Java的MyBatis框架项目搭建与hellow world示例
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2024-03-12 13:35:32
新建项目（我使用的是maven项目）mybatis-study-01
一、加入mybatis与mysql-connector依赖包到pom文件
新建项目（我使用的是maven项目）mybatis-study-01
一、加入mybatis与mysql-connector依赖包到pom文件
<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>mybatis</groupid> <artifactid>mybatis-study-01</artifactid> <version>0.0.1-snapshot</version> <packaging>jar</packaging> <name>mybatis-01</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceencoding>utf-8</project.build.sourceencoding> </properties> <dependencies> <dependency> <groupid>junit</groupid> <artifactid>junit</artifactid> <version>4.10</version> <scope>test</scope> </dependency> <dependency> <groupid>org.mybatis</groupid> <artifactid>mybatis</artifactid> <version>3.2.3</version> </dependency> <dependency> <groupid>mysql</groupid> <artifactid>mysql-connector-java</artifactid> <version>5.1.27</version> </dependency> </dependencies> </project>
二、创建数据库mybatis-test
新建一张user表用于测试。建表sql如下：
create table `user` ( `id` int(11) not null auto_increment, `password` varchar(255) default null, `user_name` varchar(50) default null, `user_age` int(11) default null, `user_address` varchar(200) default null, primary key (`id`), unique key `username` (`user_name`) ) en
插入一条数据
insert into `user` values ('1', '123131', 'summer', '100', 'shanghai,pudong');
三、在项目中编写pojo对象。
package com.zf.mybatis.pojo;
public class user {
private int id;
private string password ;
private string username;
private string userage;
private string useraddress;
public int getid() {
return id;
}
public void setid(int id) {
this.id = id;
}
public string getusername() {
return username;
}
public void setusername(string username) {
this.username = username;
}
public string getuserage() {
return userage;
}
public void setuserage(string userage) {
this.userage = userage;
}
public string getuseraddress() {
return useraddress;
}
public void setuseraddress(string useraddress) {
this.useraddress = useraddress;
}
public string getpassword() {
return password;
}
public void setpassword(string password) {
this.password = password;
}
}
四、编写pojo对应的映射文件user.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.zf.mybatis.pojo.usermapper">
<!-- 使用sql标签可以将公共的sql提取出来复用 -->
<sql id="queryfields">
id , password , user_name as username , user_age as userage , user_address as useraddress
</sql>
<select id="selectbyid" parametertype="int" resulttype="user">
select
<include refid="queryfields"/>
from `user` where id = #{id}
</select>
<insert id="add" parametertype="user" usegeneratedkeys="true" keyproperty="id" >
insert into `user`
(password , user_name , user_age , user_address)
values(#{password} , #{username} , #{userage} , #{useraddress} )
</insert>
<update id="update" parametertype="user" >
update `user`
set password = #{password} , user_name = #{username}, user_age = #{userage}, user_address = #{useraddress}
where id = #{id}
</update>
<delete id="deletebyid" parametertype="int">
delete from `user` where id = #{id}
</delete>
</mapper>
注意：上面的namespace的值为com.zf.mybatis.pojo.usermapper，可以自定义 ，usermapper不是一个类，不需要存在的。
另外，mybatis会将从数据库查询出来的记录根据列名与pojo中的字段进行匹配， 所以上面的user_name，user_age ,user_address这几个字段都取了别名，跟pojo中的字段相对应。 如果不起别名， 查询出来的对象，这几个字段是没有值的。
五、编写mybatis的配置文件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> <!-- 配置别名 --> <typealiases> <typealias alias="user" type="com.zf.mybatis.pojo.user"/> </typealiases> <!-- 数据库配置信息 --> <environments default="development"> <environment id="development"> <transactionmanager type="jdbc"/> <datasource type="pooled"> <property name="driver" value="com.mysql.jdbc.driver"/> <property name="url" value="jdbc:mysql://127.0.0.1:3306/mybatis-test"/> <property name="username" value="root"/> <property name="password" value="root"/> </datasource> </environment> </environments> <!-- 映射文件 --> <mappers> <mapper resource="conf/user.xml"/> </mappers> </configuration>
在该配置文件中配置了数据库的链接方式，以及注册所有的映射文件，还可以设置mybatis的一些参数。
现在就可以编写测试类了。来测试一下。
package com.zf.mybatis;
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;
import org.junit.before;
import org.junit.test;
import com.zf.mybatis.pojo.user;
public class testmybatis {
private sqlsessionfactory sqlsessionfactory;
private reader reader;
@before
public void init(){
try {
reader = resources.getresourceasreader("mybatis-config.xml");
sqlsessionfactory = new sqlsessionfactorybuilder().build(reader);
} catch (ioexception e) {
e.printstacktrace();
}
}
@test
public void testqueryuser(){
sqlsession session = sqlsessionfactory.opensession();
try {
user user = (user) session.selectone("com.zf.mybatis.pojo.usermapper.selectbyid" ,1);
system.out.println(user.getuseraddress());
system.out.println(user.getusername());
} finally {
session.close();
}
}
@test
public void testinsertuser(){
sqlsession session = sqlsessionfactory.opensession();
try {
user user = new user() ;
user.setusername("abcde");
user.setuserage(15) ;
user.setuseraddress("hangzhou/zhejiang");
user.setpassword("123456");
//返回值是记录条数
int resultcount = session.insert("com.zf.mybatis.pojo.usermapper.add", user );
session.commit() ;
system.out.printf("userid:%d,总记录条数:%d" , user.getid() , resultcount); //获取插入对象的id
} finally {
session.close();
}
}
@test
public void testupdateuser(){
sqlsession session = sqlsessionfactory.opensession();
try {
user user = new user() ;
user.setid(5) ;
user.setusername("updatename");
user.setuserage(101) ;
user.setuseraddress("shenzhen/guangdong");
user.setpassword("000000");
//返回值是修改条数
int updatecount = session.update("com.zf.mybatis.pojo.usermapper.update", user );
session.commit() ;
system.out.printf("修改条数:%d" ,updatecount);
} finally {
session.close();
}
}
@test
public void testdelete(){
sqlsession session = sqlsessionfactory.opensession();
try {
//返回值是删除条数
int deletecount = session.update("com.zf.mybatis.pojo.usermapper.deletebyid", 4 );
session.commit() ;
system.out.printf("删除条数:%d" ,deletecount );
} finally {
session.close();
}
}
}
运行testqueryuser结果如下：
shanghai,pudong summer
到此，一个mybatis的helloworld类型的小程序就出来了。
ps：mybaits配置文件报错解决
mybaits的配置文件校验很诡异，节点的位置还有要求
如下，会报错：
the content of element type "configuration" must match "(properties?,settings?,typealiases?,typehandlers?,objectfactory?,objectwrapperfactory?,plugins?,environments?,mappers?)".
<?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>
<environments default="development">
<environment id="development">
<transactionmanager type="jdbc"/>
<datasource type="pooled">
<property name="driver" value="oracle.jdbc.driver.oracledriver"/>
<property name="url" value="jdbc:oracle:thin:@xx:1521:xx"/>
<property name="username" value="ireport"/>
<property name="password" value="xxxx"/>
</datasource>
</environment>
</environments>
<typealiases>
<typealias type="com.ice.stat.online.model.eventflag" alias="eventflag"/>
</typealiases>
<mappers>
<mapper resource="com/ice/stat/online/model/hbm/eventflagmapper.xml"/>
</mappers>
</configuration>
把typealiases放到最上面就好了说：
<?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>
<typealiases>
<typealias type="com.ice.stat.online.model.eventflag" alias="eventflag"/>
</typealiases>
<environments default="development">
<environment id="development">
<transactionmanager type="jdbc"/>
<datasource type="pooled">
<property name="driver" value="oracle.jdbc.driver.oracledriver"/>
<property name="url" value="jdbc:oracle:thin:@xx:1521:xx"/>
<property name="username" value="ireport"/>
<property name="password" value="xxxx"/>
</datasource>
</environment>
</environments>
<mappers>
<mapper resource="com/ice/stat/online/model/hbm/eventflagmapper.xml"/>
</mappers>
</configuration>