SpringBoot基础入门

1 创建SpringBoot项目

1.1 通过pom继承parent

通过parent标签指定pom项目的父工程

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ali</groupId>
    <artifactId>springBoot_test_01</artifactId>
    <version>1.0-SNAPSHOT</version>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.4</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
</project>
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创建controller及启动类
controller层：

package com.zi.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class FirstController {

    @ResponseBody
    @RequestMapping("/first")
    public String firstController(){
        return "hello SpringBoot...";
    }
}
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package com.zi;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class MySpringBootApplication {
    public static void main(String[] args) {
        SpringApplication.run(MySpringBootApplication.class, args);
    }
}

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启动类需要与controller层、service层等包同层级【SpringBoot默认扫描启动类所在包及其子包】

1.2 通过依赖管理导入SpringBoot依赖【dependencyManagement】

在工作中我们有可能遇到我们的maven项目已经要继承一个parent项目了，此时应该使用dependencyManagement来创建SpringBoot项目

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ali</groupId>
    <artifactId>springBoot_test_01</artifactId>
    <version>1.0-SNAPSHOT</version>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
    
    <!--<parent>-->
    <!--    <groupId>org.springframework.boot</groupId>-->
    <!--    <artifactId>spring-boot-starter-parent</artifactId>-->
    <!--    <version>2.5.4</version>-->
    <!--</parent>-->

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-parent</artifactId>
                <version>2.7.1</version>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.7.1</version>
        </dependency>
    </dependencies>
</project>
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1.3 通过可视化界面

2 SpringBoot中的配置文件与资源访问

SpringBoot中的配置文件只能是以application开头【application*】

2.1 properties

# 设置端口
server.port=8081
# 设置上下文路径
server.servlet.context-path=/springboot02

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2.2 yml

# yml格式的文件，区分大小写，且层级之间要有两个空格；
# 属性与值之间要留一个空格
server:
  port: 8888
  servlet:
    context-path: /springboot02
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注意：
①yml也可以配置数组或者json格式的数据；
②如果同时存在properties与yml文件，如果存在冲突，以properties为准

2.3 访问static或public资源

访问路径上不需要加/static或者/public【并且二者之间可以互相访问】

a.html代码：

DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Titletitle>
head>
<body>
    <img src="logo.jpg"/>
body>
html>
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2.4 访问templates资源

类似于JavaWeb中的WEB-INF里面的内容，属于私密内容，外界无法直接访问，只能通过内部跳转访问
【FreeMarker thymeleaf 页面所在目录 】

SpringBoot的项目结构中不同于以前的JavaWeb项目，没有webapp目录【只有需要用到jsp技术，才会有该目录】

3 SpringBoot整合MyBatis

3.1 导入jar包并创建对应包结构

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.2</version>
        </dependency>
    </dependencies>
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对应包结构：

3.2 创建User类

package com.zi.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;

@AllArgsConstructor
@NoArgsConstructor
@Data
public class User implements Serializable {
    private Integer id;
    private String name;
    private Integer age;
    private String email;
}

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3.3 创建UserMapper接口与UserMapper.xml

UserMapper接口：

package com.zi.mapper;

import com.zi.pojo.User;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;

@Mapper
public interface UserMapper {
    /**
     * 查询所有用户
     * @return
     */
    List<User> selectAll();
}

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UserMapper.xml

DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.zi.mapper.UserMapper">

    
    <select id="selectAll" resultType="user">
        select * from t_user
    select>

mapper>
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3.4 创建UserService与UserServiceImpl

UserService:

package com.zi.service;

import com.zi.pojo.User;

import java.util.List;

public interface UserService {
    List<User> findAll();
}

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UserServiceImpl:

package com.zi.service.impl;

import com.zi.mapper.UserMapper;
import com.zi.pojo.User;
import com.zi.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public List<User> findAll() {
        return userMapper.selectAll();
    }
}

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3.5 创建UserController

package com.zi.controller;

import com.zi.pojo.User;
import com.zi.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.List;

@Controller
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;

    @ResponseBody
    @RequestMapping("/findAll")
    public List<User> findAll(){
        return userService.findAll();
    }
}

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3.6 最终结果

地址栏内容：

最终数据：

4 SpringBoot整合logback（日志）

logback的依赖，我们不需要亲自引入，spring-boot-starter或者spring-boot-starter-web中已经包含了Logback的依赖。

在resources目录下创建logback.xml:

<configuration>
    
    <property name="LOG_HOME" value="${catalina.base}/logs/"/>
    
    <appender name="Stdout" class="ch.qos.logback.core.ConsoleAppender">
        
        <layout class="ch.qos.logback.classic.PatternLayout">
            
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%npattern>
        layout>
    appender>
    
    <appender name="RollingFile"
              class="ch.qos.logback.core.rolling.RollingFileAppender">
        <rollingPolicy
                class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            

            <FileNamePattern>${LOG_HOME}/server.%d{yyyy-MM-dd}.logFileNamePattern>
            <MaxHistory>30MaxHistory>
        rollingPolicy>
        <layout class="ch.qos.logback.classic.PatternLayout">
            
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS}
                [%thread] %-5level %logger{50} - %msg%n
            pattern>
        layout>
        
        <triggeringPolicy
                class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
            <MaxFileSize>10MBMaxFileSize>
        triggeringPolicy>
    appender>

    
    <root level="info">
        <appender-ref ref="Stdout"/>
        <appender-ref ref="RollingFile"/>
    root>

    <logger name="com.zi.mapper" level="DEBUG"/>


    
    

configuration>

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5 SpringBoot整合PageHelper

5.1 导入启动依赖

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.5</version>
</dependency>
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5.2 定义EmpController

@Controller
@RequestMapping("/emp")
public class EmpController {

    @Autowired
    private EmpService empService;

    @ResponseBody
    @RequestMapping("/findByPage/{pageNum}/{pageSize}")
    public List<Emp> findAll(@PathVariable("pageNum") Integer pageNum, @PathVariable("pageSize") Integer pageSize){
        return empService.findByPage(pageNum, pageSize);
    }
}
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5.3 定义EmpMapper及EmpMapper.xml

EmpMapper:

@Mapper
public interface EmpMapper {
    List<Emp> findAll();
}
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EmpMapper.xml:

DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.zi.mapper.EmpMapper">

    <select id="findAll" resultType="emp">
        select * from emp
    select>

mapper>
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5.4 定义EmpService及实现类

EmpService：

public interface EmpService {
    List<Emp> findAll();

    List<Emp> findByPage(Integer pageNum, Integer pageSize);
}

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EmpServiceImpl：

@Service
public class EmpServiceImpl implements EmpService {

    @Autowired
    private EmpMapper empMapper;

    @Override
    public List<Emp> findAll() {
        return empMapper.findAll();
    }

    @Override
    public List<Emp> findByPage(Integer pageNum, Integer pageSize) {
        Page<Emp> page = PageHelper.startPage(pageNum, pageSize);
        List<Emp> emps = empMapper.findAll();
        PageInfo<Emp> pi =new PageInfo<>(emps);
        System.out.println("当前页"+pi.getPageNum());
        System.out.println("总页数"+pi.getPages());
        System.out.println("页大小"+pi.getSize());
        System.out.println("总记录数"+pi.getTotal());
        System.out.println("当前页数据"+pi.getList());
        return emps;
    }
}

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5.5 测试

①地址栏中输入：

②响应结果：