Mybatis入门案列

谁借莪１个温暖的怀抱￠ 2024-04-17 21:56 62阅读 0赞

### 一.前期准备 ###

在maven中创建普通java项目

直接开始：

目录(这里需要注意的是StudentDao.xml与StudentDao是对应的层级关系)：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NobGVpXw_size_16_color_FFFFFF_t_70][]

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.homejim.mybatis</groupId>
        <artifactId>helloMybatis</artifactId>
        <version>1.0-SNAPSHOT</version>
        <packaging>jar</packaging>
    
        <dependencies>
            
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.4.5</version>
            </dependency>
    
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.6</version>
            </dependency>
    
            
            <dependency>
                <groupId>org.apache.logging.log4j</groupId>
                <artifactId>log4j-core</artifactId>
                <version>2.10.0</version>
            </dependency>
    
            
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
                <scope>test</scope>
            </dependency>
        </dependencies>
    </project>

StudentDao.xml:

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.chenlei.dao.StudentDao">
        
        <select id="findAll" resultType="com.chenlei.domain.Student">
            select * from student
        </select>
    </mapper>

log4j2.xml:

<?xml version="1.0" encoding="UTF-8"?>
    <Configuration>
        <Appenders>
            <Console name="STDOUT" target="SYSTEM_OUT">
                <PatternLayout pattern="%d %-5p [%t] %C{2} (%F:%L) - %m%n"/>
            </Console>
            <RollingFile name="RollingFile" fileName="logs/strutslog1.log"
                         filePattern="logs/${date:yyyy-MM}/app-%d{MM-dd-yyyy}-%i.log.gz">
                <PatternLayout>
                    <Pattern>%d{MM-dd-yyyy} %p %c{1.} [%t] -%M-%L- %m%n</Pattern>
                </PatternLayout>
                <Policies>
                    <TimeBasedTriggeringPolicy />
                    <SizeBasedTriggeringPolicy size="1 KB"/>
                </Policies>
                <DefaultRolloverStrategy fileIndex="max" max="2"/>
            </RollingFile>
        </Appenders>
        <Loggers>
            <Logger name="com.opensymphony.xwork2" level="WAN"/>
            <Logger name="org.apache.struts2" level="WAN"/>
            <Root level="warn">
                <AppenderRef ref="STDOUT"/>
            </Root>
        </Loggers>
    
    </Configuration>

SqlMapConfig.xml:

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration
            PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-config.dtd">
    
    <configuration>
        
        <environments default="mysql">
            
            <environment id="mysql">
                
                <transactionManager type="JDBC"></transactionManager>
                
                <dataSource type="POOLED">
                    
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql:///text2"/>
                    <property name="username" value="root"/>
                    <property name="password" value="123"/>
                </dataSource>
            </environment>
        </environments>
    
        
        <mappers>
            <mapper resource="com/chenlei/dao/StudentDao.xml"/>
        </mappers>
    </configuration>

StudenDao：

* 持久层接口
     */
    public interface StudentDao {
        /**
         * 查找所有操作
         * @return
         */
        List<Student> findAll();
    }

Student:

public class Student implements Serializable {
        private Integer id;
        private String name;
        private String sex;
        private Date birthday;
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getSex() {
            return sex;
        }
    
        public void setSex(String sex) {
            this.sex = sex;
        }
    
        public Date getBirthday() {
            return birthday;
        }
    
        public void setBirthday(Date birthday) {
            this.birthday = birthday;
        }
    
        @Override
        public String toString() {
            return "Student{" +
                    "id=" + id +
                    ", name='" + name + '\'' +
                    ", sex='" + sex + '\'' +
                    ", birthday=" + birthday +
                    '}';
        }
    }

测试类：

public class MybatisTest {
        public static void main(String[] args) throws IOException {
            //1.读取配置文件
            InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
            //2.创建SqlSessionFactory工厂
            SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
            SqlSessionFactory factory = builder.build(in);
            //3.使用工厂生产SqlSession对象
            SqlSession sqlSession = factory.openSession();
            ///4.使用SqlSession创建Dao接口的代理对象
            StudentDao studentDao = sqlSession.getMapper(StudentDao.class);
            //5.使用代理对象执行方法
            List<Student> students = studentDao.findAll();
            for (Student student : students) {
                System.out.println(student);
            }
            //6.释放资源
            sqlSession.close();
            in.close();
        }
    }

二、注解方式：

需要把之前的StudentDao删掉

SqlMapConfig.xml修改部分

<mappers>
            <mapper class="com.chenlei.dao.StudentDao"/>
        </mappers>

:StudentDao：

public interface StudentDao {
        /**
         * 查找所有操作
         * @return
         */
        @Select("select * from student")
        List<Student> findAll();

其他与之前一致(项目目录中的log4j2.xml是后期加上的，不加问题不大（防止idea报警信息）)。

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