具体的就不说了，说几个注意点：
1.传递给csv.reader或者DictReader的是一个打开的文件流；
2.异常“line contains NULL byte”可以对打开的文件作如下处理，
csvfile = open(filepath,"rb"); #打开一个csv文件即将NULL byte替换掉。
reader = csv.DictReader((line.replace('\0','') for line in csvfile),delimiter=",");
3.CSV字段需要加双引号的情况：
1）Fields with embedded commas must be quoted.（当字段值中包含有半角逗号时，整个字段需要quoted），例如：
1997,Ford,E350,"Super, luxurious truck"
2）Fields with embedded double-quote characters must be quoted, and each of the embedded double-quote characters must be represented by a pair of double-quote characters.（当字段值中含有半角双引号时，整个字段需要quoted，并且被包含的每一个半角双引号都要被替换成一对半角双引号），例如：
1997,Ford,E350,"Super, ""luxurious"" truck"
3）Fields with embedded line breaks must be quoted (however, many CSV implementations simply do not support this).（当字段值中有换行是，整个字段需要quoted。然而很多CSV模块的实现都不支持字段内有换行。PS：Python是支持的），例如：
1997,Ford,E350,"Go get one now
they are going fast"
4）In CSV implementations that do trim leading or trailing spaces, fields with such spaces as meaningful data must be quoted.（字段值需要以空格开头时，整个字段需要quoted），例如：
1997,Ford,E350," Super luxurious truck "