String sql = "delete from table1 where id = " + "id";

?1001 or  1 = 1?

String sql = "delete from table1 where id = 1001 or 1 = 1";

delete from table1 where id= ?

import org.springframework.context.annotation.Configuration;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
import java.util.Enumeration;
/**
 * @Description: sql防注入過濾器
 */
@WebFilter(urlPatterns = "/*",filterName = "sqlFilter")
@Configuration
public class SqlFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {}
    /**
     * @description sql注入過濾
     */
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        ServletRequest request = servletRequest;
        ServletResponse response = servletResponse;
        // 獲得所有請求參數名
        Enumeration<String> names = request.getParameterNames();
        String sql = "";
        while (names.hasMoreElements()){
            // 得到參數名
            String name = names.nextElement().toString();
            // 得到參數對應值
            String[] values = request.getParameterValues(name);
            for (int i = 0; i < values.length; i++) {
                sql += values[i];
            }
        }
        if (sqlValidate(sql)) {
            //TODO 這里直接拋異常處理，前后端交互項目中，請把錯誤信息按前后端"數據返回的VO"對象進行封裝
            throw new IOException("您發(fā)送請求中的參數中含有非法字符");
        } else {
            filterChain.doFilter(request,response);
        }
    }
    /**
     * @description 匹配效驗
     */
    protected static boolean sqlValidate(String str){
        // 統(tǒng)一轉為小寫
        String s = str.toLowerCase();
        // 過濾掉的sql關鍵字，特殊字符前面需要加\\進行轉義
        String badStr =
                "select|update|and|or|delete|insert|truncate|char|into|substr|ascii|declare|exec|count|master|into|drop|execute|table|"+
                        "char|declare|sitename|xp_cmdshell|like|from|grant|use|group_concat|column_name|" +
                        "information_schema.columns|table_schema|union|where|order|by|" +
                        "'\\*|\\;|\\-|\\--|\\+|\\,|\\//|\\/|\\%|\\#";
        //使用正則表達式進行匹配
        boolean matches = s.matches(badStr);
        return matches;
    }
    @Override
    public void destroy() {}
}

if ($request_method !~* GET|POST) { return 444; }
 #使用444錯誤代碼可以更加減輕服務器負載壓力。
 #防止SQL注入
 if ($query_string ~* (\$|'|--|[+|(%20)]union[+|(%20)]|[+|(%20)]insert[+|(%20)]|[+|(%20)]drop[+|(%20)]|[+|(%20)]truncate[+|(%20)]|[+|(%20)]update[+|(%20)]|[+|(%20)]from[+|(%20)]|[+|(%20)]grant[+|(%20)]|[+|(%20)]exec[+|(%20)]|[+|(%20)]where[+|(%20)]|[+|(%20)]select[+|(%20)]|[+|(%20)]and[+|(%20)]|[+|(%20)]or[+|(%20)]|[+|(%20)]count[+|(%20)]|[+|(%20)]exec[+|(%20)]|[+|(%20)]chr[+|(%20)]|[+|(%20)]mid[+|(%20)]|[+|(%20)]like[+|(%20)]|[+|(%20)]iframe[+|(%20)]|[\<|%3c]script[\>|%3e]|javascript|alert|webscan|dbappsecurity|style|confirm\(|innerhtml|innertext)(.*)$) { return 555; }
 if ($uri ~* (/~).*) { return 501; }
 if ($uri ~* (\\x.)) { return 501; }
 #防止SQL注入 
 if ($query_string ~* "[;'<>].*") { return 509; }
 if ($request_uri ~ " ") { return 509; }
 if ($request_uri ~ (\/\.+)) { return 509; }
 if ($request_uri ~ (\.+\/)) { return 509; }
 #if ($uri ~* (insert|select|delete|update|count|master|truncate|declare|exec|\*|\')(.*)$ ) { return 503; }
 #防止SQL注入
 if ($request_uri ~* "(cost\()|(concat\()") { return 504; }
 if ($request_uri ~* "[+|(%20)]union[+|(%20)]") { return 504; }
 if ($request_uri ~* "[+|(%20)]and[+|(%20)]") { return 504; }
 if ($request_uri ~* "[+|(%20)]select[+|(%20)]") { return 504; }
 if ($request_uri ~* "[+|(%20)]or[+|(%20)]") { return 504; }
 if ($request_uri ~* "[+|(%20)]delete[+|(%20)]") { return 504; }
 if ($request_uri ~* "[+|(%20)]update[+|(%20)]") { return 504; }
 if ($request_uri ~* "[+|(%20)]insert[+|(%20)]") { return 504; }
 if ($query_string ~ "(<|%3C).*script.*(>|%3E)") { return 505; }
 if ($query_string ~ "GLOBALS(=|\[|\%[0-9A-Z]{0,2})") { return 505; }
 if ($query_string ~ "_REQUEST(=|\[|\%[0-9A-Z]{0,2})") { return 505; }
 if ($query_string ~ "proc/self/environ") { return 505; }
 if ($query_string ~ "mosConfig_[a-zA-Z_]{1,21}(=|\%3D)") { return 505; }
 if ($query_string ~ "base64_(en|de)code\(.*\)") { return 505; }
 if ($query_string ~ "[a-zA-Z0-9_]=http://") { return 506; }
 if ($query_string ~ "[a-zA-Z0-9_]=(\.\.//?)+") { return 506; }
 if ($query_string ~ "[a-zA-Z0-9_]=/([a-z0-9_.]//?)+") { return 506; }
 if ($query_string ~ "b(ultram|unicauca|valium|viagra|vicodin|xanax|ypxaieo)b") { return 507; }
 if ($query_string ~ "b(erections|hoodia|huronriveracres|impotence|levitra|libido)b") {return 507; }
 if ($query_string ~ "b(ambien|bluespill|cialis|cocaine|ejaculation|erectile)b") { return 507; }
 if ($query_string ~ "b(lipitor|phentermin|pro[sz]ac|sandyauer|tramadol|troyhamby)b") { return 507; }
 #這里大家根據自己情況添加刪減上述判斷參數，cURL、wget這類的屏蔽有點兒極端了，但要“寧可錯殺一千，不可放過一個”。
 if ($http_user_agent ~* YisouSpider|ApacheBench|WebBench|Jmeter|JoeDog|Havij|GetRight|TurnitinBot|GrabNet|masscan|mail2000|github|wget|curl|Java|python) { return 508; }
 #同上，大家根據自己站點實際情況來添加刪減下面的屏蔽攔截參數。
 if ($http_user_agent ~* "Go-Ahead-Got-It") { return 508; }
 if ($http_user_agent ~* "GetWeb!") { return 508; }
 if ($http_user_agent ~* "Go!Zilla") { return 508; }
 if ($http_user_agent ~* "Download Demon") { return 508; }
 if ($http_user_agent ~* "Indy Library") { return 508; }
 if ($http_user_agent ~* "libwww-perl") { return 508; }
 if ($http_user_agent ~* "Nmap Scripting Engine") { return 508; }
 if ($http_user_agent ~* "~17ce.com") { return 508; }
 if ($http_user_agent ~* "WebBench*") { return 508; }
 if ($http_user_agent ~* "spider") { return 508; } #這個會影響國內某些搜索引擎爬蟲，比如：搜狗
 #攔截各惡意請求的UA，可以通過分析站點日志文件或者waf日志作為參考配置。
 if ($http_referer ~* 17ce.com) { return 509; }
 #攔截17ce.com站點測速節(jié)點的請求，所以明月一直都說這些測速網站的數據僅供參考不能當真的。
 if ($http_referer ~* WebBench*") { return 509; }
 #攔截WebBench或者類似壓力測試工具，其他工具只需要更換名稱即可。