查询路径变量时出现内部服务器错误 jdbc

Question

我有下面的代码，运行时出现以下错误。String到VARCHAR转换似乎存在某种问题。

curl -v localhost:8080/trainer/Rach
*   Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 8080 (#0)
> GET /trainer/Rach HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.55.1
> Accept: */*
>
< HTTP/1.1 500
< Content-Type: application/json
< Transfer-Encoding: chunked
< Date: Wed, 17 Jun 2020 12:43:21 GMT
< Connection: close
<
{"timestamp":"2020-06-17T12:43:21.205+0000","status":500,"error":"Internal Server Error","message":"StatementCallback; bad SQL grammar [SELECT * fr
om TRAINERS where NAME=Rach]; nested exception is org.h2.jdbc.JdbcSQLSyntaxErrorException: Column "RACH" not found; SQL statement:nSELECT * from
TRAINERS where NAME=Rach [42122-200]","path":"/trainer/Rach"}* Closing connection 0

控制器：

@GetMapping("/trainer/{trainer_name}")
public Trainer getTrainer(@PathVariable String trainer_name) {
Trainer t = jdbcTemplate.queryForObject("SELECT * from TRAINERS where NAME=" + trainer_name , new 
TrainerRawMapper());
return t;
}

原始映射器：

public class TrainerRawMapper implements RowMapper<Trainer> {
@Override
public Trainer mapRow(ResultSet rs, int rowNum) throws SQLException {
Trainer trainer = new Trainer();
trainer.setName(rs.getString("NAME"));
trainer.setLevel(rs.getInt("LEVEL"));
trainer.setBag(new Stack<Pokemon>());
return trainer;
}
}

SQL：

CREATE TABLE TRAINERS (NAME VARCHAR(225) PRIMARY KEY,
LEVEL INT)

-- TRAINERS insertions
INSERT INTO TRAINERS (NAME,LEVEL) VALUES ('Rach',8);
INSERT INTO TRAINERS (NAME,LEVEL) VALUES ('Rache',0);
INSERT INTO TRAINERS (NAME,LEVEL) VALUES ('Rachel',1);
INSERT INTO TRAINERS (NAME,LEVEL) VALUES ('Racheli',2);

Answer 1

更新查询并放置不带引号的trainer_name，如下所示：

String sql = "SELECT * from TRAINERS where NAME = '" + trainer_name +"'";
Trainer t = jdbcTemplate.queryForObject(sql, new TrainerRawMapper());

解决方案只是为了纠正错误。

，出于安全考虑，最好使用 jdbcTemplate 来替换值，以避免像 SQL 注入这样的 SQL 攻击

String sql = "SELECT * from TRAINERS where NAME = ?";
return jdbcTemplate.queryForObject(sql, new Object[]{trainer_name}, new TrainerRawMapper());

Spring Doc：：queryForObject

Answer 2

主要问题是您使用字符串 concat 生成查询，这是非常危险的，在这种情况下会导致错误的查询。这些值不会被转义，因此查询无效。您应该做的是使用适当的 JDBC 机制来替换查询中的值。

String query = "SELECT * from TRAINERS where NAME=?"
return jdbcTemplate.queryForObject(query, new TrainerRawMapper(), trainer_name);

查询现在将正确执行，并且您也不会受到 SQL 注入攻击。额外的好处是，现在可以缓存查询，从而在再次执行时提高性能。