java动态生成SQL中的where条件

在编写接口的时候，查询关系型数据库是经常有的事情，如果我们不用hibernate，也不想写大量无聊的SQL，那该怎么办？

其实用反射的方式获取表的表名和字段名非常容易，但是拼接where条件则比较难，我尝试了一下，也是可以做到的。

代码有些冗长，还有待改进

@AllArgsConstructor
@Data
public class Condition {

    private String conditionName;
    private String operator;
    private Boolean isString;
    private Object conditionValue;


    /**
     * 构建有关键字占位符的SQL条件语句
     * @param conditions
     * @return
     */
    public static String toSql(List<Condition> conditions) {
        StringBuilder sb = new StringBuilder("where ");
        int size = conditions.size();
        for (int i = 0; i < size; i++) {
            Condition condition = conditions.get(i);
            String conditionName = condition.getConditionName();
            Object conditionValue = condition.getConditionValue();
            sb.append(conditionName)
                    .append(condition.getOperator());
            boolean conditionType = condition.getIsString();
            if (conditionType) {
                sb.append(String.format(" '%s' ",conditionValue));
            } else {
                sb.append(String.format(" %s ",conditionValue));
            }
            if (i != size - 1) {
                sb.append(" and ");
            }

        }
        return sb.toString();
    }

    public static void main(String[] args) {
        List<Condition> conditions = new ArrayList<>();
        Condition bizmonth = new Condition("bizmonth", "=", true,"2021-06");
        Condition tenant_code = new Condition("tenant_code", "=", false,"0385");
        Condition create_time = new Condition("create_time", ">", true,"2021-06-09 10:08:00");
        conditions.add(bizmonth);
        conditions.add(tenant_code);
        conditions.add(create_time);
        String sql = toSql(conditions);
        System.out.println(sql);


    }
}

 

 

结果：
where bizmonth= '2021-06'  and tenant_code= 0385  and create_time> '2021-06-09 10:08:00'