java-从SQL查询检索参数

我想从SQL查询中获取所有参数.在这种情况下,查询是数组中的纯字符串.
我有以下形式的查询对：

SELECT * FROM my_table t WHERE (t.attr1 = ? AND t.attr2 = ?) OR t.attr3= ?

它的对是(其中包含我要检索的参数)：

SELECT * FROM my_table t WHERE (t.attr1 = 3 AND t.attr2 = 'str') OR t.attr3= 4

因此输出将是：

3,'str' and 4.

如何基于此对检索这些值？

我在Java中尝试使用正则表达式,但是会很困难,因为？可以是数字
字符串等等.该字符串可以包含另一个？这是字符串的一部分,例如：

UPDATE my_table SET attr2 = ? WHERE attr5 = ?
UPDATE my_table SET attr2 = 'Is it true?' WHERE attr5 = 'What is it?'

最佳答案

您可以使用这种方法来做到这一点,在此替换掉每一个？在查询中使用(.*),然后根据它创建一个模式.然后应用另一对具有实际值的字符串,然后打印出将按？动态创建的所有组中的值.存在于查询字符串中.

这是执行相同操作的Java代码.

// This map stores your paired queries where key stores the placeholder query and value stores the query having actual parameters.
Map<String,String> pairMap = new HashMap<>();
pairMap.put("SELECT * FROM my_table t WHERE (t.attr1 = ? AND t.attr2 = ?) OR t.attr3= ?","SELECT * FROM my_table t WHERE (t.attr1 = 3 AND t.attr2 = 'str') OR t.attr3= 4");
pairMap.put("UPDATE my_table SET attr2 = ? WHERE attr5 = ?","UPDATE my_table SET attr2 = 'Is it true?' WHERE attr5 = 'What is it?'");

pairMap.forEach((k,v) -> {
    System.out.println("For query: "+k);
    k = k.replaceAll("([*+^$()\\[\\]{}])","\\\\$1"); // this escapes all the characters that have special meaning in regex so they get treated as literal characters
    k = k.replaceAll("\\?","(.*)");

    Pattern p = Pattern.compile(k);
    Matcher m = p.matcher(v);
    if (m.matches()) {
        for (int i=0;i<m.groupCount();i++) {
            System.out.println(m.group(i+1));
        }
    } else {
        System.out.println("Didn't match");
    }
    System.out.println();
});

哪个打印,

For query: SELECT * FROM my_table t WHERE (t.attr1 = ? AND t.attr2 = ?) OR t.attr3= ?
3
'str'
4

For query: UPDATE my_table SET attr2 = ? WHERE attr5 = ?
'Is it true?'
'What is it?'

如您所见,该代码适用于占位符？的任何可变值.在查询字符串中,并打印配对查询中存在的所有具有实际值的值.