小知识点集锦

1：建立数据库表的时候，
注解标签：
@Entity
@Table(name=”表名”)
//生成的ID为随机数
@Id
@GeneratedValue(generator = “system-uuid”)
@GenericGenerator(name = “system-uuid”, strategy = “uuid”)
@Column(length = 32)

2.查询数据库语句：
string hql=“from 表的model where 列名=？”

3.js获取选中单选框按钮的value
var check=$(“input[name=”单选框的name值”]:checked”).val();

4.map

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<h1 align="center">问卷调查</h1>    
<script type="text/javascript">
    var j=0;
</script>
<form readonly="true">
<c:if test="${!empty investigateAnswerList }">
        <c:forEach items="${investigateAnswerList }" varStatus="status" var="investigateAnswer">
        <input type="hidden" id="iqqid_${status.index+1}" value=${investigateAnswer.answer }> 
                <div>问题：${investigateAnswer.question.question }
                    <br> 
                    <input name="iqqname_${status.index+1}" type="radio" value="optionA" readonly="true" disabled/>A：${investigateAnswer.question.optionA} 
                    <input name="iqqname_${status.index+1}" type="radio" value="optionB" readonly="true" disabled/>B：${investigateAnswer.question.optionB} 
                    <br>
                    <input name="iqqname_${status.index+1}" type="radio" value="optionC" readonly="true" disabled/>C：${investigateAnswer.question.optionC} 
                    <input name="iqqname_${status.index+1}" type="radio" value="optionD" readonly="true" disabled/>D：${investigateAnswer.question.optionD} 
                </div>
                <script language="javascript">
                $(function(){
                    j++;
                    var returnstr =$("#iqqid_"+j).attr("value");//获取单选框的value值
                    var name="iqqname_"+${status.index+1};             
                    var radios = document.getElementsByName(name);//获取单选框
                    for(i=0;i<radios.length;i++){          //循环单选框
                    if(radios[i].value == returnstr)   //判断是否等于单选框的值
                    radios[i].checked = true;          //选中单选框
                    } 
                });
                </script>
        </c:forEach>
    </c:if>

</form>

6.spilt(“字符串”)根据字符串截取值；

7，request.setAttribute（“字符串名”，取得的对象），将对象传到字符串，送到前台。

8.@ResponseBody注解标签，将数据转化为JSon。