Data

1. 配置文件

新建项目时, 选择mysql和jdbc Driver, 导入依赖

在配置文件中配置用户名, 密码, url, 以及Driver

spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
    driver-class-name: com.mysql.cj.jdbc.Driver

注意, 由于SpringBoot中使用的mysql为8.0+ 版本, 要求url中必须带有时区信息

serverTimezone=Asia/Shanghai

2. 测试使用

package com.wang;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

@SpringBootTest
class Springboot04DataApplicationTests {

    //只要把DataSource自动装配, 我们就可以使用了
    @Autowired
    DataSource dataSource;

    @Test
    void contextLoads() throws SQLException {
        //查看默认的数据源 : hikari.HikariDataSource
        System.out.println(dataSource.getClass());

        //获得数据库连接
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        
        //关闭数据库连接
        connection.close();
    }

}

注意

• 使用自动装配绑定DataSource
• 利用getConnection方法调用jdbc
• 默认的数据源为 hikari.HikariDataSource

3. CRUD

package com.wang.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;
import java.util.Map;

@RestController
public class jdbcController {

    //XXXX Template : SpringBoot已经配置好的模板bean, 拿来即用, 封装好了CRUD
    //jdbc
    //redis
    @Autowired
    JdbcTemplate jdbcTemplate;

    //查询数据库的所有信息
    //没有实体类, 数据库中的东西怎样获取? ==> Map
    @GetMapping("/userList")
    public List<Map<String, Object>> userList() {
        String sql = "select * from user";
        List<Map<String, Object>> list_maps = jdbcTemplate.queryForList(sql);
        return list_maps;
    }

    @GetMapping("/addUser")
    public String addUser() {
        String sql = "insert into mybatis.user(id, name, pwd) values(5, ‘小明‘, ‘123456‘)";
        int update = jdbcTemplate.update(sql);
        if (update == 1) {
            return "addUser-OK";
        } else {
            return "addUser-Fail";
        }
    }

    //拼接SQL, 用RestFul风格传参, 要用@PathVariable注解
    @GetMapping("/updateUser/{id}")
    public String updateUser(@PathVariable("id") int id) {
        String sql = "update mybatis.user set name = ?, pwd = ? where id=" + id;

        //封装
        Object[] objects = new Object[2];
        objects[0] = "小明2";
        objects[1] = "1233211234567";

        //jdbcTemplate中的update重载了prepareStatement, 直接传需要的对象即可
        int update = jdbcTemplate.update(sql, objects);
        if (update == 1) {
            return "updateUser-OK";
        } else {
            return "updateUser-Fail";
        }
    }

    @GetMapping("/deleteUser/{id}")
    public String deleteUser(@PathVariable("id") int id) {
        String sql = "delete from mybatis.user where id = ?";

        //jdbcTemplate中的update重载了prepareStatement, 直接传需要的对象即可
        //int也是object, 直接传入即可
        int update = jdbcTemplate.update(sql, id);
        if (update == 1) {
            return "deleteUser-OK";
        } else {
            return "deleteUser-Fail";
        }
    }

}

注意

• XXXX Template : SpringBoot已经配置好的模板bean, 拿来即用, 封装好了CRUD
• 除了查询, 都用update语句
• jdbcTemplate中的update重载了prepareStatement, 直接传需要的对象即可
• 查询用query
• 没有实体类, 数据库中的东西怎样获取? ==> Map ==> List中存放Map, Map中以K-V形式储存数据库中的字段名和值, 字段名为String类型, 值为Object类型

4. Druid

1. 导入依赖

<!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.24</version>
</dependency>

2. 指定数据源并配置Druid

在配置文件中指定type并配置Druid

spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource

    #Spring Boot 默认是不注入这些属性值的，需要自己绑定
    #druid 数据源专有配置
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true

    #配置监控统计拦截的filters，stat:监控统计、log4j：日志记录、wall：防御sql注入
    #如果允许时报错  java.lang.ClassNotFoundException: org.apache.log4j.Priority
    #则导入 log4j 依赖即可，Maven 地址：https://mvnrepository.com/artifact/log4j/log4j
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

3. 绑定Druid到spring.datasource

package com.wang.config;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;
import java.util.HashMap;

@Configuration
public class DruidConfig {

    //将自定义的Bean与spring.datasource绑定
    @ConfigurationProperties(prefix = "spring.datasource")
    //将DruidDataSource注册到Bean
    @Bean
    public DataSource druidDataSource() {
        return new DruidDataSource();
    }
}

注意

• @ConfigurationProperties 绑定配置, 后面可以指定前缀

4. 启用后台监控

package com.wang.config;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;
import java.util.HashMap;

@Configuration
public class DruidConfig {

    //将自定义的Bean与spring.datasource绑定
    @ConfigurationProperties(prefix = "spring.datasource")
    //将DruidDataSource注册到Bean
    @Bean
    public DataSource druidDataSource() {
        return new DruidDataSource();
    }

    //后台监控, 访问 /druid 即可, 固定写法的代码
    //因为SpringBoot 内置了servlet容器, 所以没有web.xml, 替代方法: ServletRegistrationBean
    @Bean
    public ServletRegistrationBean statViewServlet() {
        ServletRegistrationBean<StatViewServlet> bean = new ServletRegistrationBean<>(new StatViewServlet(), "/druid/*");

        //后台需要有人登录, 账号密码配置
        HashMap<String, String> initParameters = new HashMap<>();
        //增加配置
        //登录的key 是固定的 loginUsername loginPassword
        initParameters.put("loginUsername", "admin");
        initParameters.put("loginPassword", "123456");

        //允许谁可以访问, 值为空则所有人都可以访问
        initParameters.put("allow", "");

        //IP白名单
        //initParameters.put("allow","192.168.1.12,127.0.0.1");
        //IP黑名单
        //initParameters.put("deny","192.168.4.23");
        //是否能够重置数据
        initParameters.put("resetEnable","false");

        bean.setInitParameters(initParameters);   //设置初始化参数

        return bean;
    }

}

key如下

public static final String SESSION_USER_KEY    = "druid-user";
public static final String PARAM_NAME_USERNAME = "loginUsername";
public static final String PARAM_NAME_PASSWORD = "loginPassword";
public static final String PARAM_NAME_ALLOW    = "allow";
public static final String PARAM_NAME_DENY     = "deny";
public static final String PARAM_REMOTE_ADDR   = "remoteAddress";

使用log4j, 要在resources下配置log4j.properties

#将等级为DEBUG的日志信息输出到console和file这两个目的地，console和file的定义在下面的代码
log4j.rootLogger=DEBUG,console,file

#控制台输出的相关设置
log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.Target = System.out
log4j.appender.console.Threshold=DEBUG
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=[%c]-%m%n

#文件输出的相关设置
log4j.appender.file = org.apache.log4j.RollingFileAppender
log4j.appender.file.File=./log/wang.log
log4j.appender.file.MaxFileSize=10mb
log4j.appender.file.Threshold=DEBUG
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=[%p][%d{yy-MM-dd}][%c]%m%n

#日志输出级别
log4j.logger.org.mybatis=DEBUG
log4j.logger.java.sql=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.ResultSet=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

注意

• JavaConfig中使用方法进行配置后, 一定要注册Bean
• 通过 ServletRegistrationBean bean = new ServletRegistrationBean<>(new StatViewServlet(), "/druid/*"); 配置stat并设置路径
• 我们要将stat注册到web,xml, 因为SpringBoot 内置了servlet容器, 所以没有web.xml, 替代方法: ServletRegistrationBean
• 以键值对的方式(map)放到setInitParameters方法中
• key是固定的, 不要乱写

5. 设置后台监控的Filter

//filter
//我们要注册filter, 同样的, 使用 FilterRegistrationBean 注册
@Bean
public FilterRegistrationBean webStatFilter() {
    FilterRegistrationBean bean = new FilterRegistrationBean();

    bean.setFilter(new WebStatFilter());

    //可以过滤哪些请求
    HashMap<String, String> initParameters = new HashMap<>();

    //这些东西不进行统计
    initParameters.put("exclusions", "*.js,*.css,/druid/*");

    bean.setInitParameters(initParameters);

    return bean;
}

key如下

public final static String PARAM_NAME_PROFILE_ENABLE         = "profileEnable";
public final static String PARAM_NAME_SESSION_STAT_ENABLE    = "sessionStatEnable";
public final static String PARAM_NAME_SESSION_STAT_MAX_COUNT = "sessionStatMaxCount";
public static final String PARAM_NAME_EXCLUSIONS             = "exclusions";
public static final String PARAM_NAME_PRINCIPAL_SESSION_NAME = "principalSessionName";
public static final String PARAM_NAME_PRINCIPAL_COOKIE_NAME  = "principalCookieName";
public static final String PARAM_NAME_REAL_IP_HEADER         = "realIpHeader";

注意

• 与stat类似, 我们需要注册filter, 使用FilterRegistrationBean
• 不要忘了注册Bean

5. MyBatis

1. 导入依赖

mybatis-spring-boot-starter

<!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.3</version>
</dependency>

2. 编写实体类

package com.wang.pojo;

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

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private int id;
    private String name;
    private String pwd;
}

3. 编写Dao层

package com.wang.mapper;

import com.wang.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;

import java.util.List;

//这个注解表示了这是一个MyBatis的Mapper类
//也可以在启动类是加@MapperScan("")扫描包
@Mapper
//这个注解表示了它是Dao层
@Repository
public interface UserMapper {

    List<User> queryUserList();

    User queryUserById(int id);

    int addUser(User user);

    int updateUser(User user);

    int deleteUser(int id);
}

注意

• @Mapper
  • 这个注解表示了这是一个MyBatis的Mapper类
  • 也可以在启动类是加@MapperScan("")扫描包
• @Repository
  • 这个注解表示了它是Dao层
• 以上两个注解缺一不可

4. 整合Mybatis

在配置文件中添加

# 整合Mybatis
mybatis:
  type-aliases-package: com.wang.pojo
  mapper-locations: classpath:MyBatis/mapper/*.xml

设置别名以及制定XXXMapper.xml的路径

注意

• 路径设置中, classpath: 后没有 /

5. 编写XXXMapper.xml

在配置文件对应的路径下(resources路径下)新建文件夹

UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.wang.mapper.UserMapper">

    <select id="queryUserList" resultType="User">
        select *
        from user;
    </select>

    <select id="queryUserById" resultType="User">
        select *
        from user
        where id = #{id};
    </select>

    <insert id="addUser" parameterType="User">
        insert into user (id, name, pwd)
        VALUES (#{id}, #{name}, #{pwd});
    </insert>

    <update id="updateUser" parameterType="User">
        update user
        set name = #{name},
            pwd  = #{pwd}
        where id = #{id};
    </update>

    <delete id="deleteUser" parameterType="_int">
        delete
        from user
        where id = #{id};
    </delete>


</mapper>

6. 编写controller

package com.wang.controller;

import com.wang.mapper.UserMapper;
import com.wang.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class UserController {

    @Autowired
    private UserMapper userMapper;

    @GetMapping("/userList")
    public List<User> queryUserList() {
        List<User> userList = userMapper.queryUserList();
        return userList;
    }

    @GetMapping("/addUser")
    public String addUser() {
        int i = userMapper.addUser(new User(6, "小明", "123456"));
        return i == 1 ? "ok" : "fail";
    }

    @GetMapping("/updateUser")
    public String updateUser() {
        int i = userMapper.updateUser(new User(6, "小明2", "654321"));
        return i == 1 ? "ok" : "fail";
    }

    @GetMapping("/deleteUser")
    public String deleteUser() {
        int i = userMapper.deleteUser(6);
        return i == 1 ? "ok" : "fail";
    }
}

注意

• 在SpringBoot中, 所有的引入要使用自动装配@AutoWired, 这里引入Dao的接口, 实际项目中应该引入Service层的类(此处偷懒没写)

SpringBoot-整合数据库