java 在javascript中创建json对象并将其发送到servlet
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Creating json object in javascript and sending it to servlet
提问by shabbir.rang
i am creating json object to save data and then sending it to the servlet. But when i try to retrieve the object and display its contents in java servlet, it throws me an error saying " A JSONObject text must begin with '{' at 1 [character 2 line 1]". I do not know how to display the json object in java which is been sent from javascript. Here's what i am doing:
我正在创建 json 对象来保存数据，然后将其发送到 servlet。但是，当我尝试检索对象并在 java servlet 中显示其内容时，它向我抛出一个错误，提示“JSONObject 文本必须以 '{' at 1 [character 2 line 1]”开头。我不知道如何在从 javascript 发送的 java 中显示 json 对象。这是我在做什么：
Javascript Code:
Javascript代码：
var arrayOfObjects = [];
arrayOfObjects.push({"divid":imageinc,"xCordinates":Xcord,"yCordinates":Ycord,"Height":canvasWidth,"Width":canvasHeight, "PageNo":pageNum});
Displaying Javascript contents:
显示 Javascript 内容：
for (var i = 0; i < arrayOfObjects.length; i++) {
var object = arrayOfObjects[i];
for (var property in object) {
alert(property + '=' + object[property]);
}
}
Sending object to servlet with jquery Ajax:
使用 jquery Ajax 将对象发送到 servlet：
var param = 'objarray=' +arrayOfObjects;
$.ajax({
url: '/ProjectName/finalXmlServGen',
type: 'POST',
dataType: 'json',
data: param,
success: function(result) {
alert('SUCCESS');
}
});
I get success message once i call the ajax. Now, i am receiving this object in servlet as:
一旦我调用 ajax，我就会收到成功消息。现在，我在 servlet 中接收这个对象为：
String objarray = request.getParameter("objarray").toString();
try {
JSONObject jsonObj = new JSONObject(objarray);
String xmlString= XML.toString(jsonObj);
System.out.println("JSON to XML: " + xmlString);
} catch (JSONException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
The message i see in my console is the error " A JSONObject text must begin with '{' at 1 [character 2 line 1]". How do i parse the object and form an xml or string?
我在控制台中看到的消息是错误“JSONObject 文本必须以 '{' at 1 [character 2 line 1]”开头。我如何解析对象并形成一个 xml 或字符串？
回答by Denys Séguret
What you build isn't a "JSON object", but a plain javascript object.
您构建的不是“JSON 对象”，而是一个普通的 javascript 对象。
You must encode your object in JSON :
您必须在 JSON 中对您的对象进行编码：
var param = '?objarray=' + JSON.stringify(arrayOfObjects);
$.ajax({
url: '/ProjectName/finalXmlServGen'+param,
type: 'POST',
dataType: 'json',
success: function(result) {
alert('SUCCESS');
}
});
Or you may let jQuery do the encoding :
或者您可以让 jQuery 进行编码：
$.ajax({
url: '/ProjectName/finalXmlServGen',
type: 'POST',
dataType: 'json',
data: {objarray: arrayOfObjects}
success: function(result) {
alert('SUCCESS');
}
});
回答by Gimby
On the Java side of things you need to convert the JSON array to a Java POJO bean first to be able to (easily) do something with it. There are multiple APIs to do this; Google GSON and Hymanson are two possibilities.
在 Java 方面，您首先需要将 JSON 数组转换为 Java POJO bean，以便能够（轻松）使用它做一些事情。有多个 API 可以做到这一点；Google GSON和Hymanson是两种可能。
Hymanson is used internally by Jersey, the reference implementation of the JAX-RS API; it works very well in my experience.
Hymanson 由 Jersey 内部使用，JAX-RS API 的参考实现；根据我的经验，它非常有效。
