❶ java后台怎样获取前台的json数据
一般是这样的，先缺枝将对象类型（在js中json就是一个对象），使用json.js（有些浏览器支持，有些需要引入）的方法：
JSON.parse(jsonstr); //可伏哪敏以将json字符串缓余转换成json对象
JSON.stringify(jsonobj); //可以将json对象转换成json对符串
的第二个转换成字符串，然后把字符串当作一个参数的值再为其添加一个key然后以key/value的格式将数据传到后台。
之后后台使用request.getParameter();的方式得到json数据。
❷ java如何返回json格式
例如：
Student st1 = new Student(1, "dg", 18, new Date());
Student st2 = new Student(2, "dg", 18, new Date());
Student st3 = new Student(3, "dg", 18, new Date());
Student st4 = new Student(4, "dg", 18, new Date());
Student st5 = new Student(5, "dg", 18, new Date());
List li = new ArrayList();
JSONObject JO1 = new JSONObject(st1);
JSONObject JO2 = new JSONObject(st2);
JSONObject JO3 = new JSONObject(st3);
JSONObject JO4 = new JSONObject(st4);
JSONObject JO5 = new JSONObject(st5);
li.add(JO1);
li.add(JO2);
li.add(JO3);
li.add(JO4);
li.add(JO5);
JSONArray Ja = new JSONArray(li);
Map ma = new HashMap();
ma.put("Result", "OK");
ma.put("Records", Ja);
JSONObject js = new JSONObject(ma);
out.print(js);
返回结果：
{"Result":"OK","Records":[{"recordDate":"Fri Dec 16 17:54:39 CST 2011","name":"dg","age":18,"personId":1},{"recordDate":"Fri Dec 16 17:54:39 CST 2011","name":"dg","age":18,"personId":2},{"recordDate":"Fri Dec 16 17:54:39 CST 2011","name":"dg","age":18,"personId":3},{"recordDate":"Fri Dec 16 17:54:39 CST 2011","name":"dg","age":18,"personId":4},{"recordDate":"Fri Dec 16 17:54:39 CST 2011","name":"dg","age":18,"personId":5}]}