springboot与jdbc

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本文将介绍如何将spring boot 与 JdbcTemplate一起工作。

Spring对数据库的操作在jdbc上面做了深层次的封装，使用spring的注入功能，可以把DataSource注册到JdbcTemplate之中。 JdbcTemplate 是在JDBC API基础上提供了更抽象的封装，并提供了基于方法注解的事务管理能力。通过使用SpringBoot自动配置功能并代替我们自动配置beans. 在maven中，我们需要增加spring-boot-starter-jdbc模块

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

通过这个模块为我们做了以下几件事

tomcat-jdbc－{version}.jar为我们自动配置DataSource.
如果你没有定义任何DataSource，SpringBoot将会自动配置一个内存的数据库资源设置
如果没有设置任一个beans，SpringBoot会自动注册它

初始化数据库

如果我们在classpath里定义了schema.sql和data.sql文件，springBoot将会使用这些文件自动初始化数据库(但你必须选建库)除了载入schema.sql和data.sql外，SpringBoot也会载入schema-${platform}.sql和data-${platform}.sql，如果在你的classpath下存在的话。

spring.datasource.schema=xxxx-db.sql 可以定义你的建库文件spring.datasource.data=xxxx-data.sql  可以定义你的数据文件spring.datasource.initialize＝true|false 可以决定是不是要初始化这些数据库文件spring.datasource.continueOnError＝true|false 有了错误是否继续运行

定义数据库驱动信息

/src/main/resources/application.yml

logging:  level:    org.springframework: INFO    com.example: DEBUG################### DataSource Configuration ##########################spring:  datasource:    driver-class-name: com.mysql.jdbc.Driver    url: jdbc:mysql://localhost:3306/gs-jdbc    username: root    password:    initialize: trueinit-db: true

其中

spring:  datasource:    driver-class-name: com.mysql.jdbc.Driver    url: jdbc:mysql://localhost:3306/gs-jdbc    username: root    password:

我是用的mysql,你也可以定义其它或者不定义，如果不定义，springBoot会自动为我们配置一个嵌入的数据库( Embedded database)

自定义数据源

如果你不想用默认的配置数据源，如你想用阿里巴巴的数据池管理数据源，你也可以自己配置

先排除tomcat-jdbc的默认配置dataSource

<dependency>    <groupId>org.springframework.boot</groupId>    <artifactId>spring-boot-starter-jdbc</artifactId>    <exclusions>        <exclusion>            <groupId>org.apache.tomcat</groupId>            <artifactId>tomcat-jdbc</artifactId>        </exclusion>    </exclusions></dependency>

定义自己的数据资源这里使用了阿里巴巴的数据池管理,你也可以使用BasicDataSource

<dependency>    <groupId>com.alibaba</groupId>    <artifactId>druid</artifactId>    <version>1.0.19</version></dependency>

/src/main/java/com/example/SpringBootJdbcDemoApplication.java

package com.example;import com.alibaba.druid.pool.DruidDataSource;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.context.annotation.Bean;import org.springframework.core.env.Environment;import javax.sql.DataSource;/** * Created by tom on 2016/5/21. */@SpringBootApplicationpublic class SpringBootJdbcDemoApplication {    public static void main(String[] args) {        SpringApplication.run(SpringBootJdbcDemoApplication.class, args);    }    @Autowired    private Environment env;    @Bean    public DataSource dataSource() {        DruidDataSource dataSource = new DruidDataSource();        dataSource.setUrl(env.getProperty("spring.datasource.url"));        dataSource.setUsername(env.getProperty("spring.datasource.username"));//用户名        dataSource.setPassword(env.getProperty("spring.datasource.password"));//密码        dataSource.setInitialSize(2);        dataSource.setMaxActive(20);        dataSource.setMinIdle(0);        dataSource.setMaxWait(60000);        dataSource.setValidationQuery("SELECT 1");        dataSource.setTestOnBorrow(false);        dataSource.setTestWhileIdle(true);        dataSource.setPoolPreparedStatements(false);        return dataSource;    }}

你也可以用别的：

<dependency>    <groupId>commons-dbcp</groupId>    <artifactId>commons-dbcp</artifactId>    <version>1.4</version></dependency>

    @Bean    public DataSource dataSource() {        BasicDataSource dataSource = new BasicDataSource();        dataSource.setDriverClassName(env.getProperty("spring.datasource.driver-class-name"));        dataSource.setUrl(env.getProperty("spring.datasource.url"));        dataSource.setUsername(env.getProperty("spring.datasource.username"));        dataSource.setPassword(env.getProperty("spring.datasource.password"));        return dataSource;    }

创建实体对象

/src/main/java/com/example/domain/User.java

package com.example.domain;/** * Created by tom on 2016/5/21. */public class User{    private Integer id;    private String name;    private String email;    public User()    {    }    public User(Integer id, String name, String email)    {        this.id = id;        this.name = name;        this.email = email;    }    public Integer getId()    {        return id;    }    public void setId(Integer id)    {        this.id = id;    }    public String getName()    {        return name;    }    public void setName(String name)    {        this.name = name;    }    public String getEmail()    {        return email;    }    public void setEmail(String email)    {        this.email = email;    }    @Override    public String toString() {        return "User{" +                "id=" + id +                ", name='" + name + '\'' +                ", email='" + email + '\'' +                '}';    }}

创建持久层

有了上面的数据源配置，我们可以注入JdbcTemplate到数据访问组件并与数据库交互。 /src/main/java/com/example/repositories/UserRepository.java

package com.example.repositories;import com.example.domain.User;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.jdbc.core.JdbcTemplate;import org.springframework.jdbc.core.PreparedStatementCreator;import org.springframework.jdbc.core.RowMapper;import org.springframework.jdbc.support.GeneratedKeyHolder;import org.springframework.jdbc.support.KeyHolder;import org.springframework.stereotype.Repository;import org.springframework.transaction.annotation.Transactional;import java.sql.*;import java.util.List;/** * Created by tom on 2016/5/21. */@Repositorypublic class UserRepository {    @Autowired    private JdbcTemplate jdbcTemplate;    @Transactional(readOnly = true)    public List<User> findAll() {        return jdbcTemplate.query("select * from users", new UserRowMapper());    }    @Transactional(readOnly = true)    public User findUserById(int id) {        return jdbcTemplate.queryForObject("select * from users where id=?", new Object[]{id}, new UserRowMapper());    }    public User create(final User user) {        final String sql = "insert into users(name,email) values(?,?)";        KeyHolder holder = new GeneratedKeyHolder();        jdbcTemplate.update(new PreparedStatementCreator() {            @Override            public PreparedStatement createPreparedStatement(Connection connection)                    throws SQLException {                PreparedStatement ps = connection.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS);                ps.setString(1, user.getName());                ps.setString(2, user.getEmail());                return ps;            }        }, holder);        int newUserId = holder.getKey().intValue();        user.setId(newUserId);        return user;    }    public void delete(final Integer id) {        final String sql = "delete from users where id=?";        jdbcTemplate.update(sql,                new Object[]{id},                new int[]{java.sql.Types.INTEGER});    }    public void update(final User user) {        jdbcTemplate.update(                "update users set name=?,email=? where id=?",                new Object[]{user.getName(), user.getEmail(), user.getId()});    }}class UserRowMapper implements RowMapper<User> {    @Override    public User mapRow(ResultSet rs, int rowNum) throws SQLException {        User user = new User();        user.setId(rs.getInt("id"));        user.setName(rs.getString("name"));        user.setEmail(rs.getString("email"));        return user;    }}

你或许己注意到，大多数时候，我们都在应用中做这些配置的事。

创建单元测试测试我们的持久层方法

/src/test/java/SpringBootJdbcDemoApplicationTests.java

import com.example.SpringBootJdbcDemoApplication;import com.example.domain.User;import com.example.repositories.UserRepository;import org.junit.Test;import org.junit.runner.RunWith;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.test.SpringApplicationConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import java.util.List;import static org.junit.Assert.*;import static org.junit.Assert.assertEquals;/** * Created by tom on 2016/5/21. */@RunWith(SpringJUnit4ClassRunner.class)@SpringApplicationConfiguration(SpringBootJdbcDemoApplication.class)public class SpringBootJdbcDemoApplicationTests{     Logger logger= LoggerFactory.getLogger(SpringBootJdbcDemoApplicationTests.class);    @Autowired    private UserRepository userRepository;    @Test public void testAll(){        findAllUsers();        findUserById();        createUser();    }    @Test    public void findAllUsers()  {        List<User> users = userRepository.findAll();        assertNotNull(users);        assertTrue(!users.isEmpty());    }    @Test    public void findUserById()  {        User user = userRepository.findUserById(1);        assertNotNull(user);    }    private void updateById(Integer id)  {        User newUser = new User(id, "JackChen", "JackChen@qq.com");        userRepository.update(newUser);        User newUser2 = userRepository.findUserById(newUser.getId());        assertEquals(newUser.getName(), newUser2.getName());        assertEquals(newUser.getEmail(), newUser2.getEmail());    }    @Test    public void createUser() {        User user = new User(0, "tom", "tom@gmail.com");        User savedUser = userRepository.create(user);        logger.debug("{}",savedUser);        User newUser = userRepository.findUserById(savedUser.getId());        assertEquals("tom", newUser.getName());        assertEquals("tom@gmail.com", newUser.getEmail());        updateById(newUser.getId());        userRepository.delete(newUser.getId());    }}

源代码请访问： https://github.com/tomlxq/best-practice/tree/master/gs-jdbc

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