一，MyBatis介紹

MyBatis是一個支援普通SQL查詢，儲存過程和高階對映的優秀持久層框架。MyBatis消除了幾乎所有的JDBC程式碼和引數的手工設定以及對結果集的檢索封裝。MyBatis可以使用簡單的XML或註解用於配置和原始對映，將介面和Java的POJO（Plain Old Java Objects，普通的Java物件）對映成資料庫中的記錄

二，MyBatis優點

不用再去寫複雜的JDBC程式碼

• 簡單易學，不依賴第三方的程式或者框架。
• 官網文件強大，開源，我們可以隨時分析原始碼’；
• 實現解耦，低耦合，高內聚
• ORM；物件關係對映
• 提供XML標籤；

三， Mybatis程式

1，搭建實驗環境，建立一個數據庫

1-1，MySQL程式碼

CREATE DATABASE `mybatis` ;
USE mybatis;
DROP TABLE IF EXISTS user;
CREATE TABLE user (
id INT(20) NOT NULL,
name VARCHAR(30) DEFAULT NULL,
pwd VARCHAR(30) DEFAULT NULL,
PRIMARY KEY (id)
) ENGINE=INNODB DEFAULT CHARSET=utf8;
INSERT  INTO user(id,name,pwd)
VALUES (1,'閃電俠','123'),(2,'蜘蛛俠','abc'
 
),(3,'鋼鐵俠','520');

1-2，執行結果

2，建立一個普通的Maven專案

2-1，建立Maven


2-2，編寫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>
<span class="hljs-tag">&lt;<span class="hljs-name">groupId</span>&gt;</span>com.Shandx<span class="hljs-tag">&lt;/<span class="hljs-name">groupId</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">artifactId</span>&gt;</span>ssm-mybatis-study<span class="hljs-tag">&lt;/<span class="hljs-name">artifactId</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">version</span>&gt;</span>1.0-SNAPSHOT<span class="hljs-tag">&lt;/<span class="hljs-name">version</span>&gt;</span>

<span class="hljs-tag">&lt;<span class="hljs-name">dependencies</span>&gt;</span>
    <span class="hljs-comment">&lt;!--單元測試--&gt;</span>
    <span class="hljs-tag">&lt;<span class="hljs-name">dependency</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">groupId</span>&gt;</span>junit<span class="hljs-tag">&lt;/<span class="hljs-name">groupId</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">artifactId</span>&gt;</span>junit<span class="hljs-tag">&lt;/<span class="hljs-name">artifactId</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">version</span>&gt;</span>4.11<span class="hljs-tag">&lt;/<span class="hljs-name">version</span>&gt;</span>
    <span class="hljs-tag">&lt;/<span class="hljs-name">dependency</span>&gt;</span>

    <span class="hljs-comment">&lt;!--mybatis的包--&gt;</span>
    <span class="hljs-tag">&lt;<span class="hljs-name">dependency</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">groupId</span>&gt;</span>org.mybatis<span class="hljs-tag">&lt;/<span class="hljs-name">groupId</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">artifactId</span>&gt;</span>mybatis<span class="hljs-tag">&lt;/<span class="hljs-name">artifactId</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">version</span>&gt;</span>3.5.1<span class="hljs-tag">&lt;/<span class="hljs-name">version</span>&gt;</span>
    <span class="hljs-tag">&lt;/<span class="hljs-name">dependency</span>&gt;</span>

    <span class="hljs-comment">&lt;!--連線資料庫的驅動包--&gt;</span>
    <span class="hljs-tag">&lt;<span class="hljs-name">dependency</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">groupId</span>&gt;</span>mysql<span class="hljs-tag">&lt;/<span class="hljs-name">groupId</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">artifactId</span>&gt;</span>mysql-connector-java<span class="hljs-tag">&lt;/<span class="hljs-name">artifactId</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">version</span>&gt;</span>5.1.47<span class="hljs-tag">&lt;/<span class="hljs-name">version</span>&gt;</span>
    <span class="hljs-tag">&lt;/<span class="hljs-name">dependency</span>&gt;</span>
<span class="hljs-tag">&lt;/<span class="hljs-name">dependencies</span>&gt;</span>

<span class="hljs-tag">&lt;<span class="hljs-name">build</span>&gt;</span>
    <span class="hljs-comment">&lt;!--希望maven在匯出專案的時候,能夠將我們的配置及資源匯出--&gt;</span>
    <span class="hljs-tag">&lt;<span class="hljs-name">resources</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">resource</span>&gt;</span>
            <span class="hljs-tag">&lt;<span class="hljs-name">directory</span>&gt;</span>src/main/java<span class="hljs-tag">&lt;/<span class="hljs-name">directory</span>&gt;</span>
            <span class="hljs-tag">&lt;<span class="hljs-name">includes</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">include</span>&gt;</span>**/*.properties<span class="hljs-tag">&lt;/<span class="hljs-name">include</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">include</span>&gt;</span>**/*.xml<span class="hljs-tag">&lt;/<span class="hljs-name">include</span>&gt;</span>
            <span class="hljs-tag">&lt;/<span class="hljs-name">includes</span>&gt;</span>
            <span class="hljs-tag">&lt;<span class="hljs-name">filtering</span>&gt;</span>false<span class="hljs-tag">&lt;/<span class="hljs-name">filtering</span>&gt;</span>
        <span class="hljs-tag">&lt;/<span class="hljs-name">resource</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">resource</span>&gt;</span>
            <span class="hljs-tag">&lt;<span class="hljs-name">directory</span>&gt;</span>src/main/resources<span class="hljs-tag">&lt;/<span class="hljs-name">directory</span>&gt;</span>
            <span class="hljs-tag">&lt;<span class="hljs-name">includes</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">include</span>&gt;</span>**/*.properties<span class="hljs-tag">&lt;/<span class="hljs-name">include</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">include</span>&gt;</span>**/*.xml<span class="hljs-tag">&lt;/<span class="hljs-name">include</span>&gt;</span>
            <span class="hljs-tag">&lt;/<span class="hljs-name">includes</span>&gt;</span>
            <span class="hljs-tag">&lt;<span class="hljs-name">filtering</span>&gt;</span>false<span class="hljs-tag">&lt;/<span class="hljs-name">filtering</span>&gt;</span>
        <span class="hljs-tag">&lt;/<span class="hljs-name">resource</span>&gt;</span>
    <span class="hljs-tag">&lt;/<span class="hljs-name">resources</span>&gt;</span>
<span class="hljs-tag">&lt;/<span class="hljs-name">build</span>&gt;</span>

</project>

3，編寫程式碼

3-1，建立pojo實體類

public class User {
<span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> id;
<span class="hljs-keyword">private</span> String name;
<span class="hljs-keyword">private</span> String pwd;

<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-title">User</span><span class="hljs-params">()</span> </span>{
}

<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-title">User</span><span class="hljs-params">(<span class="hljs-keyword">int</span> id, String name, String pwd)</span> </span>{
    <span class="hljs-keyword">this</span>.id = id;
    <span class="hljs-keyword">this</span>.name = name;
    <span class="hljs-keyword">this</span>.pwd = pwd;
}

<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> <span class="hljs-title">getId</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">return</span> id;
}

<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setId</span><span class="hljs-params">(<span class="hljs-keyword">int</span> id)</span> </span>{
    <span class="hljs-keyword">this</span>.id = id;
}

<span class="hljs-function"><span class="hljs-keyword">public</span> String <span class="hljs-title">getName</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">return</span> name;
}

<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setName</span><span class="hljs-params">(String name)</span> </span>{
    <span class="hljs-keyword">this</span>.name = name;
}

<span class="hljs-function"><span class="hljs-keyword">public</span> String <span class="hljs-title">getPwd</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">return</span> pwd;
}

<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setPwd</span><span class="hljs-params">(String password)</span> </span>{
    <span class="hljs-keyword">this</span>.pwd = password;
}

<span class="hljs-meta">@Override</span>
<span class="hljs-function"><span class="hljs-keyword">public</span> String <span class="hljs-title">toString</span><span class="hljs-params">()</span> </span>{
    <span class="hljs-keyword">return</span> <span class="hljs-string">"User{"</span> +
            <span class="hljs-string">"id="</span> + id +
            <span class="hljs-string">", name='"</span> + name + <span class="hljs-string">'\''</span> +
            <span class="hljs-string">", pwd='"</span> +pwd + <span class="hljs-string">'\''</span> +
            <span class="hljs-string">'}'</span>;
}

}

3-2，在resources下建一個mybatis-config.xml，編寫mybatis配置檔案

<?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>
    <!--配置環境，這裡可以有多套環境 default代表預設的是那一套-->
    <environments default="development">
        <!--配置一套環境 id .環境的名字-->
        <environment id="development">
            <!--transactionManager:事務管理，type:jdbc-->
            <transactionManager type="JDBC"/>
            <!--dataSource 資料來源-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <!--xml中不允許&符號直接出現，我們需要使用 &amp; 代替-->
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;charsetEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
</configuration>

3-3，建立工具類

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
//mybatis的工具類，重複的程式碼的提純
public class MyBatisUtils {
<span class="hljs-comment">//類變數不需要設定預設值；</span>
<span class="hljs-keyword">private</span> <span class="hljs-keyword">static</span> <span class="hljs-type">SqlSessionFactory</span> sqlSessionFactory;

<span class="hljs-keyword">static</span> {
    <span class="hljs-comment">//在maven中，所有的資原始檔一般都放在resources目錄下，我們可以直接拿到。</span>
    <span class="hljs-keyword">try</span> {
        <span class="hljs-type">String</span> resource = <span class="hljs-string">"mybatis-config.xml"</span>;
        <span class="hljs-type">InputStream</span> inputStream = <span class="hljs-type">Resources</span>.getResourceAsStream(resource);
        sqlSessionFactory = new <span class="hljs-type">SqlSessionFactoryBuilder</span>().build(inputStream);
    } <span class="hljs-keyword">catch</span> (<span class="hljs-type">IOException</span> e) {
        e.printStackTrace();
    }
}

<span class="hljs-comment">//設定SqlSessionFactory公共的方法</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-type">SqlSessionFactory</span> getSqlSessionFactory(){
    <span class="hljs-keyword">return</span> sqlSessionFactory;
}

}

3-4，對映檔案的介面

import com.shandx.pojo.User;
import java.util.List;
public interface UserMapper {
<span class="hljs-comment">//獲取全部的使用者</span>
<span class="hljs-function">List&lt;User&gt; <span class="hljs-title">selectUser</span><span class="hljs-params">()</span></span>;

}

3-5，編寫對應的mapper對映檔案

<?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標籤的namespace對應Mapper介面的類-->
<mapper namespace="com.Shandx.dao.UserMapper">
<!--select標籤的id對應對映介面的方法名字  resultType:返回結果的型別  中間就編寫sql語句-->
<select id="selectUser" resultType="com.Shandx.pojo.User">
select * from user
</select>
</mapper>

3-6，在mybatis配置檔案中繫結編寫對映檔案

<?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>
    <!--配置環境，這裡可以有多套環境 default代表預設的是那一套-->
    <environments default="development">
        <!--配置一套環境 id .環境的名字-->
        <environment id="development">
            <!--transactionManager:事務管理，type:jdbc-->
            <transactionManager type="JDBC"/>
            <!--dataSource 資料來源-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <!--xml中不允許&符號直接出現，我們需要使用 &amp; 代替-->
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;charsetEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
<span class="hljs-comment">&lt;!--關聯對映檔案--&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">mappers</span>&gt;</span>
    <span class="hljs-tag">&lt;<span class="hljs-name">mapper</span> <span class="hljs-attr">resource</span>=<span class="hljs-string">"com/kuang/dao/userMapper.xml"</span>/&gt;</span>
<span class="hljs-tag">&lt;/<span class="hljs-name">mappers</span>&gt;</span>

</configuration>

4，測試一下

在maven的test資料夾下編寫對應的測試類

import com.Shandx.dao.UserMapper;
import com.Shandx.pojo.User;
import com.Shandx.utils.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.junit.Test;
import java.util.List;
public class UserMapperTest {
@Test
public void selectUser(){
    <span class="hljs-comment">//1.拿到sqlSessionFactory物件</span>
    <span class="hljs-type">SqlSessionFactory</span> sqlSessionFactory = <span class="hljs-type">MyBatisUtils</span>.getSqlSessionFactory();
    <span class="hljs-comment">//2.通過sqlSessionFactory物件openSession()建立一個sqlSession。</span>
    <span class="hljs-type">SqlSession</span> sqlSession = sqlSessionFactory.openSession();
    <span class="hljs-comment">//3.通過sqlSession獲得mapper物件 ， 引數為對映檔案對應的介面類的class物件</span>
    <span class="hljs-type">UserMapper</span> mapper = sqlSession.getMapper(<span class="hljs-type">UserMapper</span>.<span class="hljs-keyword">class</span>);
    <span class="hljs-comment">//4.通過mapper物件來執行操作；</span>
    <span class="hljs-type">List</span>&lt;<span class="hljs-type">User</span>&gt; users = mapper.selectUser();

    <span class="hljs-comment">//獲得結果集</span>
    <span class="hljs-keyword">for</span> (<span class="hljs-type">User</span> user : users) {
        <span class="hljs-type">System</span>.out.<span class="hljs-built_in">println</span>(user);
    }
    
}

}

5，結果展示

四，專案結構