前言 在手写sql的时候,根据参数处理查询条件. select * from staff where 1 = 1 and staff_id in ($staffIds) and staff_name in ($staffNames) 比如staffId为空,需要把 staff_id in ($staffIds) 候设置为true,staffName正
前言
在手写sql的时候,根据参数处理查询条件.
select * from staff where 1 = 1 and staff_id in ($staffIds) and staff_name in ($staffNames)
比如staffId为空,需要把staff_id in ($staffIds) 候设置为true,staffName正常赋值
replace替换圆括号
public static void main(String[] args) { String sqlStr = "select * from staff where 1 = 1 and staff_id in ($staffIds) " + "and staff_name in ($staffNames)"; String replaceEmpty = "staff_id in ($staffIds)"; String replaceSql = sqlStr.replace(replaceEmpty, "true"); System.out.println(replaceSql); }
结果:
select * from staff where 1 = 1 and true and staff_name in ($staffNames)
直接用replace就可以了。
replaceAll替换圆括号
如果是想用replaceAll呢?
public static void main(String[] args) { String sqlStr = "select * from staff where 1 = 1 and staff_id in ($staffIds) " + "and staff_name in ($staffNames)"; String replaceEmpty = "staff_id in ($staffIds)"; String replaceAllSql = sqlStr.replaceAll(Matcher.quoteReplacement(replaceEmpty), "true"); System.out.println(replaceAllSql); }
结果:
select * from staff where 1 = 1 and staff_id in ($staffIds) and staff_name in ($staffNames)
没有替换成功,为什么呢?
看replaceAll的方法:
public String replaceAll(String regex, String replacement) { return Pattern.compile(regex).matcher(this).replaceAll(replacement); }
regex 对应的是正则的内容,因此要对圆括号进行转移下:
String replaceAllSql = replaceEmpty = replaceEmpty.replaceAll("\\(", "[( )]").replaceAll("\\)", "[( )]");
替换前,对圆括号进行转义
public static void main(String[] args) { String sqlStr = "select * from staff where 1 = 1 and staff_id in ($staffIds) " + "and staff_name in ($staffNames)"; String replaceEmpty = "staff_id in ($staffIds)"; replaceEmpty = replaceEmpty.replaceAll("\\(", "[( )]").replaceAll("\\)", "[( )]"); String replaceAllSql = sqlStr.replaceAll(Matcher.quoteReplacement(replaceEmpty), "true"); System.out.println(replaceAllSql); }
结果:
select * from staff where 1 = 1 and true and staff_name in ($staffNames)
替换成功。
补充:Java 利用replaceAll 替换中括号
Java的replaceAll函数默认是不能替换中括号的,例如想替换[b]到<b>,结果却就变成[<b>]
解决方案就是首先利用正则表达式替换中括号,然后再替换中括号内的内容:
infos = infos.replaceAll("[\\[\\]]","");
不过后来又查询了下资料,发现中括号在java中居然是特殊字符,一对中括号里的内容是一组正则表达式。所以如果打算让[b]-><b>,只要如下写法:
infos = infos.replaceAll("\\[b\\]","<b>");
总结:
字符替换的时候,优先考虑使用replace,多个时候,也是生效的。如果要使用replace的话,使用要注意特殊字符的处理。或者自己写正则进行处理。
优化: 《整体替换sql》
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