maven搭建專案--實現mybatis增刪改差、一對多及一對一關係
阿新 • • 發佈：2019-02-07
1、建立maven專案
2、配置pom.xml，引入相應的jar包
<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 3、在Eclipse安裝mybatis generator自動生成工具
（1）下載mybatis生成架包工具MyBatis_Generator_1.3.1.zip，解壓jar包把features、plugins資料夾下的架包分別拷貝到eclipse安裝目錄下的features、plugins資料夾（複製和替換eclipse原有的這兩個資料夾）。然後重啟eclipse。
（2）在pom.xml中新增mybatis-generator-maven-plugin的jar包
<!-- mybatis generator自動生成jar包 -->
<dependency>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<type>maven-plugin</type>
</dependency>（3）配置generator.xml檔案
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN" "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
<!-- 資料庫驅動包位置 (改成自己存放的具體路徑) -->
<classPathEntry location="D:/softwaretools/someNeeded/mysql-connector-java-5.1.34.jar" />
<context id="DB2Tables" targetRuntime="MyBatis3">
<commentGenerator>
<property name="suppressAllComments" value="true" />
</commentGenerator>
<!-- 資料庫連結URL、使用者名稱、密碼 -->
<jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://localhost:3306/student" userId="root" password="root"> </jdbcConnection>
<javaTypeResolver>
<property name="forceBigDecimals" value="false" />
</javaTypeResolver>
<!-- 生成模型的包名和位置 ，targetPackage：包名，targetProject：你的專案名-->
<javaModelGenerator targetPackage="com.danni.model.entity" targetProject="mybatis-maven">
<property name="enableSubPackages" value="true" />
<property name="trimStrings" value="true" />
</javaModelGenerator>
<!-- 生成的對映檔案包名和位置 -->
<sqlMapGenerator targetPackage="com.danni.model.dao" targetProject="mybatis-maven">
<property name="enableSubPackages" value="true" />
</sqlMapGenerator>
<!-- 生成DAO的包名和位置 -->
<javaClientGenerator type="XMLMAPPER" targetPackage="com.danni.model.dao" targetProject="mybatis-maven">
<property name="enableSubPackages" value="true" />
</javaClientGenerator>
<!-- tableName：資料庫中的表名，domainObjectName：表名對應的類名 -->
<table tableName="admins" domainObjectName="Admins" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false" />
<table tableName="employee" domainObjectName="Employee" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false" />
<table tableName="department" domainObjectName="Department" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false" />
</context>
</generatorConfiguration>（4）選中generator.xml，右鍵選擇Generate MyBatis/IBATIS Artifacts，點選即可生成程式碼檔案。
4、編寫資料庫和日誌的properties檔案
jdbc.properties
driver = com.mysql.jdbc.Driver
url = jdbc:mysql:///student?characterEncoding=utf-8
username = root
password = rootlog4j.properties
log4j.rootLogger=DEBUG, Console
#Console
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
#log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n
log4j.logger.java.sql.ResultSet=INFO
log4j.logger.org.apache=INFO
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG 5、配置mybatis配置檔案：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>
<!-- 載入資料庫的properties檔案 -->
<properties resource="jdbc.properties"/>
<settings>
<setting name="logImpl" value="LOG4J" />
<!-- 開啟二級快取(總開關) -->
<setting name="cacheEnabled" value="true"/>
</settings>
<!-- 配置別名 -->
<typeAliases>
<typeAlias type="com.danni.model.entity.Admins" alias="Admins"/>
<typeAlias type="com.danni.model.entity.Department" alias="Department"/>
<typeAlias type="com.danni.model.entity.Employee" alias="Employee"/>
</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="com/danni/model/dao/AdminsMapper.xml" />
<mapper resource="com/danni/model/dao/DepartmentMapper.xml" />
<mapper resource="com/danni/model/dao/EmployeeMapper.xml" />
</mappers>
</configuration>6、建立工具類來獲取SqlSession
package org.danni.utils;
import java.io.IOException;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class SqlSessionUtils {
private static SqlSessionFactory sqlSessionFactory;
private static SqlSession sqlSession;
public static SqlSessionFactory openSessionFactory() {
if (sqlSessionFactory == null) {
try {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
return sqlSessionFactory;
}
public static SqlSession openSession() {
if (sqlSession == null) {
sqlSession = openSessionFactory().openSession();
}
return sqlSession;
}
}
7、建立AdminsTest測試類來了解mybatis用法
AdminsTest：記得要提交事務
package com.danni.test;
import org.apache.ibatis.session.SqlSession;
import org.danni.utils.SqlSessionUtils;
import com.danni.model.dao.AdminsMapper;
import com.danni.model.entity.Admins;
public class AdminsTest {
// 增
public static void add() {
// 開啟sqlSession
SqlSession sqlSession = SqlSessionUtils.openSession();
Admins admins = new Admins();
admins.setAdminname("小紅");
admins.setAdminpwd("123");
// 法一：直接呼叫
Integer row = sqlSession.insert("com.danni.model.dao.AdminsMapper.insert", admins);
sqlSession.commit();
System.out.println(row);
}
// 增
public static void add1() {
// 開啟sqlSession
SqlSession sqlSession = SqlSessionUtils.openSession();
Admins admins = new Admins();
admins.setAdminname("小白");
admins.setAdminpwd("123");
// 法二：採用介面代理的方式(然後就直接呼叫介面中相應的方法，他會去實現類也就對應的xml中找對應的方法)
AdminsMapper adminsDao = sqlSession.getMapper(AdminsMapper.class);
Integer row = adminsDao.insert(admins);
// 提交事務
sqlSession.commit();
System.out.println(row);
}
// update
public static void update() {
SqlSession sqlSession = SqlSessionUtils.openSession();
// 因為update，因此需要設定id，根據id進行更新
Admins admins = new Admins();
admins.setAdminname("呵呵");
admins.setAdminpwd("123");
admins.setAid(11);
AdminsMapper adminsDao = sqlSession.getMapper(AdminsMapper.class);
adminsDao.updateByPrimaryKey(admins);
// 提交事務
sqlSession.commit();
}
public static void main(String[] args) {
// add();
// add1();
update();
}
}8、一對一關係
（1）修改Employee.java檔案：
public class Employee implements Serializable{
private Integer eid;
private String ename;
private String esex;
private Department department;
//get和set方法不貼出來了，自己補全
}（2）修改EmployeeMapper.xml檔案：需要把sql語句中對應的物件中原來的did全部換成department.did
<?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="com.danni.model.dao.EmployeeMapper">
<resultMap id="BaseResultMap" type="com.danni.model.entity.Employee">
<id column="eid" jdbcType="INTEGER" property="eid" />
<result column="ename" jdbcType="VARCHAR" property="ename" />
<result column="esex" jdbcType="VARCHAR" property="esex" />
<!-- select：去department中根據id查詢，column：表明關聯的依據 -->
<association property="department" column="did" select="com.danni.model.dao.DepartmentMapper.selectByPrimaryKey"></association>
</resultMap>
<sql id="Base_Column_List">
eid, ename, esex, did
</sql>
<select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from employee
where eid = #{eid,jdbcType=INTEGER}
</select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
delete from employee
where eid = #{eid,jdbcType=INTEGER}
</delete>
<insert id="insert" parameterType="com.danni.model.entity.Employee">
insert into employee (eid, ename, esex,
did)
values (#{eid,jdbcType=INTEGER}, #{ename,jdbcType=VARCHAR}, #{esex,jdbcType=VARCHAR},
#{department.did,jdbcType=INTEGER})
</insert>
<insert id="insertSelective" parameterType="com.danni.model.entity.Employee">
insert into employee
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="eid != null">
eid,
</if>
<if test="ename != null">
ename,
</if>
<if test="esex != null">
esex,
</if>
<if test="did != null">
did,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="eid != null">
#{eid,jdbcType=INTEGER},
</if>
<if test="ename != null">
#{ename,jdbcType=VARCHAR},
</if>
<if test="esex != null">
#{esex,jdbcType=VARCHAR},
</if>
<if test="did != null">
#{department.did,jdbcType=INTEGER},
</if>
</trim>
</insert>
<update id="updateByPrimaryKeySelective" parameterType="com.danni.model.entity.Employee">
update employee
<set>
<if test="ename != null">
ename = #{ename,jdbcType=VARCHAR},
</if>
<if test="esex != null">
esex = #{esex,jdbcType=VARCHAR},
</if>
<if test="did != null">
did = #{department.did,jdbcType=INTEGER},
</if>
</set>
where eid = #{eid,jdbcType=INTEGER}
</update>
<update id="updateByPrimaryKey" parameterType="com.danni.model.entity.Employee">
update employee
set ename = #{ename,jdbcType=VARCHAR},
esex = #{esex,jdbcType=VARCHAR},
did = #{department.did,jdbcType=INTEGER}
where eid = #{eid,jdbcType=INTEGER}
</update>
</mapper>（3）測試類EmpDepartTest：
public class EmpDepartTest {
// 查詢職工，會通知查詢出職工在的部門物件
public static void queryEmpByDid() {
SqlSession sqlSession = SqlSessionUtils.openSession();
EmployeeMapper employeeDao = sqlSession.getMapper(EmployeeMapper.class);
Employee employee = employeeDao.selectByPrimaryKey(10);
System.out.println(employee.getEname() + " " + employee.getDepartment().getDepartname());
}
public static void main(String[] args) {
queryEmpByDid();
}
}9、多對一關係
一個部門對應多個員工。因此在部門中增加員工集合作為它的屬性
（1）修改Department.java
public class Department implements Serializable{
private Integer did;
private String departname;
private List<Employee> empLists;
//get和set方法自己補，我就不貼出來了
}（2）修改DepartmentMapper.xml的結果對映
<resultMap id="BaseResultMap" type="com.danni.model.entity.Department">
<id column="did" jdbcType="INTEGER" property="did" />
<result column="departname" jdbcType="VARCHAR" property="departname" />
<!-- 一對多關係:去員工中查詢did為某個值的員工物件 -->
<collection property="empLists" column="did" select="com.danni.model.dao.EmployeeMapper.selectByDid"></collection>
</resultMap>（2）員工中新增selectByDid方法
EmployeeMapper.java：先去介面中新增對應方法宣告
EmployeeMapper.xml：增加對應的實現
<select id="selectByDid" parameterType="int" resultType="BaseResultMap">
select * from employee where did = #{did}
</select>（3）編寫測試類中對應方法
// 查詢某個部門的全部員工(查詢部門的時候同時會把屬於這個部門的所欲員工集合查詢出來，就達到了一對多的關係)
public static void queryDepartEmps() {
SqlSession sqlSession = SqlSessionUtils.openSession();
DepartmentMapper departmentMapper = sqlSession.getMapper(DepartmentMapper.class);
Department department = departmentMapper.selectByPrimaryKey(3);
System.out.println(department.getEmpLists().size());
}
public static void main(String[] args) {
// queryEmpByDid();
queryDepartEmps();
}10、分頁
（1）在EmployeeMapper.java介面中新增對應方法宣告
List<Employee> queryByPage(Map<String, Integer> map);（2）在EmployeeMapper.xml中新增實現方法
注意：這裡我傳遞的是一個map集合，集合的鍵的名字必須和測試類中map中的見得名字要對應相等
<select id="queryByPage" parameterType="map" resultMap="BaseResultMap">
select * from employee limit #{startNum},#{pageSize}
</select>（3）新增對應測試類
// 分頁(把頁碼作為引數)
public static void queryByPage(Integer pageIndex) {
SqlSession sqlSession = SqlSessionUtils.openSession();
EmployeeMapper employeeMapper = sqlSession.getMapper(EmployeeMapper.class);
Map<String, Integer> map = new HashMap<String, Integer>();
map.put("startNum", (pageIndex-1)*3); //limit的第一個引數
map.put("pageSize", 3); //limit的第二個引數
List<Employee> empLists = employeeMapper.queryByPage(map);
System.out.println("");
}
public static void main(String[] args) {
// queryEmpByDid();
// queryDepartEmps();
queryByPage(2);
}11、排序，$符號的使用
（1）首先在介面中定義方法
List<Employee> queryBySort(String name);（2）在實現類中新增相應的實現方法
<!-- 注意：這裡一定要使用value，他是預設的，不然就找不到 -->
<select id="queryBySort" parameterType="string" resultMap="BaseResultMap">
select * from employee order by ${value}
</select>（3）新增對應測試類
// 排序
public static void queryBySort() {
SqlSession sqlSession = SqlSessionUtils.openSession();
EmployeeMapper employeeMapper = sqlSession.getMapper(EmployeeMapper.class);
List<Employee> empLists = employeeMapper.queryBySort("ename");
System.out.println("");
}
public static void main(String[] args) {
// queryEmpByDid();
// queryDepartEmps();
// queryByPage(2);
queryBySort();
}12、動態sql
<insert id="insertSelective" parameterType="com.danni.model.entity.Employee">
insert into employee
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="eid != null">
eid,
</if>
<if test="ename != null">
ename,
</if>
<if test="esex != null">
esex,
</if>
<if test="did != null">
did,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="eid != null">
#{eid,jdbcType=INTEGER},
</if>
<if test="ename != null">
#{ename,jdbcType=VARCHAR},
</if>
<if test="esex != null">
#{esex,jdbcType=VARCHAR},
</if>
<if test="did != null">
#{department.did,jdbcType=INTEGER},
</if>
</trim>
</insert>update:
<update id="updateByPrimaryKeySelective" parameterType="com.danni.model.entity.Employee">
update employee
<set>
<if test="ename != null">
ename = #{ename,jdbcType=VARCHAR},
</if>
<if test="esex != null">
esex = #{esex,jdbcType=VARCHAR},
</if>
<if test="did != null">
did = #{department.did,jdbcType=INTEGER},
</if>
</set>
where eid = #{eid,jdbcType=INTEGER}
</update>