发表于： 2019-12-28 18:51:00
3 1082
今天学习的内容:
MyBatis对mysql数据库操作:
参考:https://www.cnblogs.com/xqz0618/p/javaweb03.html
MyBatis 是支持普通 SQL 查询,存储过程和高级映射的优秀持久层框架。
MyBatis 消除 了几乎所有的 JDBC 代码和参数的手工设置以及结果集的检索。
MyBatis 使用简单的 XML 或注解用于配置和原始映射,将接口和 Java 的 POJOs(Plain Old Java Objects,普通的 Java 对象)映射成数据库中的记录。pom.xml配置:
<?xml version="1.0" encoding="UTF-8"?>
<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>com.me</groupId>
<artifactId>project2</artifactId>
<version>1.0-SNAPSHOT</version>
<name>project2</name>
<!-- FIXME change it to the project's website -->
<url>http://www.example.com</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<druid.version>1.1.17</druid.version>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
<spring.version>5.2.2.RELEASE</spring.version>
<mybatis.spring.version>2.0.0</mybatis.spring.version>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.11</version>
</dependency>
<dependency>
<groupId>commons-dbcp</groupId>
<artifactId>commons-dbcp</artifactId>
<version>1.4</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.0</version>
</dependency>
<dependency>
<groupId>org.glassfish.web</groupId>
<artifactId>javax.servlet.jsp.jstl</artifactId>
<version>1.2.4</version>
</dependency>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>8.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.glassfish.web</groupId>
<artifactId>javax.servlet.jsp.jstl</artifactId>
<version>1.2.4</version>
</dependency>
<!-- MyBatis的配置 -->
<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.1</version>
</dependency>
<!-- druid数据源 -->
<!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>${druid.version}</version>
</dependency>
<dependency>
<!-- spring-jdbc spring操作数据库的驱动包 -->
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<!-- MyBatis和Spring连接的包 -->
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>${mybatis.spring.version}</version>
</dependency>
<!-- OJDBC8 -->
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.1.2</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- https://mvnrepository.com/artifact/commons-logging/commons-logging -->
<dependency>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
<version>1.1.1</version>
</dependency>
<!-- https://mvnrepository.com/artifact/log4j/log4j -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
</dependencies>
<build>
<pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
<plugins>
<!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>3.1.0</version>
</plugin>
<!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.22.1</version>
</plugin>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
</plugin>
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
</plugin>
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>
</plugin>
<!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
<plugin>
<artifactId>maven-site-plugin</artifactId>
<version>3.7.1</version>
</plugin>
<plugin>
<artifactId>maven-project-info-reports-plugin</artifactId>
<version>3.0.0</version>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>
在Resources中创建conf.xml:
配置数据库连接信息
<?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" />
<!-- 配置数据库连接信息 -->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8" />
<property name="username" value="root" />
<property name="password" value="*******" />
</dataSource>
</environment>
</environments>
<mappers>
<!-- 注册userMapper.xml文件，
userMapper.xml位于com.springdemo.mapping这个包下，所以resource写成com/springdemo/model/mapping/userMapper.xml-->
<mapper resource="com/springdemo/model/mapping/userMapper.xml"/>
</mappers>
</configuration>
创建User类
package com.springdemo.model;
public class User {
// public User(String userId, String userName, String userPwd, String userPower) {
// super();
// this.userId = userId;
// this.userName = userName;
// this.userPwd = userPwd;
// this.userPower = userPower;
// }
public User(String name){
super();
this.name=name;
}
public User() {
super();
}
private int id;
private int _key;
private String name;
// private String userId;
// private String userName;
// private String userPwd;
// private String userPower;
// public int get_key() {
// return _key;
// }
public int get_id(){
return id;
}
// public void set_key(int _key) {
// this._key = _key;
// }
//
// public String getUserId() {
// return userId;
// }
//
// public void setUserId(String userId) {
// this.userId = userId;
// }
//
// public String getUserName() {
// return userName;
// }
//
// public void setUserName(String userName) {
// this.userName = userName;
// }
//
// public String getUserPwd() {
// return userPwd;
// }
//
// public void setUserPwd(String userPwd) {
// this.userPwd = userPwd;
// }
//
// public String getUserPower() {
// return userPower;
// }
//
// public void setUserPower(String userPower) {
// this.userPower = userPower;
// }
@Override
public String toString() {
return "User [id="+id+" name=" + name + "]";
}
}
创建user表sql查询映射文件
<?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">
<!-- 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的
例如namespace="com.springdemo.mapping.userMapper"就是com.springdemo.mapping(包名)+userMapper(userMapper.xml文件去除后缀)
-->
<mapper namespace="com.springdemo.model.mapping.userMapper">
<!-- 在select标签中编写查询的SQL语句， 设置select标签的id属性为getUser，id属性值必须是唯一的，不能够重复
使用parameterType属性指明查询时使用的参数类型，resultType属性指明查询返回的结果集类型
resultType="com.springdemo.model.User"就表示将查询结果封装成一个User类的对象返回
User类就是users表所对应的实体类
-->
<!-- 根据_key查询得到一个user对象-->
<select id="getUser" parameterType="int"
resultType="com.springdemo.model.User"> <!-- 创建对应user实体类的位置 -->
select * from table_test1 where id=#{id}
</select>
</mapper>
conf.xml中注册userMapper:
<?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" />
<!-- 配置数据库连接信息 -->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8" />
<property name="username" value="root" />
<property name="password" value="123654789" />
</dataSource>
</environment>
</environments>
<mappers>
<!-- 注册userMapper.xml文件，
userMapper.xml位于com.springdemo.mapping这个包下，所以resource写成com/springdemo/model/mapping/userMapper.xml-->
<mapper resource="com/springdemo/model/mapping/userMapper.xml"/>
</mappers>
</configuration>
使用Test.java 文件添加测试
package com.springdemo.impl;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.util.List;
import com.springdemo.model.User;
//import com.springdemo.tools.DBTools;
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 Test {
public static void main(String[] args) throws IOException {
//mybatis的配置文件
String resource = "conf.xml";
//使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）
InputStream is = Resources.getResourceAsStream(resource);
//构建sqlSession的工厂
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
//使用MyBatis提供的Resources类加载mybatis的配置文件（它也加载关联的映射文件）
//Reader reader = Resources.getResourceAsReader(resource);
//构建sqlSession的工厂
//SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
//创建能执行映射文件中sql的sqlSession
SqlSession session = sessionFactory.openSession();
/**
* 映射sql的标识字符串，
* me.gacl.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
* getUser是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL
*/
/* 根据——key查找 */
String statement = "com.springdemo.model.mapping.userMapper.getUser";
//映射sql的标识字符串，getUser与映射文件中配置select标签id一致
//执行查询返回一个唯一user对象的sql
User user = session.selectOne(statement, 2);
System.out.println(user);
}
}
执行结果报错:
遇到的困难:
以上例子执行结果报错,暂时还不知道怎么解决
收获:
大致了解了下MyBatis的基础知识,以及连接数据库的方法.
明天的计划:
学习Mybatis框架,学习spring框架
返回列表
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