文章目錄
1.回顧Mybatis
1.0創建數據庫
CREATE DATABASE `mybatis`;
USE `mybatis`;
CREATE TABLE `user`(
`id` INT(20) NOT NULL PRIMARY KEY,
`name` VARCHAR(30) DEFAULT NULL,
`pwd` VARCHAR(30) DEFAULT NULL
)ENGINE=INNODB DEFAULT CHARSET=utf8;
INSERT INTO `user`(`id`,`name`,`pwd`) VALUES
(1,'王麻子','123456'),
(2,'張三','123456'),
(3,'李四','123890');
完成CRUD需要下面的操作。
- 導入依賴
- 新建實體類
- 編寫操作用戶接口
- 編寫綁定UserMapper.xml文件
- 編寫mybatis-config.xml文件
- 測試
1.1 導入依賴(pom.xml)
<dependencies>
<!-- lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.12</version>
<scope>provided</scope>
</dependency>
<!-- 單元測試的jar包-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency>
<!-- 數據庫的jar包-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<!-- 整合mybatis-spring的jar包-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>2.0.4</version>
</dependency>
<!-- 使用mybatis的jar包-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.4</version>
</dependency>
<!--使用spring的jar包-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.2.6.RELEASE</version>
</dependency>
<!-- spring連接數據庫需要spring-jdbc-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.2.6.RELEASE</version>
</dependency>
<!-- 使用AOP需要導入的jar包-->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.9.5</version>
</dependency>
</dependencies>
1.2新建實體類
新建實體類之前需要連接數據庫!
注意:新建實體類的時候字段名應該和數據庫的列名儘量保持一致!
public class User {
private int id;
private String name;
private String pwd;
public int getId(){
return id;
}
public void setId(int id){
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPwd() {
return pwd;
}
public void setPwd(String pwd) {
this.pwd = pwd;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", name='" + name + '\'' +
", pwd='" + pwd + '\'' +
'}';
}
}
1.3編寫操作用戶的接口
操作用戶的接口可以完成CRUD
public interface UserMapper {
//查詢所有的用戶信息
List<User> selectUser();
}
1.4 編寫綁定UserMapper.xml文件
<?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.li.mapper.UserMapper">
<select id="selectUser" resultType="user">
select * from user;
</select>
</mapper>
1.5編寫mybatis-config.xml文件
要和 Spring 一起使用 MyBatis,需要在 Spring 應用上下文中定義至少兩樣東西:一個 SqlSessionFactory 和至少一個數據映射器類。
在 MyBatis-Spring 中,可使用 SqlSessionFactoryBean來創建 SqlSessionFactory。 要配置這個工廠 bean,只需要把下面代碼放在 Spring 的 XML 配置文件中:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<typeAliases>
<package name="com.li.pojo"/>
</typeAliases>
<environments default="development">
<!-- 裏面的每一個environment 代表一個具體環境-->
<environment id="development">
<!-- transactionManager 事物管理器-->
<transactionManager type="JDBC"/>
<!-- dataSource 數據源的配置-->
<dataSource type="POOLED">
<!-- 連接數據庫的配置-->
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url"
value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=utf-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper class="com.li.mapper.UserMapper"/>
</mappers>
</configuration>
1.6 測試
@Test
public void test() throws IOException {
//指定全局配置文件
String resource = "mybatis-config.xml";
//讀取配置文件
InputStream inputStream = Resources.getResourceAsStream(resource);
//構建sqlSessionFactory
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//獲取sqlSession對象
SqlSession sqlSession = sessionFactory.openSession(true);
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
List<User> users = mapper.selectUser();
for (User user : users) {
System.out.println(user);
}
}
測試過程中出現錯誤下面錯誤:
只需要在pom.xml中導入處理maven靜態資源過濾問題
<!-- maven靜態資源過濾問題-->
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
</resources>
</build>
再次測試:打印輸出
User{id=1, name=‘王麻子’, pwd=‘123456’}
User{id=2, name=‘張三’, pwd=‘123456’}
User{id=3, name=‘李四’, pwd=‘123890’}
2.整合Mybatis-Spring 方式一
- 編寫spring-dao.xml文件
- 實現UserMapper接口的實現類
- 測試
2.1編寫spring-dao.xml文件
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- dataSource 使用spring配置代替mybatis-config.xml中的數據源-->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=utf-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</bean>
<!-- sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!-- 關聯mybatis-config.xml -->
<property name="configLocation" value="classpath:mybatis-config.xml"/>
<!-- value="com/li/mapper/*.xml" 關聯所有的xml文件-->
<property name="mapperLocations" value="classpath:com/li/mapper/UserMapper.xml"/>
</bean>
<!-- SqlSessionTemplate就是我們使用的sqlSession -->
<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
<!-- 使用構造方法的參數創建SqlSessionTemplate對象 因爲SqlSessionTemplate沒有set方法 -->
<constructor-arg index="0" ref="sqlSessionFactory"/>
</bean>
</beans>
爲了方便開發新建一個總的xml文件application.xml
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<import resource="spring-dao.xml"/>
<bean id="userMapper" class="com.li.mapper.UserMapperImpl">
<property name="sqlSession" ref="sqlSession"/>
</bean>
</beans>
2.2 實現UserMapper接口的實現類
- mybatis-spring爲我們提供了映射器,這樣就可以直接注入到bean中
public class UserMapperImpl implements UserMapper {
private SqlSessionTemplate sqlSession;
public void setSqlSession(SqlSessionTemplate sqlSession) {
this.sqlSession = sqlSession;
}
public List<User> selectUser() {
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
return mapper.selectUser();
}
}
2.4整合後的mybatis-config.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!-- 一般將typeAliases、settings放在mybatis-config.xml中-->
<typeAliases>
<package name="com.li.pojo"/>
</typeAliases>
</configuration>
2.3測試
public class MyTest {
@Test
public void test() throws IOException {
ApplicationContext context = new ClassPathXmlApplicationContext("spring-dao.xml");
UserMapper userMapper = context.getBean("userMapper", UserMapper.class);
List<User> users = userMapper.selectUser();
for (User user : users) {
System.out.println(user);
}
}
}
3.整合Mybatis-Spring 方式二
SqlSessionDaoSupport 是一個抽象的支持類,用來爲你提供 SqlSession。調用 getSqlSession() 方法你會得到一個 SqlSessionTemplate,之後可以用於執行 SQL 方法,就像下面這樣:
3.1接口的實現類並且繼SqlSessionDaoSupport類
public class UserMapperImpl2 extends SqlSessionDaoSupport implements UserMapper {
public List<User> selectUser() {
return getSqlSession().getMapper(UserMapper.class).selectUser();
}
}
3.2spring-dao.xml文件
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- dataSource -->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=utf-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</bean>
<!-- sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!-- 關聯mybatis-config.xml -->
<property name="configLocation" value="classpath:mybatis-config.xml"/>
<!-- value="com/li/mapper/*.xml" 關聯所有的xml文件-->
<property name="mapperLocations" value="classpath:com/li/mapper/UserMapper.xml"/>
</bean>
applicationContext.xml文件
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<import resource="spring-dao.xml"/>
<bean id="userMapper2" class="com.li.mapper.UserMapperImpl2">
<property name="sqlSessionFactory" ref="sqlSessionFactory"/>
</bean>
<bean id="userMapper" class="com.li.mapper.UserMapperImpl">
<property name="sqlSession" ref="sqlSession"/>
</bean>
</beans>
3.3測試:
public class MyTest {
@Test
public void test() throws IOException {
ApplicationContext context = new ClassPathXmlApplicationContext("spring-dao.xml");
UserMapper userMapper = context.getBean("userMapper2", UserMapper.class);
List<User> users = userMapper.selectUser();
for (User user : users) {
System.out.println(user);
}
}
}
結果:
User{id=1, name=‘王麻子’, pwd=‘123456’}
User{id=2, name=‘張三’, pwd=‘123456’}
User{id=3, name=‘李四’, pwd=‘123890’}
4.事務
一般來說,事務是必須滿足4個條件(ACID)::原子性(Atomicity,或稱不可分割性)、一致性(Consistency)、隔離性(Isolation,又稱獨立性)、持久性(Durability)。
事務用來管理 insert,update,delete 語句
-
原子性:一個事務(transaction)中的所有操作,要麼全部完成,要麼全部不完成,不會結束在中間某個環節。事務在執行過程中發生錯誤,會被回滾(Rollback)到事務開始前的狀態,就像這個事務從來沒有執行過一樣。
-
一致性:在事務開始之前和事務結束以後,數據庫的完整性沒有被破壞。這表示寫入的資料必須完全符合所有的預設規則,這包含資料的精確度、串聯性以及後續數據庫可以自發性地完成預定的工作。
-
隔離性:數據庫允許多個併發事務同時對其數據進行讀寫和修改的能力,隔離性可以防止多個事務併發執行時由於交叉執行而導致數據的不一致。事務隔離分爲不同級別,包括讀未提交(Read uncommitted)、讀提交(read committed)、可重複讀(repeatable read)和串行化(Serializable)。
-
持久性:事務處理結束後,對數據的修改就是永久的,即便系統故障也不會丟失。
4.1操作用戶的接口
public interface UserMapper {
//查詢所有的用戶信息
List<User> selectUser();
//添加用戶
int insertUser(User user);
//刪除用戶
int deleteUser(int id);
}
4.2編寫UserMapper.xml文件
<?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.li.mapper.UserMapper">
<select id="selectUser" resultType="user">
select * from mybatis.user;
</select>
<insert id="insertUser" parameterType="user">
insert into mybatis.user(id, name, pwd) values (#{id},#{name},#{pwd});
</insert>
<!-- 模擬要麼完成要麼不完成 故意寫錯delete-->
<delete id="deletesUser" parameterType="int">
deletes from mybatis.user where id = #{id};
</delete>
</mapper>
4.3spring-dao.xml
MyBatis-Spring 藉助了 Spring 中的 DataSourceTransactionManager 來實現事務管理。
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop
https://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/tx
https://www.springframework.org/schema/tx/spring-tx.xsd">
<!-- 使用spring接管mybatis-config.xml 中dataSource的內容-->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=utf-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</bean>
<!--sqlSessionFactory-->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!-- 綁定mybatis配置文件-->
<property name="configLocation" value="classpath:mybatis-config.xml"/>
<property name="mapperLocations" value="classpath:com/li/mapper/*.xml"/>
</bean>
</beans>
4.3.1applicationContext.xml
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<import resource="spring-dao.xml"/>
<bean id="userMapper" class="com.li.mapper.UserMapperImpl">
<property name="sqlSessionFactory" ref="sqlSessionFactory"/>
</bean>
</beans>
4.4編寫操作用戶接口的實現類
public class UserMapperImpl extends SqlSessionDaoSupport implements UserMapper {
public List<User> selectUser() {
User user = new User(4, "陳赫", "123456");
UserMapper mapper = getSqlSession().getMapper(UserMapper.class);
mapper.insertUser(user);
mapper.deleteUser(3);
return mapper.selectUser();
}
public int insertUser(User user) {
return getSqlSession().getMapper(UserMapper.class).insertUser(user);
}
public int deleteUser(int id) {
return getSqlSession().getMapper(UserMapper.class).deleteUser(id);
}
}
4.5測試
public class MyTest {
@Test
public void test(){
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
UserMapper userMapper = context.getBean("userMapper", UserMapper.class);
List<User> users = userMapper.selectUser();
for (User user : users) {
System.out.println(user);
}
}
}
我們發現在沒有事務的時候測試失敗但是依然可以插進數據 ,但是卻刪除不了數據。這不是我們想看到的,要麼成功要麼失敗。
所以我們需要在spring-dao.xml中配置事務
<!-- 配置聲明事務-->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
<!-- 結合AOP實現事務得織入-->
<!-- 配置事務通知 -->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<!-- 給那些方法配置事務-->
<!-- 配置事務的傳播特性-->
<tx:attributes>
<tx:method name="insert" propagation="REQUIRED"/>
<tx:method name="delete" propagation="REQUIRED"/>
<tx:method name="update" propagation="REQUIRED"/>
<tx:method name="select" propagation="REQUIRED"/>
<tx:method name="*" propagation="REQUIRED"/>
</tx:attributes>
</tx:advice>
<!--配置事務切入-->
<aop:config>
<aop:pointcut id="txPointCut" expression="execution(* com.li.mapper.*.*(..))"/>
<aop:advisor advice-ref="txAdvice" pointcut-ref="txPointCut"/>
</aop:config>
刪除四號用戶,添加新用戶五號
public class UserMapperImpl extends SqlSessionDaoSupport implements UserMapper {
public List<User> selectUser() {
User user = new User(5, "黃曉明", "123456");
UserMapper mapper = getSqlSession().getMapper(UserMapper.class);
mapper.insertUser(user);
mapper.deleteUser(4);
return mapper.selectUser();
}
public int insertUser(User user) {
return getSqlSession().getMapper(UserMapper.class).insertUser(user);
}
public int deleteUser(int id) {
return getSqlSession().getMapper(UserMapper.class).deleteUser(id);
}
}
成功插入和刪除解決了不一致性、完整性!
User{id=1, name=‘王麻子’, pwd=‘123456’}
User{id=2, name=‘張三’, pwd=‘123456’}
User{id=3, name=‘李四’, pwd=‘123456’}
User{id=5, name=‘黃曉明’, pwd=‘123456’}