9月17日Spring笔记 - 流年石刻

发布时间：2022-09-17 17:18:07

本文字数：855 字阅读完需：约 6 分钟

spring-jdbc

示例

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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.zr</groupId>
    <artifactId>SpringJdbc</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.3.22</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>5.3.22</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.3.22</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>5.3.22</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.3.22</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.17</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.27</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.9.1</version>
        </dependency>
    </dependencies>

</project>

AreaDaoImpl.java

package com.zr.dao.impl;

import com.zr.dao.AreaDao;
import com.zr.vo.Area;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.ResultSetExtractor;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

@Repository
public class AreaDaoImpl implements AreaDao {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public Area query(Integer areaId) {
        return jdbcTemplate.queryForObject("select * from t_area where area_id = ?", new RowMapper<Area>() {
            @Override
            public Area mapRow(ResultSet rs, int rowNum) throws SQLException {
                    Area area= new Area();
                    area.setAreaId(rs.getInt("area_id"));
                    area.setAreaName(rs.getString("area_name"));
                    area.setParentId(rs.getInt("parent_id"));
                    return area;
            }
        }, areaId);
    }

    @Override
    public List<Area> queryList(Integer parentId) {
        return jdbcTemplate.query("select * from t_area where parent_id = ?", new RowMapper<Area>(){

            @Override
            public Area mapRow(ResultSet rs, int rowNum) throws SQLException {
                Area area= new Area();
                area.setAreaId(rs.getInt("area_id"));
                area.setAreaName(rs.getString("area_name"));
                area.setParentId(rs.getInt("parent_id"));
                return area;
            }
        }, parentId);
    }
}

jdbc使用配置类配置

示例

SpringConfig.java

package com.zr.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.core.JdbcTemplate;

import javax.sql.DataSource;

@Configuration
@ComponentScan("com.zr")
public class SpringConfig {
    @Bean
    public JdbcTemplate jdbcTemplate(){
        // new 一个类对象
        JdbcTemplate jdbcTemplate = new JdbcTemplate();
        jdbcTemplate.setDataSource(dataSource());
        return jdbcTemplate;
    }
    @Bean
    public DataSource dataSource(){
        DruidDataSource dataSource = new DruidDataSource();
        // 使用set方法给new的对象赋值，相当于配置文件中的propeties标签
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://127.0.0.1:3306/test");
        dataSource.setUsername("root");
        dataSource.setPassword("mysql");
        return dataSource;
    }
}

TestConfig.java

package com.zr;

import com.zr.action.AreaAction;
import com.zr.config.SpringConfig;
import com.zr.vo.Area;
import org.junit.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import java.util.List;

public class TestConfig {
    @Test
    public void test(){
        AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(SpringConfig.class);
        AreaAction areaAction = ac.getBean(AreaAction.class);
        List<Area> areaList = areaAction.query(1);
        System.out.println(areaList);
    }
}

事务

事务的传播特性

事务的特性：ACID(原子性、一致性、隔离性和持久性)

原子性(Atomicity): 即事务是不可分割的最小工作单元，事务内的操作要么全做，要么全不做
一致性(Consistency): 事务执行前后数据库中的数据都处于正确状态，数据完整性没有被破坏隔离性(Isolation): 并发事务之间互相影响的程度，比如一个事务会不会读取到另一个未提交的事务修改的数据。
持久性(Durability): 事务提交后，对系统的影响是永久的。

alt alt

数据库锁

悲观锁：查询数据后锁死该数据，其他用户无法更改
乐观锁：乐观锁在操作数据时非常乐观，认为别人不会同时修改数据。. 因此乐观锁不会上锁，只是在执行更新的时候判断一下在此期间别人是否修改了数据：如果别人修改了数据则放弃操作，否则执行操作。

spring事务管理示例

声明式事务

spring-config.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"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
    <context:component-scan base-package="com.zr"></context:component-scan>
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://127.0.0.1:3306/test"></property>
        <property name="username" value="root"></property>
        <property name="password" value="mysql"></property>
    </bean>
<!--    配置事务管理器-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
    <!-- 以下配置xml声明式事务 -->
    <tx:advice id="transactionInterceptor" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="query*" isolation="DEFAULT" propagation="REQUIRED" read-only="true"/>
            <tx:method name="add*" isolation="DEFAULT" propagation="REQUIRED" read-only="false"/>
            <tx:method name="edit*" isolation="DEFAULT" propagation="REQUIRED" read-only="false"/>
            <tx:method name="remove*" isolation="DEFAULT" propagation="REQUIRED" read-only="false"/>
        </tx:attributes>
    </tx:advice>
    <aop:config>
        <aop:pointcut id="pointcut" expression="execution(* com.zr.service.*.*(..))"/>
        <aop:advisor advice-ref="transactionInterceptor" pointcut-ref="pointcut"></aop:advisor>
    </aop:config>

</beans>

如果已开启查询事务，进行修改，会报错，因为查询的read-only="true"
如果添加失败，会自动回滚(事务的一致性)

编程式事务

spring-config.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"
       xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:aop="http://www.springframework.org/schema/aop"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">
    <context:component-scan base-package="com.zr"></context:component-scan>
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://127.0.0.1:3306/test"></property>
        <property name="username" value="root"></property>
        <property name="password" value="mysql"></property>
    </bean>
<!--    配置事务管理器-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>
    <tx:annotation-driven transaction-manager="transactionManager"></tx:annotation-driven>


</beans>

AreaServiceImpl.java

package com.zr.service.impl;

import com.zr.dao.AreaDao;
import com.zr.service.AreaService;
import com.zr.vo.Area;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Service
public class AreaServiceImpl implements AreaService {
    @Autowired
    private AreaDao areaDao;

    @Override
    public List<Area> query(Integer areaId) {
        return areaDao.query(areaId);
    }
    // 声明事务
    @Transactional
    @Override
    public int add() {
        Area area = new Area();
        area.setAreaId(29);
        area.setAreaName("绿园区");
        area.setParentId(4);
        areaDao.add(area);
        return  areaDao.add(area);
    }
}

对一个表进行多次操作时可以加事务，只进行一次没必要加事务