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mysql事务

aspirin — Mon, 18 Jun 2007 07:03:00 GMT

�q�两天装了ubuntu�pȝ��Q�然后把整个开发环境都装到上面�?�?br />但发��C��个很奇怪的问题�Q�hibernate的事务无法会滚，�q�个问题困扰我好几天�Q�今天终于解决了�Q�原来mysql有配�|�有问题。mysql��d��?�U�存储方式，MyISAM 是默认存储方式，但是不支持事务，所以导致了我的问题�Q�只要把默认讄��?code class="literal">default-storage-engine=innodb��可以了�Q�当然也可以在每个table创徏的时候指定�?br />希望对碰到此�c�问题的朋友有所帮助�?br />

aspirin 2007-06-18 15:03 发表评论

aspirin — Fri, 19 May 2006 04:49:00 GMT

    Quartz作�ؓ一个开源的作业调度框架�Q�已�l�广泛应用于j2ee中。因为项目需要一个�Q务管理模块，所以选择了Quartz�q�个强大的框�Ӟ��q�对其进�? 了扩展以适应��目的要求。首先介�l�一下我们的�pȝ��构架�Q�采用webwork�Q�spring�Q�hibernate整合架构�Q�我的�Q务是无缝的把Quartz 加入到系�l�，提供一个界面，提供一些操作，使最�l�用戯��够自己定义在什么时间对什么东西做哪些事情�Q�“哪些事情”是预先定义的，提供�l�客户选择�Q�这是客�? 需求，�pȝ��地要求是能够�Ҏ��的扩展，对增加一个新的�Q务定义提供一些简单的接口。这里不对Quartz作介�l�了�Q�想了解的�h参考官方网站：http: //www.opensymphony.com/quartz/�Q�由于涉及的东西比较多，有些�l�节��带�q�了�Q�我��大致的介绍一下��M��的设计�?br />     作业调度框架�Q�主要要解决的问题是在某个时间对某些对象作某些动作�?br />     对于某个旉��Q�Quarta提供一个字�W�表辑ּ�来表�C�，�q�方面要做的是提供一个方便的界面�Q�直观的对其�q�行讄��Q�不能让最�l�客��L��那些对客��h��意义的字�W? 丌Ӏ�这个工作需要解析那些字�W�，做�v来还是有�Ҏ��思的�Q�也是比较麻烦的�Q�有兴趣的话可以自己去试试�?br />     对于某些对象作和某些动作�Q�Quartz都交�l�程序员自己��d��义，它提供一个Job接口,�Ҏ��们来说增加�Q务是比较��单的一件事�?既然Quartz提供 �q�么��单的接口,我�ؓ什么还要对其进行扩展呢?�q�就要来�?某些对象"�?在一般的�pȝ��?某个动作"所操纵的对象是固定�?比如定期删除日至,定期��? 库存�{?�׃��pȝ��地特�D��?我们"某个动作"对哪些对象是不确定的,"哪些对象"由我提供一个界�?由最�l�客户去军_��对一个或多个对象�q�行操作.
    �q�样��引入了一个范围的概念,"某个动作"是作用在一定范围内�?�q�个范围��׃��仅仅是哪些对象了,也可能是旉��范围,比如删除几天前的日志信息.到这里对 ��d��的定义有所改变�?一个�Q务包括一些范围也可以说是条�g,�q�个条�g不包括触发点�q�个条�g),一个动�?所以系�l�中定义了一个IRange接口,范围�? 表示都保存在一个XML字符�?XML字符串的�l�构和怎么解析都交�l�具体的子对�?�q�样��q��了子�cȝ��灉|��?
public interface IRange {
    public Map saveToMap(String strMap);//保存范围参数
    public List getResult(Map map);//解析范围参数,�q�返回操作对象线�E�列�?br />     public List getViewInfo();取得��面表示方式,�l�合了webwork
}
一个�Q务对应一个IRange的子�c?IRange的子�c�d��d��的各�U�参数范�?动作�q�行了实�?接着�q�加入一个IRangeManager接口,
public interface IRangeManager {
    public void saveDataMap(Long jobId, String strMap)throws SchedulerException;//保存范围参数
    public List getObjects(Map map);//取得对象列表,其中包括了对参数的解�?br />     public List getViews(Map map);
}
    实现的功能是对范围进行管�?包括对Quartz的操�?主要一些保存数据库�{�的操作,�q�样对于增加一个新的Range子类��可以不用知道Quartz�?
    �q�样因�ؓ很多东西都是可配�|�的,增加了灵�z�L�?对以后�Q务的��d��定义了一些接�?考虑��C��扩展�?在设计这个模块的时�?�ȝ��思�\是把那些不变的东襉K��装��h��,把能变得东西都交�l�具体的��d��?
上面我只是大致讲了一�?�׃��水��^有限,可能讲的不是清楚,比较�?我没有提供具体的例子,只是提供了一个思�\,希望对大家有所帮助,或者你�q�有更好的设�?请与我联�p?

aspirin 2006-05-19 12:49 发表评论

Quartz与Hibernate在数据库的连接方面的�l�合

aspirin — Fri, 19 May 2006 04:47:00 GMT

    首先介绍一下我们的�pȝ��构架�Q�采用webwork�Q�spring�Q�hibernate整合架构,现在引入Quartz框架,Quartz�? hibernate各自拥有的自己数据库配置和连接池的配�|?现在的�Q务是把两者用同一套配�|?
先谈谈Quartz,我用的版本是1.5.1,后面的版本我没去看了,没时�?接下来说的都以这个版本�ؓ�?Quartz虽然在提供一�? ConnectionProvider接口,提供�l�程序扩�?但是看它的StdSchedulerFactory实现�c?要对它进行扩展还是一件比较麻�? 一件事�?所以我��q��接修改了StdSchedulerFactory�c?以达到的我的需�?
接下来的问题是既然要�l�合,那么让Quartz来提供连接池配置呢还是有Hibernate提供.研究了两者的�q�接池方面的源代�?发现 Hibernate的连接池设计�q�远好于Quartz,Quartz目前只提供一个连接池提供�c�PoolingConnectionProvider,�? 且��用的�q�接池是dbcp,�q�个�q�接池听说问题多�?相反hibernate提供了更加灵�zȝ��配置,所以连接池由Hibernate提供.
    首先实现一个Quartz中ConnectionProvider子类HibernateConnectionProvider
public class HibernateConnectionProvider implements ConnectionProvider {
    private Connection con = null;
    protected static ThreadLocal hibernateHolder = new ThreadLocal();
    public Connection getConnection() throws SQLException {
        con = null;
        SessionFactoryImpl sessionFactory = null;
        sessionFactory = (SessionFactoryImpl) Global.getSessionFacotry();
        con = sessionFactory.getConnectionProvider().getConnection();
    return con;
}
public void shutdown() throws SQLException {
    // FIXME Auto-generated method stub
}
}
,然后修改StdSchedulerFactory,在不破坏其本来的逻辑和可配置性下�q�行了相应的修改.修改的是private Scheduler instantiate() throws SchedulerException�Ҏ��,扑ֈ�//Set up any DataSources�D�进行修�?代码如下:
String[] dsNames = cfg.getPropertyGroups(PROP_DATASOURCE_PREFIX);
        for (int i = 0; i < dsNames.length; i++) {
            PropertiesParser pp = new PropertiesParser(cfg.getPropertyGroup(
                    PROP_DATASOURCE_PREFIX + "." + dsNames[i], true));

            String dsDriver = pp
                    .getStringProperty(PROP_DATASOURCE_DRIVER, null);
            String dsURL = pp.getStringProperty(PROP_DATASOURCE_URL, null);
            boolean dsAlwaysLookup = pp.getBooleanProperty(
                    PROP_DATASOURCE_JNDI_ALWAYS_LOOKUP, false);
            String dsUser = pp.getStringProperty(PROP_DATASOURCE_USER, "");
            String dsPass = pp.getStringProperty(PROP_DATASOURCE_PASSWORD, "");
            int dsCnt = pp.getIntProperty(PROP_DATASOURCE_MAX_CONNECTIONS, 3);
            String providerClass = pp.getStringProperty(
                    PROP_DATASOURCE_PROVIDER_CLASS, null);
            String dsJndi = pp
                    .getStringProperty(PROP_DATASOURCE_JNDI_URL, null);
            String dsJndiInitial = pp.getStringProperty(
                    PROP_DATASOURCE_JNDI_INITIAL, null);
            String dsJndiProvider = pp.getStringProperty(
                    PROP_DATASOURCE_JNDI_PROVDER, null);
            String dsJndiPrincipal = pp.getStringProperty(
                    PROP_DATASOURCE_JNDI_PRINCIPAL, null);
            String dsJndiCredentials = pp.getStringProperty(
                    PROP_DATASOURCE_JNDI_CREDENTIALS, null);
            String dsValidation = pp.getStringProperty(
                    PROP_DATASOURCE_VALIDATION_QUERY, null);
            if (providerClass == null
                    || providerClass.equals("")
                    || providerClass
                            .equals("org.quartz.utils.PoolingConnectionProvider")) {
                if (dsDriver == null) {
                    initException = new SchedulerException(
                            "Driver not specified for DataSource: "
                                    + dsNames[i]);
                    throw initException;
                }
                if (dsURL == null) {
                    initException = new SchedulerException(
                            "DB URL not specified for DataSource: "
                                    + dsNames[i]);
                    throw initException;
                }
                try {
                    PoolingConnectionProvider cp = new PoolingConnectionProvider(
                            dsDriver, dsURL, dsUser, dsPass, dsCnt,
                            dsValidation);
                    dbMgr = DBConnectionManager.getInstance();
                    dbMgr.addConnectionProvider(dsNames[i], cp);
                } catch (SQLException sqle) {
                    initException = new SchedulerException(
                            "Could not initialize DataSource: " + dsNames[i],
                            sqle);
                    throw initException;
                }
            } else if (providerClass
                    .equals("org.quartz.utils.JNDIConnectionProvider")) {
                Properties props = null;
                if (null != dsJndiInitial || null != dsJndiProvider
                        || null != dsJndiPrincipal || null != dsJndiCredentials) {
                    props = new Properties();
                    if (dsJndiInitial != null)
                        props.put(PROP_DATASOURCE_JNDI_INITIAL, dsJndiInitial);
                    if (dsJndiProvider != null)
                        props.put(PROP_DATASOURCE_JNDI_PROVDER, dsJndiProvider);
                    if (dsJndiPrincipal != null)
                        props.put(PROP_DATASOURCE_JNDI_PRINCIPAL,
                                dsJndiPrincipal);
                    if (dsJndiCredentials != null)
                        props.put(PROP_DATASOURCE_JNDI_CREDENTIALS,
                                dsJndiCredentials);
                }
                JNDIConnectionProvider cp = new JNDIConnectionProvider(dsJndi,
                        props, dsAlwaysLookup);
                dbMgr = DBConnectionManager.getInstance();
                dbMgr.addConnectionProvider(dsNames[i], cp);
            } else if (providerClass
                    .equals("org.quartz.utils.HibernateConnectionProvider")) {
                HibernateConnectionProvider cp = new HibernateConnectionProvider();
                dbMgr = DBConnectionManager.getInstance();
                dbMgr.addConnectionProvider(dsNames[i], cp);
            } else {
                initException = new SchedulerException(
                        "Provider_Class not Supported: " + providerClass);
                throw initException;
            }

        }
    最后就是修攚w��|�文件quartz.properties,加入
#org.quartz.dataSource.myDS.provider_class = org.quartz.utils.JNDIConnectionProvider
#org.quartz.dataSource.myDS.provider_class = org.quartz.utils.PoolingConnectionProvider
org.quartz.dataSource.myDS.provider_class = org.quartz.utils.HibernateConnectionProvider�?的供参�?
    �l�过��试,需要对hibernate�q�接池的一些参数进行微�?�q�样��完成了Quartz与Hibernate在数据库的连接方面的�l�合,如果有更好的解决�Ҏ��,误��p�L��.

aspirin 2006-05-19 12:47 发表评论

aspirin — Tue, 28 Mar 2006 14:26:00 GMT

   最�q�同事在��到一个棘手的问题,用了一天还是调试不出到底哪里出错了,郁闷中时老大�q�来��p��了一个很好的解决�Ҏ��,用日志跟�t?没过半小�?问题��找��C��,定位很准��?�q�让我看到日志的重要性了.
       一开始我�q�是写一些log�?但是那时候觉得好像没什么必�?后来��׃��来没有写�q?因�ؓ我想不出他的好处.现在在知道日志真正的作用,而且也是一个很强大的工�?�q�x��在写代码的时�?�׃��几秒钟写个log,也许会觉得很�?但是我觉得还是值得�?
       �q�也是一个习惯的问题,好的�E�序员之所以是个好的程序员是因��Z��有好的习�?�q�些好的习惯带来的好处也是很多的.写日志只是其中一个好习惯,我也要慢慢留意一些好的习�?慢慢�ȝ��.

aspirin 2006-03-28 22:26 发表评论

aspirin — Tue, 28 Mar 2006 14:24:00 GMT

       Quartz作�ؓ一个开源的作业调度框架�Q�已�l�广泛应用于j2ee中，在这里提供一些资料以供参考：
       首先是官方网站：http://www.opensymphony.com/quartz/ �q�里可以下蝲源代码，�q�有论坛�Q�jira�{�最原始的资料。 �?
       一个写的不错的介绍Quartz的中文文章：详细讲解Quartz如何从入门到�_�N�?/b>�Q�英文不好的可以参考这个。这��文章大致的讲了Quartz的框�Ӟ��很多�l�节�q�没有涉及，�q�也难怪，一��文章不可能都写上去的�?br />        如果你想�l�箋了解Quartz�Q�官方网站有面向开发�h员的文档�Q�但是放在不��L��的角落，我以前闲逛时扑ֈ��Q�现在一时找不到�Q�什么时候什么找��C��在加上去�Q�我�? 另外地方扑ֈ�其中的几章，�q�两章是其中最重要的两章，可以作�ؓ参考，http://javaforge.com/proj/doc.do?doc_id= 1740
       如果你还要��l�深入研�IӞ��p��自己到cvs��M��载最新源码，自己研读了，��大家成功，我会接下��d��一些自�׃��中学到的东西�?img src ="http://m.tkk7.com/aspirin/aggbug/37902.html" width = "1" height = "1" />

aspirin 2006-03-28 22:24 发表评论

aspirin — Tue, 28 Mar 2006 14:22:00 GMT

在完全刚装好的fc4上用jdbc�q�行数据库操作出��C��一下错误：
java.net.SocketException: Invalid argument or cannot assign requested address
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:305)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:171)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:158)
at java.net.Socket.connect(Socket.java:452)
at java.net.Socket.connect(Socket.java:402)
at java.net.Socket.(Socket.java:309)
at java.net.Socket.(Socket.java:124)
�q�是IP地址的问�?在FC4中默认的是IPv6 socket,JDK1.4支持的应该是IPv4,具体原因可以查看SUN公司�l�出的解�?
解决办法是在�q�行JAVA�E�序时加�?-Djava.net.preferIPv4Stack=true �?

java -Djava.net.preferIPv4Stack=true application.

但是�q�个在每�ơ都要加上这句话�Q�另有解��x��法是修改 /etc/modprobe.conf 文�g,增加

alias net-pf-10 off
alias ipv6 off

�q�样��׃��用增加参�?"-Djava.net.preferIPv4Stack=true ",重�v卛_��.

但是既要ipv6又能解决�q�个问题的方法还没找到。希望高人指�?/p>

aspirin 2006-03-28 22:22 发表评论

junit with ant(转蝲)

aspirin — Tue, 28 Mar 2006 14:18:00 GMT

附：最�q�在弄cc�Q�也找了一些ant资料�Q�顺便�{载记录一�?/font>

转自http://ant.apache.org/manual/OptionalTasks/junit.html

JUnit

Description

This task runs tests from the JUnit testing framework. The latest version of the framework can be found at http://www.junit.org. This task has been tested with JUnit 3.0 up to JUnit 3.8.1; it won't work with versions prior to JUnit 3.0.

Note: This task depends on external libraries not included in the Ant distribution. See Library Dependencies for more information.

Note: You must have junit.jar and the class files for the task in the same classpath. You can do one of:

Put both junit.jar and the optional tasks jar file in ANT_HOME/lib.

Do not put either in ANT_HOME/lib, and instead include their locations in your CLASSPATH environment variable.

Do neither of the above, and instead, specify their locations using a element in the build file. See the FAQ for details.

Tests are defined by nested test or batchtest tags (see nested elements).

Parameters

Attribute Description Required

printsummary Print one-line statistics for each testcase. Can take the values on, off, and withOutAndErr. withOutAndErr is the same as on but also includes the output of the test as written to System.out and System.err. No; default is off.

fork Run the tests in a separate VM. No; default is off.

forkmode Controls how many Java Virtual Machines get created if you want to fork some tests. Possible values are "perTest" (the default), "perBatch" and "once". "once" creates only a single Java VM for all tests while "perTest" creates a new VM for each TestCase class. "perBatch" creates a VM for each nested and one collecting all nested s. Note that only tests with the same settings of filtertrace, haltonerror, haltonfailure, errorproperty and failureproperty can share a VM, so even if you set forkmode to "once", Ant may have to create more than a single Java VM. This attribute is ignored for tests that don't get forked into a new Java VM. since Ant 1.6.2 No; default is perTest.

haltonerror Stop the build process if an error occurs during the test run. No; default is off.

errorproperty The name of a property to set in the event of an error. No

haltonfailure Stop the build process if a test fails (errors are considered failures as well). No; default is off.

failureproperty The name of a property to set in the event of a failure (errors are considered failures as well). No.

filtertrace Filter out Junit and Ant stack frames from error and failure stack traces. No; default is on.

timeout Cancel the individual tests if they don't finish in the given time (measured in milliseconds). Ignored if fork is disabled. No

maxmemory Maximum amount of memory to allocate to the forked VM. Ignored if fork is disabled. No

jvm The command used to invoke the Java Virtual Machine, default is 'java'. The command is resolved by java.lang.Runtime.exec(). Ignored if fork is disabled. No; default is java.

dir The directory in which to invoke the VM. Ignored if fork is disabled. No

newenvironment Do not propagate the old environment when new environment variables are specified. Ignored if fork is disabled. No; default is false.

includeantruntime Implicitly add the Ant classes required to run the tests and JUnit to the classpath in forked mode. Note: Please read the Ant FAQ if you want to set this to false and use the XML formatter at the same time. No; default is true.

showoutput Send any output generated by tests to Ant's logging system as well as to the formatters. By default only the formatters receive the output. No

tempdir Where Ant should place temporary files. Since Ant 1.6. No; default is the project's base directory.

reloading Whether or not a new classloader should be instantiated for each test case.
Ignore if fork is set to true. Since Ant 1.6. No; default is true.

By using the errorproperty and failureproperty attributes, it is possible to perform setup work (such as starting an external server), execute the test, clean up, and still fail the build in the event of a failure.

The filtertrace attribute condenses error and failure stack traces before reporting them. It works with both the plain and XML formatters. It filters out any lines that begin with the following string patterns:

"junit.framework.TestCase"
"junit.framework.TestResult"
"junit.framework.TestSuite"
"junit.framework.Assert."
"junit.swingui.TestRunner"
"junit.awtui.TestRunner"
"junit.textui.TestRunner"
"java.lang.reflect.Method.invoke("
"sun.reflect."
"org.apache.tools.ant."

Nested Elements

The task supports a nested element that represents a PATH like structure.

jvmarg

If fork is enabled, additional parameters may be passed to the new VM via nested elements. For example:

...

would run the test in a VM without JIT.

allows all attributes described in Command-line Arguments.

sysproperty

Use nested elements to specify system properties required by the class. These properties will be made available to the VM during the execution of the test (either ANT's VM or the forked VM, if fork is enabled). The attributes for this element are the same as for environment variables.

...

would run the test in ANT's VM and make the basedir property available to the test.

syspropertyset

You can specify a set of properties to be used as system properties with syspropertysets.

since Ant 1.6.

env

It is possible to specify environment variables to pass to the forked VM via nested elements. For a description of the element's attributes, see the description in the exec task.

Settings will be ignored if fork is disabled.

bootclasspath

The location of bootstrap class files can be specified using this PATH like structure - will be ignored if fork is not true or the target VM doesn't support it (i.e. Java 1.1).

since Ant 1.6.

permissions

Security permissions can be revoked and granted during the execution of the class via a nested permissions element. For more information please see permissions

Settings will be ignored if fork is enabled.

since Ant 1.6.

assertions

You can control enablement of Java 1.4 assertions with an subelement.

Assertion statements are currently ignored in non-forked mode.

since Ant 1.6.

formatter

The results of the tests can be printed in different formats. Output will always be sent to a file, unless you set the usefile attribute to false. The name of the file is determined by the name of the test and can be set by the outfile attribute of .

There are three predefined formatters - one prints the test results in XML format, the other emits plain text. The formatter named brief will only print detailed information for testcases that failed, while plain gives a little statistics line for all test cases. Custom formatters that need to implement org.apache.tools.ant.taskdefs.optional.junit.JUnitResultFormatter can be specified.

If you use the XML formatter, it may not include the same output that your tests have written as some characters are illegal in XML documents and will be dropped.

Note: Please read the Ant FAQ if you want to set the fork attribute to true, the includeAntRuntime attribute to false and use the XML formatter at the same time.

Attribute Description Required

type Use a predefined formatter (either xml, plain, or brief). Exactly one of these.

classname Name of a custom formatter class.

extension Extension to append to the output filename. Yes, if classname has been used.

usefile Boolean that determines whether output should be sent to a file. No; default is true.

if Only use formatter if the named property is set. No; default is true.

unless Only use formatter if the named property is not set. No; default is true.

test

Defines a single test class.

Attribute Description Required

name Name of the test class. Yes

fork Run the tests in a separate VM. Overrides value set in . No

haltonerror Stop the build process if an error occurs during the test run. Overrides value set in . No

errorproperty The name of a property to set in the event of an error. Overrides value set in . No

haltonfailure Stop the build process if a test fails (errors are considered failures as well). Overrides value set in . No

failureproperty The name of a property to set in the event of a failure (errors are considered failures as well). Overrides value set in . No

filtertrace Filter out Junit and Ant stack frames from error and failure stack traces. Overrides value set in . No; default is on.

todir Directory to write the reports to. No; default is the current directory.

outfile Base name of the test result. The full filename is determined by this attribute and the extension of formatter. No; default is TEST-name, where name is the name of the test specified in the name attribute.

if Only run test if the named property is set. No

unless Only run test if the named property is not set. No

Tests can define their own formatters via nested elements.

batchtest

Define a number of tests based on pattern matching.

batchtest collects the included files from any number of nested s. It then generates a test class name for each file that ends in .java or .class.

Attribute Description Required

fork Run the tests in a separate VM. Overrides value set in . No

haltonerror Stop the build process if an error occurs during the test run. Overrides value set in . No

errorproperty The name of a property to set in the event of an error. Overrides value set in . No

haltonfailure Stop the build process if a test fails (errors are considered failures as well). Overrides value set in . No

failureproperty The name of a property to set in the event of a failure (errors are considered failures as well). Overrides value set in No

filtertrace Filter out Junit and Ant stack frames from error and failure stack traces. Overrides value set in . No; default is on.

todir Directory to write the reports to. No; default is the current directory.

if Only run tests if the named property is set. No

unless Only run tests if the named property is not set. No

Batchtests can define their own formatters via nested elements.

Examples

Runs the test defined in my.test.TestCase in the same VM. No output will be generated unless the test fails.

Runs the test defined in my.test.TestCase in a separate VM. At the end of the test, a one-line summary will be printed. A detailed report of the test can be found in TEST-my.test.TestCase.txt. The build process will be stopped if the test fails.

Runs my.test.TestCase in the same VM, ignoring the given CLASSPATH; only a warning is printed if this test fails. In addition to the plain text test results, for this test a XML result will be output to result.xml. Then, for each matching file in the directory defined for ${src.tests} a test is run in a separate VM. If a test fails, the build process is aborted. Results are collected in files named TEST-name.txt and written to ${reports.tests}.

aspirin 2006-03-28 22:18 发表评论

Attribute	Description	Required
printsummary	Print one-line statistics for each testcase. Can take the values `on`, `off`, and `withOutAndErr`. `withOutAndErr` is the same as `on` but also includes the output of the test as written to `System.out` and `System.err`.	No; default is `off`.
fork	Run the tests in a separate VM.	No; default is `off`.
forkmode	Controls how many Java Virtual Machines get created if you want to fork some tests. Possible values are "perTest" (the default), "perBatch" and "once". "once" creates only a single Java VM for all tests while "perTest" creates a new VM for each TestCase class. "perBatch" creates a VM for each nested and one collecting all nested s. Note that only tests with the same settings of `filtertrace`, `haltonerror`, `haltonfailure`, `errorproperty` and `failureproperty` can share a VM, so even if you set `forkmode` to "once", Ant may have to create more than a single Java VM. This attribute is ignored for tests that don't get forked into a new Java VM. since Ant 1.6.2	No; default is `perTest`.
haltonerror	Stop the build process if an error occurs during the test run.	No; default is `off`.
errorproperty	The name of a property to set in the event of an error.	No
haltonfailure	Stop the build process if a test fails (errors are considered failures as well).	No; default is `off`.
failureproperty	The name of a property to set in the event of a failure (errors are considered failures as well).	No.
filtertrace	Filter out Junit and Ant stack frames from error and failure stack traces.	No; default is `on`.
timeout	Cancel the individual tests if they don't finish in the given time (measured in milliseconds). Ignored if `fork` is disabled.	No
maxmemory	Maximum amount of memory to allocate to the forked VM. Ignored if `fork` is disabled.	No
jvm	The command used to invoke the Java Virtual Machine, default is 'java'. The command is resolved by `java.lang.Runtime.exec()`. Ignored if `fork` is disabled.	No; default is `java`.
dir	The directory in which to invoke the VM. Ignored if `fork` is disabled.	No
newenvironment	Do not propagate the old environment when new environment variables are specified. Ignored if `fork` is disabled.	No; default is `false`.
includeantruntime	Implicitly add the Ant classes required to run the tests and JUnit to the classpath in forked mode. Note: Please read the Ant FAQ if you want to set this to `false` and use the XML formatter at the same time.	No; default is `true`.
showoutput	Send any output generated by tests to Ant's logging system as well as to the formatters. By default only the formatters receive the output.	No
tempdir	Where Ant should place temporary files. Since Ant 1.6.	No; default is the project's base directory.
reloading	Whether or not a new classloader should be instantiated for each test case. Ignore if `fork` is set to true. Since Ant 1.6.	No; default is `true`.