01

NodeJS流程控制(同步回调并在外层获取回调返回值)

做了个Node项目,某个流程中最多五层回调进行逻辑判断,客户还要加一些业务,如果再这么做下去,至少还要加两层回调。就可读性来讲,是很差的。胃有点翻腾,要吐出来了…

在网上查了查,有很多人说Node的回调是个坑,但是个人还是愿意接受这不是Node坑的理论,回调这是Node的一个思想,我们既然选择了使用Node,就应该去分析、理解和适应它。

我相信无论遇到什么问题,总是能解决的。如果现在不能解决,那只是暂时没有想到解决办法而已。

一、generator(生成器)

是ES6标准引入的新的数据类型。一个generator看上去像一个函数,但可以返回多次。

我喜欢并在使用着这种方法,这种方法很优雅。

作用:一是同步流程控制Node回调;二是或以在外层获取回调函数内的返回值;三是如果逻辑判断层级很多,那么使代码的可读性更好; Continue reading

01

Java中修饰符private、protected、public和default的区别

public:

具有最大的访问权限,可以访问任何一个在classpath下的类、接口、异常等。它往往用于对外的情况,也就是对象或类对外的一种接口的形式。

protected:

主要的作用就是用来保护子类的。它的含义在于子类可以用它修饰的成员,其他的不可以,它相当于传递给子类的一种继承的东西

default:

有时候也称为friendly,它是针对本包访问而设计的,任何处于本包下的类、接口、异常等,都可以相互访问,即使是父类没有用protected修饰的成员也可以。

private:

访问权限仅限于类的内部,是一种封装的体现,例如,大多数成员变量都是修饰符为private的,它们不希望被其他任何外部的类访问。

690292-20160923095944481-1758567758

注意:java的访问控制是停留在编译层的,也就是它不会在.class文件中留下任何的痕迹,只在编译的时候进行访问控制的检查。其实,通过反射的手段,是可以访问任何包下任何类中的成员,例如,访问类的私有成员也是可能的。

区别:

public:可以被所有其他类所访问

private:只能被自己访问和修改

protected:自身、子类及同一个包中类可以访问

default:同一包中的类可以访问,声明时没有加修饰符,认为是friendly。

26

HTTP Content-type 对照表

 

文件扩展名 Content-Type(Mime-Type) 文件扩展名 Content-Type(Mime-Type)
.*( 二进制流,不知道下载文件类型) application/octet-stream .tif image/tiff
.001 application/x-001 .301 application/x-301
.323 text/h323 .906 application/x-906
.907 drawing/907 .a11 application/x-a11
.acp audio/x-mei-aac .ai application/postscript
.aif audio/aiff .aifc audio/aiff
.aiff audio/aiff .anv application/x-anv
.asa text/asa .asf video/x-ms-asf
.asp text/asp .asx video/x-ms-asf
.au audio/basic .avi video/avi
.awf application/vnd.adobe.workflow .biz text/xml
.bmp application/x-bmp .bot application/x-bot
.c4t application/x-c4t .c90 application/x-c90
.cal application/x-cals .cat application/vnd.ms-pki.seccat
.cdf application/x-netcdf .cdr application/x-cdr
.cel application/x-cel .cer application/x-x509-ca-cert
.cg4 application/x-g4 .cgm application/x-cgm
.cit application/x-cit .class java/*
.cml text/xml .cmp application/x-cmp
.cmx application/x-cmx .cot application/x-cot
.crl application/pkix-crl .crt application/x-x509-ca-cert
.csi application/x-csi .css text/css
.cut application/x-cut .dbf application/x-dbf
.dbm application/x-dbm .dbx application/x-dbx
.dcd text/xml .dcx application/x-dcx
.der application/x-x509-ca-cert .dgn application/x-dgn
.dib application/x-dib .dll application/x-msdownload
.doc application/msword .dot application/msword
.drw application/x-drw .dtd text/xml
.dwf Model/vnd.dwf .dwf application/x-dwf
.dwg application/x-dwg .dxb application/x-dxb
.dxf application/x-dxf .edn application/vnd.adobe.edn
.emf application/x-emf .eml message/rfc822
.ent text/xml .epi application/x-epi
.eps application/x-ps .eps application/postscript
.etd application/x-ebx .exe application/x-msdownload
.fax image/fax .fdf application/vnd.fdf
.fif application/fractals .fo text/xml
.frm application/x-frm .g4 application/x-g4
.gbr application/x-gbr . application/x-
.gif image/gif .gl2 application/x-gl2
.gp4 application/x-gp4 .hgl application/x-hgl
.hmr application/x-hmr .hpg application/x-hpgl
.hpl application/x-hpl .hqx application/mac-binhex40
.hrf application/x-hrf .hta application/hta
.htc text/x-component .htm text/html
.html text/html .htt text/webviewhtml
.htx text/html .icb application/x-icb
.ico image/x-icon .ico application/x-ico
.iff application/x-iff .ig4 application/x-g4
.igs application/x-igs .iii application/x-iphone
.img application/x-img .ins application/x-internet-signup
.isp application/x-internet-signup .IVF video/x-ivf
.java java/* .jfif image/jpeg
.jpe image/jpeg .jpe application/x-jpe
.jpeg image/jpeg .jpg image/jpeg
.jpg application/x-jpg .js application/x-javascript
.jsp text/html .la1 audio/x-liquid-file
.lar application/x-laplayer-reg .latex application/x-latex
.lavs audio/x-liquid-secure .lbm application/x-lbm
.lmsff audio/x-la-lms .ls application/x-javascript
.ltr application/x-ltr .m1v video/x-mpeg
.m2v video/x-mpeg .m3u audio/mpegurl
.m4e video/mpeg4 .mac application/x-mac
.man application/x-troff-man .math text/xml
.mdb application/msaccess .mdb application/x-mdb
.mfp application/x-shockwave-flash .mht message/rfc822
.mhtml message/rfc822 .mi application/x-mi
.mid audio/mid .midi audio/mid
.mil application/x-mil .mml text/xml
.mnd audio/x-musicnet-download .mns audio/x-musicnet-stream
.mocha application/x-javascript .movie video/x-sgi-movie
.mp1 audio/mp1 .mp2 audio/mp2
.mp2v video/mpeg .mp3 audio/mp3
.mp4 video/mpeg4 .mpa video/x-mpg
.mpd application/vnd.ms-project .mpe video/x-mpeg
.mpeg video/mpg .mpg video/mpg
.mpga audio/rn-mpeg .mpp application/vnd.ms-project
.mps video/x-mpeg .mpt application/vnd.ms-project
.mpv video/mpg .mpv2 video/mpeg
.mpw application/vnd.ms-project .mpx application/vnd.ms-project
.mtx text/xml .mxp application/x-mmxp
.net image/pnetvue .nrf application/x-nrf
.nws message/rfc822 .odc text/x-ms-odc
.out application/x-out .p10 application/pkcs10
.p12 application/x-pkcs12 .p7b application/x-pkcs7-certificates
.p7c application/pkcs7-mime .p7m application/pkcs7-mime
.p7r application/x-pkcs7-certreqresp .p7s application/pkcs7-signature
.pc5 application/x-pc5 .pci application/x-pci
.pcl application/x-pcl .pcx application/x-pcx
.pdf application/pdf .pdf application/pdf
.pdx application/vnd.adobe.pdx .pfx application/x-pkcs12
.pgl application/x-pgl .pic application/x-pic
.pko application/vnd.ms-pki.pko .pl application/x-perl
.plg text/html .pls audio/scpls
.plt application/x-plt .png image/png
.png application/x-png .pot application/vnd.ms-powerpoint
.ppa application/vnd.ms-powerpoint .ppm application/x-ppm
.pps application/vnd.ms-powerpoint .ppt application/vnd.ms-powerpoint
.ppt application/x-ppt .pr application/x-pr
.prf application/pics-rules .prn application/x-prn
.prt application/x-prt .ps application/x-ps
.ps application/postscript .ptn application/x-ptn
.pwz application/vnd.ms-powerpoint .r3t text/vnd.rn-realtext3d
.ra audio/vnd.rn-realaudio .ram audio/x-pn-realaudio
.ras application/x-ras .rat application/rat-file
.rdf text/xml .rec application/vnd.rn-recording
.red application/x-red .rgb application/x-rgb
.rjs application/vnd.rn-realsystem-rjs .rjt application/vnd.rn-realsystem-rjt
.rlc application/x-rlc .rle application/x-rle
.rm application/vnd.rn-realmedia .rmf application/vnd.adobe.rmf
.rmi audio/mid .rmj application/vnd.rn-realsystem-rmj
.rmm audio/x-pn-realaudio .rmp application/vnd.rn-rn_music_package
.rms application/vnd.rn-realmedia-secure .rmvb application/vnd.rn-realmedia-vbr
.rmx application/vnd.rn-realsystem-rmx .rnx application/vnd.rn-realplayer
.rp image/vnd.rn-realpix .rpm audio/x-pn-realaudio-plugin
.rsml application/vnd.rn-rsml .rt text/vnd.rn-realtext
.rtf application/msword .rtf application/x-rtf
.rv video/vnd.rn-realvideo .sam application/x-sam
.sat application/x-sat .sdp application/sdp
.sdw application/x-sdw .sit application/x-stuffit
.slb application/x-slb .sld application/x-sld
.slk drawing/x-slk .smi application/smil
.smil application/smil .smk application/x-smk
.snd audio/basic .sol text/plain
.sor text/plain .spc application/x-pkcs7-certificates
.spl application/futuresplash .spp text/xml
.ssm application/streamingmedia .sst application/vnd.ms-pki.certstore
.stl application/vnd.ms-pki.stl .stm text/html
.sty application/x-sty .svg text/xml
.swf application/x-shockwave-flash .tdf application/x-tdf
.tg4 application/x-tg4 .tga application/x-tga
.tif image/tiff .tif application/x-tif
.tiff image/tiff .tld text/xml
.top drawing/x-top .torrent application/x-bittorrent
.tsd text/xml .txt text/plain
.uin application/x-icq .uls text/iuls
.vcf text/x-vcard .vda application/x-vda
.vdx application/vnd.visio .vml text/xml
.vpg application/x-vpeg005 .vsd application/vnd.visio
.vsd application/x-vsd .vss application/vnd.visio
.vst application/vnd.visio .vst application/x-vst
.vsw application/vnd.visio .vsx application/vnd.visio
.vtx application/vnd.visio .vxml text/xml
.wav audio/wav .wax audio/x-ms-wax
.wb1 application/x-wb1 .wb2 application/x-wb2
.wb3 application/x-wb3 .wbmp image/vnd.wap.wbmp
.wiz application/msword .wk3 application/x-wk3
.wk4 application/x-wk4 .wkq application/x-wkq
.wks application/x-wks .wm video/x-ms-wm
.wma audio/x-ms-wma .wmd application/x-ms-wmd
.wmf application/x-wmf .wml text/vnd.wap.wml
.wmv video/x-ms-wmv .wmx video/x-ms-wmx
.wmz application/x-ms-wmz .wp6 application/x-wp6
.wpd application/x-wpd .wpg application/x-wpg
.wpl application/vnd.ms-wpl .wq1 application/x-wq1
.wr1 application/x-wr1 .wri application/x-wri
.wrk application/x-wrk .ws application/x-ws
.ws2 application/x-ws .wsc text/scriptlet
.wsdl text/xml .wvx video/x-ms-wvx
.xdp application/vnd.adobe.xdp .xdr text/xml
.xfd application/vnd.adobe.xfd .xfdf application/vnd.adobe.xfdf
.xhtml text/html .xls application/vnd.ms-excel
.xls application/x-xls .xlw application/x-xlw
.xml text/xml .xpl audio/scpls
.xq text/xml .xql text/xml
.xquery text/xml .xsd text/xml
.xsl text/xml .xslt text/xml
.xwd application/x-xwd .x_b application/x-x_b
.sis application/vnd.symbian.install .sisx application/vnd.symbian.install
.x_t application/x-x_t .ipa application/vnd.iphone
.apk application/vnd.android.package-archive .xap application/x-silverlight-app

 

22

写给女儿

法律是高压线,你不碰它,永远不会触电!

身体发肤,受之父母,不敢毁伤,孝之始也。《孝经·知开宗明义》

人无论是穷是富,都要活得干干净净!

人可以身无分文,但不可以手无寸铁!

言不轻信人不负我,诺不轻许我不负人!

工欲善其事必先利其器。《论语·卫灵公》

一、人心险诈,不可不防;二、攻城为下,攻心为上;三、仁义在口中,诡诈心中藏。《张良教给刘邦的三招》 —— 2020-05-07

发脾气是本能,收住脾气才是本事。

永远不要把你的男人关在家门外!除非他威胁到你的生命。      —— 2020-04-29

一定要早日在心理、生活、经济方面独立,因为正常的话你会比同龄人早十年失去父母。(在没有你的的时候我就想过这个问题了。)      —— 2020-04-29

宁说悬,不说闲。意思就是吹吹牛没关系,但是一定不要讲别人的闲话。这是我的姥爷(王俊儒)在我十几岁的时候教给我的。      ——- 2020-04-29

吃饭的时候,在长辈没有上桌、动筷之前,自己一定不要先上桌、动筷,因为这是对长辈的相当的不尊敬。吃饭时不要吧唧嘴,因为那样很烦人,吃东西的时候嘴一定要闭严。这是一个好习惯。这也是我的姥爷(王俊儒)在我十几岁的时候教给我的。      ——- 2020-04-29

Continue reading

13

UnicodeDecodeError: ‘utf8′ codec can’t decode byte 0xc7 in position 0: invalid continuation byte

把获取到的信息转码为gbk就可以了

 

12

python使用代理爬页面返回403: Forbidden

前几天给使用Python写的爬虫加上了可以使用代理访问爬取页面内容的功能,刚开始几天测试是正常的,可以正确返回所需内容,突然这两天一使用代理就全部返回“403: Forbidden”,怎么也没想明白是哪儿的问题,后来我都怀疑是不是我脚本哪里写错了……

上面是一段测试代码,使用代理就返回403,最后实在是没办法了,想着在群里请教一下,结果有一位群友(3245935173)说让我试试使用“https”,测试结果,返回正确数据了,原来这是错在这里。

因为之前使用http协议是正确的,一定是代理网站后来修改了访问协议(http -> https),真是万万没想到啊。

09

MySQL命令行操作

登录mysql:
mysql -u 用户名 -p
Enter password: 输入mysql密码

通过CMD进入没有设置环境变量的MYSQL
先进入到MYDQL安装目录下的./bin文件夹,之后输入
./mysql.exe -h localhost -u root -p

./mysql.exe -u root -p
回车
Enter password: 输入mysql密码

显示所有数据库列表:
mysql> show databases;

显示所有数据表列表:
mysql> show tables;

选择进入某数据库:
use mysql;

显示数据表的结构:
describe 表名;

建库:
create database 库名;

建表:
use 库名;
create table 表名 (字段设定列表);

删库和删表:
drop database 库名;
drop table 表名;

将表中记录清空:
delete from 表名;

显示表中的记录:
select * from 表名

修改表名:
ALTER TABLE admin_user RENAME TO a_user

命令行导入数据库.sql文件:
mysql> use dbname;
mysql> source /root/databack.sql
或:
mysql -u 数据库用户名 -p 数据库名 < 预导入的文件名.sql (最后没有分号)
mysql -u abc -p dbname < databack.sql

命令行导出数据库.sql文件:
mysqldump -u 数据库用户名 -p 目标数据库 > 存储的文件名
mysqldump -u root -p dbname >abc.sql
然后回车输入密码即可

命令行导出多个数据库:
mysqldump -u root -p –add-drop-database –databases dbName1 dbName2… > sqlFilePath
–add-drop-database : 该选项表示在创建数据库的时候先执行删除数据库操作
–database : 该选项后面跟着要导出的多个数据库,以空格分隔

命令行导出某个数据库的某个表:
mysqldump -u root -p dbName tableName > sqlFilePath

命令行只导出数据库结构,不带数据:
mysqldump -u root -p -d dbName > sqlFilePath
-d : 只备份结构,不备份数据。也可以使用”–no-data”代替”-d”,效果一样。

ALTER TABLE admin_user RENAMETO a_user