SSM笔记-数据库增删查改

1、步骤：
     ①创建Bean类，及对应的Mapper接口类及其mapper映射文件
     ②创建及配置Mybatis配置文件，配置数据库信息
     ③为Mapper接口类创建增删查改对应的方法
     ④在mapper映射文件中，使用<insert><select><delete><update>标签配置增删查改的sql
     ⑤在调用的时候创建SqlSessionFactory和SqlSession对象
     ⑥创建Bean对象，调用对应的增删查改方法

2、注意事项：
     ①如果数据库支持自动生成主键，则insert的标签可以使用useGeneratedKeys=“true"并且使用keyProperty指定bean中对应的主键属性名
     ②如果数据库不支持自动生成主键，则insert标签里面需要使用selectKey标签，把获取seq的sql放到selectKey标签里面，在该标签里面要使用keyProperty指定bean中对应的主键属性名，还可以用order属性设置"BEFORE”/“AFTER”，设定是先获取主键值还是先运行插入数据再获取主键

3、mybatis.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>

	<properties resource="dbConfig.properties"></properties>
	
	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC" />
			<dataSource type="POOLED">
				<property name="driver" value="${jdbc.driver}" />
				<property name="url" value="${jdbc.url}" />
				<property name="username" value="${jdbc.username}" />
				<property name="password" value="${jdbc.password}" />
			</dataSource>
		</environment>
	</environments>
	
	<mappers>
		<mapper resource="InfoMapper.xml" />
	</mappers>
</configuration>

4、InfoMapper.xml

<?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.demo.ssmtest.InfoMapper">

	<insert id="add" parameterType="com.demo.ssmtest.Info" useGeneratedKeys="true" keyProperty="id">
		insert into info (name,password,description) values (#{name},#{password},#{description})
	</insert>
	<delete id="deleteById">
		delete from info where id=#{id}
	</delete>
	<select id="getById"  resultType="com.demo.ssmtest.Info">
		select * from info where id = #{id}
	</select>
	<update id="updateById">
		update info set name=#{name},password=#{password},description=#{description} where id=#{id}
	</update>
</mapper>

5、dbConfig.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost/mybatis
jdbc.username=root
jdbc.password=

6、Info.java

package com.demo.ssmtest;


public class Info {

	Integer id;
	String name;
	String password;
	String description;
	
	public Info() {
		super();
	}
	
	public Info(Integer id, String name, String password, String description) {
		super();
		this.id = id;
		this.name = name;
		this.password = password;
		this.description = description;
	}

	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}
	@Override
	public String toString() {
		return "Info [id=" + id + ", name=" + name + ", password=" + password + ", description=" + description + "]";
	}
}

7、InfoMapper.java

package com.demo.ssmtest;

public interface InfoMapper {

	public Integer add(Info info);

	public Integer deleteById(int id);
	
	public Info getById(int id);
	
	public Integer updateById(Info info);
	
}

8、TestMain.java

package com.demo.ssmtest;

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 TestMain {
	
	
	public static void main(String[] args) throws Exception {
		test();
	}

	public static void test() throws Exception {

		String resource = "mybatis.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
		
		SqlSession openSession = sqlSessionFactory.openSession();
		try {
			//增
			InfoMapper addMapper = openSession.getMapper(InfoMapper.class);
			Info add_Info = new Info(null,"nameNew","qweqwe","dddddddd");
			int add_Index = addMapper.add(add_Info);
			System.out.println(add_Index);
			
			//删
			InfoMapper delMapper = openSession.getMapper(InfoMapper.class);
			int del_Index = delMapper.deleteById(5);
			System.out.println(del_Index);
			
			//查
			InfoMapper queryMapper = openSession.getMapper(InfoMapper.class);
			Info info = queryMapper.getById(1);
			System.out.println(info);
			
			//改
			InfoMapper updateMapper = openSession.getMapper(InfoMapper.class);
			Info update_Info = new Info(4,"nameNewUpdate","qweqweUpdate","ddddddddUpdate");
			int update_Index = updateMapper.updateById(update_Info);
			System.out.println(update_Index);
			
		} finally {
			openSession.close();
		}

	}
}

9、项目目录

10、demo
https://download.youkuaiyun.com/download/qq_22778717/10712450