有效防止sql注入的方法演示

@RestController
public class Controller {
  
  @Autowired
  SqlInject sqlInject;
  
  @GetMapping("list")
  public List<Course> courseList(@RequestParam("studentId") String studentId){
    List<Course> orders = sqlInject.orderList(studentId);
    return orders;
  }
}

@Service
public class SqlInject {

  @Autowired
  private JdbcTemplate jdbcTemplate;
  
  public List<Course> orderList(String studentId){
    String sql = "select id,course_id,student_id,status from course where student_id = "+ studentId;
    return jdbcTemplate.query(sql,new BeanPropertyRowMapper(Course.class));
  }
}

select id,course_id,student_id,status 
from course 
where student_id = 4

select id,course_id,student_id,status 
from course 
where student_id = 4 or 1 = 1 

select id,course_id,student_id,status 
from course 

union select 1,1,version(),1

union select 1,1,database(),1

union select 1,1, (SELECT GROUP_CONCAT(schema_name) FROM information_schema.schemata) schemaName,1

public List<Course> orderList(String studentId){
  String sql = "select id,course_id,student_id,status from course where student_id = ";
  return jdbcTemplate.query(sql,new Object[]{studentId},new BeanPropertyRowMapper(Course.class));
}

@Component
public class SqlInjectionFilter implements Filter {
  @Override
  public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) throws IOException, ServletException {
    HttpServletRequest req=(HttpServletRequest)servletRequest;
    HttpServletRequest res=(HttpServletRequest)servletResponse;
    //获得所有请求参数名
    Enumeration params = req.getParameterNames();
    String sql = "";
    while (params.hasMoreElements()) {
      // 得到参数名
      String name = params.nextElement().toString();
      // 得到参数对应值
      String[] value = req.getParameterValues(name);
      for (int i = 0; i < value.length; i++) {
        sql = sql + value[i];
      }
    }
    if (sqlValidate(sql)) {
      throw new IOException("您发送请求中的参数中含有非法字符");
    } else {
      chain.doFilter(servletRequest,servletResponse);
    }
  }

  /**
   * 关键词校验
   * @param str
   * @return
   */
  protected static boolean sqlValidate(String str) {
    // 统一转为小写
    str = str.toLowerCase();
    // 过滤掉的sql关键字，可以手动添加
    String badStr = "'|and|exec|execute|insert|select|delete|update|count|drop|*|%|chr|mid|master|truncate|" +
        "char|declare|sitename|net user|xp_cmdshell|;|or|-|+|,|like'|and|exec|execute|insert|create|drop|" +
        "table|from|grant|use|group_concat|column_name|" +
        "information_schema.columns|table_schema|union|where|select|delete|update|order|by|count|*|" +
        "chr|mid|master|truncate|char|declare|or|;|-|--|+|,|like|//|/|%|#";
    String[] badStrs = badStr.split("\\|");
    for (int i = 0; i < badStrs.length; i++) {
      if (str.indexOf(badStrs[i]) >= 0) {
        return true;
      }
    }
    return false;
  }
}