实现ajax和json的调用

$(function () {

$('#tfeestype').change(function(){

var p1=$(this).children('option:selected').val();//这就是selected的值

var aj = $.ajax( {

url:'http://localhost:8088/grassinfo-web/api/first_statistic_change!ajaxReturn.action',// 跳转到 action

<!--data为传入后台action的参数，name为传入的参数-->

data:{

name:p1

},

type:'post',

cache:false,

dataType:'json',

<!--data是后台json返回值，与上面data不同，可任意取名-->

success:function(data) {

if(data!=null){

var str = "";

str += "<option value=\"null\" >请选择</option>";

$.each(data, function(i, n) {

str += "<option value=\""+ n.name +"\" >"+ n.name +"</option>";

});

$("#tfeeCounty").html(str);

}

}

public String ajaxReturn(){

String cityName = getReq().getParameter("name");

Object[] objdate = null;

UserData ud = new UserData();

StringBuffer ajaxSql = new StringBuffer();

ajaxSql.append("select res.country,res.mm from(select city, country, count(1) mm "

+" from (select substr(t.address, "

+" instr(t.address, '_', 1, 1) + 1, "

+" instr(t.address, '_', 1, 2) - "

+" instr(t.address, '_', 1, 1) - 1) city, "

+" substr(t.address, "

+" instr(t.address, '_', 1, 2) + 1, "

+" instr(t.address, '_', 1, 3) - "

+" instr(t.address, '_', 1, 2) - 1) country "

+"from tuser t "

+"where t.address is not null "

+"and t.address like '%浙江省%' "

+"and t.user_state = 1) t "

+"group by t.city, country)res where city='"+cityName+"'");

Map<String, UserData> ajaxMap = jdbcTemplate.query(ajaxSql.toString(),

objdate, new ResultSetExtractor<Map<String, UserData>>() {

@Override

public Map<String, UserData> extractData(ResultSet rs)

throws SQLException, DataAccessException {

int mapKey=0;

Map<String, UserData> map = new LinkedHashMap<String, UserData>();

try {

while (rs.next()) {

String county = rs.getString("COUNTRY");

String sum = rs.getString("MM");

UserData udData = new UserData();

udData.setName(county);

udData.setNum(Integer.valueOf(sum));

map.put(String.valueOf(mapKey), udData);

mapKey++;

}

//System.out.println(com.alibaba.fastjson.JSON.toJSONString(map));

} catch (Exception e) {

logger.error("getStatisticStat", e);

// e.printStackTrace();

}

return map;

}

});

getRes().setCharacterEncoding("UTF-8");

PrintWriter out = null;

try {

out = getRes().getWriter();

out.print(com.alibaba.fastjson.JSON.toJSONString(ajaxMap));

} catch (IOException e) {

e.printStackTrace();

} finally {

if (out != null) {

out.flush();

out.close();

}

}

return null;

}