Spring

原创已于 2023-07-11 16:37:47 修改 · 146 阅读

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#spring #java

于 2023-07-10 09:35:50 首次发布

以IOC和AOP为内核的分层全栈轻量开源框架。

快速入门

创建mavenweb项目，pom文件中引入依赖

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
    </dependencies>

com.kdy.dao包下创建dao接口

public interface UserDao {
    public void save();
}

com.kdy.dao.impl包下创建dao接口的实现类

public class UserDaoImpl implements UserDao {
    @Override
    public void save() {
        System.out.println("is saving...");
    }
}

resource目录下new一个xml config file->spring config文件，在<beans></beans>中加上

 <bean id="userDao" class="com.kdy.dao.impl.UserDaoImpl"></bean>

com.kdy.demo包下创建测试demo类

public class UserDaoDemo {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao = (UserDao)app.getBean("userDao");
        userDao.save();
    }
}

getBean()是通过类的无参构造创建的实例。

右键运行这个demo类的main方法即可。

Spring配置文件

id：该Bean实例在Spring容器中的唯一标识 class：Bean的全限定名 scope：作用范围

scope：(1singleton单例，不写scope也默认单例；2prototype多例；3request为Web项目Spring创建bean对象后存入request域中；4session为存入session域；5global session为Portlet环境时相当session)。

单例模式singleton多次app.getBean("userDao")是同一个对象。在ApplicationContext加载配置文件时创建实例。生命周期同容器。

多例模式prototype多次app.getBean("userDao")不是同一个对象。在getBean时创建实例。生命周期同普通java对象，可被GC回收。

Junit

依赖

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <!--<scope>test</scope>--><!--如果加上test只在test目录中可用，在main目录中不可用-->
        </dependency>

测试类中@Test

public class SpringTest {
    @Test
    public void test1(){
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao = (UserDao)app.getBean("userDao");
        userDao.save();
    }
}

Bean的三种实例化方式

无参构造方法实例化、工厂静态方法实例化、工厂实例方法实例化

无参构造方法实例化

getBean()是通过类的无参构造创建的实例。

工厂静态方法实例化

com.kdy.factory包下创建StaticFactory类

public class StaticFactory {
    public static UserDao getUserDao(){
        return new UserDaoImpl();
    }
}

applicationContext.xml中<beans></beans>里创建静态工厂bean，指定工厂方法

<bean id="userDao" class="com.kdy.factory.StaticFactory" factory-method="getUserDao"></bean>

执行测试类即可

public class SpringTest {
    @Test
    public void test1(){
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao = (UserDao)app.getBean("userDao");
        userDao.save();
    }
}

工厂实例方法实例化

com.kdy.factory包下创建DynamicFactory类

public class DynamicFactory {
    public UserDao getUerDao(){
        return new UserDaoImpl();
    }
}

applicationContext.xml中<beans></beans>里创建bean指定实例工厂bean和指定工厂方法

    <bean id="factory" class="com.kdy.factory.DynamicFactory"></bean>
    <bean id="userDao" factory-bean="factory" factory-method="getUerDao"></bean>

执行测试类即可

public class SpringTest {
    @Test
    public void test1(){
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao = (UserDao)app.getBean("userDao");
        userDao.save();
    }
}

Bean的依赖注入（DI）

DI是IOC的核心。userDao的bean注入给userService的bean可通过set方式和构造方法的方式。

set方式DI依赖注入

com.kdy.dao.impl包中创建UserDaoImpl实现UserDao

public class UserDaoImpl implements UserDao {
    @Override
    public void save() {
        System.out.println("is saving...");
    }
}

com.kdy.service.impl创建UserServiceImpl实现userService

如果不注入，需要在applicationContext.xml中声明userDao的bean和userService的bean，然后在userServiceImpl中去通过app.getBean获取dao的bean，然后使用。

通过set注入的话直接定义为userServiceImpl的属性再提供set方法通过spring配置文件进行set注入即可在userServiceImpl中直接使用该属性对象实例方法。

public class UserServiceImpl implements UserService {

    //set方式依赖注入，需在被注入的类中定义需要注入的属性，并生成set方法
    private UserDao userDao;
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public void save() {
/*        //既然userDao通过spring注入给userService，则可不用在下方通过上下文去拿实例化的userDao的bean了
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao = (UserDao)app.getBean("userDao");*/
        userDao.save();
    }
}

resource目录下的applicationContext.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 http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="userDao" class="com.kdy.dao.impl.UserDaoImpl"></bean>
<!--    <bean id="userDao" class="com.kdy.factory.StaticFactory" factory-method="getUserDao"></bean>-->
<!--    <bean id="factory" class="com.kdy.factory.DynamicFactory"></bean>
    <bean id="userDao" factory-bean="factory" factory-method="getUerDao"></bean>-->

    <bean id="userService" class="com.kdy.service.impl.UserServiceImpl">
       <!--set方式实现依赖注入-->
        <property name="userDao" ref="userDao"></property><!--name需和UserServiceImpl中属性名一致。ref需和该配置文件中某个bean的id一致-->
    </bean>
</beans>

除了上面的property方式set注入，也可通过p命名空间set注入，如下

<?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:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="userDao" class="com.kdy.dao.impl.UserDaoImpl"></bean>
    <!--首先在上方引入p命名空间   xmlns:p="http://www.springframework.org/schema/p"   
    然后使用p:的方式注入其他bean作为该bean的属性-->
    <bean id="userService" class="com.kdy.service.impl.UserServiceImpl" p:userDao-ref="userDao"></bean>
</beans>

在com.kdy.demo包中创建模拟controller的类

public class UserController {
    public static void main(String[] args) {
/*        UserServiceImpl userService = new UserServiceImpl();*/
        //我们也将userServiceImpl接管给spring,上行代码变成下面代码
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserService userService = (UserService)app.getBean("userService");
        userService.save();
    }
}

运行main方法即可。

构造方法方式DI依赖注入

com.kdy.service.impl中的userServiceImpl

public class UserServiceImpl implements UserService {
    //构造方法方式依赖注入，提供被注入的属性和生成有参无参构造方法
    private UserDao userDao;
    public UserServiceImpl() {
    }
    public UserServiceImpl(UserDao userDao) {
        this.userDao = userDao;
    }
    @Override
    public void save() {
        userDao.save();
    }
}

resource下的applicationContext.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 http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="userDao" class="com.kdy.dao.impl.UserDaoImpl"></bean>
    <bean id="userService" class="com.kdy.service.impl.UserServiceImpl">
        <constructor-arg name="userDao" ref="userDao"></constructor-arg>
    </bean>
</beans>

Bean依赖注入的数据类型

普通数据类型、引用数据类型、集合数据类型

普通数据类型注入

set方式注入普通数据类型演示

com.kdy.dao.impl的UserDaoImpl

public class UserDaoImpl implements UserDao {
    private String name;
    private int age;
    public void setName(String name) {
        this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public void save() {
        System.out.println(name+":"+age);
        System.out.println("is saving...");
    }
}

resource下的applicationContext.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 http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="userDao" class="com.kdy.dao.impl.UserDaoImpl">
        <property name="name" value="zhangsan"/>
        <property name="age" value="18"/>
    </bean>
</beans>

com.kdy.demo中模拟controller类

public class UserController {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserDao userDao= (UserDao)app.getBean("userDao");
        userDao.save();
    }
}

集合数据类型注入

list集合、map集合、properties集合

com.kdy.pojo包中创建User类，并提供set、get、和toStirng方法

public class User {
    private String name;
    private String addr;
}

com.kdy.dao.impl包中创建UserDaoImpl

public class UserDaoImpl implements UserDao {
    private List<String> strList;
    private Map<String, User> userMap;
    private Properties properties;
    public void setStrList(List<String> strList) {
        this.strList = strList;
    }
    public void setUserMap(Map<String, User> userMap) {
        this.userMap = userMap;
    }
    public void setProperties(Properties properties) {
        this.properties = properties;
    }
    @Override
    public void save() {
        System.out.println(strList);
        System.out.println(userMap);
        System.out.println(properties);
        System.out.println("is saving...");
    }
}

applicationContext.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 http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="user1" class="com.kdy.pojo.User">
        <property name="name" value="tom"/>
        <property name="addr" value="beijing"/>
    </bean>
    <bean id="user2" class="com.kdy.pojo.User">
        <property name="name" value="杰瑞"/>
        <property name="addr" value="南京"/>
    </bean>
    <bean id="userDao" class="com.kdy.dao.impl.UserDaoImpl">
        <property name="strList">
            <list><!--如果集合元素是基本数据类型就使用value，如果是引用数据类似引用其他bean，就使用ref-->
                <value>aaa</value>
                <value>bbb</value>
                <value>ccc</value>
            </list>
        </property>
        <property name="userMap">
            <map><!--基本数据类型就使用keyh和value，如果是引用数据类似引用其他bean，就使用key-ref和value-ref-->
                <entry key="mapaaa" value-ref="user1"></entry>
                <entry key="mapbbb" value-ref="user2"></entry>
            </map>
        </property>
        <property name="properties">
            <props>
                <prop key="p1">ppp1</prop>
                <prop key="p2">ppp2</prop>
                <prop key="p3">ppp3</prop>
            </props>
        </property>
    </bean>
</beans>

Spring配置文件

引入其他配置文件（分模块开发）

可以在主配置文件中引入其他配置文件

<import resource="applicationContext-xxx.xml”/>

ApplicationContext实现类

ClassPathXmlApplicationContext("applicationContext.xml")

FileSystemXmlApplicationContext("C:\\Users\\app\\IdeaProject\\SpringModule\\src\\main\\resouorce\\applicationContext.xml")

AnnotationConfigApplicationContext

getBean()方法的使用

spring配置中userServiceImpl类只有一个bean时可用getBean(userService.class)

配置文件userServiceImpl多个bean和id时，只能用getBean("userService1")这种。

Spring配置数据源

以C3P0和druid为例

手动测试c3p0和druid数据源连接

pom文件依赖

<?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>org.example</groupId>
    <artifactId>SpringModule</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.8</version>
        </dependency>
        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.1.2</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.1</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <!--<scope>test</scope>--><!--如果加上test只在test目录中可用，在main目录中不可用-->
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.2</version>
                <configuration>
                    <port>8080</port>
                    <path>/SpringModule</path><!--虚拟目录-->
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

test目录下com.kdy.test包中创建DataSourceTest

public class DataSourceTest {

    @Test
    //测试手动创建c3p0数据源
    public void test1() throws Exception{
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass("com.mysql.jdbc.Driver");
        dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/test");
        dataSource.setUser("root");
        dataSource.setPassword("root123");
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }

    @Test
    public void test2() throws Exception{
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://localhost:3306/test");
        dataSource.setUsername("root");
        dataSource.setPassword("root123");
        DruidPooledConnection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }
}

运行测试用例。

抽取配置数据库连接参数到properties文件中

resource目录下创建jdbc.properties文件

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=root123

test目录下的DataSource中加上以下测试用例

    @Test
    public void test3() throws Exception{
        ResourceBundle rb = ResourceBundle.getBundle("jdbc");
        String driver = rb.getString("jdbc.driver");
        String url = rb.getString("jdbc.url");
        String username = rb.getString("jdbc.username");
        String password = rb.getString("jdbc.password");
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass(driver);
        dataSource.setJdbcUrl(url);
        dataSource.setUser(username);
        dataSource.setPassword(password);
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }

运行测试用例。

spring配置数据源

继上，applicationContext.xml中的内容改为

<?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">

    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/test"></property>
        <property name="user" value="root"></property>
        <property name="password" value="root123"></property>
    </bean>
</beans>

test目录的测试类DataSourceTest加上下面测试用例

    @Test
    public void  test4() throws Exception {
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        DataSource dataSource = app.getBean(DataSource.class);
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }

spring配置数据源-抽取jdbc配置文件

继上，在resource中创建jdbc.properties文件

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=root123

修改resource下的applicationContext.xml文件为

<?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">

    <!--首先引入上面context命名空间xmlns:context="http://www.springframework.org/schema/context"和
    http://www.springframework.org/schema/context http://www.springframework.org/schema/beans/spring-context.xsd-->

    <context:property-placeholder location="classpath:jdbc.properties"/><!--引入配置文件，使用el获取-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}"></property>
        <property name="jdbcUrl" value="${jdbc.url}"></property>
        <property name="user" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>
    </bean>
</beans>

运行上面的测试用例test4即可。

Spring注解开发

1Spring原始注解

原始注解用来替代<Bean>的配置

@Component写在普通类上实例化Bean、@Controller写在web层的类上实例化Bean、

@Service写在service层的impl类上实例化Bean、@Repository写在dao层类上实例化、

@Autowired写在字段上根据类型依赖注入、@Qualifier结合@Autowired根据名称注入、

@Resource写在字段上名称注入、@Value注入普通属性、@Scope标柱Bean作用范围、

@PostConstruct写在Bean的初始化方法上、@PreDestroy写在Bean的销毁方法上。

mavenWeb项目，pom文件中引入spring依赖

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>

jdbc.properties文件，用于在配置文件中property-placeholder加载后被@Value注解读取el

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=root123

spring核心配置applicationContext.xml中开启组件扫描和引入jdbc.properties

<?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">

    <!--首先引入上面context命名空间xmlns:context="http://www.springframework.org/schema/context"和
    http://www.springframework.org/schema/context http://www.springframework.org/schema/beans/spring-context.xsd-->
   
    <context:component-scan base-package="com.kdy"/><!--开启组件扫描-->
    <context:property-placeholder location="classpath:jdbc.properties"/><!--引入配置文件，使用el获取。包括类中的@Value注解也可读取el表达式-->
</beans>

com.kdy.dao.impl中创建userDaoImpl

//@Component("userDao")
//@Component//不写参数，默认id为类名首字母小写
@Repository("userDao")
public class UserDaoImpl implements UserDao {
    @Override
    public void save() {
        System.out.println("is saving...");
    }
}

com.kdy.service.impl中创建userServiceImpl

//@Component//不写参数，默认id为类名首字母小写
@Service("userService")
//@Scope("prototype")  @Scope("singleton") 不写@Scope也默认singleton
public class UserServiceImpl implements UserService {

    @Value("${jdbc.username}")
    private String username;

    @Autowired//不写@Qualifier的话按类型注入
//    @Qualifier("userDaoImpl")//UserDaoImpl的@Component不写参数，默认id为类名首字母小写
    @Qualifier("userDao")
//    @Resource("userDao")//@Resource(name="")等于@Autowired+@Qualifier，根据bean的名称id注入
    private UserDao userDao;//不需要提供set方法，注解输入通过反射注入

    @Override
    public void save() {
        System.out.println(username);
        userDao.save();
    }

    //测试@PostConstruct注解，会在web应用启动，spring容器创建时，实例化本bean时调用
    @PostConstruct
    public void init(){
        System.out.println("service对象初始化方法");
    }
    //测试@PreDestroy，会在web应用关闭，spring容器销毁时，销毁本bean前调用
    @PreDestroy
    public void destroy(){
        System.out.println("service对象销毁方法");
    }

}

模拟controller：userController

public class UserController {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
//        UserService userService = (UserService) app.getBean("userServiceImpl");//@Component不加参数默认id为类名小写
        UserService userService = app.getBean(UserService.class);
        userService.save();
        app.close();//关闭web应用，会销毁spring容器，会执行到userServiceImpl中写的销毁方法

    }
}

1Spring新注解

配置c3p0数据源的bean"com.mchange.v2.c3p0.ComboPooledDataSource"第三方类我们无法通过上面旧注解注入属性，需使用新注解

@Configuration写在配置类上，指明为spring配置类，创建容器时会从该类加载注解。

@ComponentScan写在配置类上声明spring容器初始化的包扫描。

@Bean写在方法上，方法返回值作为bean存放容器中。

@PropertySource写在配置类上，声明用于加载.properties文件

@Import写在配置类上，用于导入spring的其他配置类。

mavenWeb项目pom文件引入spring、mysql、c3p0依赖

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.8</version>
        </dependency>
        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.1.2</version>
        </dependency>

resource下jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=root123

resource下applicationContext.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 http://www.springframework.org/schema/beans/spring-beans.xsd">

</beans>

com.kdy.config包下spring核心配置类

@Configuration//声明该类为spring配置类
@ComponentScan("com.kdy")//声明包扫描
@PropertySource("classpath:jdbc.properties")
//@Import({DataSourceConfiguration.class,XXX.class})//引入其他声明的配置类：引入多个写个大括号，里面逗号隔开
public class SpringConfiguration {

    @Value("${jdbc.driver}")
    private String driver;

    @Value("${jdbc.url}")
    private String url;

    @Value("${jdbc.username}")
    private String username;

    @Value("${jdbc.password}")
    private String password;

    @Bean("dataSource")
    public DataSource getDataSource() throws PropertyVetoException{
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass(driver);
        dataSource.setJdbcUrl(url);
        dataSource.setUser(username);
        dataSource.setPassword(password);
        return dataSource;
    }
}

com.kdy.dao.impl下UserDaoImpl

@Repository("userDao")
public class UserDaoImpl implements UserDao {
    @Override
    public void save() {
        System.out.println("is saving...");
    }
}

com.kdy.service.impl下userServiceImpl

@Service("userService")
public class UserServiceImpl implements UserService {

    @Value("${jdbc.username}")
    private String username;

    @Autowired
    @Qualifier("userDao")
    private UserDao userDao;//不需要提供set方法，注解注入通过反射方式注入

    @Resource(name = "dataSource")
    private DataSource dataSource;

    @Override
    public void save() throws SQLException {
        System.out.println(username);
        System.out.println(dataSource.getConnection());
        userDao.save();
    }
}

模拟controller在com.kdy.demo下UserController

public class UserController {
    public static void main(String[] args) throws SQLException {
        ApplicationContext app = new AnnotationConfigApplicationContext(SpringConfiguration.class);
        UserService userService = app.getBean(UserService.class);
        userService.save();
    }
}

运行上面main方法即可。

Spring集成Junit

原始junit问题：每个测试用例的方法中都有以下两行代码：

        ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        DataSource dataSource = app.getBean(DataSource.class);

pom文件中引入junit和spring-test依赖

         <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.0.5.RELEASE</version>
        </dependency>

test目录中写测试类加上@RunWith和@ContextConfiguration，注容器中的bean，即可使用：

@RunWith(SpringJUnit4ClassRunner.class)
//@ContextConfiguration("classpath:applicationContext.xml")//配置文件的方式
@ContextConfiguration(classes = {SpringConfiguration.class})//全注解的方式
public class SpringJunitTest {

    @Autowired
    private UserService userService;

    @Test
    public void test1() throws SQLException {
        userService.save();
    }
}

Spring集成web环境

创建mavenWeb项目模块，pom文件引入spring、junit、spring-test、servlet、jsp依赖

<?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>org.example</groupId>
    <artifactId>SpringModule</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.0.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.0.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.2</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.2</version>
                <configuration>
                    <port>8080</port>
                    <path>/SpringModule</path><!--虚拟目录-->
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

com.kdy.dao.impl包创建userDao

public class UserDaoImpl implements UserDao {
    @Override
    public void save() {
        System.out.println("is saving...");
    }
}

com.kdy.service.impl包中创建userService

public class UserServiceImpl implements UserService {
    private UserDao userDao;
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
    @Override
    public void save() {
        userDao.save();
    }
}

resource目录下applicationContext.xml中配置bean和注入

<?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">

    <bean id="userDao" class="com.kdy.dao.impl.UserDaoImpl"></bean>
    <bean id="userService" class="com.kdy.service.impl.UserServiceImpl">
        <property name="userDao" ref="userDao"></property>
    </bean>
</beans>

web.xml中我们定义一个全局初始化参数contextConfigLocation值为applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <context-param><!--配置一个全局初始化参数，即application域的初始化参数，
    在web的servlet类(即继承HttpServlet的类，通过this.getServletContext可获取servletContext)的代码中通过
    servletContext.getInitParameter("contextConfigLocation)获取，
    也可在jsp中通过el表达式直接获取-->
        <param-name>contextConfigLocation</param-name>
        <param-value>applicationContext.xml</param-value>
    </context-param>
</web-app>

com.kdy.listener包下创建servletContext监听器

@WebListener
public class ContextLoaderListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        ServletContext servletContext = servletContextEvent.getServletContext();
        //获取web.xml中配置的application的全局初始化参数：
        String contextConfigLocation = servletContext.getInitParameter("contextConfigLocation");//其值为applicationContext.xml
        ApplicationContext app = new ClassPathXmlApplicationContext(contextConfigLocation);
        servletContext.setAttribute("app",app);
    }
    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {
    }
}

为了不在servlet中写死数据，所以再次抽取一个工具类，解释如下：

之前servlet中从死数据"applicationContext.xml"获取app被监听器和web.xml初始化参数解耦了，但servlet中还需要servletContext.getAttribute("app")拿到，这里的"app"还是死数据，所以我们用一个工具类直接拿到这个applicaiton，避免在项目代码mvc层代码中写死数据了。

在com.kdy.util包下创建返回application的工具类

public class WebApplicationContextUtils {
    public static ApplicationContext getApplicationContext(ServletContext servletContext){
        return (ApplicationContext)servletContext.getAttribute("app");
    }
}

com.kdy.web包中创建servlet

@WebServlet("/userServlet")
public class UserServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        /*
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserService userService = app.getBean(UserService.class);
        上述注释的代码的这种方式，每次访问该servlet会重复创建很多次applicationContext对象，
        web容器tomcat启动后为每一个web应用创建上下文对象servletContext，我们可用使用web监听器
        ServletContextListener来当web应用启动时创建一个让其new一个应用上下文对象app通过setAttribute放入servletContext域对象中，
        之后再通过ServletConfig.getServletContext或this.getServletContext的getAttribute取到该app对象。
        */
        ServletContext servletContext = this.getServletContext();
        ApplicationContext app = WebApplicationContextUtils.getApplicationContext(servletContext);
        UserService userService = app.getBean(UserService.class);
        userService.save();
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}