web后端基础1

1.springboot入门
需求
需求：基于SpringBoot的方式开发一个web应用，浏览器发起请求/hello后，给浏览器返回字符串 "Hello xxx ~"。

点击查看代码

package com.itheima;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController//请求处理类
public class HelloController {
    @RequestMapping("/hello")//路径
    public String hello(String name){
        System.out.println("name:" + name);//任务栏返回
        return "hello" + name + "~";//浏览器输出
    }
}

2.请求协议
包括请求行（第一行）、请求头（key:value） 、请求体

点击查看代码

package com.itheima;

import jakarta.servlet.http.HttpServletRequest;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class RequestController {
    @RequestMapping("/request")
    public String request(HttpServletRequest request){
        //1.获取请求方式
        String method = request.getMethod();
        System.out.println("请求方式"+method);
        //2.获取请求URL地址
        String url = request.getRequestURL().toString();
        System.out.println("请求URL地址"+url);
        String uri = request.getRequestURI();
        System.out.println("请求URI地址"+request.getRequestURI());
        //3.获取请求协议
        String protocol = request.getProtocol();
        System.out.println("请求协议"+protocol);
        //4.获取请求参数 name,age
        String name = request.getParameter("name");
        String age = request.getParameter("age");
        System.out.println("name:"+name+",age:"+age);
        //5.获取请求头 -Accept
        String accept = request.getHeader("Accept");
        System.out.println("请求头Accept:"+accept);
        return "OK";
    }
}

3.响应协议

点击查看代码

package com.itheima;

import jakarta.servlet.http.HttpServletResponse;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.io.IOException;

@RestController
public class ResponseController {

    //1.
    @RequestMapping("/response")
    public void response(HttpServletResponse response) throws IOException {
        //1.响应状态码
        response.setStatus(401);
        //2.响应头
        response.setHeader("name","hao");
        //3.响应体
        response.getWriter().write("<h1>hello response</h1>");
    }

    //2.
    @RequestMapping("/response2")
    public ResponseEntity<String> response2(){
        return (ResponseEntity<String>) ResponseEntity
                .status(401)
                .header("name","javaweb")
                .body("<h1>hello response2</h1>");
    }
}

4. SpringBootWeb案例
   基于SpringBoot开发web程序，完成用户列表的渲染展示
   当在浏览器地址栏，访问前端静态页面（http://localhost:8080/usre.html）后，在前端页面上，会发送ajax请求，请求服务端（http://localhost:8080/list），服务端程序加载 user.txt 文件中的数据，读取出来后最终给前端页面响应json格式的数据，前端页面再将数据渲染展示在表格中。
   1.在 com.itheima 下再定义一个包 pojo，专门用来存放实体类。 在该包下定义一个实体类User：

点击查看代码

package com.itheima.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.time.LocalDateTime;

/**
 * 封装用户信息
 */
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private Integer id;
    private String username;
    private String password;
    private String name;
    private Integer age;
    private LocalDateTime updateTime;
}

2.导入pom依赖

点击查看代码

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.4.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.itheima</groupId>
    <artifactId>springboot-web-01</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-web-01</name>
    <description>springboot-web-01</description>
    <url/>
    <licenses>
        <license/>
    </licenses>
    <developers>
        <developer/>
    </developers>
    <scm>
        <connection/>
        <developerConnection/>
        <tag/>
        <url/>
    </scm>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.8.27</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
        <dependency><groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.30</version>
            <scope>provided</scope></dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

3.在com.itheima包下新建一个子包controller，在其中创建一个UserController

点击查看代码

package com.itheima.controller;

import cn.hutool.core.io.IoUtil;
import cn.hutool.json.JSONConfig;
import cn.hutool.json.JSONUtil;
import com.itheima.pojo.User;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

@RestController
public class UserController {

    @RequestMapping("/list")
    public List<User> list() throws Exception{
        //1.加载并读取文件
        InputStream in = this.getClass().getClassLoader().getResourceAsStream("user.txt");
        ArrayList<String> lines = IoUtil.readLines(in, StandardCharsets.UTF_8, new ArrayList<>());

        //2.解析数据，封装成对象 --> 集合
        List<User> userList = lines.stream().map(line -> {
            String[] parts = line.split(",");
            Integer id = Integer.parseInt(parts[0]);
            String username = parts[1];
            String password = parts[2];
            String name = parts[3];
            Integer age = Integer.parseInt(parts[4]);
            LocalDateTime updateTime = LocalDateTime.parse(parts[5], DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));

            return new User(id, username, password, name, age, updateTime);
        }).toList();

        //3.响应数据
        //return JSONUtil.toJsonStr(userList, JSONConfig.create().setDateFormat("yyyy-MM-dd HH:mm:ss"));
        return userList;
    }

}