JSON简介：
JSON:JavaScriptObjectNotation(JavaScript 对象表示法)
JSON 是存储和交换文本信息的语法。类似 XML。
JSON 比 XML 更小、更快，更易解析。
JSON 文本格式在语法上与创建 JavaScript 对象的代码相同。
由于这种相似性，无需解析器，JavaScript 程序能够使用内建的 eval() 函数，用 JSON 数据来生成原生的 JavaScript 对象。
1.新建一个实体类（student）.
public class Student {private int number;private String name;private String address;public Student(){}public Student(int number, String name, String address) {this.number = number;this.name = name;this.address = address;}public int getNumber() {return number;}public void setNumber(int number) {this.number = number;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;};}
2.新建Dao接口，给出两个方法（向数据库添加数据和取出数据）。
import java.util.List;import org.json.JSONObject;public interface Dao {public boolean insertDate(Student stu);public List<JSONObject> selectAll();}
3.实现两个方法
import java.sql.Connection;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.json.JSONObject;import .yong.Dao.Dao;import .yong.Util.DBConnection;public class Student implements Dao {@Overridepublic boolean insertDate(.yong.pro.Student stu) {Connection con=DBConnection.getDBConnectionInstance().getDBConnection();String sql="insert into student (number,name,address) value(?,?,?)";try {java.sql.PreparedStatement ps=con.prepareStatement(sql);ps.setInt(1, stu.getNumber());ps.setString(2, stu.getName());ps.setString(3, stu.getAddress());int i=ps.executeUpdate();if(i>0){return true;}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return false;}@Overridepublic List<JSONObject> selectAll() {Connection con=DBConnection.getDBConnectionInstance().getDBConnection();List<JSONObject> list=new ArrayList<JSONObject>();String sql="select number,name,address from student";try {ResultSet rs=con.createStatement().executeQuery(sql);while(rs.next()){Map<String, Object> map=new HashMap<String, Object>();map.put("number", rs.getInt(1));map.put("name",rs.getString(2));map.put("address", rs.getString(3));list.add(new JSONObject(map));}} catch (SQLException e) {e.printStackTrace();}return list;}}
4.新建用于表单提交的html文件（为方便提交和获取放在一块）。
<!DOCTYPE html><html><head><title>show3.html</title><meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="this is my page"><meta http-equiv="content-type" content="text/html; charset=UTF-8"><!--<link rel="stylesheet" type="text/css" href="./styles.css">--><script type="text/javascript" src="js/student3.js"></script></head><body><!-- json表单注册 -->><form action="" method="post"></form>编号：<input type="text" name="number" id="number"/><br>姓名：<input type="text" name="name" id="name"/><br>住址：<input type="text" name="address" id="address"/><br><input type="button" value="提交" οnclick="insertStu()"/></form><!-- 读取数据 --><input type="button" οnclick="insertStu()" value="获取信息"><table border="1px" width="100%" align="center"><thead><tr><th>学号</th><th>姓名</th><th>住址</th></tr></thead><tbody id="main" align="center"></tbody></table></body></html>
5.新建js文件
//浏览器协议var xmlHttp;function creatXMLHttpRequest(){if(window.XMLHttpRequest){xmlHttp=new XMLHttpRequest();}else if(window.ActiveXObject){xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");}}//触发函数function insertStu(){//向浏览器发出异步请求creatXMLHttpRequest();//获取表单数据var number=document.getElementById("number").value;var name=document.getElementById("name").value;var address=document.getElementById("address").value;//若将多个表单数据转换成json格式，前提先把这些数据存储到js的对象中var jsObject=new fromObject(number,name,address);//将对象转换成JSON格式的数据json=JSON.stringify(jsObject);alert(json);//开启对服务器端的连接var url="insertServlet";xmlHttp.open("post", url, true);//向服务器发送请求，将json格式的数据传输到servlet中xmlHttp.send(json);//回调匿名函数,接受服务器传来的数据xmlHttp.onreadystatechange=function (){//判断服务器响应状态和请求状态 200表示响应ok 4表示请求完成alert("1");if(xmlHttp.status==200 && xmlHttp.readyState==4){var msg=xmlHttp.responseText;//javascript能够使用内置的eval()函数生成javascript对象var stus=eval("("+msg+")");tbody=document.getElementById("main");for ( var i = 0; i < stus.length; i++) {var stu = stus[i];alert(stu.name);var tr=document.createElement("tr");var td1=document.createElement("td");td1.innerHTML=stu.number;//td1.appendChild(document.createTextNode(stu.number));tr.appendChild(td1);var td2=document.createElement("td");//td2.appendChild(document.createTextNode(stu.name));td2.innerHTML=stu.name;tr.appendChild(td2);var td3=document.createElement("td");//td3.appendChild(document.createTextNode(stu.address));td3.innerHTML=stu.address;tr.appendChild(td3);tbody.appendChild(tr);}}};}//相当于我们的实体类，转化js对象时调用function fromObject(number,name,address){this.number=number;this.name=name;this.address=address;}
6.Servlet
import java.io.BufferedReader;import java.io.IOException;import java.io.PrintWriter;import java.util.List;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.json.JSONArray;import org.json.JSONException;import org.json.JSONObject;import .yong.ImplementDao.Student;@WebServlet("/insertServlet")public class insertServlet extends HttpServlet {private static final long serialVersionUID = 1L;public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {System.out.println("-----------");request.setCharacterEncoding("UTF-8");//创建带有缓冲区的字符串对象jsn，用来存储读取到的jsonStringBuffer jsn=new StringBuffer();//用io流的方式读取js页面传过来的对象jsonBufferedReader br=request.getReader();String line=null;while((line=br.readLine())!=null){jsn.append(line);}//拆分json表单中的数据try {JSONObject jo=new JSONObject(jsn.toString());int number=jo.getInt("number");String name=jo.getString("name");String address=jo.getString("address");System.out.println(number+name+address);.yong.pro.Student st=new .yong.pro.Student(number, name, address);Student stu=new Student();stu.insertDate(st);} catch (JSONException e) {e.printStackTrace();}System.out.println("-------------------------------------------------------");Student stu=new Student();List<JSONObject> list=stu.selectAll();//转换成jeson格式JSONArray ja=new JSONArray(list);System.out.println(ja.toString());response.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");//以io流的方式返回PrintWriter pw=response.getWriter();pw.write(ja.toString());pw.flush();pw.close();}}
