mybatis

案例源码地址：https://download.csdn.net/download/gj_user/12236230

一、架构

SqlMapConfig.xml：mybatis的核心配置文件，主要用于配置数据库连接等一些信息

Mappers.xml：这些配置文件有多个，每一个配置文件对应数据库当中的一张表，主要用于我们数据库中的字段与我们JavaBean实体类中的字段的相互映射，mappers.xml一定要被sqlMapConfig.xml加载

SqlSessionFactory：工厂类，主要用于产生我们的sqlSession

SqlSession：mybatis里面的一个核心的类，用于操作我们的数据库，通过executor来操作我们的数据库，executor是mybaits里面一个封装的对象，不需要我们去处理

MappedStatement：主要作用就是连接我们的输入映射与我们的输出映射，将我们的输入映射拿到之后，去执行我们数据库操作，然后将执行后的结果包装成我们的输出映射

二、案例
创建表sql
CREATE TABLE account (
id int(11) NOT NULL AUTO_INCREMENT,
name varchar(11) NOT NULL COMMENT ‘姓名’,
money double(32) NOT NULL COMMENT ‘金额’,
PRIMARY KEY (id)
) ENGINE=Inno
使用Maven构建项目

添加pom文件

4.0.0

com.mc
Java
1.0-SNAPSHOT

org.bgee.log4jdbc-log4j2 log4jdbc-log4j2-jdbc4.1 1.16 org.slf4j slf4j-api 1.7.13 org.slf4j slf4j-log4j12 1.7.5 log4j log4j 1.2.16 org.mybatis mybatis 3.5.4 junit junit 4.13 test junit junit 4.13 compile mysql mysql-connector-java 5.1.32 org.apache.maven.plugins maven-compiler-plugin 1.8 1.8 UTF-8 为了是信息更加详细加入log4j

三、案例
项目结构

编写sqlMapConfig.xml文件

编写mapper.xml select * from account where id = #{id} javabean；类 public class Account { private int id; private String name; private double money;

public Account() {
// TODO Auto-generated constructor stub
}

public int getId() {
return id;
}

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

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public double getMoney() {
return money;
}

public void setMoney(double money) {
this.money = money;
}

@Override
public String toString() {
return “Account [id=” + id + “, name=” + name + “, money=” + money + “]”;
}

}
测试类
@Test
public void select() throws IOException {
SqlSessionFactoryBuilder b =new SqlSessionFactoryBuilder();
SqlSessionFactory factory=b.build(Resources.getResourceAsStream(“sqlMapConfig.xml”));
SqlSession session = factory.openSession();
Account one = session.selectOne(“select”,1);
System.out.println(one);
}

结果

DEBUG [main] - ==> Preparing: select * from account where id = ?
DEBUG [main] - > Parameters: 1(Integer)
DEBUG [main] - < Total: 1
Account [id=1, name=小明, money=11000.0]

避免重复代码太多可以使用@before注解在每次进行单元测试的时候调用一些重复的初始话代码
SqlSession session;
@Before
public void init() throws IOException {
SqlSessionFactoryBuilder b = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = b.build(Resources.getResourceAsStream(“sqlMapConfig.xml”));
session = factory.openSession();
}
增删改查CRUD
mapper.xml

select * from account where id = #{id} select * from account insert into account values (null ,#{name},#{money}) update account set name=#{name},id=#{id},money=#{money}where id=#{id} delete from account where id=#{id} 进行单元测试 public class MyTest { SqlSession session; @Before public void init() throws IOException { SqlSessionFactoryBuilder b = new SqlSessionFactoryBuilder(); SqlSessionFactory factory = b.build(Resources.getResourceAsStream("sqlMapConfig.xml")); session = factory.openSession(); } @Test public void select() throws IOException { // SqlSessionFactoryBuilder b =new SqlSessionFactoryBuilder(); // SqlSessionFactory factory=b.build(Resources.getResourceAsStream("sqlMapConfig.xml")); // SqlSession session = factory.openSession(); Account one = session.selectOne("select",1); System.out.println(one); }

@Test
public void selectALL() {
//查询name带’小’的
List selectList = session.selectList(“selectall”);
session.close();
System.out.println(selectList);
}

@Test
public void insert() {
Account a=new Account();
a.setName(“jason”);
a.setMoney(1234);
session.insert(“insert”, a);
session.commit();
session.close();
}
@Test
public void update() {
Account a=new Account();
a.setId(2);
a.setMoney(1111);
a.setName(“张三”);
session.update(“update”, a);
session.commit();
session.close();
}

@Test
public void delete() {
Account a=new Account();
a.setId(3);
session.update(“delete”, a);
session.commit();
session.close();
}
}
四、 #{}与${}
#{} ：这个用来做我们的占位符，不带字符串连接功能
$:这个也是用来做占位符，带有字符串连接功能，常用语模糊查询案例：模糊查询@TestpublicvoidselectLike()//查询name{带}^{\prime }{小}^{\prime }的List<Account>selectList=session.selectList("selectLike","j");session.close();System.out.println(selectList);mapper.xml<selectid="selectLike"resultType="com.jdbc.Account">select\ast fromaccountwherenamelike"$