初始 Spring MVC【中】

2023-11-13 12:55:10

Spring MVC 入门

五、图片上传
六、JSON数据交换
七、RESTFul

ps：接上篇

五、图片上传

5.1 概述

spring mvc 默认使用 commons-fileupload 完成文件上传。

5.2 入门案例

5.2.1 导入坐标

<!--文件上传-->
<dependency>
	<groupId>commons-fileupload</groupId>
	<artifactId>commons-fileupload</artifactId>
	<version>1.4</version>
</dependency>

5.2.2 配置类

使用 CommonsMultipartResolver 对上传文件进行参数设置

package com.czxy.mvc.config;

        import org.springframework.context.annotation.Bean;
        import org.springframework.context.annotation.ComponentScan;
        import org.springframework.context.annotation.Configuration;
        import org.springframework.format.FormatterRegistry;
        import org.springframework.format.datetime.DateFormatter;
        import org.springframework.web.multipart.commons.CommonsMultipartResolver;
        import org.springframework.web.servlet.config.annotation.EnableWebMvc;
        import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
        import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

        import java.util.Date;


/**
 * @Author: 小新
 * @Date: 2021-12-07 16:48
 */
@Configuration
@ComponentScan(basePackages = {"com.czxy.mvc.controller")
@EnableWebMvc
public class MvcConfiguration implements WebMvcConfigurer {
    /**
     * 上传文件处理器
     * @return
     */
    @Bean
    public CommonsMultipartResolver multipartResolver(){
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
        //设置所有的上传文件的总大小 10m
        multipartResolver.setMaxInMemorySize(10 * 1024 * 1024);
        //设置单个文件上传的大小 4m
        multipartResolver.setMaxUploadSize(4 * 1024 * 1024);
        multipartResolver.setDefaultEncoding("utf-8");
        return multipartResolver;
    }
}

5.2.3 单文件上传

需求：选择一张图片上传到服务器，并保存到指定位置
编写处理类Controller：

package com.czxy.mvc.controller;

import org.apache.commons.io.FileUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;
import java.util.List;

/**
 * @Author: 小新
 * @Date: 2021-12-10 19:54
 */
@Controller
@RequestMapping("/demo05")
public class Demo05UploadController {

    /**
     * 单文件上传
     * @param image
     * @return
     * @throws IOException
     */
    @RequestMapping("/upload")
    public String upload(MultipartFile image) throws IOException {
        System.out.println("上传文件名：" + image.getOriginalFilename());
        System.out.println("上传文件流：" + image.getInputStream());

        File file = new File("D:\\image", image.getOriginalFilename());
        FileUtils.copyInputStreamToFile(image.getInputStream(), file);
        return "file";
    }
}

访问路径 + 表单:

<!--单文件上传-->
<form action="${pageContext.request.contextPath}/demo05/upload.action" method="post" enctype="multipart/form-data">
    选择文件: <input type="file" name="image" /> <br/>
    <input type="submit" value="单文件上传"/> <br/>
</form>

5.2.4 多文件上传

需求：选择三张图片上传到服务器，并保存到指定位置
编写处理类Controller：

package com.czxy.mvc.controller;

import org.apache.commons.io.FileUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;
import java.util.List;

/**
 * @Author: 小新
 * @Date: 2021-12-10 19:54
 */
@Controller
@RequestMapping("/demo05")
public class Demo05UploadController {
    /**
     * 多文件上传
     * @param images
     * @return
     * @throws IOException
     */
    @RequestMapping("/upload2")
    public String upload2(List<MultipartFile> images) throws IOException {
        for (MultipartFile image : images) {
            System.out.println("上传文件名：" + image.getOriginalFilename());
            System.out.println("上传文件流：" + image.getInputStream());

            File file = new File("D:\\image", image.getOriginalFilename());
            FileUtils.copyInputStreamToFile(image.getInputStream(), file);
        }
        return "file";
    }
}

访问路径 + 表单：

<form action="${pageContext.request.contextPath}/demo05/upload2.action" method="post" enctype="multipart/form-data">
    选择文件: <input type="file" name="images" /> <br/>
    选择文件: <input type="file" name="images" /> <br/>
    选择文件: <input type="file" name="images" /> <br/>
    <input type="submit" value="多文件上传"/> <br/>
</form>

六、JSON数据交换

6.1 json数据格式

6.1.1 什么是JSON数据？

是一种轻量级的数据交换格式。
轻量级，不依赖任何框架、任何语言。

6.1.2 数据分类：对象、数组

对象：
- key必须使用双引号。
- value除特殊类型外，都需要使用双引号（特殊类型：数字、布尔true/false）
- 实例：

{
    "k":"v",
    "k2":"v2",....
}

数组：

[
	元素,元素2,....
]

6.2 JSON使用流程

6.3 入门案例

6.3.1 目标

目标：请求JSON数据，响应JSON数据。
需求：用户条件查询。
请求：查询条件User 。
响应：查询结果List

6.3.2 实现

前提：spring mvc 底层jackson 出来JSON数据。

<!-- mvc json -->
<dependency>
	<groupId>com.fasterxml.jackson.core</groupId>
	<artifactId>jackson-databind</artifactId>
	<version>2.10.2</version>
</dependency>

编写JavaBean User类

public class User {
    private Integer id;
    private String username;
    private String password;
    private Integer age;
    @JsonIgnore
    private List<String> hobbies;
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss",timezone = "GMT+8")
    //@DateTimeFormat(pattern = "yyyy-MM-dd hh:mm:ss")
    private Date birthday;

    public User(Integer id, String username, String password, Date birthday) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.birthday = birthday;
    }

    public User(Integer id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public User(String username, String password, Integer age) {
        this.username = username;
        this.password = password;
        this.age = age;
    }

    public User() {
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", hobbies=" + hobbies +
                ", birthday=" + 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 List<String> getHobbies() {
        return hobbies;
    }

    public void setHobbies(List<String> hobbies) {
        this.hobbies = hobbies;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public User(Integer id, String username, String password, List<String> hobbies, Date birthday) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.hobbies = hobbies;
        this.birthday = birthday;
    }
}

编写controller，接收请求数据 @RequestBody

@Controller
@RequestMapping("/demo06")
public class Demo06JsonController {

    @RequestMapping("/list")
    public void list(@RequestBody User user) {
        System.out.println(user);
    }
}

编写controller，响应数据 @ResponseBody

package com.czxy.mvc.controller;

import com.czxy.mvc.domain.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * @Author: 小新
 * @Date: 2021-12-10 20:14
 */
@Controller
@RequestMapping("/demo06")
public class Demo06JsonController {

    /**
     * 请求JSON数据，响应JSON数据
     * @param user
     * @return
     */
    @RequestMapping(/*value = "/list" , method = RequestMethod.POST*/"/list")
    @ResponseBody
    public List<User> list(@RequestBody User user){
        System.out.println(user);
        //响应数据
        ArrayList<User> list = new ArrayList<>();
        list.add(new User(1,"小瓶子","54250",new Date()));
        list.add(new User(2,"胖胖","6666"));
        list.add(new User(3,"小新","牛掰"));

        return list;
    }
}

post Man 测试

6.4 常见注解

注解	描述
@RequestBody	请求数据为JSON字符串
@ResponseBody	响应数据为JSON字符串
@@JsonIgnore	忽略指定属性
@JsonFormat	JSON数据日期的格式化

@JsonIgnore 作用是json序列化时将java bean中的一些属性忽略掉

public class User {
    @JsonIgnore
    private List<String> hobby;
}

@JsonFormat 格式化日期

public class User {
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss",timezone = "GMT+8")
    private Date birthday;
}

七、RESTFul

7.1 什么是RESTFul

RESTFul编写程序是一种风格，不是协议

对http协议诠释（落地方案），请求方式的落地

http协议共7中，常见四种，最常使用2种
get、post、put、delete

RESTFul对服务器程序操作进行约定：
- 每一个操作组成：请求路径 + 请求方式。（同一个路径因为请求方式不同，可以完成不同操作）。

7.2 数据传输方式：JSON数据

RESTFul 风格路径：

查询：get    http://localhost:8080/user/
详情：get    http://localhost:8080/user/123
添加：post   http://localhost:8080/user/
修改：put    http://localhost:8080/user/
删除：delete http://localhost:8080/user/123

7.3 注解

7.3.1 类级别

@RestController ：合成注入（@Controller 、@ResponseBody）

7.3.2 方法级别

@GetMapping
@PostMapping
@PutMapping
@DeleteMapping

7.3.3 参数

@PathVariable ：用于获取路径参数

7.4 方法返回值

//根据约束，基于RESTFul风格，方法的的返回值，建议使用 ResponseEntity 类型
// ResponseEntity 用于封装返回值信息，含状态码
// 返回200状态码，ResponseEntity.ok("添加成功");
// 其他状态码，new ResponseEntity<>("添加成功", HttpStatus.UNAUTHORIZED)

7.5 入门案例（增删改查）

7.5.1 实现

配置类 WebInitializer：

package com.czxy.config;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.servlet.DispatcherServlet;

import javax.servlet.FilterRegistration;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

/**
 * @Author: 小新
 * @Date: 2021-12-07 16:49
 */
public class WebInitializer  implements WebApplicationInitializer {
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        //1 配置spring工厂
        AnnotationConfigWebApplicationContext application = new AnnotationConfigWebApplicationContext();
        // 注册所有的配置类
        application.register(MvcConfiguration.class);

        //2 post中文乱码
        FilterRegistration.Dynamic encodingFilter = servletContext.addFilter("encoding", new CharacterEncodingFilter("UTF-8"));
        encodingFilter.addMappingForUrlPatterns(null, true, "/*");

        //3 核心控制器
        ServletRegistration.Dynamic mvcServlet = servletContext.addServlet("springmvc", new DispatcherServlet(application));
        //mvcServlet.addMapping("*.action");
        mvcServlet.addMapping("/");
        mvcServlet.setLoadOnStartup(2);	//tomcat启动时，执行servlet的初始化方法
    }
}

配置类 MvcConfiguration：

package com.czxy.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;


/**
 * @Author: 小新
 * @Date: 2021-12-07 16:48
 */
@Configuration
@ComponentScan(basePackages = {"com.czxy.controller"})
@EnableWebMvc
public class MvcConfiguration implements WebMvcConfigurer {
}

javaBean User：

package com.czxy.domain;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonIgnore;

import java.util.Date;
import java.util.List;

/**
 * @Author: 小新
 * @Date: 2021-12-13 20:02
 */
public class User {
    private Integer id;
    private String username;
    private String password;
    private Integer age;
    @JsonIgnore
    private List<String> hobbies;
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss",timezone = "GMT+8")
    //@DateTimeFormat(pattern = "yyyy-MM-dd hh:mm:ss")
    private Date birthday;

    public User(Integer id, String username, String password, Date birthday) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.birthday = birthday;
    }

    public User(Integer id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public User(String username, String password, Integer age) {
        this.username = username;
        this.password = password;
        this.age = age;
    }

    public User() {
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", hobbies=" + hobbies +
                ", birthday=" + 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 List<String> getHobbies() {
        return hobbies;
    }

    public void setHobbies(List<String> hobbies) {
        this.hobbies = hobbies;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public User(Integer id, String username, String password, List<String> hobbies, Date birthday) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.hobbies = hobbies;
        this.birthday = birthday;
    }
}

控制器 controller ：

package com.czxy.controller;

import com.czxy.domain.User;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * @Author: 小新
 * @Date: 2021-12-13 20:02
 */
@RestController
@RequestMapping("/user")
public class Demo01Controller {

    /**
     * 查询所有
     * get
     * @return
     */
    @GetMapping
    public List<User> selectAll(){
        ArrayList<User> list = new ArrayList<>();
        list.add(new User(1,"jack","1234"));
        list.add(new User(2,"rose","4567"));
        list.add(new User(3,"tom","5678"));

        return list;
    }

    /**
     * 根据id查询详情
     * @param uid
     * @return
     */
    @GetMapping("/{id}")
    public String selectAll(@PathVariable("id") String uid){
        System.out.println("selectById" + uid);
        return "selectById success";
    }


    /**
     * 添加
     * post
     * @param user
     * @return
     */
    @PostMapping
    public User insert(@RequestBody  User user){
        System.out.println("添加成功：" + user);
        return user;
    }


    /**
     * 更新
     * put
     * @param user
     * @return
     */
    @PutMapping
    public User update(@RequestBody  User user){
        System.out.println("更新成功" + user);
        return user;
    }

    /**
     * 删除
     * delete
     * @param uid
     * @return
     */
    @DeleteMapping("/{id}")
    public String delete(@PathVariable("id") String uid){
        System.out.println("delete" + uid);
        return "delete success";
    }
}

码农公寓

Spring MVC 入门

五、图片上传

5.1 概述

5.2 入门案例

5.2.1 导入坐标

5.2.2 配置类

5.2.3 单文件上传

5.2.4 多文件上传

六、JSON数据交换

6.1 json数据格式

6.1.1 什么是JSON数据？

6.1.2 数据分类：对象、数组

6.2 JSON使用流程

6.3 入门案例

6.3.1 目标

6.3.2 实现

6.4 常见注解

七、RESTFul

7.1 什么是RESTFul

7.2 数据传输方式：JSON数据

7.3 注解

7.3.1 类级别

7.3.2 方法级别

7.3.3 参数

7.4 方法返回值

7.5 入门案例（增删改查）

7.5.1 实现

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