Spring Boot 系列教程4-JDBC

JDBC

Java Data Base Connectivity,是一种用于执行SQL语句的Java API，可以为多种关系数据库提供统一访问，它由一组用Java语言编写的类和接口组成。不管是Hibernate，还是JPA或者MyBatis都是对JDBC做了一次封装。

Spring简化了JDBC那些内容

Spring JDBC抽象框架所带来的价值将在以下几个方面得以体现：（注：使用了Spring JDBC抽象框架之后，应用开发人员只需要完成斜体字部分的编码工作。）

- 定义数据库连接参数

- 打开数据库连接

- 声明SQL语句

- 预编译并执行SQL语句

- 遍历查询结果（如果需要的话）

- 处理每一次遍历操作

- 处理抛出的任何异常

- 处理事务

- 关闭数据库连接

项目图片

pom.xml

-只需要在pom.xml引入需要的数据库配置，就会自动访问此数据库，如果需要配置其他数据库，可以在application.properties进行添加

-默认使用org.apache.tomcat.jdbc.pool.DataSource创建连接池

<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.jege.spring.boot</groupId>
    <artifactId>spring-boot-jdbc</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>spring-boot-jdbc</name>
    <url>http://maven.apache.org</url>

    <!-- 公共spring-boot配置，下面依赖jar文件不用在写版本号 -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.1.RELEASE</version>
        <relativePath />
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

        <!-- 持久层 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

        <!-- h2内存数据库 -->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <build>
        <finalName>spring-boot-jdbc</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

User.java

package com.jege.spring.boot.jdbc.entity;

/**
 * @author JE哥
 * @email 1272434821@qq.com
 * @description:模型对象
 */
public class User {
  private Long id;
  private String name;
  private Integer age;

  public User() {

  }

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

  public Long getId() {
    return id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public Integer getAge() {
    return age;
  }

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

UserDaoImpl.java

package com.jege.spring.boot.jdbc.dao.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

import com.jege.spring.boot.jdbc.dao.IUserDao;
import com.jege.spring.boot.jdbc.entity.User;

/**
 * @author JE哥
 * @email 1272434821@qq.com
 * @description:jdbc CRUD
 */
@Repository
public class UserDaoImpl implements IUserDao {
  @Autowired
  JdbcTemplate jdbcTemplate;

  @Override
  public void dropTable() {
    jdbcTemplate.update("drop table t_user if exists");
  }

  @Override
  public void createTable() {
    jdbcTemplate.update(
    "create table t_user (id bigint generated by default as identity, age integer, name varchar(255), primary key (id))");
  }

  @Override
  public void save(User user) {
    jdbcTemplate.update("insert into t_user(name,age) values(?,?)", user.getName(), user.getAge());
  }

  @Override
  public List<User> findAll() {
    return jdbcTemplate.query("select id,name,age from t_user", BeanPropertyRowMapper.newInstance(User.class));
  }

  @Override
  public void deleteAll() {
    jdbcTemplate.update("delete from t_user");
  }

  @Override
  public List<User> findByNameLike(String name) {
    return jdbcTemplate.query("select id,name,age from t_user where name like ?", new Object[] { name },
    BeanPropertyRowMapper.newInstance(User.class));
  }

}

Application.java

package com.jege.spring.boot;

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

/**
 * @author JE哥
 * @email 1272434821@qq.com
 * @description:spring boot 启动类
 */

@SpringBootApplication
public class Application {

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

}

不需要application.properties

UserDaoTest.java

package com.jege.spring.boot.data.jpa;

import static org.assertj.core.api.Assertions.assertThat;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import com.jege.spring.boot.jdbc.dao.IUserDao;
import com.jege.spring.boot.jdbc.entity.User;

/**
 * @author JE哥
 * @email 1272434821@qq.com
 * @description:
 */
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest()
public class UserDaoTest {
  @Autowired
  IUserDao userDao;

  // 每次执行Test之前先删除表，创建表
  @Before
  public void before() throws Exception {
    userDao.dropTable();
    userDao.createTable();
  }

  @Test
  public void save() throws Exception {
    for (int i = 0; i < 10; i++) {
      User user = new User("jege" + i, 25 + i);
      userDao.save(user);
    }
  }

  @Test
  public void all() throws Exception {
    save();
    assertThat(userDao.findAll()).hasSize(10);
  }

  @Test
  public void findByName() throws Exception {
    save();
    assertThat(userDao.findByNameLike("jege%")).hasSize(10);
  }

  @After
  public void destroy() throws Exception {
    userDao.deleteAll();
  }

}

源码地址

https://github.com/je-ge/spring-boot

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