使用基于XML的IoC完成单表的CRUD

# 41.使用基于XML的IoC完成单表的CRUD

对IoC有基本的认知后，我们来试着完成对单表的增删改查（分别使用XML和注解的方式），在实际运用中使用Spring。　　‍

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# 环境准备

为了方便，我们引用一些依赖dbutils、c3p0，Junit

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.28</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.0.2.RELEASE</version>
    </dependency>

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

    <dependency>
        <groupId>c3p0</groupId>
        <artifactId>c3p0</artifactId>
        <version>0.9.1.2</version>
    </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.13.2</version>
        <scope>test</scope>
    </dependency>
</dependencies>

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然后我们可以删除我们之前所有的Java代码，只保留pom.xml：

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# 创建实体类

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package com.peterjxl.domain;
import java.io.Serializable;

/**
 * 账户的实体类
 */
public class Account implements Serializable {

    private Integer id;
    private String name;
    private Float money;
}

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注：请读者自行生成 getter 和 setter

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# 创建dao层接口

我们创建dao的接口：

package com.peterjxl.dao;
import com.peterjxl.domain.Account;
import java.util.List;

public interface IAccountDao {
    List<Account> findAllAccount();
    Account findAccountById(Integer accountId);
    void saveAccount(Account account);
    void updateAccount(Account account);
    void deleteAccount(Integer accountId);
}

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# 创建service层

我们新建一个接口，并定义常用的CRUD操作：

package com.peterjxl.service;
import com.peterjxl.domain.Account;
import java.util.List;

public interface IAccountService {
    List<Account> findAllAccount();
    Account findAccountById(Integer accountId);
    void saveAccount(Account account);
    void updateAccount(Account account);
    void deleteAccount(Integer accountId);
}

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然后我们创建service实现类：注意有个IAccountDao变量，并且有个set方法，后期由Spring帮我们注入

package com.peterjxl.service.impl;
import com.peterjxl.dao.IAccountDao;
import com.peterjxl.domain.Account;
import com.peterjxl.service.IAccountService;
import java.util.List;

public class AccountServiceImpl implements IAccountService {

    private IAccountDao accountDao;

    public void setAccountDao(IAccountDao accountDao) {
        this.accountDao = accountDao;
    }

    @Override
    public List<Account> findAllAccount() {
        return accountDao.findAllAccount();
    }

    @Override
    public Account findAccountById(Integer accountId) {
        return accountDao.findAccountById();
    }

    @Override
    public void saveAccount(Account account) {
        accountDao.saveAccount(account);
    }

    @Override
    public void updateAccount(Account account) {
        accountDao.updateAccount(account);
    }

    @Override
    public void deleteAccount(Integer accountId) {
        accountDao.deleteAccount(accountId);
    }
}

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# 创建dao实现类

注意有个QueryRunner变量，并且有个set方法，后期由Spring帮我们注入

package com.peterjxl.dao.impl;

import com.peterjxl.dao.IAccountDao;
import com.peterjxl.domain.Account;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;

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

/**
 * 账户的持久层实现类
 */
public class AccountDaoImpl implements IAccountDao {

    private QueryRunner runner;

    public void setRunner(QueryRunner runner) {
        this.runner = runner;
    }

    @Override
    public List<Account> findAllAccount() {
        try {
            return runner.query("select * from account", new BeanListHandler<Account>(Account.class));
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public Account findAccountById(Integer accountId) {
        try {
            return runner.query("select * from account where id = ? ", new BeanHandler<Account>(Account.class), accountId);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void saveAccount(Account account) {
        try {
            runner.update("insert into account (name, money) values(?, ?) ", account.getName(), account.getMoney());
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void updateAccount(Account account) {
        try {
            runner.update("update account  set name = ? money = ? where id = ?", account.getName(), account.getMoney(), account.getId());
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void deleteAccount(Integer accountId) {
        try {
            runner.update("delete from account  where id = ?", accountId);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}

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# 搭建Spring并注入对象

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我们新建一个配置文件bean.xml：并配置数据源、QueryRunner、dao和service对象

<?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">

    <!-- 配置数据源 -->
    <bean id = "dataSource" class = "com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="com.mysql.cj.jdbc.Driver"/>
        <property name = "jdbcUrl" value = "jdbc:mysql://localhost:3306/learnSpring"/>
        <property name = "user" value = "learnSpringUser"/>
        <property name = "password" value = "learnSpringPassword"/>
    </bean>

    <!-- 配置QueryRunner -->
    <bean id = "runner" class = "org.apache.commons.dbutils.QueryRunner" scope = "prototype">
        <constructor-arg name = "ds" ref = "dataSource"/>
    </bean>

    <!-- 配置Dao对象 -->
    <bean id = "accountDao" class = "com.peterjxl.dao.impl.AccountDaoImpl">
        <property name = "runner" ref = "runner"/>
    </bean>

    <!-- 配置service -->
    <bean id = "accountService" class = "com.peterjxl.service.impl.AccountServiceImpl">
        <property name = "accountDao" ref = "accountDao"/>
    </bean>
</beans>

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注意：QueryRunner我们是使用多例对象的，如果使用单例对象，那么多个dao使用时可能会有线程安全问题。

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# 编写测试类

我们写个测试方法并运行：

package com.peterjxl.test;

import com.peterjxl.domain.Account;
import com.peterjxl.service.IAccountService;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.List;

public class AccountServiceTest {

    @Test
    public void testFindAll() {
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        IAccountService as = ac.getBean("accountService", IAccountService.class);
        List<Account> allAccount = as.findAllAccount();
        for (Account account : allAccount) {
            System.out.println(account);
        }
    }
}

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如无意外，是可以正常查询出数据的，运行结果：

Account{id=1, name='aaa', money=1000.0}
Account{id=2, name='bbb', money=1000.0}
Account{id=3, name='ccc', money=1000.0}

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其他测试方法同理，这里就不一一演示了：

package com.peterjxl.test;

import com.peterjxl.domain.Account;
import com.peterjxl.service.IAccountService;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.List;

public class AccountServiceTest {

    @Test
    public void testFindAll() {
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        IAccountService as = ac.getBean("accountService", IAccountService.class);
        List<Account> allAccount = as.findAllAccount();
        for (Account account : allAccount) {
            System.out.println(account);
        }
    }

    @Test
    public void testFindOne() {
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        IAccountService as = ac.getBean("accountService", IAccountService.class);
        Account account = as.findAccountById(1);
        System.out.println(account);
    }

    @Test
    public void testSave() {
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        IAccountService as = ac.getBean("accountService", IAccountService.class);
        Account account = new Account();
        account.setName("test");
        account.setMoney(12345f);
        as.saveAccount(account);
    }

    @Test
    public void testUpdate() {
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        IAccountService as = ac.getBean("accountService", IAccountService.class);
        Account account = as.findAccountById(4);
        account.setMoney(23456f);
        as.updateAccount(account);
    }

    @Test
    public void testDelete() {
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        IAccountService as = ac.getBean("accountService", IAccountService.class);
        as.deleteAccount(4);
    }
}

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# 总结

本次案例的重点不在于CRUD的代码怎么写，关键是QueryRunner的注入配置，以及是使用多例对象，数据源的配置。

# 源码

本项目已将源码上传到GitHub (opens new window)和Gitee (opens new window)上。并且创建了分支demo5，读者可以通过切换分支来查看本文的示例代码。

在GitHub上编辑此页

上次更新: 2023/5/15 16:02:46

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