mybatis写xml时数字类型千万别用 !=‘‘(不为空串)进行判断的示例详解

<update id="update" parameterType="com.chengfengfeng.test.domain.People">
    update people
    set
    <if test="age!=null and age !=''">
      age=#{age},
    </if>,
    modified = sysdate()
    where user_id = #{userId}
 </update>

<update id="update" parameterType="com.chengfengfeng.test.domain.People">
    update people
    set
    <if test="age!=null">
      age=#{age},
    </if>,
    modified = sysdate()
    where user_id = #{userId}
 </update>

public abstract class OgnlOps implements NumericTypes {
	//省略其他无用代码
  public static double doubleValue(Object value) throws NumberFormatException {
    if (value == null) {
      return 0.0D;
    } else {
      Class c = value.getClass();
      if (c.getSuperclass() == Number.class) {
        return ((Number)value).doubleValue();
      } else if (c == Boolean.class) {
        return (Boolean)value ? 1.0D : 0.0D;
      } else if (c == Character.class) {
        return (double)(Character)value;
      } else {
        String s = stringValue(value, true);
        //这个位置会把'‘空串处理成0
        return s.length() == 0 ? 0.0D : Double.parseDouble(s);
      }
    }
  }
}