Ajax技术【Ajax 实战】(二)-全面详解（学习总结---从入门到深化）

 

目录

Ajax 实战

---

Ajax 实战

创建项目

创建Java项目

 

 

 点击finish完成项目创建，然后右键选择"add Framework Support..."

 勾选红框中的选项，点击"OK"，完成后项目下出现web文件夹

 点击"project structure"

 点击Modules，选择"Web"模块，再按图示点击"+"，按默认路径， 再点击"OK"

 配置tomcat服务器

 选择Edit Configuration...

 选择Deployment标签，点击右侧"+"，选择要部署的项目，按默认就可以

 

 添加要部署的war文件，Application context设置为"/"，点击ok。

添加依赖包

 在"dependencies"标签中，点击右侧"+"，选择Library...，添加 Tomcat

 根据实际情况继续添加其它必要的依赖，如fastjson，commonslang等。

 导入jquery包

在web目录下，创建js文件夹，把jquery-3.6.0.js放到js目录下

 创建实体类User

package com.itbaizhan.ajax.pojo;
public class User {
    private Integer id;
    private String username;
    private String password;
    private Double salary;
    private String birthday;
    public Integer getId() {
        return id;
   }
    public void setId(Integer id) {
        this.id = id;
   }
    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 getSalary() {
        return salary;
   }
    public void setSalary(Double salary) {
        this.salary = salary;
   }
    public String getBirthday() {
        return birthday;
   }
    public void setBirthday(String birthday)
   {
        this.birthday = birthday;
 }
    public User(Integer id, String username,
    String password, Double salary, String birthday) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.salary = salary;
        this.birthday = birthday;
   }
    public User() {
   }
}

创建页面

创建index.jsp中的静态部分

    

        

            

                
ID：
                

                
姓名：
                

                
密码：
                

            
            

                
收入：
                

                
出生日期：
                

                

            
            

                

                    
                    
                
            
        
 

        

            

            

                
ID
                
姓名
                
密码
                
收入
                
生日
                
操作
            
        
            

        
    

创建UserServlet

@WebServlet("/user.do")
public class UserServlet extends HttpServlet
{
 @Override
    public void init() throws ServletException {
   }
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
   }
    
     @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
   }
}

配置web.xml

     UserServlet
     
        com.itbaizhan.ajax.servlet.UserServlet
     


    UserServlet
    /

查询用户列表

页面相关

$(function () {
     //初始化用户数据
     getData();
 });
// 获取页面初始化数据
function getData(){
    $.getJSON("user.do", {flag:"getData"},function (result) {
        listUser(result);
   });
}
// 遍历数据生成数据
function listUser(obj){
    var str ="";
    $.each(obj,function(){
        str+= "" +
            ""+this.id +""+
            ""+this.username+"" +
            ""+this.password+"" +
            ""+this.salary+"" +
            ""+this.birthday+"" +
            "更新
  删除 
"
   });
    $("#tBody").prepend(str);
}

servlet相关

@Override
public void init() throws ServletException {
    ArrayList list = new ArrayList<>();
    User user1 = new User(1,"zhangsan","123",2000d,"1997-09-01");
    User user2 = new User(2,"lisi","123",3000d,"1998-08-23");
    User user3 = new User(3,"zhaoliu","123",2500d,"1996-05-16");
    User user4 = new User(4,"wangwu","123",2080d,"1995-10-12");
    User user5 = new User(5,"zhengsan","123",3200d,"1999-12-20");
    User user6 = new User(6,"liugang","123",4200d,"1994-04-10");
    list.add(user1);
    list.add(user2);
    list.add(user3);
    list.add(user4);
    list.add(user5);
    list.add(user6);
    ServletContext servletContext = this.getServletContext();
    servletContext.setAttribute("list",list);
}
// 获取页面初始化数据
private void getData(HttpServletRequest req, HttpServletResponse resp) throws IOException
{
    List list = (List)
      this.getServletContext().getAttribute("list");
      String s = JSON.toJSONString(list);
      resp.setContentType("application/json");
      PrintWriter pw = resp.getWriter();
      pw.print(s);
      pw.flush();
      pw.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws
ServletException, IOException {
    String flag = req.getParameter("flag");
    if("getData".equals(flag)){
        this.getData(req,resp);
   }
}

添加用户

页面相关

//添加按钮绑定点击事件
$("#add").click(function(){
    addOrUpdateUser("addUser");
});
// 用户添加或者用户更新
function addOrUpdateUser(flag){
    // 从页面中获取数据
    var userid = $("#id").val();
    var username = $("#username").val();
    var password = $("#password").val();
    var salary = $("#salary").val();
    var birthday = $("#birthday").val();
    var data = {
        userid:userid,
        username:username,
        password:password,
        salary:salary,
        birthday:birthday,
        flag:flag
   }
    $.get("user.do",data,function(result){
        alert(result);
        location.reload();
   });
}

servlet相关

/**
     * 处理添加用户请求
     * @param req
     * @param resp
     * @throws ServletException
     * @throws IOException
     */
private void addUser(HttpServletRequest req, HttpServletResponse resp) throws IOException
{
    User user = this.createUser(req);
    ServletContext servletContext = this.getServletContext();
    List list = (List)servletContext.getAttribute("list");
    list.add(user);
    resp.setContentType("text/plain;charset=utf-8");
    PrintWriter pw = resp.getWriter();
    pw.print("添加成功");
    pw.flush();
    pw.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws
ServletException, IOException {
    String flag = req.getParameter("flag");
    if("getData".equals(flag)){
        this.getData(req,resp);
   }else if("addUser".equals(flag)){
        this.addUser(req,resp);
   }
}
// 获取请求数据
private User createUser(HttpServletRequest
req){
    String userid = req.getParameter("userid");
    String username = req.getParameter("username");
    String password = req.getParameter("password");
    String salary = req.getParameter("salary");
    String birthday = req.getParameter("birthday");
    User user = new User();
    user.setId(Integer.parseInt(userid));
    user.setUsername(username);
    user.setPassword(password);
    user.setSalary(Double.valueOf(salary));
    user.setBirthday(birthday);
    return user;
}

更新用户

页面相关

// 更新之前的数据选择
function preUpdateUser(userid){
    var arr = new Array();  
$("#"+userid).closest("tr").children().each(
function(index,ele){
        if(index <=4){
            arr[index]= ele.innerText
       }
   });
    $("#id").val(arr[0]);
    $("#id").attr("readonly",true);
    $("#username").val(arr[1]);
    $("#password").val(arr[2]);
    $("#salary").val(arr[3]);
    $("#birthday").val(arr[4]);
}
//更新按钮绑定点击事件
$("#update").click(function(){
 addOrUpdateUser("updateUser");
});
// 用户添加或者用户更新
function addOrUpdateUser(flag){
    // 从页面中获取数据
    var userid = $("#id").val();
    var username = $("#username").val();
    var password = $("#password").val();
    var salary = $("#salary").val();
    var birthday = $("#birthday").val();
    var data = {
        userid:userid,
        username:username,
        password:password,
        salary:salary,
        birthday:birthday,
        flag:flag
   }
    $.get("user.do",data,function(result){
       alert(result);
       location.reload();
   });
}

servlet相关

/**
     * 处理更新用户请求
     * @param req
     * @param resp
     * @throws IOException
     */
private void updateUser(HttpServletRequest req,
                        HttpServletResponse resp) throws IOException{
    User user = this.createUser(req);
    ServletContext servletContext = this.getServletContext();
    List userList = (List) servletContext.getAttribute("list");
    //list转map
    Map userMap = userList.stream().collect(Collectors.toMap(User::getId, Function.identity()));
    //根据id获取user
    User user1 = userMap.get(user.getId());
    //删除指定的user
    userList.remove(user1);
    //添加新的user
    userList.add(user);
    //按id排序
    userList.sort(new Comparator() {
        @Override
        public int compare(User o1, User o2)
         {
            return o1.getId() - o2.getId();
       }
   });
    //输出至页面
    resp.setContentType("text/plain;charset=utf-8");
    PrintWriter pw = resp.getWriter();
    pw.print("更新成功");
    pw.flush();
    pw.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws
ServletException, IOException {
    String flag = req.getParameter("flag");
    if("getData".equals(flag)){
        this.getData(req,resp);
   }else if("addUser".equals(flag)){
        this.addUser(req,resp);
   }else if("updateUser".equals(flag)){
        this.updateUser(req,resp);
   }
}

删除用户

页面相关

// 删除用户
function deleteUser(userid){
    $("#"+userid).closest("tr").remove();
 $.post("user.do", {userid:userid,flag:"delete"},function(result){
        alert(result)
   })
}

servlet相关

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws
ServletException, IOException {
    String flag = req.getParameter("flag");
    if("getData".equals(flag)){
        this.getData(req,resp);
   }else if("addUser".equals(flag)){
        this.addUser(req,resp);
   }else if("updateUser".equals(flag)){
        this.updateUser(req,resp);
   }else if("delete".equals(flag)){
        this.deleteUser(req,resp);
   }
}
/**
     * 处理删除用户请求
     * @param req
     * @param resp
     * @throws ServletException
     * @throws IOException
     */
private void deleteUser(HttpServletRequest req,
                        HttpServletResponse resp) throws ServletException, IOException{
    ServletContext servletContext = this.getServletContext();
    List userList = (List)servletContext.getAttribute("list");
    String userid = req.getParameter("userid");
    //list转map
    Map userMap = userList.stream().collect(Collectors.toMap(User::getId, Function.identity()));
    //根据id获取user
    if(StringUtils.isNotEmpty(userid)){
        User user1 = userMap.get(Integer.parseInt(userid));
        //删除指定的user
        userList.remove(user1);
        resp.setContentType("text/plain;charset=utf-8");
        PrintWriter pw = resp.getWriter();
        pw.print("删除成功");
        pw.flush();
        pw.close();
   }else{
        resp.setContentType("text/plain;charset=utf-8");
        PrintWriter pw = resp.getWriter();
        pw.print("删除失败");
        pw.flush();
        pw.close();
   }
}

运行效果

复习：

 Java对象的序列化和反序列化

 序列化和反序列化是什么

当两个进程远程通信时，彼此可以发送各种类型的数据。 无论是何 种类型的数据，都会以二进制序列的形式在网络上传送。比如，我 们可以通过http协议发送字符串信息；我们也可以在网络上直接发 送Java对象。发送方需要把这个Java对象转换为字节序列，才能在 网络上传送；接收方则需要把字节序列再恢复为Java对象才能正常 读取。 把Java对象转换为字节序列的过程称为对象的序列化。把字节序列 恢复为Java对象的过程称为对象的反序列化。

 序列化涉及的类和接口

ObjectOutputStream代表对象输出流，它的writeObject(Object obj)方法可对参数指定的obj对象进行序列化，把得到的字节序列写 到一个目标输出流中。

ObjectInputStream代表对象输入流，它的readObject()方法从一个 源输入流中读取字节序列，再把它们反序列化为一个对象，并将其 返回。 只有实现了Serializable接口的类的对象才能被序列化。 Serializable接口是一个空接口，只起到标记作用。

 将对象序列化到文件

 ObjectOutputStream可以将一个内存中的Java对象通过序列化的方 式写入到磁盘的文件中。被序列化的对象必须要实现Serializable序 列化接口，否则会抛出异常。

 创建对象

public class Users implements Serializable {
    private int userid;
    private String username;
    private String userage;
    public Users(int userid, String username, String userage) {
        this.userid = userid;
        this.username = username;
        this.userage = userage;
    }
    public Users() { }
    public int getUserid() {
        return userid;
   }
    public void setUserid(int userid) {
        this.userid = userid;
   }
    public String getUsername() {
        return username;
   }
    public void setUsername(String username)
   {
        this.username = username;
   }
    public String getUserage() {
        return userage;
   }
    public void setUserage(String userage) {
        this.userage = userage;
   }
    @Override
    public String toString() {
 return "Users{" +
                "userid=" + userid +
                ", username='" + username + '\'' +
                ", userage='" + userage + '\'' +
                '}';
   }

序列化对象

public class TestObjectOutputStream {
    public static void main(String[] args) {
        //创建对象输出字节流与文件输出字节流对象
        try(ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("d:/data3"))){
            //创建Users对象
            Users users = new Users(1,"Oldlu","18");
            //将对象序列化到文件中
            oos.writeObject(users);
            //刷新
            oos.flush();
       }catch(IOException e){
            e.printStackTrace();
       }
   }
}

将对象反序列化到内存中

public class TestObjectInputStream {
    public static void main(String[] args) {
        //创建对象输入字节流与文件字节输入流对象
        try(ObjectInputStream ois = new ObjectInputStream(new FileInputStream("d:/data3"))) 
       {
            //将对象反序列化到内存中
            Users users = (Users) ois.readObject();
            System.out.println(users);
       }catch(Exception e){
            e.printStackTrace();
       }
   }
}

File类在IO中的作用

 当以文件作为数据源或目标时，除了可以使用字符串作为文件以及 位置的指定以外，我们也可以使用File类指定。

public class TestFile {
    public static void main(String[] args) {
        //创建字符缓冲流与文件字符输入流对象
        try(BufferedReader br =  new BufferedReader(new FileReader(new File("d:/sxt.txt")));
            //创建字符输出流对象
            PrintWriter pw = new PrintWriter(new File("d:/sxt8.txt"))){
            //操作流
            String temp = "";
            int i=1;
            while((temp = br.readLine()) != null){
                pw.println(i+","+temp);
                i++;
}
            pw.flush();
       }catch(IOException e){
            e.printStackTrace();
       }
   }
}

装饰器模式构建IO流体系

装饰器模式简介

装饰器模式是GOF23种设计模式中较为常用的一种模式。它可以实 现对原有类的包装和装饰，使新的类具有更强的功能。

 装饰器模式

class Iphone {
 private String name;
 public Iphone(String name) {
     this.name = name;
}
 public void show() {
    System.out.println("我是" + name + ",可以在屏幕上显示");
  }
}
class TouyingPhone {
    public Iphone phone;
    public TouyingPhone(Iphone p) {
        this.phone = p;
 }
 // 功能更强的方法
 public void show() {
     phone.show();
     System.out.println("还可以投影，在墙壁上显示");
 }
}
public class TestDecoration {
 public static void main(String[] args) {
     Iphone phone = new Iphone("iphone30");
     phone.show();
     System.out.println("===============装饰后");
     TouyingPhone typhone = newTouyingPhone(phone);
     typhone.show();
 }
}

IO流体系中的装饰器模式

IO流体系中大量使用了装饰器模式，让流具有更强的功能、更强的 灵活性。比如：

FileInputStream  fis = new FileInputStream(src);
BufferedInputStream  bis = new BufferedInputStream(fis);

 显然BufferedInputStream装饰了原有的FileInputStream，让普通 的FileInputStream也具备了缓存功能，提高了效率。