ajax查询数据库，服务器传回json字符串，js解析json

来源：互联网发布：java泛型 pdf 编辑：程序博客网时间：2024/06/05 11:36

服务器端获得要查询的东西，查询数据库，将查询的信息，以json字符串的形式返回给浏览器

public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        String departmentID=request.getParameter("departmentID");        DataBaseHandle dataBaseHandle=new DataBaseHandle("commonUser", "common", "jdbc:mysql://127.0.0.1:3306/firstwebsite");        String SQL="select * from speciality where departmentID='"+departmentID+"'";        String json="{'specialities':[";        response.setContentType("text/html; charset=utf-8");        response.setCharacterEncoding("UTF-8");        try {            ResultSet rs=dataBaseHandle.exeuteSQL(SQL);            while(rs.next())            {                json=json+"{'"+"specialityID':'"+rs.getString(1)+"',"+"'SPname':'"+rs.getString(2)+"'},";                System.out.println(rs.getString(1)+rs.getString(2));            }            json=json.substring(0,json.length()-1);            json=json+"]}";            PrintWriter pwriter=response.getWriter();            pwriter.print(json);            rs.close();            dataBaseHandle.closeResourse();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }

js解析json，获得返回的内容

   function updateSpeciality(str)        {            var xmlhttp;            if (str=="")            {                alert("请选择非空的值!");                return;            }            if (window.XMLHttpRequest)            {// code for IE7+, Firefox, Chrome, Opera, Safari                xmlhttp=new XMLHttpRequest();            }            else            {// code for IE6, IE5                xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");            }            xmlhttp.onreadystatechange=function()            {                if (xmlhttp.readyState==4 && xmlhttp.status==200)                {                    var dataObj=eval("("+xmlhttp.responseText+")");//转换为json对象                    for(var o in dataObj.specialities)                    {                        alert(dataObj.specialities[o].specialityID);                        alert(dataObj.specialities[o].SPname);                    }                }            }            xmlhttp.open("GET","/First/servlet/GetMessage?departmentID="+str,true);            xmlhttp.send();        }

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