文章目錄
1. JdbcTemplate對象
- JdbcTemplated是Spring提供的一個連接數據庫的org.springframework.jdbc.core.JdbcTemplate
- dbutils.QueryRunner是dbutils包提供的一個連接數據庫
- 兩者類似。
2. 由JdbcTemplate對象自己提供的數據庫
- JdbcTemplate中的DriverManagerDataSource可以準備數據源;
- execute方法執行SQL語句,直接把參數值寫死,不用佔位符?。
JdbcTemplateDemo1
package com.jh.jdbctemplate;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
/**JdbcTemplate的最基本用法*/
public class JdbcTemplateDemo1 {
public static void main(String[] args) {
//準備數據源
DriverManagerDataSource ds=new DriverManagerDataSource();
ds.setDriverClassName("com.mysql.cj.jdbc.Driver");
ds.setUrl("jdbc:mysql://localhost:3306/maven?serverTimezone=GMT%2B8");
ds.setUsername("root");
ds.setPassword("jh7851192");
//1.創建JdbcTemplate對象
JdbcTemplate jt = new JdbcTemplate();
//給jt設置數據源
jt.setDataSource(ds);
//2.執行操作
jt.execute("insert into account(name,money)values ('ccc',1200)");
}
}
3.JdbcTemplate採用XML配置的方法配置數據庫
不用像JdbcTemplateDemo1一樣把數據庫寫死
JdbcTemplateDemo2
package com.jh.jdbctemplate;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
/**JdbcTemplate的最基本用法
* 採用XML配置的方法配置數據源,不用像JdbcTemplateDemo1一樣把數據庫寫死
* */
public class JdbcTemplateDemo2 {
public static void main(String[] args) {
//1.獲取容器
ApplicationContext ac=new ClassPathXmlApplicationContext("bean.xml");
//2.獲取bean對象JdbcTemplate
JdbcTemplate jt=ac.getBean("jdbcTemplate",JdbcTemplate.class);
//3.執行操作
//execute 沒有佔位符?,直接寫參數值
jt.execute("insert into account(name,money)values ('ddd',2200)");
}
}
bean.xml
- 這裏也是配置數據源class="org.springframework.jdbc.datasource.DriverManagerDataSource
- 只是把DriverManagerDataSource寫到xml裏,不再寫到類中。
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- 配置賬戶的持久層-->
<bean id="accountDao" class="com.jh.dao.impl.AccountDaoImpl">
<!--注入JdbcTemplate對象-->
<property name="jdbcTemplate" ref="jdbcTemplate"></property>
<!--<property name="dataSource" ref="dataSource"></property>-->
</bean>
<!--配置JdbcTemplate-->
<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
<property name="dataSource" ref="dataSource"></property>
</bean>
<!--配置數據源-->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.cj.jdbc.Driver"></property>
<property name="url" value="jdbc:mysql://localhost:3306/maven?serverTimezone=GMT%2B8"></property>
<property name="username" value="root"></property>
<property name="password" value="jh7851192"></property>
</bean>
</beans>
4. JdbcTemplate對象 CRUD操作(數據庫xml已配置)
- 執行操作(這裏寫佔位符? 和QueryRunner(query,update)一樣,但是和execute方法不一樣)
- Spring提供一個BeanPropertyRowMapper,類似於dbutils.QueryRunner中的BeanListHandler,BeanHandler
JdbcTemplateDemo3
public class JdbcTemplateDemo3 {
public static void main(String[] args) {
//1.獲取容器
ApplicationContext ac=new ClassPathXmlApplicationContext("bean.xml");
//2.獲取bean對象JdbcTemplate
JdbcTemplate jt=ac.getBean("jdbcTemplate",JdbcTemplate.class);
//3.執行操作(這裏寫佔位符? 和QueryRunner(query,update)一樣,但是和execute方法不一樣)
/*//保存
jt.update("insert into account(name,money)values (?,?)","eee",2345f);
//更新
jt.update("update account set name=?,money=? where id=?","jh2",2324f,6);
//刪除
jt.update("delete from account where id=?",6);*/
//查詢所有
//List<Account>accounts = jt.query("select * from account where money > ?",new AccountRowMapper(),1000f);
/**Spring提供一個BeanPropertyRowMapper,類似於dbutils.QueryRunner中的BeanListHandler,BeanHandler
* 以後不用自己寫實現類:class AccountRowMapper*/
/*List<Account>accounts = jt.query("select * from account where money > ?",new BeanPropertyRowMapper<Account>(Account.class),1000f);
for (Account account:accounts){
System.out.println(account);
Account{id=1, name='aaa', money=4566.0}
Account{id=5, name='jh', money=12213.0}
Account{id=7, name='ddd', money=2200.0}
}*/
//查詢一個
List<Account> accounts = jt.query("select * from account where id = ?",new BeanPropertyRowMapper<Account>(Account.class),1);
System.out.println(accounts.isEmpty()?"沒有內容":accounts.get(0));
//Account{id=1, name='aaa', money=4566.0}
//查詢返回一行一列(使用聚合函數,但不加group by子句)
Long count = jt.queryForObject("select count(*) from account where money >?", Long.class, 1000f);
System.out.println(count);//3
}
}
//這是自己寫的類AccountRowMapper
class AccountRowMapper implements RowMapper<Account>{
/**
* 把結果集中的數據封裝到Account中,然後由Spring把每個Account加到集合中
* */
@Override
public Account mapRow(ResultSet rs, int rowNum) throws SQLException {
Account account=new Account();
account.setId(rs.getInt("id"));
account.setName(rs.getString("name"));
account.setMoney(rs.getFloat("money"));
return account;
}
}
5. 將SQL語句寫在持久層
- 通過獲取IAccountDao的bean對象,已在bean.xml裏逐步注入對象,進行調用,實現數據庫的調用;
- accountDao—>jdbcTemplate—>dataSource
JdbcTemplateDemo4
public class JdbcTemplateDemo4 {
public static void main(String[] args) {
//1.獲取容器
ApplicationContext ac=new ClassPathXmlApplicationContext("bean.xml");
//2.獲取bean對象
IAccountDao accountDao=ac.getBean("accountDao",IAccountDao.class);
//3.執行操作
Account account = accountDao.findAccountById(2);
System.out.println(account);//Account{id=1, name='aaa', money=4566.0}
account.setMoney(1200f);
accountDao.updateAccount(account);//下一次就更新爲Account{id=1, name='aaa', money=1230.0}
}
}
Account
package com.jh.domain;
import java.io.Serializable;
/**賬戶的實體類*/
public class Account implements Serializable {
private Integer id;
private String name;
private Float money;
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 Float getMoney() {
return money;
}
public void setMoney(Float money) {
this.money = money;
}
@Override
public String toString() {
return "Account{" +
"id=" + id +
", name='" + name + '\'' +
", money=" + money +
'}';
}
}
IAccountDao
package com.jh.dao;
import com.jh.domain.Account;
/**持久層*/
public interface IAccountDao {
//根據id查詢賬戶
Account findAccountById(Integer accountId);
//根據名稱查詢賬戶
Account findAccountByName(String accountName);
//更新賬戶
void updateAccount(Account account);
}
SQL語句在持久層實現類寫
package com.jh.dao.impl;
import com.jh.dao.IAccountDao;
import com.jh.domain.Account;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import java.util.List;
/**持久層實現類*/
public class AccountDaoImpl implements IAccountDao {
private JdbcTemplate jdbcTemplate;
public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
@Override
public Account findAccountById(Integer accountId) {
List<Account> accounts = jdbcTemplate.query("select * from account where id=?", new BeanPropertyRowMapper<Account>(Account.class), accountId);
return accounts.isEmpty()?null:accounts.get(0);
}
@Override
public Account findAccountByName(String accountName) {
List<Account> accounts = jdbcTemplate.query("select * from account where name=?", new BeanPropertyRowMapper<Account>(Account.class), accountName);
if (accounts.isEmpty()){
return null;
}if (accounts.size()>1){
throw new RuntimeException("結果集不唯一");
}
return accounts.get(0);
}
@Override
public void updateAccount(Account account) {
jdbcTemplate.update("update account set name=?,money=? where id=?",account.getName(),account.getMoney(),account.getId());
}
}
抽取重複代碼:可以省略private JdbcTemplate jdbcTemplate;和set方法
extends JdbcDaoSupport
package com.jh.dao.impl;
import com.jh.dao.IAccountDao;
import com.jh.domain.Account;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.support.JdbcDaoSupport;
import java.util.List;
/**持久層實現類
*抽取重複代碼:可以省略private JdbcTemplate jdbcTemplate;和set方法
* */
public class AccountDaoImpl2 extends JdbcDaoSupport implements IAccountDao {
@Override
public Account findAccountById(Integer accountId) {
List<Account> accounts = super.getJdbcTemplate().query("select * from account where id=?", new BeanPropertyRowMapper<Account>(Account.class), accountId);
return accounts.isEmpty()?null:accounts.get(0);
}
@Override
public Account findAccountByName(String accountName) {
List<Account> accounts = super.getJdbcTemplate().query("select * from account where name=?", new BeanPropertyRowMapper<Account>(Account.class), accountName);
if (accounts.isEmpty()){
return null;
}if (accounts.size()>1){
throw new RuntimeException("結果集不唯一");
}
return accounts.get(0);
}
@Override
public void updateAccount(Account account) {
super.getJdbcTemplate().update("update account set name=?,money=? where id=?",account.getName(),account.getMoney(),account.getId());
}
}