初识Spring框架

1.引入Spring依赖包

<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.fy</groupId>
    <artifactId>spring-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <!--spring的基础包 spring-core   -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>
        <!--spring的基础包 spring-beans   -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>
        <!--spring的基础包 spring-context   -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>
        <!--spring的基础包 spring-expression   -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>
        <!--spring的基础包 spring-logging   -->
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.2</version>
        </dependency>
    </dependencies>
</project>

2.编写用户类

package com.pojo;
public class User {
    private int id;
    private String username;
    private String password;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public User() {
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }

    public User(int id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }
}

3.编写DAO层以及实现类UserDaoImpl

//UserDao
public interface UserDao {
    public boolean login(String name,String password);
}
//UserDaoImpl
public class UserDaoImpl implements UserDao {
    public boolean login(String name, String password) {
        if (name.equals("张三")&&password.equals("123")){
            return true;
        }
        return false;
    }
}

4.编写Service层以及实现类UserServiceImpl

//UserService
public interface UserService {
    public boolean login(String name,String password);
}
//UserServiceImpl 
public class UserServiceImpl implements UserService {
    UserDao userDao;
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
    public boolean login(String name, String password) {
        return userDao.login(name, password);
    }
}

5.在src/main/resources目录下创建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 http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!--userDao    <bean>元素创建UserDaoImpl类的实例-->
    <bean id="userDao" class="com.dao.UserDaoImpl"/>
    <!--UserService    <bean>元素创建UserServiceImpl类的实例-->
    <bean id="userService" class="com.service.UserServiceImpl">
    <!-- ref:引用Spring容器中的某个Bean实例  -->
        <property name="userDao" ref="userDao"/>
    </bean>
</beans>

6.编写测试类

public class TestSpring {
    public static void main(String[] args) {
        //加载applicationContext.xml配置
        ApplicationContext applicationContext = new
                ClassPathXmlApplicationContext("applicationContext.xml");
        //获取配置中的UserService实例
        UserService userService = (UserService) applicationContext.getBean("userService");
        boolean flag = userService.login("张三","123");
        if (flag){
            System.out.println("登录成功");
        }else{
            System.out.println("登录失败");
        }
    }
}