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。

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》