>> 一行代码即可使页面适应手机屏幕，具体介绍可参考链接，很好用

>>

> 3. rem

>> rem之后好像没怎么用，以后有更多了解再来补充

>>

> 4. 微信JSSDK开发文档

>> 这个不太懂具体作用，以后了解了再来补充(..›ᴗ‹..)

>>

>

# 2. AJAX

>

> 之前开发中也有用到，经常用到，在这里总结一下，主要为代码举例(两个select级联)：

>

> 1. html:

请选择 ${value}

>>

> 2. js:

function getCRList() {

var $tblist = $(“#tblist”).val();

$('#tblist').val($tblist); //让第一个下拉框保持显示选中的值

$('#crlist').html(""); //把ci内容设为空

var $crValue = $('#crlist');

$crValue.append('请选择');

$.ajax({

url : "/showCRList",

type : "GET",

dataType : "json",

async: false,//default is true ,and if it is true,the flag in ajax cant return

//cant be false because in chinese it means "异步"

data: {

tblist : $tblist //传给后台的值

},

success : function(data, textStatus, jqXHR) { //data为从后台取回的值

if (data && data.length > 0) {

var html = [];

for (var i = 0; i < data.length; i++) {

html.push(''+data[i]+'');

}

$crValue.append(html.join(''));

}

}

});

}

>>

> 3. Servlet

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

response.setContentType("application/json"); //使用json格式

response.setCharacterEncoding("UTF-8");

request.setCharacterEncoding("UTF-8");

tblist = (String) request.getParameter("tblist"); //不可以用getAttribute...

rtn2 = crUtil.getCRList(tblist);

PrintWriter writer = response.getWriter();

JSONArray array = JSONArray.fromObject(rtn2);

writer.append(array.toString());

}

>>

> 4. CRUtil

public List getCRList(String tbname){

List rtn2 = new ArrayList();

String sql2="SELECT NAME FROM crinfo WHERE tbId = (SELECT id FROM tbinfo WHERE NAME = '" + tbname + "')";

rtn2 = dbutil.getListInfo(sql2);

return rtn2;

}

> 5. DatabaseUtil

/*

* 获得列表信息

*/

public List getListInfo(String sql){

List rsList = new ArrayList();

String result = null;

Connection conn=null;

String url="jdbc:mysql://localhost:3306/person_seat_detection";

String user_="root";

String psd="123456";

try {

Class.forName("com.mysql.jdbc.Driver");

conn=DriverManager.getConnection(url,user_,psd);

PreparedStatement ps=

conn.prepareStatement(sql);

ResultSet rs=ps.executeQuery();

while(rs.next()){

rsList.add(rs.getString(1));

}

} catch (Exception e) {

System.out.println(e.getMessage());

}finally {

if (conn!=null) {

try {

conn.close();

} catch (Exception e2) {

}

}

}

return rsList;

}

>>

> 6. web.xml配置

>>

crServlet

com.imooc.servlet.CRServlet

crServlet

/showCRList

```

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