mybatis之初體驗——helloworld

mybatis之前叫ibatis，2010年從apache遷到google code改名為mybatis。實習的公司中項目多用mybatis作為持久層架構，本文将實作最簡單的mybatis的helloworld。本文使用的工具是intellij  idea14+maven。

1.建立project

打開idea，建立一個maven項目。使用maven是因為管理依賴友善。new->project

選擇項目的jdk版本，next

groupid和artifactid随便起名，next

選擇項目存儲的位置,finish

項目建好了，目錄樹如下，已自動生成了pom.xml檔案，即maven的配置檔案

2.建立資料庫

mybatis連接配接的自然是資料庫，資料庫使用的是mysql 5.6.

為了可視化地檢視資料庫，安裝了navicat for mysql，建立連接配接，輸入連接配接名，主機為本機localhost,端口3306，這裡使用者名密碼都是root，可以點選測試連接配接驗證是否可以成功連接配接到資料庫。注意：要保證mysql服務已開啟，可右鍵計算機->管理->服務裡檢視mysql服務的開啟狀況。

建立資料庫mydata,并建立user表。user表字段設計如下，id為主鍵

插入兩條測試記錄

3.配置mybatis和編寫相應類

首先在maven的配置檔案pom.xml中加入依賴的jar包，mybatis的jar包肯定需要，還需要一個java連mysql的驅動包

<?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.sw</groupId>
    <artifactId>mybatisHello</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.2.8</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.21</version>
        </dependency>
    </dependencies>


</project>
           

建立User類，即和資料庫中的user表對應的類。這裡注意：如mysql裡的user表裡image_url字段對應到User類中imageUrl這裡是在userMapper.xml中配置的對應關系.這裡因為是測試項目就沒有建包了，直接在java下建類

public class User {
    private Integer id;

    private String username;

    private String sex;

    private Byte age;

    private String phone;

    private String qq;

    private String password;

    private String email;

    private String name;

    private String birthday;

    private String imageUrl;

    private String addTs;

    private String lastUpdateTs;

    private String lastLoginTs;

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username == null ? null : username.trim();
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex == null ? null : sex.trim();
    }

    public Byte getAge() {
        return age;
    }

    public void setAge(Byte age) {
        this.age = age;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone == null ? null : phone.trim();
    }

    public String getQq() {
        return qq;
    }

    public void setQq(String qq) {
        this.qq = qq == null ? null : qq.trim();
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password == null ? null : password.trim();
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email == null ? null : email.trim();
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    public String getBirthday() {
        return birthday;
    }

    public void setBirthday(String birthday) {
        this.birthday = birthday == null ? null : birthday.trim();
    }

    public String getImageUrl() {
        return imageUrl;
    }

    public void setImageUrl(String imageUrl) {
        this.imageUrl = imageUrl == null ? null : imageUrl.trim();
    }

    public String getAddTs() {
        return addTs;
    }

    public void setAddTs(String addTs) {
        this.addTs = addTs == null ? null : addTs.trim();
    }

    public String getLastUpdateTs() {
        return lastUpdateTs;
    }

    public void setLastUpdateTs(String lastUpdateTs) {
        this.lastUpdateTs = lastUpdateTs == null ? null : lastUpdateTs.trim();
    }

    public String getLastLoginTs() {
        return lastLoginTs;
    }

    public void setLastLoginTs(String lastLoginTs) {
        this.lastLoginTs = lastLoginTs == null ? null : lastLoginTs.trim();
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", sex='" + sex + '\'' +
                ", age=" + age +
                ", phone='" + phone + '\'' +
                ", qq='" + qq + '\'' +
                ", password='" + password + '\'' +
                ", email='" + email + '\'' +
                ", name='" + name + '\'' +
                ", birthday='" + birthday + '\'' +
                ", imageUrl='" + imageUrl + '\'' +
                ", addTs='" + addTs + '\'' +
                ", lastUpdateTs='" + lastUpdateTs + '\'' +
                ", lastLoginTs='" + lastLoginTs + '\'' +
                '}';
    }
}
           

在java下建立UserMapper接口

public interface UserMapper {

    User selectUserById(Integer id);

}
           

resources目錄下建立userMapper.xml，切記select标簽中的id一定要與UserMapper接口中的方法名一緻！namespace路徑要仔細檢查，多一個空格都會報錯。

<?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="UserMapper">
  <resultMap id="BaseResultMap" type="User" >
    <id column="id" property="id" jdbcType="INTEGER" />
    <result column="username" property="username" jdbcType="VARCHAR" />
    <result column="sex" property="sex" jdbcType="VARCHAR" />
    <result column="age" property="age" jdbcType="TINYINT" />
    <result column="phone" property="phone" jdbcType="VARCHAR" />
    <result column="qq" property="qq" jdbcType="VARCHAR" />
    <result column="password" property="password" jdbcType="VARCHAR" />
    <result column="email" property="email" jdbcType="VARCHAR" />
    <result column="name" property="name" jdbcType="VARCHAR" />
    <result column="birthday" property="birthday" jdbcType="VARCHAR" />
    <result column="image_url" property="imageUrl" jdbcType="VARCHAR" />
    <result column="add_ts" property="addTs" jdbcType="VARCHAR" />
    <result column="last_update_ts" property="lastUpdateTs" jdbcType="VARCHAR" />
    <result column="last_login_ts" property="lastLoginTs" jdbcType="VARCHAR" />
  </resultMap>
  <select id="<span style="font-family: 宋體; font-size: 9pt; background-color: rgb(228, 228, 255);">selectUserById</span>" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select
    *
    from user
    where id = #{id,jdbcType=INTEGER}
  </select>

</mapper>
           

在resources目錄下建立mybatis的配置檔案,properties标簽下定義了jdbc的資訊，url中的mydata就是之前建立的資料庫名。mapper标簽下定義映射的xml檔案路徑。

<?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>
    <properties>
        <property name="driver" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/mydata?" />
        <property name="username" value="root" />
        <property name="password" value="root" />
    </properties>
    <typeAliases>
        <typeAlias type="User" alias="User"/>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="${driver}" />
                <property name="url" value="${url}" />
                <property name="username" value="${username}" />
                <property name="password" value="${password}" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="UserMapper.xml" />
    </mappers>
</configuration>
           

最後，看一下目錄樹

4.測試

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.Reader;


public class testUserService {

    public static void main(String[] args) throws IOException {
        String resource = "mybatis_conf.xml";
        Reader reader = Resources.getResourceAsReader(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        SqlSession session = sqlSessionFactory.openSession();
        int id = 1;
        User user = session.selectOne("UserMapper.selectUserById</span>",id);
        System.out.println(user);
    }
}
           

正确輸出id=1的記錄