spring 依赖注入案例（bean.xml以及注解两种配置方式）

准备工作：

Account实体类

package com.itheima.domain;

/**
* 账户的实体类
* */

public class Account {

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

    public Integer getId() {
        return id;
    }

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", money=" + money +
                '}';
    }

    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;
    }
}

IAccountDao接口及其实现类：使用QueryRunner操作mysql

package com.itheima.dao.impl;

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

import java.util.List;

public class AccountDaoImpl implements IAccountDao {

    private QueryRunner runner;

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

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

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

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

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

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

IAccountService接口及其实现类

package com.itheima.service.impl;

/*
* 账户的业务层实现类
* */

import com.itheima.dao.IAccountDao;
import com.itheima.domain.Account;
import com.itheima.service.IAccountService;

import java.util.List;

public class AccountServiceImpl implements IAccountService {

    private IAccountDao accountDao;

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


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

    public Account findAccountById(Integer integer) {
        return accountDao.findAccountById(integer);
    }

    public void saveAccount(Account account) {
        accountDao.saveAccount(account);

    }

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

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

 

使用bean.xml进行配置

<?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service对象-->
    <bean id="accountService" class="com.itheima.service.impl.AccountServiceImpl">
        <!--用set方式注入dao-->
        <property name="accountDao" ref="accountDao"></property>
    </bean>

    <!--配置dao对象-->
    <bean id="accountDao" class="com.itheima.dao.impl.AccountDaoImpl">
        <!--用set方式注入QueryRunner-->
        <property name="runner" ref="runner"></property>
    </bean>

    <!--配置QueryRunner,采用多例模式-->
    <bean id="runner" class="org.apache.commons.dbutils.QueryRunner" scope="prototype">
        <!--用构造函数注入数据源-->
        <constructor-arg name="ds" ref="dataSource"></constructor-arg>
    </bean>

    <!--配置数据源-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <!--链接数据库的必备信息-->
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql://127.0.0.1:3306/eesy?useSSL=false&amp;serverTimezone=GMT%2B8"></property>
        <property name="user" value="root"></property>
        <property name="password" value="nimahaoma49"></property>
    </bean>
</beans>

 

修改为使用注解进行配置

修改IAccountDao接口及其实现类，删掉setrunner方法

@Repository("accountDao") //加在类处

@Autowired//加在runnner声明处

修改IAccountService接口及其实现类

@Service("accountService") //加在类处

@Autowired
private IAccountDao accountDao;//自动注入dao

/*public void setAccountDao(IAccountDao accountDao) {
        this.accountDao = accountDao;
    } 注释掉set方法 */

 

修改bean.xml的配置

<?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
        http://www.springframework.org/schema/context/spring-context.xsd">


    <!--告知spring在创建容器时要扫描的包-->
    <context:component-scan base-package="com.itheima">
    </context:component-scan>

    <!--配置QueryRunner,采用多例模式-->
    <bean id="runner" class="org.apache.commons.dbutils.QueryRunner" scope="prototype">
        <!--用构造函数注入数据源-->
        <constructor-arg name="ds" ref="dataSource"></constructor-arg>
    </bean>

    <!--配置数据源-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <!--链接数据库的必备信息-->
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql://127.0.0.1:3306/eesy?useSSL=false&amp;serverTimezone=GMT%2B8"></property>
        <property name="user" value="root"></property>
        <property name="password" value="nimahaoma49"></property>
    </bean>
</beans>

 

尝试完全使用注解代替bean.xml进行配置

新建一个配置类 SpringConfiguration

package config;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.apache.commons.dbutils.QueryRunner;
import org.springframework.beans.factory.annotation.Configurable;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;

import javax.sql.DataSource;

/**
 * 该类是一个配置类，它的作用和bean.xml是一样的
 * spring中的新注解
 *      @Configuration：
 *          作用：指定当前类是一个配置类
 *      @ComponentScan
 *          作用：用于通过注解指定spring在创建容器时要扫描的包
 *          属性：
 *              value：它和basePackages的作用一样，用于指定创建容器时要扫描的包
 *                     我们使用此注解就等同于在xml中配置了
 *                     <context:component-scan base-package="com.itheima"></context:component-scan>
 *      @Bean
 *          作用：用于把当前方法的返回值作为bean对象存入spring的ioc容器中
 *          属性：
 *              name:用于指定bean的id，默认值(当不写时)是当前方法的名称
 *          细节：
 *              当我们使用注解配置方法时，如果方法有参数，spring框架回去容器中查找有没有可用的bean对象
 *              查找的方式和Autowired注解的作用是一样的
 */

@Configurable
@ComponentScan(basePackages = "com.itheima")
public class SpringConfiguration {

    /**
     * 用于创建一个QueryRunner对象
     * @param dataSource
     * @return
     */
    @Bean(name="runner")
    public QueryRunner createQueryRunner(DataSource dataSource){
        return new QueryRunner(dataSource);
    }

    /**
     * 创建数据源对象
     * @return
     */
    @Bean(name="dataSource")
    public DataSource createDataSource(){
        try{
            ComboPooledDataSource ds = new ComboPooledDataSource();
            ds.setDriverClass("com.mysql.jdbc.Driver");
            ds.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/eesy?useSSL=false&serverTimezone=GMT%2B8");
            ds.setUser("root");
            ds.setPassword("nimahaoma49");
            return ds;
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }

}

同时获取核心容器时改变方法

//1.获取容器
        //ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        ApplicationContext ac = new AnnotationConfigApplicationContext(SpringConfiguration.class);

这样就可以把bean.xml完全删掉了

 

一些新配置注解

@Import(JdbcConfig.class)

可以用在父配置类下指定很多子配置类

@Import
 *          作用：用于导入其他配置类，有该注解的是父配置类，导入的是子配置类
 *          属性:
 *              value:用于指定其他配置类的字节码

/**      @Import
 *          作用：用于导入其他配置类，有该注解的是父配置类，导入的是子配置类
 *          属性:
 *              value:用于指定其他配置类的字节码
 *      @PropertySource
 *          作用：用于指定properties文件的位置
 *          属性：
 *              value：指定文件的名称和路径
 *              关键字classpath：表示类路径下
*/

 

比如将jdbc的配置移动到子配置类JdbcConfig中

package config;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.apache.commons.dbutils.QueryRunner;
import org.springframework.beans.factory.annotation.Configurable;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Scope;

import javax.sql.DataSource;

/**
* 和数据库相关的配置类
* */
@Configuration //此处Configurable不可省略
public class JdbcConfig {

    /**
     * 用于创建一个QueryRunner对象
     * @param dataSource
     * @return
     */
    @Bean(name="runner")
    @Scope("singleton")
    public QueryRunner createQueryRunner(DataSource dataSource){
        return new QueryRunner(dataSource);
    }

    /**
     * 创建数据源对象
     * @return
     */
    @Bean(name="dataSource")
    public DataSource createDataSource(){
        try{
            ComboPooledDataSource ds = new ComboPooledDataSource();
            ds.setDriverClass("com.mysql.jdbc.Driver");
            ds.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/eesy?useSSL=false&serverTimezone=GMT%2B8");
            ds.setUser("root");
            ds.setPassword("nimahaoma49");
            return ds;
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }

}

此时父配置类SpringConfiguration 只要如下即可

@Configuration
@ComponentScan(basePackages = "com.itheima")
@Import(JdbcConfig.class)
public class SpringConfiguration {
}