java - 在 Java 中解析 CSV

Question

我有这种奇怪的情况，我必须水平阅读。所以我得到一个 csv 文件，其中包含水平格式的数据。如下所示:

CompanyName,RunDate,10/27/2010,11/12/2010,11/27/2010,12/13/2010,12/27/2010....

RunDate 之后显示的所有日期都是运行日期字段的值，我必须在我的系统中为该公司更新该字段。日期值不是固定的数字，它们可以是单个值到 10 到 n 个数字。所以我需要读取所有这些值并在系统中更新。我正在用 Java 编写这个。

Answer 1

String,split(",") 不太可能起作用。
它会拆分嵌入逗号(“Foo, Inc.”)的字段，即使它们是 CSV 行中的单个字段。

如果公司名称是:
公司, Inc.
或者更糟:
乔的“又好又快又便宜”的食物

根据维基百科: ( http://en.wikipedia.org/wiki/Comma-separated_values )

Fields with embedded commas must be enclosed within double-quote characters.

   1997,Ford,E350,"Super, luxurious truck"

Fields with embedded double-quote characters must be enclosed within double-quote characters, and each of the embedded double-quote characters must be represented by a pair of double-quote characters.

   1997,Ford,E350,"Super ""luxurious"" truck"

更糟糕的是，引用字段可能嵌入了换行符(换行符；“\n”):

Fields with embedded line breaks must be enclosed within double-quote characters.

   1997,Ford,E350,"Go get one now  
   they are going fast"

这演示了 String,split(",") 解析逗号的问题:

CSV 行是:

a,b,c,"Company, Inc.", d, e,"Joe's ""Good, Fast, and Cheap"" Food", f, 10/11/2010,1/1/2011, g, h, i

// Test String.split(",") against CSV with
// embedded commas and embedded double-quotes in
// quoted text strings:
//
// Company names are:
//        Company, Inc.
//        Joe's "Good, Fast, and Cheap" Food
//
// Which should be formatted in a CSV file as:
//        "Company, Inc."
//        "Joe's ""Good, Fast, and Cheap"" Food"
//
//
public class TestSplit {
    public static void TestSplit(String s, String splitchar) {
        String[] split_s    = s.split(splitchar);

        for (String seg : split_s) {
            System.out.println(seg);
        }
    }


    public static void main(String[] args) {
        String csvLine = "a,b,c,\"Company, Inc.\", d,"
                            + " e,\"Joe's \"\"Good, Fast,"
                            + " and Cheap\"\" Food\", f,"
                            + " 10/11/2010,1/1/2011, h, i";

        System.out.println("CSV line is:\n" + csvLine + "\n\n");
        TestSplit(csvLine, ",");
    }
}

产生以下内容:

D:\projects\TestSplit>javac TestSplit.java

D:\projects\TestSplit>java  TestSplit
CSV line is:
a,b,c,"Company, Inc.", d, e,"Joe's ""Good, Fast, and Cheap"" Food", f, 10/11/2010,1/1/2011, g, h, i


a
b
c
"Company
 Inc."
 d
 e
"Joe's ""Good
 Fast
 and Cheap"" Food"
 f
 10/11/2010
1/1/2011
 g
 h
 i

D:\projects\TestSplit>

CSV 行应该被解析为:

a
b
c
"Company, Inc."
 d
 e
"Joe's ""Good, Fast, and Cheap"" Food"
 f
 10/11/2010
1/1/2011
 g
 h
 i