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网站流量很少,福州seo按天收费,网站百度快照怎么做,凡科免费做网站的真的吗操作步骤创建数据库建立user表放入数据 1、创建javaweb工程并添加Jar包用到的jar包 junit 用于测试 mybatis框架：mybatis-3.5.9.jar mysql数据库：mysql-connector-java-8.0.28.jar 2、添加MyBatis核心配置文件 <?xml version"1.0"…

操作步骤

创建数据库

建立user表

放入数据

1、创建javaweb工程并添加Jar包

用到的jar包

junit 用于测试

mybatis框架：mybatis-3.5.9.jar

mysql数据库：mysql-connector-java-8.0.28.jar

2、添加MyBatis核心配置文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><!-- 配置内容在这里 --></configuration>

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis
username=root
password=root

编写”mybatis-config.xml”的配置内容

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd" >
<configuration><properties resource="database.properties"></properties><typeAliases><package name="entity"/></typeAliases><environments default="development"><environment id="development"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="${driver}"/><property name="url" value="${url}?useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=UTC&amp;useSSL=false"/><property name="username" value="${username}"/><property name="password" value="${password}"/></dataSource></environment></environments><mappers><mapper resource="mapper/UserMapper.xml"></mapper></mappers>
</configuration>

”mybatis-config.xml”的配置节点说明

1、configuration：

配置文件的根元素节点

2、environments：

表示配置MyBaits的多套运行环境，该元素节点下可以配置多个environment子元素节点

3、environment：

配置Mybaits的一套运行环境，需指定运行环境ID、事务管理(transactionManager)和数据源(dataSource)配置等相关信息

4、mappers：

其下可以配置多个mapper节点来具体指定SQL映射文件的路径，resource属性的值表述了类资源路径下的SQL映射文件的路径

3、创建实体类

package entity;public class User {private String username;private String password;private Integer age;private String sex;private String birthDate;public User() {}public User(String username, String password, Integer age, String sex, String birthDate) {this.username = username;this.password = password;this.age = age;this.sex = sex;this.birthDate = birthDate;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public String getBirthDate() {return birthDate;}public void setBirthDate(String birthDate) {this.birthDate = birthDate;}@Overridepublic String toString() {return "User{" +"username='" + username + '\'' +", password='" + password + '\'' +", age=" + age +", sex='" + sex + '\'' +", birthDate=" + birthDate +'}';}
}

注： 1、类的名称不一定和表名相同

2、属性名称和数据库字段名称相同，才能自动映射

3、属性类型需要和数据库字段类型对应

4、每一个属性都要生成get/set方法

4、创建SQL映射文件

<?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="/"><!-- SQL映射写在这里 -->
</mapper>

编辑”UserMapper.xml”SQL映射内容

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="/"><select id="findAll" resultType="user">
select * from user</select><select id="findAll2" resultType="map">
select * from user</select><select id="myCount" resultType="int" parameterType="map">select count(*) from smbms_bill join smbms_provider on smbms_bill.providerId=smbms_provider.id where smbms_provider.proName like concat('%',#{proName},'%') and isPayment=#{isPayment}</select>
</mapper><!--建立映射关系-->

配置节点说明

select：表示查询语句

id属性：表示该SQL语句的唯一标识符

resultType属性：表示SQL语句返回值类型，此处通过SQL语句查询数据，将数据直接映射到User实体类上

5、代码测试，输出结果

import entity.User;
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.Test;import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;public class UserMapperTest {@Testpublic void Test01() throws IOException {System.out.println(" = ");InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();SqlSessionFactory build = sqlSessionFactoryBuilder.build(inputStream);SqlSession sqlSession = build.openSession();List<User> findAll = sqlSession.selectList("findAll");for (User user: findAll) {System.out.println("user = " + user);}sqlSession.close();}@Testpublic void Test02() throws IOException {InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();SqlSessionFactory build = sqlSessionFactoryBuilder.build(inputStream);SqlSession sqlSession = build.openSession();List<Map<String,Object>> findAll = sqlSession.selectList("findAll2");for (Map<String, Object> stringObjectMap : findAll) {System.out.println("stringObjectMap = " + stringObjectMap);}sqlSession.close();}}

结果为list集合对象