Mybatis环境搭建（二）

1. 创建Maven Project，选择war，修改pom.xml

<properties>
    <!-- JDK版本 -->
    <java.version>1.8</java.version>
    <!-- mybatis版本 -->
    <mybatis.version>3.5.2</mybatis.version>
    <!-- mysql driver 版本 -->
    <mysql.version>5.1.48</mysql.version>
</properties>

<dependencies>
    <!-- web project基本配置 -->
    <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>
    <dependency>
        <groupId>jstl</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>

    <!-- mybatis 核心包 -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>${mybatis.version}</version>
    </dependency>
    <!-- asm -->
    <dependency>
        <groupId>asm</groupId>
        <artifactId>asm</artifactId>
        <version>3.3.1</version>
    </dependency>
    <!-- cglib -->
    <dependency>
        <groupId>cglib</groupId>
        <artifactId>cglib</artifactId>
        <version>3.2.7</version>
        <exclusions>
            <exclusion>
                <groupId>org.ow2.asm</groupId>
                <artifactId>asm</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <!-- javassist -->
    <dependency>
        <groupId>org.javassist</groupId>
        <artifactId>javassist</artifactId>
        <version>3.23.1-GA</version>
    </dependency>

    <!-- log4j -->
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.17</version>
    </dependency>
    <!-- log4j-api -->
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>2.11.1</version>
    </dependency>
    <!-- slf4j-api -->
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.28</version>
    </dependency>
    <!-- slf4j-log4j12 -->
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.28</version>
        <scope>test</scope>
    </dependency>
    
    <!-- mysql driver -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>${mysql.version}</version>
    </dependency>
</dependencies>

<build>
    <!-- 资源拷贝，默认不会将xml文件编译到classpath下 -->
    <resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.xml</include>
            </includes>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.xml</include>
                <include>**/*.properties</include>
            </includes>
        </resource>
    </resources>
</build>

2. 在src/main/resources目录下创建mybatis.xml全局配置文件

<?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>
    <!-- mybatis使用properties来引入外部properties配置文件的内容 
        resource 引入类路径下资源 
        url 引入网络路径或磁盘路径下资源
     -->
    <properties resource="jdbc.properties"></properties>

    <!-- default指定的是当前使用的环境 -->
    <environments default="default">
        <!-- 声明可能使用到的环境 -->
        <environment id="default">
            <!-- 使用原生的JDBC事务，默认是自动提交的 -->
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.name}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>
        </environment>
    </environments>
    
</configuration>

jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://192.168.178.5:12345/ssm?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai
jdbc.name=root
jdbc.password=123456

3. 创建映射文件

(1) 实体类

public class User {
    private Integer userId;
    private String userName;
    private Integer age;
    
    public User() {
    }
    public User(Integer userId, String userName, Integer age) {
        this.userId = userId;
        this.userName = userName;
        this.age = age;
    }
    public Integer getUserId() {
        return userId;
    }
    public void setUserId(Integer userId) {
        this.userId = userId;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "User [userId=" + userId + ", userName=" + userName + ", age=" + age + "]";
    }
}

(2) 映射接口

public interface UserMapper {

    public List<User> selectAll();
}

(3) xml映射文件（可以看做是UserMapper接口的实现类）

<?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">

<!-- namespace对象接口的全限定名称（包名+类名） -->
<mapper namespace="com.linhw.demo.mapper.UserMapper">
    <!-- id对应接口的方法名称 -->
    <select id="selectAll" resultMap="UserInfo">
        select * from user
    </select>
    
    <!-- 数据列与实体属性的映射 -->
    <resultMap type="com.linhw.demo.pojo.User" id="UserInfo">
        <id column="user_id" property="userId" jdbcType="INTEGER"/>
        <result column="user_name" property="userName" jdbcType="VARCHAR"/>
        <result column="age" property="age" jdbcType="INTEGER"/>
    </resultMap>
    
</mapper>

(4) 修改mybatis.xml，配置映射文件的路径

放在配置文件所有标签的最后。

<!-- 配置映射文件 -->
<mappers>
    <mapper resource="com/linhw/demo/mapper/UserMapper.xml"/>
</mappers>

4. 测试

//加载全局配置文件
InputStream inputStream = Resources.getResourceAsStream("mybatis.xml");
//使用工厂设计模式
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//生产SqlSession
SqlSession session = sessionFactory.openSession();

List<User> userList = session.selectList("com.linhw.demo.mapper.UserMapper.selectAll");

for(User user : userList){
    System.out.println(user.toString());
}
//关闭连接
session.close();

附：xml配置文件自动提示 

在全局配置文件或者mapper映射文件的约束中点击，电脑会提示下载文件到本地：

config：http://mybatis.org/dtd/mybatis-3-config.dtd
mapper：http://mybatis.org/dtd/mybatis-3-mapper.dtd

配置eclipse：打开window–>Preferences–>XML–>XML catalog

点击add，Location地方找到你下载好的dtd文件，key type用System-ID，key为http://mybatis.org/dtd/mybatis-3-config.dtd 或 http://mybatis.org/dtd/mybatis-3-mapper.dtd，然后确定保存，再返回xml文件，你就会发现自动提示能用啦（如果没有提示，需要重新选择xml文件的开发方式Open With Xml Editor）。