package web.servlet;
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 java.io.IOException;
import java.io.Serial;
@WebServlet(name = "SelectUserServlet", value = "/selectUser")
public class SelectUserServlet extends HttpServlet {
@Serial private static final long serialVersionUID = 7592892756611769375L;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 1.接收参数
String username = request.getParameter("username");
// 2.调用service查询user对象
boolean flag = true;
// 3.响应标记
response.getWriter().write("" + flag);
// 然后去注册页面找username的id
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {}
}
2. jsp页面 --AJAX
3. jsp页面 --注册部分
版本二 2. jsp页面 2.1 根据ajax实现
<%--
Created by IntelliJ IDEA.
User: xiaomi
Date: 2021/3/4
Time: 17:02
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
$Title$
index.jsp
username:
2.2 根据jquery实现
<%--
Created by IntelliJ IDEA.
User: xiaomi
Date: 2021/3/4
Time: 17:02
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
$Title$
jquery_ajax.jsp
username:
3. TestServlet
package servlet;
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 java.io.IOException;
import java.io.PrintWriter;
@WebServlet(urlPatterns = "/testuname")
public class TestServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.接收参数
String username = req.getParameter("username");
resp.setContentType("text/html;charset=utf-8");
PrintWriter writer = resp.getWriter();
if("admin".equals(username)){
writer.println("账户已被注册");
}else{
writer.println("账户可用");
}
}
}
JSON
1. JSON的存值取值
Title
2. JSON与JAVA对象之间的转换
实体类
package bean;
//实体类
public class Users {
private Integer uid;
private String username;
private String password;
private Double money;
@Override
public String toString() {
return "Users{" +
"uid=" + uid +
", username='" + username + ''' +
", password='" + password + ''' +
", money=" + money +
'}';
}
public Users() {
}
public Users(Integer uid, String username, String password, Double money) {
this.uid = uid;
this.username = username;
this.password = password;
this.money = money;
}
public Integer getUid() {
return uid;
}
public void setUid(Integer uid) {
this.uid = uid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Double getMoney() {
return money;
}
public void setMoney(Double money) {
this.money = money;
}
}
JSON与JAVA的转换
package test;
import bean.Users;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import java.util.ArrayList;
public class Demo {
public static void main(String[] args) {
//java->json
Users users = new Users(11,"aaa","123456",123.456);
JSONObject jsonObject = JSONObject.fromObject(users);
System.out.println(jsonObject);//json
//json-java
String str="{"money":123.456,"password":"123456","uid":11,"username":"aaa"}";
JSONObject jsonObject1 = JSONObject.fromObject(str);
Object o = JSONObject.toBean(jsonObject1, Users.class);
System.out.println("o="+o);
//java集合->json
ArrayList arrayList = new ArrayList();
arrayList.add(new Users(1,"张三","123",12.34));
arrayList.add(new Users(2,"张三2","12322",1244.34));
arrayList.add(new Users(3,"张三3","12333",1255.34));
JSONArray jsonArray = JSONArray.fromObject(arrayList);//json
System.out.println(jsonArray);
//json->java集合
String str2="[{"money":12.34,"password":"123","uid":1,"username":"张三"},{"money":1244.34,"password":"12322","uid":2,"username":"张三2"},{"money":1255.34,"password":"12333","uid":3,"username":"张三3"}]";
JSONArray jsonArray2 = JSONArray.fromObject(str2);
Object[] o1 = (Object[])JSONArray.toArray(jsonArray2, Users.class);
for (Object o2 : o1) {
System.out.println("o2="+o2);
}
}
}
json和AJAX案例
通过id回显用户信息
1. GetUsersServletpackage servlet;
import bean.Users;
import net.sf.json.JSONObject;
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 java.io.IOException;
import java.io.PrintWriter;
@WebServlet(urlPatterns = "/getuser")
public class GetUsersServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.接收参数
String uid = req.getParameter("uid");
int userid=Integer.parseInt(uid);
Users users=null;
switch (userid){
case 1:
users=new Users(1,"张三","abc",11.22);
break;
case 2:
users=new Users(2,"张三2","abc2",222.1);
break;
case 3:
users=new Users(3,"张三3","abc3",33.2);
break;
case 4:
users=new Users(4,"张三4","abc4",44.4);
break;
default:
users=new Users();
}
//java->json
JSONObject jsonObject = JSONObject.fromObject(users);//json
resp.setContentType("text/html;charset=utf-8");
PrintWriter writer = resp.getWriter();
writer.print(jsonObject);
}
}
2. jsp页面
<%--
Created by IntelliJ IDEA.
User: xiaomi
Date: 2021/3/5
Time: 11:22
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
Title
uid:
name:
pass:
money:
如果启动tomcat 报错显示找不到类，就把lib里的东西复制到tomcat的lib里面
