ajax调用提供重复和意外的输出
这是我的ajax电话：
<script type="text/javascript">
var dataString ={ "EmployeeNum" : 50};
var queryObject="";
var queryObjectLen="";
console.log("loading");
google.load('visualization', '1.0', {'packages':['corechart']});
google.setOnLoadCallback(RequestData);
create function RequestData()
{
$.ajax
(
{
type : 'POST',
asynch :'false',
data: dataString,
url : 'http://localhost:8080/Charts/db',
success : function(data)
{
alert("success");
queryObject = jQuery.parseJSON(data);
queryObjectLen = queryObject.Details.length;
console.log("queryObj: "+queryObject+" Length: "+queryObjectLen);
drawChart();
},
error : function(xhr, type)
{
alert('server error occoured')
}
})
);
function drawChart()
{
console.log("Inside drawChart()");
var arrdata = new google.visualization.DataTable();
arrdata.addColumn('string', 'DeptName');
arrdata.addColumn('number', 'NumberOfEmployees');
for(var i=0; i<queryObjectLen; i++)
{
console.log(queryObject.Details[i].DeptName);
var dept= queryObject.Details[i].DeptName;
var emp = queryObject.Details[i].NumberOfEmployees;
arrdata.addRows([
[dept,parseInt(emp)]
]);
}
var options = {
title: 'Department vs. Number of Employees on Horizontal Axis',
vAxis: {title: 'DeptName', titleTextStyle: {color: 'red'}},
'width':400,
'height':300
};
var option2 = {
title: 'Department vs. Number of Employees on vertical Axis',
hAxis: {title: 'NumberOfEmployees', titleTextStyle: {color: 'blue'}},
'width':400,
'height':300
};
var option3 = {
title: 'Department vs. Number of Employees on Pie Chart',
'width':400,
'height':300
};
var option4 = {
title: 'Department vs. Number of Employees on Line Chart',
'width':400,
'height':300
};
var chart = new google.visualization.BarChart(document.getElementById('chart_div'));//this is altogether a different object
var chart2 = new google.visualization.ColumnChart(document.getElementById('chart_div2'));
var chart3 = new google.visualization.PieChart(document.getElementById('chart_div3'));
var chart4 = new google.visualization.LineChart(document.getElementById('chart_div4'));
chart.draw(arrdata, options);
chart2.draw(arrdata, option2);
chart3.draw(arrdata, option3);
chart4.draw(arrdata, option4);
}
</script>
</head>
<body>
<div id="chart_div" style="width: 400px; height: 300px;"></div>
<div id="chart_div2" style="width: 800px; height: 400px;"></div>
<div id="chart_div3" style="width: 400px; height: 300px;"></div>
<div id="chart_div4" style="width: 400px; height: 500px;"></div>
</body>
</html>
它转到url http://localhost:8080/Charts/db的servlet，并根据传递给它的参数，执行查询。
问题：我的输出和流量控制完全出乎意料。
以下是我在输出中的内容：
servlet的doGet函数如下所示：
问题：
1.为什么我打印了两次查询？
-
为什么我有两次警报？
-
异常会在最外面的块中捕获，然后如何打印查询？
这是我的功能：
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
try
{
List<JSONObject> Details = new LinkedList<JSONObject>();
PrintWriter out = response.getWriter();
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
c = DriverManager.getConnection(dbURL, user, password);
query = "select DeptName, NumberOfEmployees from Departments where 1 = 1";
String Dept = "";
String EmployeeNum= "";
try
{
EmployeeNum = request.getParameter("EmployeeNum");
}
catch(Exception e)
{
System.out.println("error in get param" + e );
}
int NumOfEmp;
try {
NumOfEmp = Integer.parseInt(EmployeeNum);
} catch(NumberFormatException e){
StringBuilder sb = new StringBuilder();
sb.append("Error parsing this EployeeNum: ");
sb.append(EmployeeNum);
e.printStackTrace();
throw new RuntimeException(sb.toString());
}
if (NumOfEmp > 0) {
// add criteria for Age
query += " AND NumberOfEmployees = "+ NumOfEmp ;
}
System.out.println("QUERY ......... " + query);
pst = c.prepareStatement(query);
rs = pst.executeQuery();
resobj = new JSONObject();
while(rs.next())
{
String DeptName = rs.getString(1);
System.out.println("name " + DeptName);
int NumberOfEmployees = rs.getInt(2);
System.out.println("num " + NumberOfEmployees );
obj = new JSONObject();
obj.put("DeptName", DeptName);
obj.put( "NumberOfEmployees",NumberOfEmployees );
Details.add(obj);
}
resobj.put("Details", Details);
out.write(resobj.toString());
}
catch(Exception e)
{
System.out.println("Exception aayi: " + e);
}
}
编辑以回答：
2015-03-27T21:35:46.964+0530|INFO: QUERY ......... select DeptName, NumberOfEmployees from Departments where 1 = 1 AND NumberOfEmployees = 50
2015-03-27T21:35:47.685+0530|SEVERE: SLF4J: The requested version 1.6 by your slf4j binding is not compatible with [1.5.5, 1.5.6]
2015-03-27T21:35:47.685+0530|SEVERE: SLF4J: See http://www.slf4j.org/codes.html#version_mismatch for further details.
2015-03-27T21:36:00.325+0530|INFO: Exception aayi: java.lang.RuntimeException: Error parsing this EployeeNum: null
2015-03-27T21:36:00.325+0530|SEVERE: java.lang.NumberFormatException: null
2 个答案:
答案 0 :(得分：0)
- 可能是你的
setOnLoadCallback被叫了两次。 - 见1
- 您的代码不会抛出异常，因此会调用以下语句：
System.out.println("QUERY ......... " + query);
答案 1 :(得分：0)
SERVLET
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
try
{
List<JSONObject> Details = new LinkedList<JSONObject>();
PrintWriter out = response.getWriter();
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
c = DriverManager.getConnection(dbURL, user, password);
query = "select DeptName, NumberOfEmployees from Departments where 1 = 1";
String Dept = "";
int EmployeeNum = 0;
try
{
EmployeeNum = request.getParameter("EmployeeNum");
}
catch(Exception e)
{
System.out.println("error in get param" + e );
}
int NumOfEmp;
try {
NumOfEmp = EmployeeNum;
} catch(NumberFormatException e){
StringBuilder sb = new StringBuilder();
sb.append("Error parsing this EployeeNum: ");
sb.append(EmployeeNum);
e.printStackTrace();
throw new RuntimeException(sb.toString());
}
if (NumOfEmp > 0) {
// add criteria for Age
query += " AND NumberOfEmployees = "+ NumOfEmp ;
}
System.out.println("QUERY ......... " + query);
pst = c.prepareStatement(query);
rs = pst.executeQuery();
resobj = new JSONObject();
while(rs.next())
{
String DeptName = rs.getString(1);
System.out.println("name " + DeptName);
int NumberOfEmployees = rs.getInt(2);
System.out.println("num " + NumberOfEmployees );
obj = new JSONObject();
obj.put("DeptName", DeptName);
obj.put( "NumberOfEmployees",NumberOfEmployees );
Details.add(obj);
}
resobj.put("Details", Details);
out.write(resobj.toString());
}
catch(Exception e)
{
System.out.println("Exception aayi: " + e);
}
}
JS
script type="text/javascript">
var dataString ={ "EmployeeNum" : 50};
var queryObject="";
var queryObjectLen="";
console.log("loading");
google.load('visualization', '1.0', {'packages':['corechart']});
google.setOnLoadCallback(RequestData);
function RequestData(){
$.ajax({
type : 'POST',
asynch :'false',
data: dataString,
url : 'http://localhost:8080/Charts/db',
success : function(data)
{
alert("success");
queryObject = jQuery.parseJSON(data);
queryObjectLen = queryObject.Details.length;
console.log("queryObj: "+queryObject+" Length: "+queryObjectLen);
drawChart();
},
error : function(xhr, type)
{
alert('server error occoured')
}
})
}
function drawChart(){
console.log("Inside drawChart()");
var arrdata = new google.visualization.DataTable();
arrdata.addColumn('string', 'DeptName');
arrdata.addColumn('number', 'NumberOfEmployees');
for(var i=0; i<queryObjectLen; i++)
{
console.log(queryObject.Details[i].DeptName);
var dept= queryObject.Details[i].DeptName;
var emp = queryObject.Details[i].NumberOfEmployees;
arrdata.addRows([
[dept,parseInt(emp)]
]);
}
var options = {
title: 'Department vs. Number of Employees on Horizontal Axis',
vAxis: {title: 'DeptName', titleTextStyle: {color: 'red'}},
'width':400,
'height':300
};
var option2 = {
title: 'Department vs. Number of Employees on vertical Axis',
hAxis: {title: 'NumberOfEmployees', titleTextStyle: {color: 'blue'}},
'width':400,
'height':300
};
var option3 = {
title: 'Department vs. Number of Employees on Pie Chart',
'width':400,
'height':300
};
var option4 = {
title: 'Department vs. Number of Employees on Line Chart',
'width':400,
'height':300
};
var chart = new google.visualization.BarChart(document.getElementById('chart_div'));//this is altogether a different object
var chart2 = new google.visualization.ColumnChart(document.getElementById('chart_div2'));
var chart3 = new google.visualization.PieChart(document.getElementById('chart_div3'));
var chart4 = new google.visualization.LineChart(document.getElementById('chart_div4'));
chart.draw(arrdata, options);
chart2.draw(arrdata, option2);
chart3.draw(arrdata, option3);
chart4.draw(arrdata, option4);
}
</script>
</head>
<body>
<div id="chart_div" style="width: 400px; height: 300px;"></div>
<div id="chart_div2" style="width: 800px; height: 400px;"></div>
<div id="chart_div3" style="width: 400px; height: 300px;"></div>
<div id="chart_div4" style="width: 400px; height: 500px;"></div>
</body>
</html>
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