MyBatis的数据库操作入门（一）

旧城等待， 2021-09-27 10:36 309阅读 0赞

数据库代码

CREATE DATABASE /*!32312 IF NOT EXISTS*/`smbms` /*!40100 DEFAULT CHARACTER SET utf8 COLLATE utf8_unicode_ci */;
    
    
    USE `smbms`;
    
    
    
    CREATE TABLE `smbms_user` (
      `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键ID',
      `userCode` varchar(15) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '用户编码',
      `userName` varchar(15) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '用户名称',
      `userPassword` varchar(15) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '用户密码',
      `gender` int(10) DEFAULT NULL COMMENT '性别（1:女、 2:男）',
      `birthday` date DEFAULT NULL COMMENT '出生日期',
      `phone` varchar(15) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '手机',
      `address` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '地址',
      `userRole` int(10) DEFAULT NULL COMMENT '用户角色（取自角色表-角色id）',
      `createdBy` bigint(20) DEFAULT NULL COMMENT '创建者（userId）',
      `creationDate` datetime DEFAULT NULL COMMENT '创建时间',
      `modifyBy` bigint(20) DEFAULT NULL COMMENT '更新者（userId）',
      `modifyDate` datetime DEFAULT NULL COMMENT '更新时间',
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=16 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
    
    
    
    
    insert  into `smbms_user`(`id`,`userCode`,`userName`,`userPassword`,`gender`,`birthday`,`phone`,`address`,`userRole`,`createdBy`,`creationDate`,`modifyBy`,`modifyDate`) values (1,'admin','系统管理员','1234567',1,'1983-10-10','13688889999','北京市海淀区成府路207号',1,1,'2013-03-21 16:52:07',NULL,NULL),(2,'liming','李明','0000000',2,'1983-12-10','13688884457','北京市东城区前门东大街9号',2,1,'0000-00-00 00:00:00',NULL,NULL),(5,'hanlubiao','韩路彪','0000000',2,'1984-06-05','18567542321','北京市朝阳区北辰中心12号',2,1,'2014-12-31 19:52:09',NULL,NULL),(6,'zhanghua','张华','0000000',1,'1983-06-15','13544561111','北京市海淀区学院路61号',3,1,'2013-02-11 10:51:17',NULL,NULL),(7,'wangyang','王洋','0000000',2,'1982-12-31','13444561124','北京市海淀区西二旗辉煌国际16层',3,1,'2014-06-11 19:09:07',NULL,NULL),(8,'zhaoyan','赵燕','0000000',1,'1986-03-07','18098764545','北京市海淀区回龙观小区10号楼',3,1,'2016-04-21 13:54:07',NULL,NULL),(10,'sunlei','孙磊','0000000',2,'1981-01-04','13387676765','北京市朝阳区管庄新月小区12楼',3,1,'2015-05-06 10:52:07',NULL,NULL),(11,'sunxing','孙兴','0000000',2,'1978-03-12','13367890900','北京市朝阳区建国门南大街10号',3,1,'2016-11-09 16:51:17',NULL,NULL),(12,'zhangchen','张晨','0000000',1,'1986-03-28','18098765434','朝阳区管庄路口北柏林爱乐三期13号楼',3,1,'2016-08-09 05:52:37',1,'2016-04-14 14:15:36'),(13,'dengchao','邓超','0000000',2,'1981-11-04','13689674534','北京市海淀区北航家属院10号楼',3,1,'2016-07-11 08:02:47',NULL,NULL),(14,'yangguo','杨过','0000000',2,'1980-01-01','13388886623','北京市朝阳区北苑家园茉莉园20号楼',3,1,'2015-02-01 03:52:07',NULL,NULL),(15,'zhaomin','赵敏','0000000',1,'1987-12-04','18099897657','北京市昌平区天通苑3区12号楼',2,1,'2015-09-12 12:02:12',NULL,NULL);

数据库弄好了，顺便改下

UPDATE smbms\_user SET creationDate=NOW() WHERE ID=2;

使用Myeclipse创建一个Java project，Web project也行

![70][]

然后新建一个文件夹lib

![70 1][]

导入MyBatis的jar包,放到lib文件夹

![70 2][]

（第一个是日志，第三个是源文件，第四个是数据库链接要用的）

然后选中这些jar包，右键

![70 3][]

完成后会成为这样

![70 4][]

编写实体类User.java

在src新建一个包，取包名字cn.bdqn.pojo

![70 5][]

新建一个java类，名字为User.java

（toString方法的快捷键：alt+shift+s   s，然后勾选你要生成的确定就行了）

（get/set方法的快捷键：alt+shift+r ,然后选择你要生成的确定就行了）

（无参数的构造函数:alt+shift+c）

(带参数的构造函数:alt+shift+o,选择你要生成的就行了)

从上面几个我们可以看到，alt+shift后要点击什么呢？是看下划线决定的

![70 6][]

回到正题，实体类代码如下：

package cn.bdqn.pojo;
    
    import java.util.Date;
    
    public class User {
    	/*CREATE TABLE `smbms_user` (
    			  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键ID',
    			  `userCode` varchar(15) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '用户编码',
    			  `userName` varchar(15) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '用户名称',
    			  `userPassword` varchar(15) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '用户密码',
    			  `gender` int(10) DEFAULT NULL COMMENT '性别（1:女、 2:男）',
    			  `birthday` date DEFAULT NULL COMMENT '出生日期',
    			  `phone` varchar(15) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '手机',
    			  `address` varchar(30) COLLATE utf8_unicode_ci DEFAULT NULL COMMENT '地址',
    			  `userRole` int(10) DEFAULT NULL COMMENT '用户角色（取自角色表-角色id）',
    			  `createdBy` bigint(20) DEFAULT NULL COMMENT '创建者（userId）',
    			  `creationDate` datetime DEFAULT NULL COMMENT '创建时间',
    			  `modifyBy` bigint(20) DEFAULT NULL COMMENT '更新者（userId）',
    			  `modifyDate` datetime DEFAULT NULL COMMENT '更新时间',
    			  PRIMARY KEY (`id`)
    			) ENGINE=InnoDB AUTO_INCREMENT=16 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;*/
    
    	private Long id;
    	private String userCode;
    	private String userName;
    	private String userPassword;
    	private Integer gender;
    	private String phone;
    	private String address;
    	private Date birthday;
    	private Integer userRole;
    	private Integer createdBy;
    	private Date creationDate;
    	private Integer modifyBy;
    	private Date modifyDate;
    	@Override
    	public String toString() {
    		return "User [address=" + address + ", birthday=" + birthday
    				+ ", createdBy=" + createdBy + ", creationDate=" + creationDate
    				+ ", gender=" + gender + ", id=" + id + ", modifyBy="
    				+ modifyBy + ", modifyDate=" + modifyDate + ", phone=" + phone
    				+ ", userCode=" + userCode + ", userName=" + userName
    				+ ", userPassword=" + userPassword + ", userRole=" + userRole
    				+ "]";
    	}
    	public User() {
    		super();
    		// TODO Auto-generated constructor stub
    	}
    	public User(Long id, String userCode, String userName, String userPassword,
    			Integer gender, String phone, String address, Date birthday,
    			Integer userRole, Integer createdBy, Date creationDate,
    			Integer modifyBy, Date modifyDate) {
    		super();
    		this.id = id;
    		this.userCode = userCode;
    		this.userName = userName;
    		this.userPassword = userPassword;
    		this.gender = gender;
    		this.phone = phone;
    		this.address = address;
    		this.birthday = birthday;
    		this.userRole = userRole;
    		this.createdBy = createdBy;
    		this.creationDate = creationDate;
    		this.modifyBy = modifyBy;
    		this.modifyDate = modifyDate;
    	}
    	public Long getId() {
    		return id;
    	}
    	public void setId(Long id) {
    		this.id = id;
    	}
    	public String getUserCode() {
    		return userCode;
    	}
    	public void setUserCode(String userCode) {
    		this.userCode = userCode;
    	}
    	public String getUserName() {
    		return userName;
    	}
    	public void setUserName(String userName) {
    		this.userName = userName;
    	}
    	public String getUserPassword() {
    		return userPassword;
    	}
    	public void setUserPassword(String userPassword) {
    		this.userPassword = userPassword;
    	}
    	public Integer getGender() {
    		return gender;
    	}
    	public void setGender(Integer gender) {
    		this.gender = gender;
    	}
    	public String getPhone() {
    		return phone;
    	}
    	public void setPhone(String phone) {
    		this.phone = phone;
    	}
    	public String getAddress() {
    		return address;
    	}
    	public void setAddress(String address) {
    		this.address = address;
    	}
    	public Date getBirthday() {
    		return birthday;
    	}
    	public void setBirthday(Date birthday) {
    		this.birthday = birthday;
    	}
    	public Integer getUserRole() {
    		return userRole;
    	}
    	public void setUserRole(Integer userRole) {
    		this.userRole = userRole;
    	}
    	public Integer getCreatedBy() {
    		return createdBy;
    	}
    	public void setCreatedBy(Integer createdBy) {
    		this.createdBy = createdBy;
    	}
    	public Date getCreationDate() {
    		return creationDate;
    	}
    	public void setCreationDate(Date creationDate) {
    		this.creationDate = creationDate;
    	}
    	public Integer getModifyBy() {
    		return modifyBy;
    	}
    	public void setModifyBy(Integer modifyBy) {
    		this.modifyBy = modifyBy;
    	}
    	public Date getModifyDate() {
    		return modifyDate;
    	}
    	public void setModifyDate(Date modifyDate) {
    		this.modifyDate = modifyDate;
    	}
    }

编写SQL映射文件UserMapper.xml

在src新建一个包，包名字为cn.bdqn.dao,新建一个file文件，名字为UserMapper.xml

![70 7][]

代码可以从帮助文档找（后面有说如何找）（入门-探究已映射的 SQL 语句）

![70 8][]

我们根据需要，改为

<?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="cn.bdqn.dao.UserMapper">
    
    	<select id="count" resultType="int">
    		select count(1) from smbms_user
    	</select>
    </mapper>

命名空间namespace里面是sql的映射文件，可以右键那个xml文件，copy qualified name,复制进去，.xml和src前面都不要，还有/要变为.

这里可以写很多select文件，但是id要不一样，这里的id我设为count,id是唯一标识符

注意返回类型是什么，在这里返回是int类型（记录数）

sql语句的意思是查询smbms\_user表的记录数，平时我们用的是\*，不过1的速度更快

接下来要做的：创建MyBatis配置文件mybatis-config.xml，配置数据库信息

在项目new一个Source Folder的文件夹，命名为resource，这个文件夹在程序编译的时候也会编译进去

![70 9][]

然后在resource文件夹创建MyBatis配置文件mybatis-config.xml

方法一：点这里

![70 10][]

然后在resource文件夹右键new的时候你可以看到

![70 11][]

创建这个，名字为mybatis-config.xml

方法二：我按方法一还是没有看到

点击resource文件夹，右键，new,other

![70 12][]

输入xml，你也可以看到

![70 13][]

直接点击，输入名字，确定就行

![70 14][]

怎么写这个文件？？？

百度MyBatis帮助文档

![70 15][]

找到入门，往下拉

把这一段复制进去

![70 16][]

然后在resource文件夹new两个File文件夹，名字分别是database.properties和log4j.properties

![70 17][]

database.properties怎么写？？

jdbc.driver=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://127.0.0.1:3306/smbms?useUnicode=true&characterEncoding=utf-8
    jdbc.user=root
    jdbc.password=12345678

注意了：1：如果你是连接别人的mysql数据库，那么ip地址要和它的一致，可能就不是127.0.0.1了

2：你的密码要和你的数据库密码一致

3：因为你写了jdbc.，那么你在mybatis-config.xml也要改为相应的，当然你也可以删掉database.properties的jdbc.

<?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="database.properties"></properties>
    	
    	<settings>
    		<setting name="logImpl" value="LOG4J" />
    	</settings>
    	
    	<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="${jdbc.user}" />
    				<property name="password" value="${jdbc.password}" />
    			</dataSource>
    		</environment>
    	</environments>
    	<mappers>
    		<mapper resource="cn/bdqn/dao/UserMapper.xml" />
    	</mappers>
    </configuration>

在这里我的value就改为了相应的了

在这里还要写入1：引入属性文件 2：日志（这个最好写，有错误也能看得舒服点，在帮助文档-日志里面就有代码）3：把映射文件（UserMapper.xml）路径写进去，修改完后，你可以全选-source-format,整理一下代码格式

log4j.properties怎么写？？？

log4j.rootLogger=DEBUG,CONSOLE,file
    #log4j.rootLogger=ERROR,ROLLING_FILE
    log4j.logger.cn.smbms.dao=debug
    log4j.logger.com.ibatis=debug 
    log4j.logger.com.ibatis.common.jdbc.SimpleDataSource=debug 
    log4j.logger.com.ibatis.common.jdbc.ScriptRunner=debug 
    log4j.logger.com.ibatis.sqlmap.engine.impl.SqlMapClientDelegate=debug 
    log4j.logger.java.sql.Connection=debug 
    log4j.logger.java.sql.Statement=debug 
    log4j.logger.java.sql.PreparedStatement=debug 
    log4j.logger.java.sql.ResultSet=debug 
    log4j.logger.org.tuckey.web.filters.urlrewrite.UrlRewriteFilter=debug
    
    ######################################################################################
    # Console Appender  \u65e5\u5fd7\u5728\u63a7\u5236\u8f93\u51fa\u914d\u7f6e
    ######################################################################################
    log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
    log4j.appender.Threshold=error
    log4j.appender.CONSOLE.Target=System.out
    log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
    log4j.appender.CONSOLE.layout.ConversionPattern= [%p] %d %c - %m%n
    
    
    ######################################################################################
    # DailyRolling File  \u6bcf\u5929\u4ea7\u751f\u4e00\u4e2a\u65e5\u5fd7\u6587\u4ef6\uff0c\u6587\u4ef6\u540d\u683c\u5f0f:log2009-09-11
    ######################################################################################
    log4j.appender.file=org.apache.log4j.DailyRollingFileAppender
    log4j.appender.file.DatePattern=yyyy-MM-dd
    log4j.appender.file.File=log.log
    log4j.appender.file.Append=true
    log4j.appender.file.Threshold=error
    log4j.appender.file.layout=org.apache.log4j.PatternLayout
    log4j.appender.file.layout.ConversionPattern=%d{yyyy-M-d HH:mm:ss}%x[%5p](%F:%L) %m%n
    
    
    log4j.logger.com.opensymphony.xwork2=error

最后：编写测试类Test.java，运行输出结果

在src新建一个包cn.bdqn.test，创建一个java类，名字为Test

参考帮助文档（一般都在入门那里）

![70 18][]

改写后

package cn.bdqn.test;
    
    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;
    import org.apache.log4j.Logger;
    
    public class Test {
    	
    	private static Logger logger=Logger.getLogger("Test");
    
    	public static void main(String[] args) {
    		SqlSession session = null;
    		try {
    			//读取核心配置文件mybatis-config.xml
    			String resource = "mybatis-config.xml";
    			InputStream inputStream = Resources.getResourceAsStream(resource);
    			//创建SqlSessionFactory对象，读取配置文件
    			SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    			//创建SqlSession对象
    			session = sqlSessionFactory.openSession();
    			//调用mapper文件进行数据操作
    			int count=session.selectOne("cn.bdqn.dao.UserMapper.count");
    			
    			logger.debug("用户数量是："+count);
    			
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}finally{
    			if(session!=null){
    				session.close();
    			}
    		}
    		
    		
    	}
    }

运行后

\[DEBUG\] 2018-09-29 11:30:48,335 org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.  
/\*使用“类Org.apache.ibatis.log.4j.log4jimpl”适配器初始化的日志记录。\*/

\[DEBUG\] 2018-09-29 11:30:48,335 org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.

\[DEBUG\] 2018-09-29 11:30:48,351 org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.  
/\*数据源有力地关闭/删除了所有连接。\*/

\[DEBUG\] 2018-09-29 11:30:48,351 org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.  
\[DEBUG\] 2018-09-29 11:30:48,351 org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.  
\[DEBUG\] 2018-09-29 11:30:48,351 org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.

\[DEBUG\] 2018-09-29 11:30:48,429 org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection  
/\*打开jdbc连接\*/

\[DEBUG\] 2018-09-29 11:30:48,619 org.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 972765878.  
/\*创建连接972765878。\*/

\[DEBUG\] 2018-09-29 11:30:48,619 cn.bdqn.dao.UserMapper.count - ooo Using Connection \[com.mysql.jdbc.JDBC4Connection@39fb3ab6\]

\[DEBUG\] 2018-09-29 11:30:48,619 cn.bdqn.dao.UserMapper.count - ==>  Preparing: select count(1) from smbms\_user （准备，sql语句）

\[DEBUG\] 2018-09-29 11:30:48,650 cn.bdqn.dao.UserMapper.count - ==> Parameters: (参数)

\[DEBUG\] 2018-09-29 11:30:48,665 Test - 用户数量是:12（结果）

\[DEBUG\] 2018-09-29 11:30:48,665 org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection \[com.mysql.jdbc.JDBC4Connection@39fb3ab6\]

\[DEBUG\] 2018-09-29 11:30:48,665 org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection \[com.mysql.jdbc.JDBC4Connection@39fb3ab6\]  
/\*关闭数据库链接\*/

\[DEBUG\] 2018-09-29 11:30:48,665   
org.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 972765878 to pool.

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MyBatis的数据库操作入门（一）

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