版本下，运行会报错的接口。
| unsupported in sys interface |
注2：名词解释
| hvm: numa： |
说实话，这么多信息中，笔者关注的不多，有很多甚至说不出其代表的含义，笔者关注只是cpu的个数，核心数，内存总量等直观信息。有就足以。
看完了主机，再看看虚拟机。一个虚拟化环境中的核心资源自然是虚拟机，所以其属性和信息也自然多很多，上测试代码：
- /**
- * 测试探测虚拟机接口
- *
- * @author lihzh
- * @date 2012-5-16 上午11:14:20
- */
- @Test
- public void testDetectDomains() {
- // KVM
- doDetectDomains(kvmConn);
- // XEN
- doDetectDomains(xenConn);
- }
- /**
- * 执行探测虚拟机测试函数
- *
- * @param conn
- * @author lihzh
- * @date 2012-5-16 上午11:15:27
- */
- private void doDetectDomains(Connect conn) {
- try {
- // Lists the active domains.(列出所有处于启动(激活)状态的虚拟机的id)
- for (int activeDomId : conn.listDomains()) {
- System.out.println("Active vm id: " + activeDomId);
- // 根据Id，探测各个虚拟机的详细信息
- Domain domain = conn.domainLookupByID(activeDomId);
- // Gets the hypervisor ID number for the domain
- System.out.println("Domain id: " + domain.getID());
- // Gets the public name for this domain
- System.out.println("Domain name: " + domain.getName());
- // Gets the type of domain operation system.
- System.out.println("Domain os type: " + domain.getOSType());
- // Gets the UUID for this domain as string.
- System.out.println("Domain uuid: " + domain.getUUIDString());
- // Retrieve the maximum amount of physical memory allocated to a
- // domain.
- System.out.println("Domain max memory: "
- + domain.getMaxMemory());
- // Provides the maximum number of virtual CPUs supported for the
- // guest VM. If the guest is inactive, this is basically the
- // same as virConnectGetMaxVcpus. If the guest is running this
- // will reflect the maximum number of virtual CPUs the guest was
- // booted with.
- System.out.println("Domain max vcpu: " + domain.getMaxVcpus());
- // Provides an XML description of the domain. The description
- // may be
- // reused later to relaunch the domain with createLinux().
- System.out.println("Domain xml description: "
- + domain.getXMLDesc(0));
- System.out.println("Domain maxMen allowed: "
- + domain.getInfo().maxMem);
- System.out.println("Domain memory: " + domain.getInfo().memory);
- // domain.getJobInfo()
- // 不支持
- System.out.println("Domain state: " + domain.getInfo().state);
- // Provides a boolean value indicating whether the network is
- // configured to be automatically started when the host machine
- // boots.
- System.out.println("Domain network autostart: "
- + domain.getAutostart());
- // Extracts information about virtual CPUs of this domain
- for (VcpuInfo vcpuInfo : domain.getVcpusInfo()) {
- System.out.println("cpu: " + vcpuInfo.cpu);
- System.out.println("cpu time: " + vcpuInfo.cpuTime);
- System.out.println("cpu number: " + vcpuInfo.number);
- System.out.println("cpu state: " + vcpuInfo.state);
- }
- // 如果是KVM环境
- if (conn.getURI().startsWith("qemu")) {
- // This function returns block device (disk) stats for block
- // devices attached to the domain
- DomainBlockInfo blockInfo = domain
- .blockInfo("/opt/awcloud/instance/admin/"
- + domain.getName() + "/disk");
- System.out.println("Disk Capacity: "
- + blockInfo.getCapacity());
- System.out.println("Disk allocation: "
- + blockInfo.getAllocation());
- System.out.println("Disk physical: "
- + blockInfo.getPhysical());
- DomainBlockStats blockStats = domain.blockStats("vda");
- // 磁盘读取请求总数
- System.out.println("read request num: " + blockStats.rd_req);
- // 磁盘读取总bytes数
- System.out.println("read request num: " + blockStats.rd_bytes);
- // 磁盘写入请求总数
- System.out.println("read request num: " + blockStats.wr_req);
- // 磁盘写入总bytes数
- System.out.println("read request num: " + blockStats.wr_bytes);
- }
- }
- // 列出所有停止态的虚拟机
- for (String name : conn.listDefinedDomains()) {
- System.out.println("Inactive domain name: " + name);
- }
- } catch (LibvirtException e) {
- e.printStackTrace();
- }
- }
循环较多，摘取部分结果如下：
i-546A099E e608560a-2c03-8e48-2e60-d0d01693f530 131072 131072 1 hvm /usr/lib/xen/boot/hvmloader destroy restart restart /usr/lib64/xen/bin/qemu-dm
Domain maxMen allowed: 147456Domain memory: 139140Domain state: VIR_DOMAIN_BLOCKEDDomain network autostart: falsecpu: 31cpu time: 2225977676675cpu number: 0cpu state: VIR_VCPU_BLOCKEDDomain network autostart: falseInactive domain name: i-46A70811Inactive domain name: i-38C20705Inactive domain name: i-498E09B2Inactive domain name: nullInactive domain name: nullInactive domain name: nullInactive domain name: nullInactive domain name: null
结果分析：
结果中基本包含了一个虚拟机组成的全部元素信息。如果你想做一个监控系统，你可以发现这里有：
虚拟机的名字
虚拟机的Id
虚拟机的内存大小
虚拟CPU个数
虚拟机磁盘文件信息，磁盘文件的大小。甚至包括log等信息。
虚拟磁盘读写速率。
虚拟机网络设备信息。Mac地址，设备类型等。
虚拟机网卡读写速率。
基本可以满足一个监控系统的需求。
说明一下上面的测试代码。libvirt Java API的入口基本都是通过Connect这个类，也就是首先建立与被管理主机之间的连接：
- Connect kvmConn = new Connect("qemu+tcp://10.4.54.10/system");
然后通过该连接获取信息：
- conn.listDomains()
一个接口的如果需要接受参数：
- conn.domainLookupByID(activeDomId)
肯定可以从其他的接口返回中找到答案：
- for (int activeDomId : conn.listDomains())
只是有的获取的直接，有可能需要解析xml格式的返回值来获取需要参数值。比如：disk的paht和interface的path。
最后再简单介绍一下管控接口：
- /**
- * 测试虚拟机的简单操作
- *
- * @author lihzh
- * @date 2012-5-16 下午3:35:43
- */
- @Test
- public void testControlVM() {
- try {
- Domain domain = kvmConn.domainLookupByID(8);
- System.out.println("Domain state: " + domain.getInfo().state);
- domain.suspend();
- System.out.println("Domain state: " + domain.getInfo().state);
- for (int i = 0; i < 5; i++) {
- System.out.println("wait for: " + (5 - i));
- Thread.sleep(1000);
- }
- System.out.println("Resume vm.");
- domain.resume();
- System.out.println("Domain state: " + domain.getInfo().state);
- } catch (LibvirtException e) {
- e.printStackTrace();
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
该用例主要测试了虚拟机的挂起和恢复操作。这类操作是比较简单的（因为无需参数）。一个复杂系统肯定需要包括虚拟机创建等操作。libvirt主要通过xml表述来创建资源，首先需要生成被创建虚拟机的完整描述，然后传递给创建的方法即可。描述的格式？呵呵，自然是上面测试结果给出的数据了。有兴趣的，大家可以自己尝试一下。libvirt的文档，还不完善，不过对于创建这样重要的功能，还是给出了说明。大家也可以下载官方的手册作为参考。
好了，相对于VMware、Xenserver等虚拟化平台的SDK，libvirt的Java API还是比较简单的，上手很快，结构很简单。当然，功能上可能还是有所欠缺，信息量上，没有其他的那么充足。基于XML的方式操作资源，减少了接口的个数，使调用更直接，但是对开发人员却增加了困难。不过仍不失为一个不错的虚拟机环境操作的API，尤其是针对KVM/XEN的环境来说，可谓不二的选择。