junit java MyBatis入门

开发流程

引入MyBatis依赖创建核心配置文件创建实体（Entity）类创建Mapper映射文件初始化SessionFactory利用SqlSession对象操作数据

单元测试

单元测试是指对软件中的最小可测试单元进行检查和验证测试用例是指编写一段代码对已有功能（方法）进行校验JUnit 4是Java中最著名的单元测试工具，主流IDE内置支持

JUnit 4使用方法

引入JUnit jar包或增加Maven依赖编写测试用例验证目标方法是否正确运行在测试用例上增加@Test注解开始单元测试

使用Maven 新建项目 选择Maven 下一步 在pom.xml中添加依赖

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">

4.0.0

org.example

meven-junit4

1.0-SNAPSHOT

//指定下载服务器

aliyun

aliyun

https://maven.aliyun.com/repository/public

//依赖

junit

junit

4.12

左侧出现对应包表示下载成功 引入JUnit jar包 新建Java项目 新建文件夹lib将jar包导入 将lib目录进入项目库中 生成测试用例类 先写一个加减乘除类

public class Calculator {

//加法运算

public int add(int a , int b){

return a + b;

}

//减法运算

public int subtract(int a , int b){

return a - b;

}

//乘法运算

public int multiply(int a , int b){

return a * b;

}

//除法运算

public float divide(int a,int b){

if(b==0){

throw new ArithmeticException("除数不能为0");

}

return (a*1f) / b;

}

}

鼠标右键 选择test 生成测试代码 添加测试内容

public class CalculatorTest {

private Calculator cal = new Calculator();

@Test

public void add() {

int result = cal.add(1, 2);

System.out.println(result);

}

@Test

public void subtract() {

int result = cal.subtract(1, 2);

System.out.println(result);

}

@Test

public void multiply() {

int result = cal.multiply(1, 2);

System.out.println(result);

}

@Test

public void divide() {

float result = cal.divide(1, 2);

System.out.println(result);

}

}

运行

MyBatis基本使用

配置文件：mybatis-config.xml MyBatis采用XML格式配置数据库环境信息 MyBatis环境配置标签 environment包含数据驱动、URL、用户名与密码 使用Maven创建新项目 添加依赖 pom.xml

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">

4.0.0

org.example

mybatis

1.0-SNAPSHOT

aliyun

aliyun

https://maven.aliyun.com/repository/public

org.mybatis

mybatis

3.5.1

mysql

mysql-connector-java

5.1.47

8

8

使用IDE创数据库 填写mysql信息 点击Test Connection进行测试 通过后点击ok 导入数据库脚本 等待运行成功 配置MyBatis

PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-config.dtd">

SqlSessionFactory

SqlSessionFactory是MyBatis的核心对象 用于初始化MyBatis,创建SqlSession对象 保证SqlSessionFactory在应用中全局唯一 SqlSession SqlSession是MyBatis操作数据库的核心对象 SqlSession使用JDBC方式与数据库交互 SqlSession对象提供了数据表CRUD对应方法 引入单元测试依赖 新建包创建单元测试类 编写测试代码

package com.mybatis;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import org.junit.Test;

import org.apache.ibatis.io.Resources;

import java.io.IOException;

import java.io.Reader;

import java.sql.Connection;

public class MybatisTestor {

@Test

public void testSqlSessionFactory() throws IOException {

//利用Reader加载classpath下的mybatis-config.xml核心配置文件

Reader reader = Resources.getResourceAsReader("mybatis-config.xml");

//初始化SqlSessionFactory对象,同时解析mybatis-config.xml文件

SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);

System.out.println("sqlSessionFactory加载成功");

SqlSession sqlSession = null;

try {

//创建SqlSession对象，SqlSession是JDBC的扩展类，用于与数据库交互

sqlSession = sqlSessionFactory.openSession();

//创建数据库连接（测试用 ）

Connection connection = sqlSession.getConnection();

System.out.println(connection);

}catch (Exception e){

e.printStackTrace();

}finally {

if(sqlSession!=null){

//如果type="POOLED",代表使用连接池,close则是将连接回收到连接池中

//如果type="UNPOOLED",代表直连,close则会调用Connection.close()方法关闭连接

sqlSession.close();

}

}

}

}

初始化工具类MyBatisUtils

新建工具类 代码

package com.mybatis.utils;

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工具类,创建全局唯一的SqlSessionFactory对象

*/

public class MyBatisUtils {

//利用static(静态)属于类不属于对象,且全局唯一

private static SqlSessionFactory sqlSessionFactory = null;

//利用静态块在初始化类时实例化sqlSessionFactory

static {

Reader reader = null;

try{

reader = Resources.getResourceAsReader("mybatis-config.xml");

sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);

} catch (IOException e) {

e.printStackTrace();

//初始化错误时,通过抛出异常ExceptionInInitializerError通知调用者

throw new ExceptionInInitializerError(e);

}

}

/**

* openSession 创建一个新的SqlSession对象

* @return SqlSession对象

*/

public static SqlSession openSession(){

return sqlSessionFactory.openSession();

}

/**

* 释放一个有效的SqlSession对象

* @param session 准备释放SqlSession对象

*/

public static void closeSession(SqlSession session){

if(session != null){

session.close();

}

}

}

测试工具类 MybatisTestor.java

/**

* MyBatisUtils使用指南

**/

@Test

public void testMyBatisUtils(){

SqlSession sqlSession = null;

try{

sqlSession = MyBatisUtils.openSession();

Connection connection =sqlSession.getConnection();

System.out.println(connection);

}catch (Exception e){

throw e;

}finally {

MyBatisUtils.closeSession(sqlSession);

}

}

MyBatis数据查询

MyBatis数据查询步骤

创建实体类(Entity)创建Mapper XML编写SQL标签开启驼峰命名映射新增SqlSession执行select语句

创建实体类

package com.mybatis.entity;

public class Goods {

private Integer goodsId;//商品编号

private String title;//标题

private String subTitle;//子标题

private Float originalCost;//原始价格

private Float currentPrice;//当前价格

private Float discount;//折扣率

private Integer isFreeDelivery;//是否包邮 ,1-包邮 0-不包邮

private Integer categoryId;//分类编号

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;

}

}

创建goods.xml

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

select * from t_goods order by goods_id desc limit 10

在mybatis-config.xml中进行声明 测试 MybatisTestor.java中

@Test

public void testSelectAll(){

SqlSession session = null;

try{

session = MyBatisUtils.openSession();

List list= session.selectList("goods.selectAll");

for(Goods g:list){

System.out.println(g.getTitle());

}

}catch (Exception e){

throw e;

}finally {

MyBatisUtils.closeSession(session);

}

}

解决驼峰命名和分段命名不一样问题 mybatis-config.xml中添加

测试结果

SQL传参

查询 在goods…xml中添加一个select

select * from t_goods where goods_id = #{value}

测试 MybatisTestor.java中

@Test

public void testSelectById() throws Exception{

SqlSession session = null;

try{

session = MyBatisUtils.openSession();

Goods goods= session.selectOne("goods.selectById",1602);

System.out.println(goods.getTitle());

}catch (Exception e){

throw e;

}finally {

MyBatisUtils.closeSession(session);

}

}

测试结果：

按价格范围查询

goods.xml中

select * from t_goods

where

current_price between #{min} and #{max}

order by current_price

limit 0,#{limt}

测试 MybatisTestor.java中

@Test

public void testSelectByPriceRange() throws Exception{

SqlSession session = null;

try{

session = MyBatisUtils.openSession();

Map param = new HashMap();

param.put("min",100);

param.put("max",500);

param.put("limt",10);

List list= session.selectList("goods.selectByPriceRange",param);

for(Goods g:list){

System.out.println(g.getTitle()+":"+g.getCurrentPrice());

}

}catch (Exception e){

throw e;

}finally {

MyBatisUtils.closeSession(session);

}

}

获取多表关联查询结果

利用LinkedHashMap保存多表关联结果 MyBatis会将每一条记录包装为LinkedHashMap对象 key是字段名 value是字段对应的值 , 字段类型根据表结构进行自动判断 优点: 易于扩展,易于使用 缺点: 太过灵活,无法进行编译时检查 goods.xml中

select g.*,c.category_name from t_goods g, t_category c

where g.category_id = c.category_id

测试： MybatisTestor.java中

@Test

public void testSelectGoodsMap() throws Exception{

SqlSession session = null;

try{

session = MyBatisUtils.openSession();

List

for(Map g:list){

System.out.println(g);

}

}catch (Exception e){

throw e;

}finally {

MyBatisUtils.closeSession(session);

}

}

ResultMap结果映射

ResultMap可以将查询结果映射为复杂类型的Java对象ResultMap适用于Java对象保存多表关联结果ResultMap支持对象关联查询等高级特性

创建Category类

package com.mybatis.entity;

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;

}

}

创建GoodsDTO类

package com.mybatis.dto;

import com.mybatis.entity.Category;

import com.mybatis.entity.Goods;

public class GoodsDTO {

private Goods goods = new Goods();

private Category category = new Category();

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;

}

}

goods.xml中

select g.* , c.*,'1' as test from t_goods g , t_category c

where g.category_id = c.category_id

测试： MybatisTestor.java中

@Test

public void testSelectGoodsDTO() throws Exception{

SqlSession session = null;

try{

session = MyBatisUtils.openSession();

List list= session.selectList("goods.selectGoodsDTO");

for(GoodsDTO g:list){

System.out.println(g.getGoods().getTitle());

}

}catch (Exception e){

throw e;

}finally {

MyBatisUtils.closeSession(session);

}

}

MyBatis数据写入

数据库事务 数据库事务是保证数据操作完整性的基础 数据先写入日志中后同时写入数据表 如果有数据执行不成功则发生回滚 要么全部成功要么全部回滚

MyBatis写操作包含三种

插入-更新-删除-

插入-

INSERT INTO 'babytun'.'t goods'( 'title', 'sub_title', 'original_cost' , 'current price')

VALUES ( #{title}, #{subTitle}, #{originalCost}, #{currentPrice})

select last insert id()

插入数据 goods.xml

INSERT INTO t_goods(title, sub_title, original_cost, current_price, discount, is_free_delivery, category_id)

VALUES (#{title} , #{subTitle} , #{originalCost}, #{currentPrice}, #{discount}, #{isFreeDelivery}, #{categoryId})

select last_insert_id()

MybatisTestor.java

@Test

public void testInsert() throws Exception{

SqlSession session = null;

try{

session = MyBatisUtils.openSession();

Goods goods = new Goods();

goods.setTitle("测试商品");

goods.setSubTitle("子标题");

goods.setOriginalCost(200f);

goods.setCurrentPrice(100f);

goods.setDiscount(0.5f);

goods.setIsFreeDelivery(1);

goods.setCategoryId(43);

//insert()方法返回值代表本次成功插入的记录总数

int num = session.insert("goods.insert", goods);

session.commit();//提交事务数据

}catch (Exception e){

if(session!=null)

session.rollback();//回滚事务

throw e;

}finally {

MyBatisUtils.closeSession(session);

}

}

测试

selectKey与useGeneratedKeys的区别

selectKey标签用法

insert into sql语句

select last_insert_id()

useGeneratedKeys属性用法

useGeneratedKeys="true"

keyProperty="goodsId"

keyColumn="goods_id">

INSERT INTO SQL语句

二者区别-显示与隐示

selectKey标签需要明确编写获取最新主键的SQL语句useGeneratedKeys属性会自动根据驱动生成对应SQL语句selectKey适用与所有的关系型数据库useGeneratedKeys只支持"自增主键"类型的数据库

selectKey标签是通用方案，适用与所有数据库，但编写麻烦 useGeneratedKeys属性只支持“自增主键”数据库，使用简单

更新与删除操作

更新-

UPDATE t_goods

SET 'title' = #{title}

WHERE 'goods_id'=#{goodsId}

删除-

delete from t_goods where goods_id = #{value}

更新操作 goods.xml中

UPDATE 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}

MybatisTestor.java中

@Test

public void testUpdate() throws Exception{

SqlSession session = null;

try{

session = MyBatisUtils.openSession();

Goods goods = session.selectOne("goods.selectById", 500);

goods.setTitle("更新测试");

int num=session.update("goods.update",goods);

session.commit();//提交事务数据

}catch (Exception e){

if(session!=null)

session.rollback();//回滚事务

throw e;

}finally {

MyBatisUtils.closeSession(session);

}

}

测试结果 删除操作 goods.xml

delete from t_goods where goods_id = #{value}

MybatisTestor.java中

@Test

public void testDelete() throws Exception{

SqlSession session = null;

try{

session = MyBatisUtils.openSession();

int num=session.delete("goods.delete",739);

session.commit();//提交事务数据

}catch (Exception e){

if(session!=null)

session.rollback();//回滚事务

throw e;

}finally {

MyBatisUtils.closeSession(session);

}

}

测试结果

好文阅读

 您阅读本篇文章共花了：