标签：att vat 传输 int name out 集合 json对象 one
JSON数据格式
JSON 是一种数据传输格式
JSON 是要结合 Ajax(异步请求) 使用的,
在后端一般会将一个对象转换成 JSON 格式的数据之后返回给客户端,
可以自己写工具转换, 也可以使用第三方工具 : gjson, fastjson 等
Demo: JSON 表示一个数字
2.90
Demo: JSON 表示一个字符串
"Hello world"
Demo: JSON 表示一个对象
{
"name":"smith".
"age":30,
"sex":"男"
}
Demo: JSON对象的属性可以是对象
{
"name":"smith".
"age":28,
"sex":"男"
"school":{
"sname":"南京大学".
"address":"南京市鼓楼区汉口路22号"
}
}
Demo: JSON 格式表示数组
保存名字的数组: ["张三","李四","王五"]
保存雇员的信息: ["smith",1001,"clerck",7788,2000.00,200.0]
[
["smith",1001,"clerck",7788,2000.00,200.0]
["smith",1001,"clerck",7788,2000.00,200.0]
["smith",1001,"clerck",7788,2000.00,200.0]
]
[
{"name":"smith","empno":1001,"job":"clerck","sal":9000.00,"comm":5000.00},
{"name":"smith","empno":1001,"job":"clerck","sal":9000.00,"comm":5000.00},
{"name":"smith","empno":1001,"job":"clerck","sal":9000.00,"comm":5000.00},
]
Demo: 对象数组
在一个数组保存多个 json 对象 (在一个数组中保存多个对象)
[
{
"title":"Java 开发",
"edition":3,
"author":["smith","张三","李四"]
},
{
"title":"Web 开发",
"edition":3,
"author":["Allen","王五","赵六"]
}
]
二维数组保存
[
["Java 开发",3,["smith","张三","李四"]],
["Web 开发",3["Allen","王五","赵六"]]
]
Demo: 将一个对象转换成 json 数据
@WebServlet(urlPatterns= {"/emp/*"})
public class EmpServlet extends BaseServlte{
private IEmpService empservice = (IEmpService)ServiceFactory.getInstance(EmpServiceImpl.class);
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String pathInfo = req.getPathInfo();
try {
if ("/getOne".equals(pathInfo))) {
this.getOne(req, resp);
}
} catch (Exception e) {
e.printStackTrace();
}
}
//将一个对象转换成 json 数据输出到客户端
public void getOne(HttpServletRequest req, HttpServletResponse resp) throws Exception {
//获取要查询的雇员编号
Integer id = Integer.parseInt(req.getParameter("id"));
Emp emp = empservice.findEmpById(id);
//将查询到的对象转换成json 数据格式
String jsonEmp = JSON.toJSONString(emp);
System.out.println(jsonEmp);
PrintWriter out = null;
out=resp.getWriter();
//将转换后的 json 数据输出到客户端
out.print(jsonEmp);
out.close();
}
}
Demo: 将一个 List 集合转换为 json 数据
@WebServlet(urlPatterns= {"/emp/*"})
public class EmpServlet extends BaseServlte{
private IEmpService empservice = (IEmpService)ServiceFactory.getInstance(EmpServiceImpl.class);
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String pathInfo = req.getPathInfo();
try {
if ("/getOne".equals(pathInfo))) {
this.getOne(req, resp);
}else if ("/jsonList".equals(pathInfo)) {
this.jsonList(req, resp);
}
} catch (Exception e) {
e.printStackTrace();
}
}
//模糊分页查询: 将一个 List 集合转换为 json 数据
public void jsonList(HttpServletRequest req, HttpServletResponse resp) throws Exception {
String kw = req.getParameter("kw");
Integer cp = Integer.parseInt(req.getParameter("cp"));
Integer ls = Integer.parseInt(req.getParameter("ls"));
//将 List 集合转换为 json 数据格式
String jsonListEmp = JSON.toJSONString(this.empservice.findAllSplit(kw, cp, ls).get("emplist"));
System.out.println(jsonListEmp);
}
}
Demo: 将Map 数据转换为 json 数据
转换 Mao 集合则是键值对的形式
@WebServlet(urlPatterns= {"/emp/*"})
public class EmpServlet extends BaseServlte{
private IEmpService empservice = (IEmpService)ServiceFactory.getInstance(EmpServiceImpl.class);
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String pathInfo = req.getPathInfo();
try {
if ("/getOne".equals(pathInfo))) {
this.getOne(req, resp);
}else if ("/jsonList".equals(pathInfo)) {
this.jsonList(req, resp);
} else if ("/jsonMap".equals(pathInfo)) {
this.jsonMap(req, resp);
}
} catch (Exception e) {
e.printStackTrace();
}
}
//模糊分页查询: 将一个 Map 集合转换为 json 数据
public void jsonMap(HttpServletRequest req, HttpServletResponse resp) throws Exception {
String kw = req.getParameter("kw");
Integer cp = Integer.parseInt(req.getParameter("cp"));
Integer ls = Integer.parseInt(req.getParameter("ls"));
//将 Map 集合转换为 json 数据格式
String jsonMapEmp = JSON.toJSONString(this.empservice.findAllSplit(kw, cp, ls));
System.out.println(jsonMapEmp);
}
}
标签：att vat 传输 int name out 集合 json对象 one
原文地址：https://www.cnblogs.com/yslf/p/10846487.html
