如何在 java 中拆分不区分大小写的字符串？

Question

如何在 java 中拆分不区分大小写的字符串？

String sql = SELECT * FROM employee OFFSET 0 LIMIT 25;
String[] sqlWithoutPagination = sql.split("offset");

OFFSET可以是lower-case/upper-case 。

Answer 1

使用正则表达式如下

String sql = "SELECT * FROM employee OFFset 0 LIMIT 25";
System.out.println(sql.split("(?i)offset")[0]);

Answer 2

您不必使用正则表达式，您可以简单地使用indexOf和toLowerCase ：

String sql = "SELECT * FROM employee OFFSET 0 LIMIT 25";
int idx = sql.toLowerCase().indexOf("offset");
String sqlWithoutPagination = sql.substring(0, idx);

当然，您必须检查idx是否大于等于 0。

Answer 3

我实际上建议在不区分大小写的模式下使用String#replaceAll ，如果它们发生，只需OFFSET和LIMIT子句：

String sql1 = "SELECT * FROM employee OFFSET 0 LIMIT 25";
String sql1New = sql1.replaceAll("(?i)(?:\\s+OFFSET \\d+)?\\s+LIMIT \\d+$", "");
System.out.println(sql1 + "\n" + sql1New);
String sql2 = "SELECT * FROM employee LIMIT 25";
String sql2New = sql2.replaceAll("(?i)(?:\\s+OFFSET \\d+)?\\s+LIMIT \\d+$", "");
System.out.println(sql2 + "\n" + sql2New);

这打印：

SELECT * FROM employee OFFSET 0 LIMIT 25
SELECT * FROM employee
SELECT * FROM employee LIMIT 25
SELECT * FROM employee