使用SVN 1.6 之前版本 checkout出来的代码，在本地每个文件夹下都有个 .svn ，可利用这个命令来删除
Linux
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find . -name .svn -print0 | xargs -0 rm -r -f |
Windows(需要在批处理文件中执行）
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for /r . %%a in (.) do @if exist %%a\.svn rd /s /q %%a\.svn |
对于Git的目录也可以如此操作：
Linux
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find . -name .git -print0 | xargs -0 rm -r -f |
Windows(需要在批处理文件中执行）
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for /r . %%a in (.) do @if exist %%a\.git rd /s /q %%a\.git |
使用 WordPress 构筑的 Blog 最近总是会报告 “建立数据库连接时出错” ，查看 Apache 的日志得到如下信息
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$ sudo vim /var/log/apache2/error.log |
在日志的最后得到类似如下的内容
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[Mon Jan 06 16:30:06 2014] [error] [client 5.10.83.83] WordPress SELECT * FROM wp_posts WHERE (post_type = 'page' AND post_status = 'publish') ORDER BY menu_order,wp_posts.post_title .......MySQL server has gone away |
这个 “MySQL server has gone away” 有些莫名奇妙，MySql 怎么会无缘无故的没有了呢。
于是查看系统日志
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$ sudo vim /var/log/syslog |
看到如下的输出
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Jan 6 16:30:05 AY130422143404983ad9 kernel: [236491.346180] Out of memory: Kill process 755 (mysqld) score 91 or sacrifice child Jan 6 16:30:05 AY130422143404983ad9 kernel: [236491.346267] Killed process 755 (mysqld) total-vm:887016kB, anon-rss:45820kB, file-rss:0kB Jan 6 16:30:05 AY130422143404983ad9 kernel: [236491.422036] init: mysql main process (755) killed by KILL signal Jan 6 16:30:05 AY130422143404983ad9 kernel: [236491.422096] init: mysql main process ended, respawning |
可以明显看到，是由于系统内存不足，导致了 Linux 系统自带的 OOM Killer 动作。执行
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$ free -lm |
可以看到，实际的内存已经严重不足了，这台机器只配置了512M内存，跑一阵子之后，系统的剩余内存不足 10MB的样子了。
没办法，花钱加内存到1G。悲剧的是，还是会死掉，具体解决办法可以查看
Ubuntu 12.04下安装配置Worker工作模式的Apache 支持PHP
Ubuntu 12.04 Apache2 安装 PHP-FPM 增强 PHP5-CGI 的功能
通过限制DefaultMaxClassProcessCount 的数量来限制php5-cgi 的数量来避免太多的并发进程耗尽资源。
两个APK 通过Content Provider 来共享数据，在Android 4.2.2 API 17 之前都是正常的，但是到Android 4.2.2 API 17 上面就会报告异常类似如下的异常信息
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09-17 12:15:52.221: E/AndroidRuntime(4551): FATAL EXCEPTION: main 09-17 12:15:52.221: E/AndroidRuntime(4551): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.identifier.gamecenter.gctictactoe/com.identifier.gamecenter.game.MainActivity}: java.lang.SecurityException: Permission Denial: opening provider com.identifier.gamecenterapp.contentprovider.MyGamesContentProvider from ProcessRecord{42622078 4551:com.identifier.gamecenter.gctictactoe/u0a10108} (pid=4551, uid=10108) that is not exported from uid 10072 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.ActivityThread.access$600(ActivityThread.java:141) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.os.Handler.dispatchMessage(Handler.java:99) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.os.Looper.loop(Looper.java:137) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.ActivityThread.main(ActivityThread.java:5103) 09-17 12:15:52.221: E/AndroidRuntime(4551): at java.lang.reflect.Method.invokeNative(Native Method) 09-17 12:15:52.221: E/AndroidRuntime(4551): at java.lang.reflect.Method.invoke(Method.java:525) 09-17 12:15:52.221: E/AndroidRuntime(4551): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 09-17 12:15:52.221: E/AndroidRuntime(4551): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 09-17 12:15:52.221: E/AndroidRuntime(4551): at dalvik.system.NativeStart.main(Native Method) 09-17 12:15:52.221: E/AndroidRuntime(4551): Caused by: java.lang.SecurityException: Permission Denial: opening provider c.identifier.gamecenterapp.contentprovider.MyGamesContentProvider from ProcessRecord{42622078 4551:com.identifier.gamecenter.gctictactoe/u0a10108} (pid=4551, uid=10108) that is not exported from uid 10072 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.os.Parcel.readException(Parcel.java:1431) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.os.Parcel.readException(Parcel.java:1385) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.ActivityManagerProxy.getContentProvider(ActivityManagerNative.java:2611) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.ActivityThread.acquireProvider(ActivityThread.java:4515) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.ContextImpl$ApplicationContentResolver.acquireUnstableProvider(ContextImpl.java:2036) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.content.ContentResolver.acquireUnstableProvider(ContentResolver.java:1149) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.content.ContentResolver.query(ContentResolver.java:398) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.content.ContentResolver.query(ContentResolver.java:357) 09-17 12:15:52.221: E/AndroidRuntime(4551): at ch.ethz.csg.wlanopp.gapi.GameCenterController.getIdByGameTitle(GameCenterController.java:602) 09-17 12:15:52.221: E/AndroidRuntime(4551): at ch.ethz.csg.wlanopp.gapi.GameCenterController.isRegistered(GameCenterController.java:343) 09-17 12:15:52.221: E/AndroidRuntime(4551): at ch.ethz.csg.wlanopp.gapi.GameCenterController.addGame(GameCenterController.java:352) 09-17 12:15:52.221: E/AndroidRuntime(4551): at ch.ethz.csg.gamecenter.gctictactoe.MainActivity.onCreate(MainActivity.java:130) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.Activity.performCreate(Activity.java:5133) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 09-17 12:15:52.221: E/AndroidRuntime(4551): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175) 09-17 12:15:52.221: E/AndroidRuntime(4551): ... 11 more 09-17 12:20:52.487: I/Process(4551): Sending signal. PID: 4551 SIG: 9 |
在AndroidManifest.xml中原来的定义如下
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<provider android:name="com.identifier.gamecenterapp.contentprovider.MyGamesContentProvider" android:authorities="com.identifier.gamecenterapp.contentprovider" > </provider> |
并且没有定义 android:targetSdkVersion
查找了很多地方，最终发现原因
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Content providers are no longer exported by default. That is, the default value for the android:exported attribute is now “false". If it’s important that other apps be able to access your content provider, you must now explicitly set android:exported="true". This change takes effect only if you set either android:targetSdkVersion or android:minSdkVersion to 17 or higher. Otherwise, the default value is still “true" even when running on Android 4.2 and higher. |
具体的网页在 http://developer.android.com/about/versions/android-4.2.html
因此修改为如下即可 也就是增加 android:exported="true"
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<provider android:name="com.identifier.gamecenterapp.contentprovider.MyGamesContentProvider" android:authorities="com.identifier.gamecenterapp.contentprovider" android:exported="true"> </provider> |
工作中很多时候需要编辑修改16进制的文件，在Windows下面常用UltraEdit来编辑，切换到Mac下面后，找了很多，最后发现一个免费的好用软件 Hex Fiend
每一次登录Ubuntu的时候小键盘都是关着的。可是每次又得输入密码，所以还是得手动打开数字键，亮了Numlock的灯。
Ubuntu 13.04 下面执行如下操作
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sudo apt-get install numlockx |
编辑文件
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sudo vim /etc/lightdm/lightdm.conf |
在文件最后增加
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greeter-setup-script=/usr/bin/numlockx on |
Ubuntu 13.10 下面执行如下操作
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sudo apt-get install numlockx |
编辑文件
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sudo vim /etc/lightdm/lightdm.conf.d/50-unity-greeter.conf |
在文件最后增加
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greeter-setup-script=/usr/bin/numlockx on |
Ubuntu 16.04 LTS 下面执行如下操作
创建文件
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sudo vim /etc/lightdm/lightdm.conf.d/50-unity-greeter.conf |
在文件最后增加
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greeter-setup-script=/usr/bin/numlockx on |
运行虚拟机提示：
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The virtual machine 'XXX' has terminated unexpectedly during startup with exit code 1. |
之后提示：
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Kernel driver not installed (rc=-1908) The VirtualBox Linux kernel driver (vboxdrv) is either not loaded or there is a permission problem with /dev/vboxdrv. Please reinstall the kernel module by executing '/etc/init.d/vboxdrv setup' as root. If it is available in your distribution, you should install the DKMS package first. This package keeps track of Linux kernel changes and recompiles the vboxdrv kernel module if necessary. |
在终端下运行：
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sudo /etc/init.d/vboxdrv setup |
提示信息
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Stopping VirtualBox kernel modules [ OK ] * Recompiling VirtualBox kernel modules * Look at /var/log/vbox-install.log to find out what went wrong |
提示有错误，查看了一下错误日志
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cat /var/log/vbox-install.log |
内容如下
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Makefile:181: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR= and run Make again。 停止。 |
根据提示应该是没有找到对应的源文件，查看了一下系统版本号：
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uname -r |
在进入/usr/src里发现果然没有对应的版本号头文件。
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sudo apt-get install dkms build-essential linux-headers-generic sudo /etc/init.d/vboxdrv setup |
系统负载是系统监控工具GNOME里的一个小应用。它能在面板上展示出CPU、内存、网络使用、硬盘I/O等信息
Eclipse 中使用 svn 插件，原本正常，未作任何更改，最近几天突然eclipse 中查看文件时，文件后面的 版本号 、 文件的状态图标 等等都不见了。以为有插件冲突，卸载了好多其他的相关的插件，不行，卸载了SVN插件重新安装也不行。
检查插件都在，更新，提交等操作都能正常使用，唯独看不到状态了。
经过一番查找，找到问题解决办法。
Windows ,Linux 中
打开 ： windows ->preferences->General->Appearance->Lable Decorations 勾选其中的 SVN 项即可。
Mac
打开 ： preferences->General->Appearance->Lable Decorations 勾选其中的 SVN 项即可。
选择【Run As】-【Maven build】的时候，报：
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[INFO] Scanning for projects…[INFO] [INFO] BUILD FAILURE[INFO] [INFO] Total time: 0.109s[INFO] Finished at: Wed Apr 13 11:04:20 CST 2011[INFO] Final Memory: 1M/4M[INFO] ERROR] No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process- test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-site, site, post-site, site-deploy, pre-clean, clean, post-clean. -> [Help 1][ERROR] [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.[ERROR] Re-run Maven using the -X switch to enable full debug logging.[ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles:[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/NoGoalSpecifiedException |
eclipse安装的maven插件是m2eclipse，在控制台使用命令mvn compile并未报错。后在pom.xml文件<build>标签后面加上
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<defaultGoal>compile</defaultGoal> |
即可。
其实使用命令行时就已经指定了phase，而使用m2eclipse的【Run As】-【Maven build】时并未为其指定goal或phase，所以才报这个错误。
使用 Struts2 编写页面，遇到一个要长时间运行的接口，因此增加了一个execAndWait ，结果在 Action 中调用 getText的时候报告异常
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java.lang.NullPointerException at com.opensymphony.xwork2.util.LocalizedTextUtil.findText(LocalizedTextUtil.java:361) at com.opensymphony.xwork2.TextProviderSupport.getText(TextProviderSupport.java:208) at com.opensymphony.xwork2.TextProviderSupport.getText(TextProviderSupport.java:123) at com.opensymphony.xwork2.ActionSupport.getText(ActionSupport.java:103) at com.infy.action.LoginAction.execute(LoginAction.java:19) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:450) at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:289) at org.apache.struts2.interceptor.BackgroundProcess$1.run(BackgroundProcess.java:57) at java.lang.Thread.run(Thread.java:662) |
查询了很多评论，最终找到原因跟解决方案，具体解释在 http://stackoverflow.com/questions/16692658/execandwait-interceptor-not-redirecting-to-success-page-after-waiting
execAndWait causes the action to be executed in a new thread.ActionContext is ThreadLocal, the new thread will not get the values stored in the parent thread version of ActionContext. Every thread has a unique version of ActionContextgetText() will throw a NPE when it tries to execute in the new thread because it depends onActionContext简单解释一下，就是说
execAndWait 会导致执行的Action 在另外一个线程中被执行，而getText 依赖 ActionContext ，他从 ActionContext 中获得当前的Locale 从而根据语言的不同加载不同的文字，可是，由于ActionContext 是ThreadLocal 的，而execAndWait 新开线程的时候并没有把父线程的ActionContext 传递给子线程 结果导致在新开的子线程中的ActionContext中的数据都是null ,因此出现异常信息就不足为怪了。
解决方法为
To fix this, you need to copy the parent threads ActionContext into the execAndWait thread. You can do this by extending the BackgroundProcess class, implementing the beforeInvocation()and afterInvocation() methods, and extending ExecuteAndWaitInterceptor, implementing the getNewBackgroundProcess() method.
代码例子如下,注意，原文中作者的代码存在多线程同步问题，具体体现在
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beforeInvocation |
被调用的时候，得到的 context 为null ,导致注入失败。
因此需要重载两个类，来解决这个问题
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import org.apache.struts2.interceptor.BackgroundProcess; import org.apache.struts2.interceptor.ExecuteAndWaitInterceptor; import com.opensymphony.xwork2.ActionContext; import com.opensymphony.xwork2.ActionInvocation; public class ExecAndWaitInterceptorEx extends ExecuteAndWaitInterceptor { private static final long serialVersionUID = -4456744368791451159L; /** * {@inheritDoc} */ @Override protected BackgroundProcess getNewBackgroundProcess(String arg0, ActionInvocation arg1, int arg2) { ActionInvocationEx aActionInvocationEx = new ActionInvocationEx(arg1,ActionContext.getContext()); return new BackgroundProcessEx(arg0, aActionInvocationEx, arg2); } private class BackgroundProcessEx extends BackgroundProcess { public BackgroundProcessEx(String threadName, ActionInvocation invocation, int threadPriority) { super(threadName, invocation, threadPriority); } private static final long serialVersionUID = -9069896828432838638L; /** * {@inheritDoc} * @throws InterruptedException */ @Override protected void beforeInvocation() throws InterruptedException { ActionInvocationEx aActionInvocationEx = (ActionInvocationEx)this.invocation; ActionContext context = aActionInvocationEx.getContext(); ActionContext.setContext(context); } /** * {@inheritDoc} */ @Override protected void afterInvocation() { ActionContext.setContext(null); } } } |
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import com.opensymphony.xwork2.ActionContext; import com.opensymphony.xwork2.ActionEventListener; import com.opensymphony.xwork2.ActionInvocation; import com.opensymphony.xwork2.ActionProxy; import com.opensymphony.xwork2.Result; import com.opensymphony.xwork2.interceptor.PreResultListener; import com.opensymphony.xwork2.util.ValueStack; public class ActionInvocationEx implements ActionInvocation { /** * */ private static final long serialVersionUID = 1L; private final ActionInvocation mActionInvocation; private final ActionContext context; public ActionInvocationEx(ActionInvocation aActionInvocation,ActionContext aContext) { mActionInvocation = aActionInvocation; context = aContext; } public Object getAction() { return mActionInvocation.getAction(); } public boolean isExecuted() { return mActionInvocation.isExecuted(); } public ActionContext getInvocationContext() { return mActionInvocation.getInvocationContext(); } public ActionProxy getProxy() { return mActionInvocation.getProxy(); } public Result getResult() throws Exception { return mActionInvocation.getResult(); } public String getResultCode() { return mActionInvocation.getResultCode(); } public void setResultCode(String resultCode) { mActionInvocation.setResultCode(resultCode); } public ValueStack getStack() { return mActionInvocation.getStack(); } public void addPreResultListener(PreResultListener listener) { mActionInvocation.addPreResultListener(listener); } public String invoke() throws Exception { return mActionInvocation.invoke(); } public String invokeActionOnly() throws Exception { return mActionInvocation.invokeActionOnly(); } public void setActionEventListener(ActionEventListener listener) { mActionInvocation.setActionEventListener(listener); } public void init(ActionProxy proxy) { mActionInvocation.init(proxy); } public ActionInvocation serialize() { return mActionInvocation.serialize(); } public ActionInvocation deserialize(ActionContext actionContext) { return mActionInvocation.deserialize(actionContext); } /** * @return the context */ public ActionContext getContext() { return context; } } |
写完之后，在struts.xml 中配置一下拦截器，覆盖掉默认的拦截器，下面是我的配置例子
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<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> <struts> <constant name="struts.i18n.encoding" value="utf-8"></constant> <constant name="struts.multipart.maxSize" value="20971520"/> <constant name="struts.devMode" value="true" /> <package name="FaeSupport" namespace="/" extends="struts-default"> <!-- 安装自定义的 execAndWait 拦截器，覆盖掉系统默认的，目的是解决在 execAndWait 出现的时候，Action调用 getText 报java.lang.NullPointerException--> <interceptors > <interceptor name="execAndWait" class="com.FaeSupport.Interceptor.ExecAndWaitInterceptorEx"/> </interceptors > <action name="faesupport" class="com.FaeSupport.Action.FaeSelAction" method="SelParametersCheck"> <interceptor-ref name="defaultStack"/> <interceptor-ref name="execAndWait"> <param name="delay">1500</param> </interceptor-ref> <result name="wait">/build_wait.jsp</result> <result name="success">/build_wait.jsp</result> </action> </package> </struts> |