Hot For Coding
  • Java字符串与数字互转

    字符串转数字

    String s = "8532";
    
    short t = Short.parseShort(s);
    int i = Integer.parseInt(s);
    long l = Long.parseLong(s);
    Float f = Float.parseFloat(s);
    Double d = Double.parseDouble(s);
    

    如果字符串转换不成功会抛出一个运行时错误,需要注意一下

    数字转字符串

    // 其中 something 为任意一种数字类型
    String s = String.valueOf(something);
    
    // 如果确保 something 不会为null
    String s = something.toString();
    
    // 还有一种
    String s = something + "";
    

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  • Nginx 403 Forbidden 问题

    今天在一个新的环境上安装Nginx,结果访问的都是403

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    通常显示403我立马都会想到路径配置不对,但我仔细看了一下,目录路径没问题

    nginx.conf

    server {
      listen       80;
      server_name  localhost;
    
      #charset koi8-r;
    
      #access_log  logs/host.access.log  main;
    
      location / {
        root   /root/html;
        index  index.html index.htm;
      }
    }
    

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  • cwRsync命令行带密码

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    cwRsync是基于Win平台的rsync解决方法,但经过测试有一个选项参数--password-file始终都不起作用

    @ECHO OFF
    D:
    cd "\Program Files (x86)\cwRsync\bin"
    rsync ^
    -vzrtopg ^
    --progress ^
    --delete ^
    /cygdrive/d/Workspace/Aptana/demo/ ^
    user@192.168.1.48::demo ^
    --port=7876 ^
    --password-file=/cygdrive/d/Workspace/Aptana/demo/rsyncd/passwd.txt ^
    --exclude-from=/cygdrive/d/Workspace/Aptana/demo/rsyncd/filter.txt
    pause
    

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  • MySQLdb ImportError libmysqlclient.so.18

    安装MySQLdb后,导入包时MySQLdb出错如下

    [root@lizhong MySQL-python-1.2.3]# /usr/local/bin/python2.7
    Python 2.7.6 (default, Apr 10 2014, 15:45:39) 
    [GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import MySQLdb
    /usr/local/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-linux-x86_64.egg/_mysql.py:3: UserWarning: Module _mysql was already imported from /usr/local/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-linux-x86_64.egg/_mysql.pyc, but /soft/MySQL-python-1.2.3 is being added to sys.path
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "MySQLdb/__init__.py", line 19, in <module>
        import _mysql
      File "build/bdist.linux-x86_64/egg/_mysql.py", line 7, in <module>
      File "build/bdist.linux-x86_64/egg/_mysql.py", line 6, in __bootstrap__
    ImportError: libmysqlclient.so.18: cannot open shared object file: No such file or direc
    

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  • 关于Linux动态链接so文件

    在Linux下写C程序时,常常有很多基础通用重复性的代码,最常见的比如重复使用CURL库创建HTTP请求,动态链接库就为了解决这个问题,可以把重复性的函数库单独编译成so文件,然后多个程序可以共享一个so文件提供的函数库

    Linux内置了一些常见的类库so文件,我们也可以自己编译自己需要的类库文件放到/usr/lib目录下,使用动态链接库有以下优势

    • 提升编译速度,类库部分不需要重新编译
    • 更容易升级部分功能,比如所有程序依赖curl库,那么如果curl可以单独升级而不用重新编译程序
    • 由于源码体积减少,所以编译出来的可执行文件体积也小

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  • Nginx定义404页面

    前几天,一朋友出程序出问题却怎么查都没看出问题,于是让我帮它看看。其实它是Ajax请求了很多个模板,然后把模板写到页面中。关键是所有请求的页面都是200正常状态码返回,表面上看没什么问题,实际上有些请求虽然返回200状态码,但给回的状态码是200。WebServer是Nginx,我觉得有可能配置了Nginx的404错误页面,虽然请求不存在的资源可以成功返回404页面,但返回状态码确是200。

    404.html

    This is 404 page.
    

    请求一个不存在的页面:

    full

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  • Django自带加密模块的使用

    在Win平台开发Python项目往往因为加密模块不能使用crypt加密模块而感到蛋疼,这次使用Django在Win平台开发项目就又为这个加密模块而发愁。但考虑到Django有用户验证模块,证明它已具备跨平台的加密模块。于是阅读文档,在https://docs.djangoproject.com/en/1.6/topics/auth/passwords/页面发现有这样一段话

    Manually managing a user’s password
    The django.contrib.auth.hashers module provides a set of functions to create and validate hashed password. You can use them independently from the User model.
    check_password(password, encoded)
    If you’d like to manually authenticate a user by comparing a plain-text password to the hashed password in the database, use the convenience function check_password(). It takes two arguments: the plain-text password to check, and the full value of a user’s password field in the database to check against, and returns True if they match, False otherwise. Changed in Django 1.6:
    In Django 1.4 and 1.5, a blank string was unintentionally considered to be an unusable password, resulting in this method returningFalse for such a password.
    make_password(password[, salt, hashers])
    Creates a hashed password in the format used by this application. It takes one mandatory argument: the password in plain-text. Optionally, you can provide a salt and a hashing algorithm to use, if you don’t want to use the defaults (first entry of PASSWORD_HASHERS setting). Currently supported algorithms are: 'pbkdf2_sha256', 'pbkdf2_sha1', 'bcrypt_sha256'(see Using bcrypt with Django), 'bcrypt', 'sha1', 'md5', 'unsalted_md5' (only for backward compatibility) and 'crypt' if you have the crypt library installed. If the password argument is None, an unusable password is returned (a one that will be never accepted by check_password()).

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  • IE11打不开网页,菜单项变灰

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    IE11浏览器突然打不开任何网页

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    点击设置按钮大多数设置都是灰的:

    full

    到 控制面板 > 程序和功能 > 打开或关闭window功能 中IE11取消勾选,确定

    full

    重启,在进去把它勾选回去安装,重启,打开IE11依旧还是没有解决问题。从官网下载IE11安装包进行安装却总提示已安装最新版本。

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  • MySQL导入sql脚本错误 2006 - MySQL server has gone away

    MySQL导入sql 10M脚本时出错,如图

    full

    Error occured at:2014-03-24 11:42:24
    Line no.:85
    Error Code: 2006 - MySQL server has gone away
    

    最终找到原因,原来是MySQL导入大批量数据的时候超出了默认允许最大的数据包所以就提示2006 - MySQL server has gone away

    于是找到my.cnf,在[mysqld]加入:

    max_allowed_packet=300M
    wait_timeout=200000
    interactive_timeout = 200000
    

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  • Django1.6访问static内容提示编码错误

    今天用Django搭建一个环境,在访问的时候感觉有点怪

    full

    感觉页面CSS似乎没有被加载进来,于是单独访问某个CSS文件结果浏览器提示

    A server error occurred. Please contact the administrator.

    控制台

    Traceback (most recent call last):
      File "D:\Python27\lib\wsgiref\handlers.py", line 85, in run
        self.result = application(self.environ, self.start_response)
      File "D:\Python27\lib\site-packages\django\contrib\staticfiles\handlers.py", line 68, in __call__
        return super(StaticFilesHandler, self).__call__(environ, start_response)
      File "D:\Python27\lib\site-packages\django\core\handlers\wsgi.py", line 206, in __call__
        response = self.get_response(request)
      File "D:\Python27\lib\site-packages\django\contrib\staticfiles\handlers.py", line 58, in get_response
        return self.serve(request)
      File "D:\Python27\lib\site-packages\django\contrib\staticfiles\handlers.py", line 51, in serve
        return serve(request, self.file_path(request.path), insecure=True)
      File "D:\Python27\lib\site-packages\django\contrib\staticfiles\views.py", line 41, in serve
        return static.serve(request, path, document_root=document_root, **kwargs)
      File "D:\Python27\lib\site-packages\django\views\static.py", line 61, in serve
        content_type, encoding = mimetypes.guess_type(fullpath)
      File "D:\Python27\lib\mimetypes.py", line 297, in guess_type
        init()
      File "D:\Python27\lib\mimetypes.py", line 358, in init
        db.read_windows_registry()
      File "D:\Python27\lib\mimetypes.py", line 258, in read_windows_registry
        for subkeyname in enum_types(hkcr):
      File "D:\Python27\lib\mimetypes.py", line 249, in enum_types
        ctype = ctype.encode(default_encoding) # omit in 3.x!
      File "D:\Python27\lib\encodings\utf_8.py", line 16, in decode
        return codecs.utf_8_decode(input, errors, True)
    UnicodeDecodeError: 'utf8' codec can't decode byte 0xb0 in position 1: invalid start byte
    

    ...

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