MyBatis入门案列

MyBatis入门案列

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开发Mybatis程序的步骤：

1、配置mybatis
conf.xml: 配置数据库信息 和 需要加载的映射文件

２、表 - 类
映射文件xxMapper.xml: 增删改查标签

３、测试类:
session.selectOne(“需要查询的SQL的namespace.id”, “SQL的参数值”);

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运行环境：数据库 Oracle19c，Java8，数据库连接驱动 ojdbc8.jar，mybatis-3.4.6.jar 、eclipse

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具体实现类：

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１、建表：

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CREATE TABLE person(id NUMBER,  name VARCHAR2(20), age NUMBER);

INSERT　into person  VALUES(1,'zs', 23);

commit;

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２、配置mybatis

conf.xml:配置数据库信息 和 需要加载的映射文件

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DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC" />
			<dataSource type="POOLED">
				
				<property name="driver" value="oracle.jdbc.OracleDriver" />
				<property name="url" value="jdbc:oracle:thin:@127.0.0.1:1521:ORCL" />
				<property name="username" value="scott" />
				<property name="password" value="tiger" />
			dataSource>
		environment>
	environments>
	<mappers>
		
		<mapper resource="org/lanqiao/entity/personMapper.xml" />
	mappers>
configuration>

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３、表 - 类：新建与数据库对应的Bean类，同时构建映射文件。

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package org.lanqiao.entity;

public class Person {
	private int id;
	private String name;
	private int age;

	public Person() {
	}

	public Person(int id, String name, int age) {
		super();
		this.id = id;
		this.name = name;
		this.age = age;
	}

	// getter and setter
	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 int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	@Override
	public String toString() {
		return "Person [id=" + id + ", name=" + name + ", age=" + age + "]";
	}

}

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映射文件personMapper.xml:增删改查标签

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DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.lanqiao.entity.personMapper">

	<select id="queryPersonById" resultType="org.lanqiao.entity.Person" parameterType="int">
		select * from person where id = #{id}
	select>

mapper>

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４、编写测试类TestMybatis.java：

session.selectOne(“需要查询的SQL的namespace.id”, “SQL的参数值”);

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package org.lanqiao.entity;

import java.io.IOException;
import java.io.Reader;

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 TestMybatis {
	public static void main(String[] args) throws IOException {
		// 加载myBatis配置文件（为了访问数据库）
		Reader reader = Resources.getResourceAsReader("conf.xml");
		SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

		// SqlSessionFactory connection
		SqlSession session = sessionFactory.openSession();
		String statement = "org.lanqiao.entity.personMapper.queryPersonById";
		Person person = session.selectOne(statement,1);
		System.out.println(person);
		session.close();

	}

}

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５、执行结果

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６、小结

1. parameterType=“int”> 的 int 对应 select 语句的 #{id}

select * from person where id = #{id}

2. namespace：映射文件的路径

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