SpringBoot2（Spring Boot 的Web开发 springMVC 请求处理 参数绑定 常用注解 数据传递 文件上传）

时间：2024-10-01 07:10:06

SpringBoot2（Spring Boot 的Web开发 springMVC 请求处理 参数绑定 常用注解 数据传递 文件上传）

一、Spring Boot的Web开发

1.静态资源映射规则

在这里插入图片描述

总结：只要静态资源放在类路径下：

called /static (or /public or /resources or //METAINF/resources

一启动服务器就能访问到静态资源文件

springboot只需要将图片放在 static 下 就可以被访问到了

** 总结： **

只要静态资源放在类路径下： called /static (or INF/resources

访问 ： 当前项目根路径/ + 静态资源名

**静态资源访问前缀 **

spring:
  mvc:
    static-path-pattern: static/test/**

2.enjoy模板引擎

“四个步骤”

1.添加坐标

<dependency>
    <groupId>com.jfinal</groupId>
    <artifactId>enjoy</artifactId>
    <version>5.0.3</version>
</dependency>

2.开启配置

package com.stringzhua.springboot_web_demo01.config;


import com.jfinal.template.Engine;
import com.jfinal.template.ext.spring.JFinalViewResolver;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class SpringBootConfig {

    @Bean(name = "jfinalViewResolver")
    public JFinalViewResolver getJFinalViewResolver() {

        // 创建用于整合 spring boot 的 ViewResolver 扩展对象
        JFinalViewResolver jfr = new JFinalViewResolver();

        // 对 spring boot 进行配置
        jfr.setSuffix(".html");
        jfr.setContentType("text/html;charset=UTF-8");
        jfr.setOrder(0);

        // 设置在模板中可通过 #(session.value) 访问 session 中的数据
        jfr.setSessionInView(true);

        // 获取 engine 对象，对 enjoy 模板引擎进行配置，配置方式与前面章节完全一样
        Engine engine  = JFinalViewResolver.engine;

        // 热加载配置能对后续配置产生影响，需要放在最前面
        engine.setDevMode(true);

        // 使用 ClassPathSourceFactory 从 class path 与 jar 包中加载模板文件
        engine.setToClassPathSourceFactory();

        // 在使用 ClassPathSourceFactory 时要使用 setBaseTemplatePath
        // 代替 jfr.setPrefix("/view/")
        engine.setBaseTemplatePath("/templates/");


        // 更多配置与前面章节完全一样
        // engine.addDirective(...)
        // engine.addSharedMethod(...);

        return jfr;
    }
}

3.将页面保存在templates目录下

4.编写代码

Spring整合mybatis-plus

“四步”

1.导入坐标

 <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3</version>
        </dependency>

<!--        <dependency>-->
<!--            <groupId>org.mybatis.spring.boot</groupId>-->
<!--            <artifactId>mybatis-spring-boot-starter</artifactId>-->
<!--            <version>2.2.2</version>-->
<!--        </dependency>-->

2.编写配置实体类与关系表映射关系

package com.stringzhua.springboot_mybatis_demo01.pojo;

import com.baomidou.mybatisplus.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import java.io.Serializable;

/**
 * @Author Stringzhua
 * @Date 2024/9/19 17:21
 * description:
 */
@TableName(value = "student")
public class Student implements Serializable {
    @TableId(value = "stu_id", type = IdType.AUTO)
    private int stuId;
    @TableField(value = "stu_name")
    private String stuName;
    @TableField(value = "nick_name")
    private String nickName;
    @TableField(value = "stu_age")
    private int stuAge;
    //逻辑查询
    @TableLogic(value = "0", delval = "1")
    private int isDelete;

    //数据库无关字段
    @TableField(exist = false)
    private MultipartFile file;

    @Override
    public String toString() {
        return "Student{" +
                "stuId=" + stuId +
                ", stuName='" + stuName + '\'' +
                ", nickName='" + nickName + '\'' +
                ", stuAge=" + stuAge +
                '}';
    }

    public int getStuId() {
        return stuId;
    }

    public void setStuId(int stuId) {
        this.stuId = stuId;
    }

    public String getStuName() {
        return stuName;
    }

    public void setStuName(String stuName) {
        this.stuName = stuName;
    }

    public String getNickName() {
        return nickName;
    }

    public void setNickName(String nickName) {
        this.nickName = nickName;
    }

    public int getStuAge() {
        return stuAge;
    }

    public void setStuAge(int stuAge) {
        this.stuAge = stuAge;
    }

    public Student() {
    }

    public Student(String stuName, String nickName, int stuAge) {
        this.stuName = stuName;
        this.nickName = nickName;
        this.stuAge = stuAge;
    }
}

3.1使用公共的数据访问层

@Mapper
public interface StudentMapper extends BaseMapper<Student> {
    @Select("select * from student")
    public List<Student> selectAll();
}

3.2使用公共业务层

4.编写配置文件

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mavendb?serverTimezone=Asia/Shanghai
    username: root
    password: 12345678
mybatis:
  configuration:
    map-underscore-to-camel-case: true
mybatis-plus:
  configuration:
    map-underscore-to-camel-case: true
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #日志

mybatis-plus的增删改查：

@SpringBootTest
public class Test01 {
    @Autowired(required = false)
    StudentMapper studentMapper;

    //新增
    @Test
    public void add() {
        Student student = new Student("一猫人", "大熊猫本猫", 3);
        int count = studentMapper.insert(student);
        System.out.println("主键回填" + student.getStuId());
        System.out.println("影响的行数" + count);
    }

    //根据学生id修改
    @Test
    public void modifyById() {
        Student student = new Student();
        student.setStuId(12);
        student.setStuName("李前");
        student.setStuAge(18);
        int count = studentMapper.updateById(student);
        System.out.println("影响行数" + count);
    }

    //根据姓名修改,条件
    @Test
    public void modifyByName() {
        //1.修改数据
        Student student = new Student();
        student.setNickName("猫眼电影");
        student.setStuAge(18);
        //2.创建条件
        QueryWrapper<Student> wrapper = new QueryWrapper<>();
        wrapper.eq("stu_name", "猫猫");
        //3.执行sql
        studentMapper.update(student, wrapper);
    }

    //根据学生id查询
    @Test
    public void selectById() {
        Student student = studentMapper.selectById(10);
        System.out.println(student);
    }

    //根据多个学生id查询
    @Test
    public void selectByMoreId() {
        List<Student> students = studentMapper.selectBatchIds(Arrays.asList(1, 2, 3, 4, 5, 6));
        for (int i = 0; i < students.size(); i++) {
            Student student = students.get(i);
            System.out.println(student);
        }
    }

    //查询count
    @Test
    public void selectCount() {
        QueryWrapper<Student> wrapper = new QueryWrapper<>();
        wrapper.eq("stu_name", "猫猫");
//        int count = studentMapper.selectCount(null);//全查
        int count = studentMapper.selectCount(wrapper);//条件查询
        System.out.println(count);
    }

    //条件查询
    @Test
    public void selectByCondition() {
        QueryWrapper<Student> wrapper = new QueryWrapper<>();
//        wrapper.eq("stu_name","猫猫");//相当于这里有个and
//        wrapper.eq("nick_name","猫眼电影");
        //or查询
        wrapper.eq("stu_name", "猫猫").or().eq("nick_name", "猫眼电影");
        List<Student> list = studentMapper.selectList(wrapper);
        for (int i = 0; i < list.size(); i++) {
            Student student = list.get(i);
            System.out.println(student);
        }
    }
}

mybatis-plus的分页插件[自带]

package com.stringzhua.springboot_mybatis_demo01.config;

import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @Author Stringzhua
 * @Date 2024/9/20 12:10
 * description:
 */
@Configuration
public class MyBatisConfig {
    //注入mp拦截器
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor(){
        //1.实例化拦截器
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        //2.分页拦截器
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());

        return mybatisPlusInterceptor;
    }
}

@SpringBootTest
public class Test01 {
    @Autowired(required = false)
    StudentMapper studentMapper;

    /**
     * mp分页使用
     * 注意：
     * 1.page.setCurrent(2);当前页码从1开始
     * 2.mybatis分页需要配置插件,mp不用
     */
    //这里为逻辑分页
    @Test
    public void Page() {
        //1.定义分页规则
        Page<Student> page = new Page<>();
        page.setSize(4);//每页记录数
        page.setCurrent(2);//当前页码
        //2.条件查询(可选)
        QueryWrapper queryWrapper = new QueryWrapper();
        queryWrapper.eq("stu_sex", "男");

        Page<Student> iPage = studentMapper.selectPage(page, null);

        List<Student> list = iPage.getRecords();
        System.out.println("总记录数" + iPage.getTotal());
        System.out.println("总记页数" + iPage.getPages());

        for (int i = 0; i < list.size(); i++) {
            Student student = list.get(i);
            System.out.println(student);
        }
    }


    //逻辑删除
    //数据库中只是把is_delete设置为1,mp查询时默认查询为0字段的
    //这里用mp查询时只有12条记录
    @Test
    public void deleteById() {
        int count = studentMapper.deleteById(13);
        System.out.println("影响的行数" + count);
    }

    //这里用mp查询时只有12条记录
    @Test
    public void selectAll() {
        //queryWrapper为null,则没有查询条件,为全查
        List<Student> list = studentMapper.selectList(null);
        for (int i = 0; i < list.size(); i++) {
            Student student = list.get(i);
            System.out.println(student);
        }
    }
}

这里使用mp进行全查，则为12条记录，原因是mp走@TableLogic注解时，走的是查询表中is_delete字段为0的值。

//逻辑查询
@TableLogic(value = "0", delval = "1")
private int isDelete;

这里使用mybatis进行全查，则为13条记录

package com.stringzhua.springboot_mybatis_demo01;

import com.stringzhua.springboot_mybatis_demo01.mapper.StudentMapper;
import com.stringzhua.springboot_mybatis_demo01.pojo.Student;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
class SpringbootMybatisDemo01ApplicationTests {
    @Autowired(required = false)
    StudentMapper studentMapper;
    //如果是mybatis的话,走自己写的sql,则是全查,相当于count(*)
    //13条记录
    @Test
    void test01() {
        List<Student> students = studentMapper.selectAll();
        for (int i = 0; i < students.size(); i++) {
            Student student = students.get(i);
            System.out.println(student);
        }
    }

}

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