ajax中解析json数据的各种方法(返回类型为json或text)
对于json
从servlet中返回给ajax的dataType类型可以是text,json
1、在servlet中构造json文本，再response.getWriter()给ajax，返回json text文本
servlet中，一面一段写在doPost或doGet中，但要相互调用this.doGet(rq,rs)或this.doGet(rq,rs)
用jquery的ajax异步提交，数据必须有一个明确的ID（不再是name，和form提交方式不一样），比如下面jsp中的username就是ID
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;;charset=utf-8");//注意要是返回文本，那么类型为text/html
String username1 = request.getParameter("username");
String username = URLDecoder.decode(username1,"UTF-8");
StringBuilder message = new StringBuilder("");
if(username!=null)
{
EmployeeDao employeeDao = new EmployeeDao();
ArrayList employees = employeeDao.select(username);
if(employees!=null&&employees.size()>0)
{
message.append("{\"emp\":[");
// for(Employee employee: employees)
// {
//对于这样的集合类型的数据，不推荐使用构造字符串的方式来构造json数组
// System.out.println(employee.getEmpNo());
// message.append("{\"eno\":"+employee.getEmpNo()+","+"\"ename\""+employee.getEname()+"}");
// }
//为了说明构造json文本，仅使用2条记录
message.append("{\"eno\":"+"\""+employees.get(0).getEmpNo()+"\""+","+"\"ename\""+":"+"\""+employees.get(0).getEname()+"\""+"}");
message.append(",");
message.append("{\"eno\":"+"\""+employees.get(1).getEmpNo()+"\""+","+"\"ename\""+":"+"\""+employees.get(1).getEname()+"\""+"}");
message.append("]}");
}
PrintWriter out = response.getWriter();
out.println(new String(message));
}
在ajax中
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
Insert title here
输入用户名
2、用字符串构造json数据，返回json对象
servlet中返回application/json
ajax中dateType用json
servlet代码，和上面没有什么区别，主要是把contentype改为application/json
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("application/json;charset=utf-8");
String username1 = request.getParameter("username");
String username = URLDecoder.decode(username1,"UTF-8");
StringBuilder message = new StringBuilder("");
if(username!=null)
{
EmployeeDao employeeDao = new EmployeeDao();
ArrayList employees = employeeDao.select(username);
if(employees!=null&&employees.size()>0)
{
message.append("{\"emp\":[");
// for(Employee employee: employees)
// {
//对于这样的集合类型的数据，不推荐使用构造字符串的方式来构造json数组
// System.out.println(employee.getEmpNo());
// message.append("{\"eno\":"+employee.getEmpNo()+","+"\"ename\""+employee.getEname()+"}");
//
// }
//为了说明构造json文本，仅使用2条记录
message.append("{\"eno\":"+"\""+employees.get(0).getEmpNo()+"\""+","+"\"ename\""+":"+"\""+employees.get(0).getEname()+"\""+"}");
message.append(",");
message.append("{\"eno\":"+"\""+employees.get(1).getEmpNo()+"\""+","+"\"ename\""+":"+"\""+employees.get(1).getEname()+"\""+"}");
message.append("]}");
}
System.out.println(message);
PrintWriter out = response.getWriter();
out.println(new String(message));
}
}
jsp中代码
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
Insert title here
输入用户名
3、返回json对象，但是在servlet中直接用把一个数组或集合转换成为json类型的数组对象
如果抛出 NestableRuntimeException异常，
说明没有导包，注意导入相关的jar包commons-beanutils-1.8.3
commons-lang-2.6 (注：导入最新的 3.1 版本会继续报如下错误)
commons-collections-3.2.1
commons-logging-1.1.1
ezmorph-1.0.6
参考：http://blog.csdn.net/wugewuge/article/details/8074272在servlet写法
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("application/json;charset=utf-8");
String username1 = request.getParameter("username");
String username = URLDecoder.decode(username1,"UTF-8");
StringBuilder message = new StringBuilder("");
if(username!=null)
{
EmployeeDao employeeDao = new EmployeeDao();
ArrayList employees = employeeDao.select(username);
JSONArray jsonArray=JSONArray.fromObject(employees);
PrintWriter out = response.getWriter();
out.println(jsonArray.toString());//在jsp中的数据类型dataType："json"
}
} 在jsp中
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
Insert title here
输入用户名