1.Mybatis入門

1.1Mybatis入門使用

1.2Mybatis高級特性(mybatis-2.md)

2.Mybatis介紹

2.1框架的作用

1.軟件開發(fā)中的框架
    框架是可被應用開發(fā)者定制的應用骨架
    框架是一種規(guī)則畏吓，保證開發(fā)者遵循相同的方式開發(fā)程序
    框架提倡“不要重復造輪子”肾砂，對基礎功能進行封裝
2.框架的優(yōu)點
    極大提高了開發(fā)效率
    統(tǒng)一的編碼規(guī)則宏悦，利于團隊管理
    靈活配置的應用饼煞，擁有更好的維護性
3.SSM開發(fā)框架
    Spring   Spring MVC  Mybatis

2.2介紹Mybatis

2.2.1 什么是Mybatis

1.Mybatis是最優(yōu)秀持久層框架（dao）
2.Mybatis使用XML將SQL與程序解耦砖瞧，便于維護
3.Mybatis學習簡單块促，執(zhí)行高效竭翠，是JDBC的延伸
Mybatis中文文檔 https://mybatis.org/mybatis-3/zh/index.html

2.2.2 Mybatis開發(fā)流程

1.引入Mybatis依賴
2.創(chuàng)建核心配置文件
3.創(chuàng)建實體（Entity）類
4.創(chuàng)建Mapper映射文件
5.初始化SessionFactory
6.利用SqlSession對象操作數(shù)據(jù)

2.3 單元測試與JUnit4

單元測試是指對軟件中的最小可測試單元進行核查和驗證
測試用例是指編寫一段代碼對已有的功能（方法）進行核驗
JUnit4是java中最著名的單元測試工具斋扰，主流IDE內(nèi)置支持
    JUnit是JUnit的第4代版本

    JUnit4使用方法
1.引入JUnit Jar包或增加Maven依賴
2.編寫測試用例驗證目標方法是否正確運行
3.在測試用例上增加@Test注解開始單元測試

//junit4.12 maven依賴
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
</dependency>

3.MyBatis基本使用

3.1 Mybatis環(huán)境配置

核心文件：mybatis-config.xml
    Mybatis采用XML格式配置數(shù)據(jù)庫環(huán)境信息
    Mybatis環(huán)境配置標簽<environment>
    environment包含數(shù)據(jù)庫驅(qū)動传货、URL损离、用戶名與密碼

<!--配置環(huán)境僻澎，不同的環(huán)境 不同的id名字-->
<environment id="dev">
    <!--采用JDBC方式對數(shù)據(jù)庫事務進行commit/rollback-->
    <transactionManager type="JDBC"></transactionManager>
    <!--采用連接池方式管理數(shù)據(jù)庫連接-->
    <dataSource type="POOLED">
        <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/babytun窟勃？useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF8&amp;serverTimezone=Asia/Shanghai&amp;allowPublicKeyRetrieval=true"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
    </dataSource>
</environment>

<!--采用maven的方式增加依賴 寫在pom.xml中-->
<!--mybatis依賴-->
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.1</version>
</dependency>
 <!--mysql驅(qū)動-->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.21</version>
</dependency>

mybatis-config.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>
    <!--設置默認指向的數(shù)據(jù)庫-->
    <environments default="dev">
        <environment id="dev">
            <!--采用JDBC方式對數(shù)據(jù)庫事務進行commit/rollback-->
            <transactionManager type="JDBC"></transactionManager>
            <!--采用連接池方式管理數(shù)據(jù)庫連接-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url"
                          value="jdbc:mysql://localhost:3306/babytun?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=Asia/Shanghai&amp;allowPublicKeyRetrieval=true"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
</configuration>

3.2SqlSessionFactory

1.SqlSessionFactory是Mybatis的核心對象
2.用于初始化Mybatis,創(chuàng)建SqlSession對象
3.保證SqlSessionFactory在應用中全局唯一

3.3 SqlSession

1.SqlSession是Mybatis操作數(shù)據(jù)庫的核心對象
2.SqlSession使用JDBC方式與數(shù)據(jù)庫交互
3.SqlSession對象提供了數(shù)據(jù)表CRUD對應的方法

3.4 SqlSessionFactory創(chuàng)建細節(jié)

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 org.junit.Test;

import java.io.IOException;
import java.io.Reader;
import java.sql.Connection;


public class MybatisTestor {
    @Test
    public void testSqlSessionFactory() throws IOException {
        //利用Reader加載classpath下的mybatis-config.xml核心配置文件
       Reader reader= Resources.getResourceAsReader("mybatis-config.xml");
       //初始化SqlSessionFactory對象，同時解析mybatis-config.xml文件
        SqlSessionFactory sqlSessionFactory= new SqlSessionFactoryBuilder().build(reader);
        System.out.println("SqlSessionFactory加載成功");
        SqlSession sqlSession=null;
        try{
            //創(chuàng)建SqlSession對象亚斋，SqlSession是JDBC的擴展類帅刊，用于與數(shù)據(jù)庫交互
            sqlSession =sqlSessionFactory.openSession();
            //創(chuàng)建數(shù)據(jù)庫連接（測試用）
            Connection connection=sqlSession.getConnection();
            System.out.println(connection);
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if (sqlSession!=null){
                //如果type="POOLED",代表使用連接池,close則是將連接回收到連接池
                //如果type="UNPOOLED",代表直連赖瞒，close則會調(diào)用Connection.close（）方法關閉
                sqlSession.close();
            }
        }

    }
}

3.5 初始化工作類MybatisUtils

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;

/**
 * MybatisUtils工具類栏饮，創(chuàng)建全局唯一的SqlSessionFactory對象
 */
public class MybatisUtils {
    //利用static（靜態(tài)）屬于類不屬于對象袍嬉，且全局唯一
    private  static SqlSessionFactory sqlSessionFactory=null;
    //利用靜態(tài)塊在初始化類時實例化SqlSessionFactory
    static {
        Reader reader= null;
        try {
            reader = Resources.getResourceAsReader("mybatis-config.xml");
            sqlSessionFactory= new SqlSessionFactoryBuilder().build(reader);
        } catch (IOException e) {
            e.printStackTrace();
            //初始化錯誤時伺通，通過拋出異常ExceptionInInitializerError通知調(diào)用者
            throw  new ExceptionInInitializerError(e);
        }

    }

    /**
     * openSession 創(chuàng)建一個新的SqlSession對象
     * @return SqlSession對象
     */
    public static SqlSession openSession(){
        return  sqlSessionFactory.openSession();
    }

    /**
     * 釋放一個有效的SqlSession對象
     * @param session 準備釋放SqlSession對象
     */
    public static void closeSession(SqlSession session){
        if(session!=null){
            session.close();
        }
    }
}

3.6 Mybatis數(shù)據(jù)查詢

3.6.1 Mybatis數(shù)據(jù)查詢步驟

1.創(chuàng)建實體類（Entity）
2.創(chuàng)建Mapper XML
3.編寫<select> SQL標簽
4.開啟駝峰命名映射
5.新增<mapper>
6.SqlSession執(zhí)行select語句

3.6.2Mybatis數(shù)據(jù)查詢具體實現(xiàn)

1.創(chuàng)建實體類（Entity）

public class Goods {
    private Integer goodsId;
    private String  title;
    private String  subTitle;
    private Float originalCost;
    private Float currentPrice;
    private Float  discount;
    private Integer isFreeDelivery;
    private Integer categoryId;

    public Integer getGoodsId() {
        return goodsId;
    }

    public void setGoodsId(Integer goodsId) {
        this.goodsId = goodsId;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getSubTitle() {
        return subTitle;
    }

    public void setSubTitle(String subTitle) {
        this.subTitle = subTitle;
    }

    public Float getOriginalCost() {
        return originalCost;
    }

    public void setOriginalCost(Float originalCost) {
        this.originalCost = originalCost;
    }

    public Float getCurrentPrice() {
        return currentPrice;
    }

    public void setCurrentPrice(Float currentPrice) {
        this.currentPrice = currentPrice;
    }

    public Float getDiscount() {
        return discount;
    }

    public void setDiscount(Float discount) {
        this.discount = discount;
    }

    public Integer getIsFreeDelivery() {
        return isFreeDelivery;
    }

    public void setIsFreeDelivery(Integer isFreeDelivery) {
        this.isFreeDelivery = isFreeDelivery;
    }

    public Integer getCategoryId() {
        return categoryId;
    }

    public void setCategoryId(Integer categoryId) {
        this.categoryId = categoryId;
    }
}

2.創(chuàng)建Mapper XML

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="goods">
  
</mapper>

3.編寫 < select > SQL標簽

<select id="selectAll" resultType="com.xiaofeng.mybatis.entity.Goods">
    select * from t_goods order by goods_id asc  limit 10
</select>

4.開啟駝峰命名映射

<!--mybatis-config.xml 下的configuration標簽中添加這段代碼 開啟駝峰命名-->
<settings>
    <setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>

5.新增< mapper >

<!--mybatis-config.xml 下的configuration標簽中添加這段代碼-->
<mappers>
    <mapper resource="mappers/goods.xml"/>
</mappers>

6.SqlSession執(zhí)行select語句

@Test
public void testSelectAll(){
    SqlSession session=null;
    try{
       session= MybatisUtils.openSession();
        //主要看這里
       List<Goods>  list=session.selectList("goods.selectAll");
       for (Goods g:list){
           System.out.println(g.getTitle());
       }
    }catch (Exception e){
        e.printStackTrace();
    } finally {
        MybatisUtils.closeSession(session);
    }
}

4.SQL傳參

4.1單參數(shù)傳遞

<!-- 單參數(shù)傳遞拼苍，使用parameterType指定參數(shù)的數(shù)據(jù)類型即可疮鲫， SQL中的#{value}提取參數(shù) -->
<select id="selectById" parameterType="Integer" resultType="com.xiaofeng.mybatis.entity.Goods">
    select * from t_goods where goods_id=#{value}
</select>

@Test
public void testSelectById(){
    SqlSession session=null;
    try{
        session= MybatisUtils.openSession();
        //看這里
        Goods  goods=session.selectOne("goods.selectById",739);
        System.out.println(goods.getTitle());

    }catch (Exception e){
        e.printStackTrace();
    } finally {
        MybatisUtils.closeSession(session);
    }
}

4.2多參數(shù)傳遞

<!--多參數(shù)傳遞時俊犯，使用parameterType指定Map接口燕侠， SQL中的#{key}提取參數(shù) -->
<select id="selectByPriceRange" parameterType="java.util.Map" resultType="com.xiaofeng.mybatis.entity.Goods">
        select * from t_goods
         where current_price between #{min} and  #{max}
         order by current_price
         limit 0 ,#{limt}
</select>

@Test
public void testSelectByPriceRange(){
    SqlSession session=null;
    try{
        session= MybatisUtils.openSession();
        //看這里
        Map param=new HashMap();
        param.put("min",100);
        param.put("max",500);
        param.put("limt",10);
        List<Goods>  list=session.selectList("goods.selectByPriceRange",param);
        for (Goods g:list){
            System.out.println(g.getTitle()+":"+g.getCurrentPrice());
        }

    }catch (Exception e){
        e.printStackTrace();
    } finally {
        MybatisUtils.closeSession(session);
    }
}

5.多表關聯(lián)查詢

5.1 獲取多表關聯(lián)查詢結果

<!-- select id="selectGoodsMap"  resultType="java.util.Map"  返回結果亂序-->
<!--LinkedHashMap 返回結果有序-->
<!--利用LinkedHashMap保存多表關聯(lián)結果
    Mybatis會將每一條記錄包裝為LinkedHashMap對象
    key是字段名七问，value是字段所對應的值械巡，字段類型根據(jù)表結構進行自動判斷
    優(yōu)點：易于擴展，易于使用
    缺點：太過靈活有勾，無法進行編譯時檢查
-->
<select id="selectGoodsMap"  resultType="java.util.LinkedHashMap">
    select g.*,c.category_name from t_goods g,t_category c
     where g.category_id=c.category_id
</select>

@Test
public void testSelectGoodsMap(){
    SqlSession session=null;
    try{
        session= MybatisUtils.openSession();
        //看這里
        List<Map>  list=session.selectList("goods.selectGoodsMap");
        for (Map map:list){
            System.out.println(map);
        }

    }catch (Exception e){
        e.printStackTrace();
    } finally {
        MybatisUtils.closeSession(session);
    }
}

5.2 ResultMap結果映射

 1.ResultMap可以將查詢結果映射為復雜類型的Java對象
 2.ResultMap適用于Java對象保存多表關聯(lián)結果
 3.ResultMap支持對象關聯(lián)查詢等高級特性

<!--結果映射-->
<resultMap id="rmGoods" type="com.xiaofeng.mybatis.dto.GoodsDTO">
    <!--設置主鍵字段與屬性映射-->
    <id property="goods.goodsId" column="goods_id"></id>
    <!--設置非主鍵字段與屬性映射-->
    <result property="goods.title" column="title"></result>
    <result property="goods.subTitle" column="sub_title"></result>
    <result property="goods.originalCost" column="original_cost"></result>
    <result property="goods.currentPrice" column="current_price"></result>
    <result property="goods.discount" column="discount"></result>
    <result property="goods.isFreeDelivery" column="is_free_delivery"></result>
    <result property="goods.categoryId" column="category_id"></result>
    <result property="categoryName" column="category_name"></result>
    <result property="test" column="test"></result>
</resultMap>
<select id="selectGoodsDTO" resultMap="rmGoods" resultType="java.util.LinkedHashMap">
    select g.*,c.category_name,'1' as test from t_goods g,t_category c
     where g.category_id=c.category_id
</select>

import com.xiaofeng.mybatis.entity.Goods;
//Data Transfer Object 數(shù)據(jù)傳輸對象
public class GoodsDTO {
    private Goods goods=new Goods();
    private String categoryName;
    private String test;

    public Goods getGoods() {
        return goods;
    }

    public void setGoods(Goods goods) {
        this.goods = goods;
    }

    public String getCategoryName() {
        return categoryName;
    }

    public void setCategoryName(String categoryName) {
        this.categoryName = categoryName;
    }

    public String getTest() {
        return test;
    }

    public void setTest(String test) {
        this.test = test;
    }
}

@Test
public void testSelectGoodsDTO(){
    SqlSession session=null;
    try{
        session= MybatisUtils.openSession();
        //看這里
        List<GoodsDTO>  list=session.selectList("goods.selectGoodsDTO");
        for (GoodsDTO g:list){
            System.out.println(g.getGoods().getTitle());
        }

    }catch (Exception e){
        e.printStackTrace();
    } finally {
        MybatisUtils.closeSession(session);
    }
}

兩張表

//category實體類
public class Category {
    private Integer categoryId;
    private String categoryName;
    private Integer parentId;
    private Integer categoryLevel;
    private Integer categoryOrder;

    public Integer getCategoryId() {
        return categoryId;
    }

    public void setCategoryId(Integer categoryId) {
        this.categoryId = categoryId;
    }

    public String getCategoryName() {
        return categoryName;
    }

    public void setCategoryName(String categoryName) {
        this.categoryName = categoryName;
    }

    public Integer getParentId() {
        return parentId;
    }

    public void setParentId(Integer parentId) {
        this.parentId = parentId;
    }

    public Integer getCategoryLevel() {
        return categoryLevel;
    }

    public void setCategoryLevel(Integer categoryLevel) {
        this.categoryLevel = categoryLevel;
    }

    public Integer getCategoryOrder() {
        return categoryOrder;
    }

    public void setCategoryOrder(Integer categoryOrder) {
        this.categoryOrder = categoryOrder;
    }
}

<!--結果映射-->
<resultMap id="rmGoods" type="com.xiaofeng.mybatis.dto.GoodsDTO">
    <!--設置主鍵字段與屬性映射-->
    <id property="goods.goodsId" column="goods_id"></id>
    <!--設置非主鍵字段與屬性映射-->
       <!--goods-->
    <result property="goods.title" column="title"></result>
    <result property="goods.subTitle" column="sub_title"></result>
    <result property="goods.originalCost" column="original_cost"></result>
    <result property="goods.currentPrice" column="current_price"></result>
    <result property="goods.discount" column="discount"></result>
    <result property="goods.isFreeDelivery" column="is_free_delivery"></result>
    <result property="goods.categoryId" column="category_id"></result>
    <!--Category-->
    <result property="category.categoryId" column="category_id"></result>
    <result property="category.categoryName" column="category_name"></result>
    <result property="category.parentId" column="parent_id"></result>
    <result property="category.categoryLevel" column="category_level"></result>
    <result property="category.categoryOrder" column="category_order"></result>
    <result property="test" column="test"></result>
</resultMap>
<select id="selectGoodsDTO" resultMap="rmGoods" resultType="java.util.LinkedHashMap">
    select g.*,c.*,'1' as test from t_goods g,t_category c
     where g.category_id=c.category_id
</select>

@Test
public void testSelectGoodsDTO(){
    SqlSession session=null;
    try{
        session= MybatisUtils.openSession();
        //看這里
        List<GoodsDTO>  list=session.selectList("goods.selectGoodsDTO");
        for (GoodsDTO g:list){
            System.out.println(g.getGoods().getTitle());
        }

    }catch (Exception e){
        e.printStackTrace();
    } finally {
        MybatisUtils.closeSession(session);
    }
}

import com.xiaofeng.mybatis.entity.Category;
import com.xiaofeng.mybatis.entity.Goods;
//Data Transfer Object 數(shù)據(jù)傳輸對象
public class GoodsDTO {
    private Goods goods=new Goods();
    private Category category=new Category();
    private String test;

    public Goods getGoods() {
        return goods;
    }

    public void setGoods(Goods goods) {
        this.goods = goods;
    }

    public Category getCategory() {
        return category;
    }

    public void setCategory(Category category) {
        this.category = category;
    }

    public String getTest() {
        return test;
    }

    public void setTest(String test) {
        this.test = test;
    }
}

6.MyBatis的數(shù)據(jù)插入趋急、修改與刪除

6.1 MyBatis的數(shù)據(jù)寫入

6.1.1 數(shù)據(jù)庫事務

數(shù)據(jù)庫事務是保證數(shù)據(jù)操作完整性的基礎

                |               MySQL                                       |
                |       事務日志                                數(shù)據(jù)表        |
客戶端-------->   |    新增日志1                                   數(shù)據(jù)1        |
                |    新增日志2              commit------>         數(shù)據(jù)2        |
                |    新增日志3              <-----rollback         數(shù)據(jù)3       |

6.1.2 MyBatis寫操作

插入 ------ <insert>
更新 ------ <update>
刪除 ------ <delete>

新增 -<insert>
 <insert id="insert" parameterType="com.xiaofeng.mybatis.entity.Goods">
        INSERT INTO babytun.t_goods( title, sub_title, original_cost, current_price, discount, is_free_delivery, category_id) 
        VALUES (#{title},#{subTitle},#{originalCost},#{currentPrice},#{discount},#{isFreeDelivery},#{categoryId});
        <selectKey resultType="Integer" keyProperty="goodsId" order="AFTER">
            -- 當前連接中最后產(chǎn)生的id號
            select last_insert_id();
        </selectKey>
    </insert>

@Test
public void testInsert() {
    SqlSession session = null;
    try {
        session = MybatisUtils.openSession();
        //看這里
        Goods goods = new Goods();
        goods.setTitle("測試數(shù)據(jù)");
        goods.setSubTitle("測試子標題");
        goods.setOriginalCost(300f);
        goods.setCurrentPrice(200f);
        goods.setDiscount(0.7f);
        goods.setIsFreeDelivery(0);
        goods.setCategoryId(44);
        //insert()方法返回值代表本次成功插入的記錄總數(shù)
        int num = session.insert("goods.insert", goods);
        session.commit();//提交事務數(shù)據(jù)
        System.out.println(goods.getGoodsId());

    } catch (Exception e) {
        if(session !=null) {
            session.rollback();//回滾事務
        }
        e.printStackTrace();
    } finally {
        MybatisUtils.closeSession(session);
    }
}

6.1.3 selectKey與useGeneratedKeys的區(qū)別

1）< selectKey >標簽的用法

<insert id="insert" parameterType="com.xiaofeng.mybatis.entity.Goods">
    INSERT INTO SQL語句
    <selectKey resultType="Integer" keyProperty="goodsId" order="AFTER">
        -- 當前連接中最后產(chǎn)生的id號
        select last_insert_id();
    </selectKey>
</insert>

2）useGeneratedKeys屬性的用法

<insert id="insert" parameterType="com.xiaofeng.mybatis.entity.Goods"
useGeneratedKeys="true"  keyProperty="goodsId" keyColumn="goods_id">
     INSERT INTO SQL語句
</insert>

3）二者區(qū)別

1）顯示與隱式
    1.selectKey標簽需要明確編寫獲取最新主鍵的SQL語句
    2.useGeneratedKeys屬性會自動根據(jù)驅(qū)動生成對應的SQL語句
2）應用場景不同
    1.selectKey適用于使用的關系型數(shù)據(jù)庫
    2.useGeneratedKeys只支持"自增主鍵"類型的數(shù)據(jù)庫
3）總結
    1.selectKey標簽是通用方案，適用于所有數(shù)據(jù)庫查近，但編寫麻煩
    2.useGeneratedKeys屬性只支持"自增主鍵"類型的數(shù)據(jù)庫霜威，使用簡單  ---->個人推薦這個

4）在Oracle中selectKey的用法

<insert id="insert" parameterType="com.xiaofeng.mybatis.entity.Goods">
     INSERT INTO SQL語句
    <selectKey resultType="Integer" keyProperty="goodsId" order="BEFORE">
        SELECT seq_goods.nextval as id from dual;
    </selectKey>
</insert>

6.2 MyBatis的數(shù)據(jù)更新與刪除

6.2.1 MyBatis更新操作

<update id="update" parameterType="com.xiaofeng.mybatis.entity.Goods">
  UPDATE babytun.t_goods 
  SET 
    title =  #{title}, 
    sub_title =  #{subTitle}, 
    original_cost =  #{originalCost},
    current_price =  #{currentPrice}, 
    discount =  #{discount}, 
    is_free_delivery =  #{isFreeDelivery}, 
    category_id =  #{categoryId}
 WHERE 
    goods_id = #{goodsId}
</update>

@Test
public void testUpdate() throws  Exception {
    SqlSession session = null;
    try {
        session = MybatisUtils.openSession();
        //看這里
        Goods goods=session.selectOne("goods.selectById",12679);
        goods.setIsFreeDelivery(1);
        //update()方法返回值代表本次成功修改的記錄總數(shù)
        int num = session.update("goods.update", goods);
        session.commit();//提交事務數(shù)據(jù)

    } catch (Exception e) {
        if(session !=null) {
            session.rollback();//回滾事務
        }
        e.printStackTrace();
    } finally {
        MybatisUtils.closeSession(session);
    }
}

6.2.2 MyBatis刪除操作

<delete id="delete" parameterType="Integer">
     delete from t_goods where  goods_id = #{value}
</delete>

@Test
public void testDelete() throws  Exception {
    SqlSession session = null;
    try {
        session = MybatisUtils.openSession();
        //看這里
        //delete()方法返回值代表本次成功刪除的記錄總數(shù)
        int num = session.delete("goods.delete", 12679);
        session.commit();//提交事務數(shù)據(jù)

    } catch (Exception e) {
        if(session !=null) {
            session.rollback();//回滾事務
        }
        e.printStackTrace();
    } finally {
        MybatisUtils.closeSession(session);
    }
}

7.預防SQL注入攻擊

7.1SQL注入攻擊

SQL注入是指攻擊者利用SQL漏洞婿禽，繞過系統(tǒng)約束扭倾，越權獲取數(shù)據(jù)的攻擊方式

SQL代碼："select * from a where name='" +name+"'";
正常情況：
        name：張三 -> select * from a where name='張三';
SQL注入攻擊:
    name: 'or 1=1 or 1=' ->  select * from a where name='' or 1=1 or 1='';

7.2Mybatis兩種傳值方式

1.${} 文本替換膛壹，未經(jīng)任何處理對SQL文本替換（原文傳值）
2.#{} 預編譯傳值，使用預編譯傳值可以預防SQL注入

8.MyBatis工作流程

                                                                                          Session Close
                                                                                                /\
                                                                                                |
應用  --->    mybatis-config.xml --->  SqlSessionFactory --->  SqlSession  --->   insert | update | delete | select
                    |                       |                   |               |               |   
                    |                       |   bullid()         |               |               |  
                    \/                      \/                  \/              \/              \/
                全局設置項       SqlSessionFactoryBulider        mapper.xml        commit         rollback
                環(huán)境配置
                mapper聲明