1、添加数据源
既然要使用JdbcTemplate，就需要添加jdbc的依赖。
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
2、连接数据源，以mysql为例：
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
3、在src/main/resources/application.properties中配置数据源信息
注意：其中driver-class可以不写，Spring Boot会自动从url中解析使用的数据源类
Spring Boot默认采用tomcat-jdbc连接池，如果需要C3P0，DBCP，Druid等作为连接池，需要加入相关依赖以及配置，这里不作说明，采用默认配置即可。
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=...
spring.datasource.password=...
底层默认使用tomcat-jdbc连接池，所以在默认情况下会创建一个基于Tomcat连接池的DataSource，并注入到Spring IOC容器中。
abstract class DataSourceConfiguration {
@SuppressWarnings("unchecked")
protected <T> T createDataSource(DataSourceProperties properties,
Class<? extends DataSource> type) {
return (T) properties.initializeDataSourceBuilder().type(type).build();
}
/**
* Tomcat Pool DataSource configuration.
*/
@ConditionalOnClass(org.apache.tomcat.jdbc.pool.DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.tomcat.jdbc.pool.DataSource", matchIfMissing = true)
static class Tomcat extends DataSourceConfiguration {
//创建一个基于Tomcat连接池的DataSource的Bean
//由于底层使用Tomcat连接池，在不引入外部数据连接池的jar包之前，默认使用Tomcat的DataSource
@Bean
@ConfigurationProperties(prefix = "spring.datasource.tomcat")
public org.apache.tomcat.jdbc.pool.DataSource dataSource(
DataSourceProperties properties) {
org.apache.tomcat.jdbc.pool.DataSource dataSource = createDataSource(
properties, org.apache.tomcat.jdbc.pool.DataSource.class);
DatabaseDriver databaseDriver = DatabaseDriver
.fromJdbcUrl(properties.determineUrl());
String validationQuery = databaseDriver.getValidationQuery();
if (validationQuery != null) {
dataSource.setTestOnBorrow(true);
dataSource.setValidationQuery(validationQuery);
}
return dataSource;
}
}
/**
* Hikari DataSource configuration.
*/
@ConditionalOnClass(HikariDataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "com.zaxxer.hikari.HikariDataSource", matchIfMissing = true)
static class Hikari extends DataSourceConfiguration {
//创建基于hikari的DataSource的Bean
@Bean
@ConfigurationProperties(prefix = "spring.datasource.hikari")
public HikariDataSource dataSource(DataSourceProperties properties) {
return createDataSource(properties, HikariDataSource.class);
}
}
/**
* DBCP DataSource configuration.
*
* @deprecated as of 1.5 in favor of DBCP2
*/
@ConditionalOnClass(org.apache.commons.dbcp.BasicDataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.commons.dbcp.BasicDataSource", matchIfMissing = true)
@Deprecated
static class Dbcp extends DataSourceConfiguration {
//创建基于dbcp的DataSource的Bean
@Bean
@ConfigurationProperties(prefix = "spring.datasource.dbcp")
public org.apache.commons.dbcp.BasicDataSource dataSource(
DataSourceProperties properties) {
org.apache.commons.dbcp.BasicDataSource dataSource = createDataSource(
properties, org.apache.commons.dbcp.BasicDataSource.class);
DatabaseDriver databaseDriver = DatabaseDriver
.fromJdbcUrl(properties.determineUrl());
String validationQuery = databaseDriver.getValidationQuery();
if (validationQuery != null) {
dataSource.setTestOnBorrow(true);
dataSource.setValidationQuery(validationQuery);
}
return dataSource;
}
}
/**
* DBCP DataSource configuration.
*/
@ConditionalOnClass(org.apache.commons.dbcp2.BasicDataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.commons.dbcp2.BasicDataSource", matchIfMissing = true)
static class Dbcp2 extends DataSourceConfiguration {
//创建基于dbcp2的DataSource的Bean
@Bean
@ConfigurationProperties(prefix = "spring.datasource.dbcp2")
public org.apache.commons.dbcp2.BasicDataSource dataSource(
DataSourceProperties properties) {
return createDataSource(properties,
org.apache.commons.dbcp2.BasicDataSource.class);
}
}
/**
* Generic DataSource configuration.
*/
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type")
static class Generic {
//可以在配置文件中通过spring.datasource.type指定外部的dataSource类型，并创建基于该type的DataSource的Bean
@Bean
public DataSource dataSource(DataSourceProperties properties) {
return properties.initializeDataSourceBuilder().build();
}
}
}
4、使用JdbcTemplate操作数据库
SpringBoot中的 JdbcTemplate 是自动配置的，可以直接使用 @Autowired 或者 @Resource 来注入到需要的类中。
JdbcTemplateAutoConfiguration
@Configuration
@ConditionalOnClass({ DataSource.class, JdbcTemplate.class })
@ConditionalOnSingleCandidate(DataSource.class)
//在DataSourceAutoConfiguration自动配置类完成后再进行自动配置该类JdbcTemplateAutoConfiguration
@AutoConfigureAfter(DataSourceAutoConfiguration.class)
public class JdbcTemplateAutoConfiguration {
private final DataSource dataSource;
public JdbcTemplateAutoConfiguration(DataSource dataSource) {
this.dataSource = dataSource;
}
//创建一个JdbcTemplate的Bean
@Bean
@Primary
@ConditionalOnMissingBean(JdbcOperations.class)
public JdbcTemplate jdbcTemplate() {
return new JdbcTemplate(this.dataSource);
}
@Bean
@Primary
@ConditionalOnMissingBean(NamedParameterJdbcOperations.class)
public NamedParameterJdbcTemplate namedParameterJdbcTemplate() {
return new NamedParameterJdbcTemplate(this.dataSource);
}
}
在JdbcTemplateAutoConfiguration类中会创建一个JdbcTemplate的Bean，所以在使用的时候可以直接注入。
DataSourceAutoConfiguration
@Configuration
@ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })
//启动DataSourceProperties配置类
@EnableConfigurationProperties(DataSourceProperties.class)
@Import({ Registrar.class, DataSourcePoolMetadataProvidersConfiguration.class })
public class DataSourceAutoConfiguration {
private static final Log logger = LogFactory
.getLog(DataSourceAutoConfiguration.class);
@Bean
@ConditionalOnMissingBean
public DataSourceInitializer dataSourceInitializer(DataSourceProperties properties,
ApplicationContext applicationContext) {
//根据配置文件属性创建DataSource的初始化器
return new DataSourceInitializer(properties, applicationContext);
}
//...
}
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DataSourceInitializer
class DataSourceInitializer implements ApplicationListener<DataSourceInitializedEvent> {
private final DataSourceProperties properties;
private final ApplicationContext applicationContext;
private DataSource dataSource;
private boolean initialized = false;
DataSourceInitializer(DataSourceProperties properties,
ApplicationContext applicationContext) {
this.properties = properties;
this.applicationContext = applicationContext;
}
@PostConstruct
public void init() {
//当DataSourceProperties初始化完成后
if (!this.properties.isInitialize()) {
logger.debug("Initialization disabled (not running DDL scripts)");
return;
}
if (this.applicationContext.getBeanNamesForType(DataSource.class, false,
false).length > 0) {
//获取DataSource的bean
this.dataSource = this.applicationContext.getBean(DataSource.class);
}
if (this.dataSource == null) {
logger.debug("No DataSource found so not initializing");
return;
}
//执行schema脚本
runSchemaScripts();
}
private void runSchemaScripts() {
//查看全局配置文件中是否有spring.datasource.schema
List<Resource> scripts = getScripts("spring.datasource.schema",
this.properties.getSchema(), "schema");
if (!scripts.isEmpty()) {
String username = this.properties.getSchemaUsername();
String password = this.properties.getSchemaPassword();
runScripts(scripts, username, password);
try {
this.applicationContext
.publishEvent(new DataSourceInitializedEvent(this.dataSource));
// The listener might not be registered yet, so don't rely on it.
if (!this.initialized) {
//执行数据插入脚本
runDataScripts();
this.initialized = true;
}
}
catch (IllegalStateException ex) {
logger.warn("Could not send event to complete DataSource initialization ("
+ ex.getMessage() + ")");
}
}
}
@Override
public void onApplicationEvent(DataSourceInitializedEvent event) {
if (!this.properties.isInitialize()) {
logger.debug("Initialization disabled (not running data scripts)");
return;
}
// NOTE the event can happen more than once and
// the event datasource is not used here
//如果初始化完成后，执行数据插入
if (!this.initialized) {
runDataScripts();
this.initialized = true;
}
}
private void runDataScripts() {
List<Resource> scripts = getScripts("spring.datasource.data",
this.properties.getData(), "data");
String username = this.properties.getDataUsername();
String password = this.properties.getDataPassword();
runScripts(scripts, username, password);
}
private List<Resource> getScripts(String propertyName, List<String> resources,
String fallback) {
if (resources != null) {
//如果配置了，则从指定的资源文件中加载脚本
return getResources(propertyName, resources, true);
}
//如果未配置，则使用classpath*:schema-all.sql或者classpath*：schema.sql作为脚本名，其中platform默认为all
String platform = this.properties.getPlatform();
List<String> fallbackResources = new ArrayList<String>();
fallbackResources.add("classpath*:" + fallback + "-" + platform + ".sql");
fallbackResources.add("classpath*:" + fallback + ".sql");
return getResources(propertyName, fallbackResources, false);
}
private List<Resource> getResources(String propertyName, List<String> locations,
boolean validate) {
List<Resource> resources = new ArrayList<Resource>();
for (String location : locations) {
for (Resource resource : doGetResources(location)) {
if (resource.exists()) {
resources.add(resource);
}
else if (validate) {
throw new ResourceNotFoundException(propertyName, resource);
}
}
}
return resources;
}
private Resource[] doGetResources(String location) {
try {
SortedResourcesFactoryBean factory = new SortedResourcesFactoryBean(
this.applicationContext, Collections.singletonList(location));
factory.afterPropertiesSet();
return factory.getObject();
}
catch (Exception ex) {
throw new IllegalStateException("Unable to load resources from " + location,
ex);
}
}
private void runScripts(List<Resource> resources, String username, String password) {
if (resources.isEmpty()) {
return;
}
ResourceDatabasePopulator populator = new ResourceDatabasePopulator();
populator.setContinueOnError(this.properties.isContinueOnError());
populator.setSeparator(this.properties.getSeparator());
if (this.properties.getSqlScriptEncoding() != null) {
populator.setSqlScriptEncoding(this.properties.getSqlScriptEncoding().name());
}
for (Resource resource : resources) {
populator.addScript(resource);
}
DataSource dataSource = this.dataSource;
if (StringUtils.hasText(username) && StringUtils.hasText(password)) {
dataSource = DataSourceBuilder.create(this.properties.getClassLoader())
.driverClassName(this.properties.determineDriverClassName())
.url(this.properties.determineUrl()).username(username)
.password(password).build();
}
DatabasePopulatorUtils.execute(populator, dataSource);
}
} List<Resource> scripts = getScripts("spring.datasource.schema",
this.properties.getSchema(), "schema");
if (!scripts.isEmpty()) {
String username = this.properties.getSchemaUsername();
String password = this.properties.getSchemaPassword();
runScripts(scripts, username, password);
try {
this.applicationContext
.publishEvent(new DataSourceInitializedEvent(this.dataSource));
// The listener might not be registered yet, so don't rely on it.
if (!this.initialized) {
//执行数据插入脚本
runDataScripts();
this.initialized = true;
}
}
catch (IllegalStateException ex) {
logger.warn("Could not send event to complete DataSource initialization ("
+ ex.getMessage() + ")");
}
}
}
@Override
public void onApplicationEvent(DataSourceInitializedEvent event) {
if (!this.properties.isInitialize()) {
logger.debug("Initialization disabled (not running data scripts)");
return;
}
// NOTE the event can happen more than once and
// the event datasource is not used here
//如果初始化完成后，执行数据插入
if (!this.initialized) {
runDataScripts();
this.initialized = true;
}
}
private void runDataScripts() {
List<Resource> scripts = getScripts("spring.datasource.data",
this.properties.getData(), "data");
String username = this.properties.getDataUsername();
String password = this.properties.getDataPassword();
runScripts(scripts, username, password);
}
private List<Resource> getScripts(String propertyName, List<String> resources,
String fallback) {
if (resources != null) {
//如果配置了，则从指定的资源文件中加载脚本
return getResources(propertyName, resources, true);
}
//如果未配置，则使用classpath*:schema-all.sql或者classpath*：schema.sql作为脚本名，其中platform默认为all
String platform = this.properties.getPlatform();
List<String> fallbackResources = new ArrayList<String>();
fallbackResources.add("classpath*:" + fallback + "-" + platform + ".sql");
fallbackResources.add("classpath*:" + fallback + ".sql");
return getResources(propertyName, fallbackResources, false);
}
private List<Resource> getResources(String propertyName, List<String> locations,
boolean validate) {
List<Resource> resources = new ArrayList<Resource>();
for (String location : locations) {
for (Resource resource : doGetResources(location)) {
if (resource.exists()) {
resources.add(resource);
}
else if (validate) {
throw new ResourceNotFoundException(propertyName, resource);
}
}
}
return resources;
}
private Resource[] doGetResources(String location) {
try {
SortedResourcesFactoryBean factory = new SortedResourcesFactoryBean(
this.applicationContext, Collections.singletonList(location));
factory.afterPropertiesSet();
return factory.getObject();
}
catch (Exception ex) {
throw new IllegalStateException("Unable to load resources from " + location,
ex);
}
}
private void runScripts(List<Resource> resources, String username, String password) {
if (resources.isEmpty()) {
return;
}
ResourceDatabasePopulator populator = new ResourceDatabasePopulator();
populator.setContinueOnError(this.properties.isContinueOnError());
populator.setSeparator(this.properties.getSeparator());
if (this.properties.getSqlScriptEncoding() != null) {
populator.setSqlScriptEncoding(this.properties.getSqlScriptEncoding().name());
}
for (Resource resource : resources) {
populator.addScript(resource);
}
DataSource dataSource = this.dataSource;
if (StringUtils.hasText(username) && StringUtils.hasText(password)) {
dataSource = DataSourceBuilder.create(this.properties.getClassLoader())
.driverClassName(this.properties.determineDriverClassName())
.url(this.properties.determineUrl()).username(username)
.password(password).build();
}
DatabasePopulatorUtils.execute(populator, dataSource);
}
}
DataSourceConfiguration
底层默认使用tomcat-jdbc连接池，所以在默认情况下会创建一个基于Tomcat连接池的DataSource，并注入到Spring IOC容器中。
abstract class DataSourceConfiguration {
@SuppressWarnings("unchecked")
protected <T> T createDataSource(DataSourceProperties properties, Class<? extends DataSource> type) {
return (T) properties.initializeDataSourceBuilder().type(type).build();
}
/**
* Tomcat Pool DataSource configuration.
*/
@ConditionalOnClass(org.apache.tomcat.jdbc.pool.DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.tomcat.jdbc.pool.DataSource", matchIfMissing = true)
static class Tomcat extends DataSourceConfiguration {
//创建一个基于Tomcat连接池的DataSource的Bean
//由于底层使用Tomcat连接池，在不引入外部数据连接池的jar包之前，默认使用Tomcat的DataSource
@Bean
@ConfigurationProperties(prefix = "spring.datasource.tomcat")
public org.apache.tomcat.jdbc.pool.DataSource dataSource(DataSourceProperties properties) {
org.apache.tomcat.jdbc.pool.DataSource dataSource = createDataSource(properties, org.apache.tomcat.jdbc.pool.DataSource.class);
DatabaseDriver databaseDriver = DatabaseDriver.fromJdbcUrl(properties.determineUrl());
String validationQuery = databaseDriver.getValidationQuery();
if (validationQuery != null) {
dataSource.setTestOnBorrow(true);
dataSource.setValidationQuery(validationQuery);
}
return dataSource;
}
}
/**
* Hikari DataSource configuration.
*/
@ConditionalOnClass(HikariDataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "com.zaxxer.hikari.HikariDataSource", matchIfMissing = true)
static class Hikari extends DataSourceConfiguration {
//创建基于hikari的DataSource的Bean
@Bean
@ConfigurationProperties(prefix = "spring.datasource.hikari")
public HikariDataSource dataSource(DataSourceProperties properties) {
return createDataSource(properties, HikariDataSource.class);
}
}
/**
* DBCP DataSource configuration.
*
* @deprecated as of 1.5 in favor of DBCP2
*/
@ConditionalOnClass(org.apache.commons.dbcp.BasicDataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.commons.dbcp.BasicDataSource", matchIfMissing = true)
@Deprecated
static class Dbcp extends DataSourceConfiguration {
//创建基于dbcp的DataSource的Bean
@Bean
@ConfigurationProperties(prefix = "spring.datasource.dbcp")
public org.apache.commons.dbcp.BasicDataSource dataSource(DataSourceProperties properties) {
org.apache.commons.dbcp.BasicDataSource dataSource = createDataSource(properties, org.apache.commons.dbcp.BasicDataSource.class);
DatabaseDriver databaseDriver = DatabaseDriver.fromJdbcUrl(properties.determineUrl());
String validationQuery = databaseDriver.getValidationQuery();
if (validationQuery != null) {
dataSource.setTestOnBorrow(true);
dataSource.setValidationQuery(validationQuery);
}
return dataSource;
}
}
/**
* DBCP DataSource configuration.
*/
@ConditionalOnClass(org.apache.commons.dbcp2.BasicDataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.commons.dbcp2.BasicDataSource", matchIfMissing = true)
static class Dbcp2 extends DataSourceConfiguration {
//创建基于dbcp2的DataSource的Bean
@Bean
@ConfigurationProperties(prefix = "spring.datasource.dbcp2")
public org.apache.commons.dbcp2.BasicDataSource dataSource(DataSourceProperties properties) {
return createDataSource(properties,org.apache.commons.dbcp2.BasicDataSource.class);
}
}
/**
* Generic DataSource configuration.
*/
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type")
static class Generic {
//可以在配置文件中通过spring.datasource.type指定外部的dataSource类型，并创建基于该type的DataSource的Bean
@Bean
public DataSource dataSource(DataSourceProperties properties) {
return properties.initializeDataSourceBuilder().build();
}
}
}
SpringBoot默认支持：
- org.apache.tomcat.jdbc.pool.DataSource
- com.zaxxer.hikari.HikariDataSource
- org.apache.commons.dbcp.BasicDataSource
- org.apache.commons.dbcp2.BasicDataSource
上面讲到DataSourceInitializer是ApplicationListener类型的监听器
它的作用主要有：
i）、runSchemaScripts();运行建表语句
ii）、runDataScripts();运行插入数据的sql语句
默认只需要将文件命名为：
schema-*.sql 用于建表操作
data-*.sql 用于数据操作
默认规则：schema.sql或者schema-all.sql
自定义规则：spring.datasource.schema=[classpath:department.sql]
最后使用JdbcTemplate操作数据库，就类似在Spring框架中使用JdbcTemplate一样，这里就不再累赘了。
附上代码：
User实体类：
public class User implements Serializable {
private Integer uid;
private String uname;
private int uage;
//getter和setter
}
User控制器：
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private IUserService userService;
@PostMapping("/")
public String insertUser(User user){
int count = userService.insertUser(user);
if(count != 1){
return "error";
}else{
return "success";
}
}
@GetMapping("/{uid}")
public User getUserById(@PathVariable Integer uid){
User user = userService.getUserById(uid);
return user;
}
@GetMapping("/")
public List<User> getAllUsers(){
return userService.getAllUsers();
}
@PutMapping("/{uid}")
public String updateUserById(@PathVariable Integer uid, User user){
return userService.updateUserById(uid, user) == 1 ? "success" : "error";
}
@DeleteMapping("/{uid}")
public String deleteUserById(@PathVariable Integer uid){
return userService.deleteUserById(uid) == 1 ? "success" : "error";
}
}
User业务层接口：
public interface IUserService {
int insertUser(User user);
User getUserById(Integer id);
List<User> getAllUsers();
int updateUserById(Integer uid, User user);
int deleteUserById(Integer uid);
}
User业务层接口实现类：
@Service
public class UserServiceImpl implements IUserService {
@Autowired
private IUserDao userDao;
@Override
public int insertUser(User user) {
return userDao.insertUser(user);
}
@Override
public User getUserById(Integer id) {
return userDao.getUserById(id);
}
@Override
public List<User> getAllUsers() {
return userDao.getAllUsers();
}
@Override
public int updateUserById(Integer uid, User user) {
return userDao.updateUserById(uid, user);
}
@Override
public int deleteUserById(Integer uid) {
return userDao.deleteUserById(uid);
}
}
User持久层接口：
public interface IUserDao {
int insertUser(User user);
User getUserById(Integer id);
List<User> getAllUsers();
int updateUserById(Integer uid, User user);
int deleteUserById(Integer uid);
}
User持久层接口实现类：
@Repository
public class UserDaoImpl implements IUserDao {
@Autowired
private JdbcTemplate jdbcTemplate;
@Override
public int insertUser(User user) {
return jdbcTemplate.update("insert into user values(null, ?, ?)", user.getUname(), user.getUage());
}
@Override
public User getUserById(Integer id) {
Object[] params = {id};
return jdbcTemplate.queryForObject("select * from user where uid=?", params, new UserRowMapper());
}
@Override
public List<User> getAllUsers() {
return jdbcTemplate.query("select * from user", new UserRowMapper());
}
@Override
public int updateUserById(Integer uid, User user) {
StringBuilder sb = new StringBuilder();
List<Object> params = new ArrayList<>();
boolean isUpdate = false;
if (user != null) {
sb.append("update user set ");
if (user.getUname() != null && !"".equals(StringUtils.trimWhitespace(user.getUname()))) {
isUpdate = true;
sb.append(" uname = ?,");
params.add(StringUtils.trimWhitespace(user.getUname()));
}
if (user.getUage() != 0) {
isUpdate = true;
sb.append(" uage = ?,");
params.add(user.getUage());
}
}
if (isUpdate) {
sb.deleteCharAt(sb.length() - 1);
sb.append(" where uid = ? ");
params.add(user.getUid());
return jdbcTemplate.update(sb.toString(), params.toArray());
} else {
return 0;
}
}
@Override
public int deleteUserById(Integer uid) {
return jdbcTemplate.update("delete from user where uid = ?", uid);
}
}
User数据映射类：
public class UserRowMapper implements RowMapper<User> {
@Override
public User mapRow(ResultSet resultSet, int i) throws SQLException {
User user = new User();
user.setUid(resultSet.getInt("uid"));
user.setUname(resultSet.getString("uname"));
user.setUage(resultSet.getInt("uage"));
return user;
}
}
本节使用Restful风格进行编写，大概知道Restful格式即可，此处不多讲述。
