Eclipse创建一个mybatis工程实现连接数据库查询

Eclipse上创建第一mybatis工程实现数据库查询

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步骤：

1.创建一个java工程

2.创建lib文件夹，加入mybatis核心包、依赖包、数据驱动包。并为jar包添加路径

3.创建resources资源文件夹，加入log4j.properties和SqlMapConfig.xml配置文件

4.创建POJO类

5.在resources下的sqlmap目录下创建sql映射文件User.xml

6.在SqlMapConfig.xml中加载映射文件

7.在resources下的sqlmap目录下创建sql映射文件User.xml实现根据id查询用户

8.编写测试程序

9.测试成功

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1.创建一个java工程

2.创建lib文件夹，加入mybatis核心包、依赖包、数据驱动包。并为jar包添加路径

mybaits的代码由github.com管理

下载地址：https://github.com/mybatis/mybatis-3/releases

mybatis-3.4.6.jar       mybatis的核心包

lib文件夹                  mybatis的依赖包所在

mybatis-3.4.6.pdf      mybatis使用手册

3.创建resources资源文件夹，加入log4j.properties和SqlMapConfig.xml配置文件

log4j.properties文件下加入如下头文件

# Global logging configuration

log4j.rootLogger=DEBUG, stdout

# Console output...

log4j.appender.stdout=org.apache.log4j.ConsoleAppender

log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

SqlMapConfig.xml加入如下信息，连接数据库

<?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>

    <!-- 和spring整合后 environments配置将废除 -->

    <environments default="development">

       <environment id="development">

           <!-- 使用jdbc事务管理 -->

           <transactionManager type="JDBC" />

           <!-- 数据库连接池 -->

           <dataSource type="POOLED">

              <property name="driver" value="com.mysql.jdbc.Driver" />

              <property name="url"

                  value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />

              <property name="username" value="root" />

              <property name="password" value="root" />

           </dataSource>

       </environment>

    </environments>

</configuration>

4.创建POJO类    //此处pojo类的属性和类型与数据库User表中的属性和类型相同

package com.mybatis.pojo;

import java.sql.Date;

public class User {

       private int id;

       private String username;// 用户姓名

       private String sex;// 性别

       private Date birthday;// 生日

       private String address;// 地址    

       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 getSex() {

             return sex;

       }

       public void setSex(String sex) {

             this.sex = sex;

       }

       public Date getBirthday() {

             return birthday;

       }

       public void setBirthday(Date birthday) {

             this.birthday = birthday;

       }

       public String getAddress() {

             return address;

       }

       public void setAddress(String address) {

             this.address = address;

       }

       @Override

       public String toString() {

             return "User [id=" + id + ", username=" + username + ", sex=" + sex + ", birthday=" + birthday + ", address="

                           + address + "]";

       }

}

5.在resources下的sqlmap目录下创建sql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">

<!-- namespace：命名空间-->

<mapper namespace="test">

</mapper>

6.在SqlMapConfig.xml中加载映射文件

                    </environment>

       </environments>

       <mappers>

       <mapper resource="sqlmap/User.xml"></mapper>

       </mappers>

</configuration>

7.在resources下的sqlmap目录下创建sql映射文件User.xml实现根据id查询用户

<?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">

<!-- namespace：命名空间-->

<mapper namespace="test">

 

    <!-- id:statement的id 或者叫做sql的id-->

    <!-- parameterType:声明输入参数的类型 -->

    <!-- resultType:声明输出结果的类型，应该填写pojo的全路径 -->

    <!-- #{}：输入参数的占位符，相当于jdbc的？ -->

    <select id="queryUserById" parameterType="int"

       resultType="com.mybatis.pojo.User">

       SELECT * FROM `user` WHERE id  = #{id}

    </select>

</mapper>

8.编写测试程序

public class MybatisTest {

    private SqlSessionFactory sqlSessionFactory = null;

 

    @Before

    public void init() throws Exception {

       // 1. 创建SqlSessionFactoryBuilder对象

       SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();

 

       // 2. 加载SqlMapConfig.xml配置文件

       InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");

 

       // 3. 创建SqlSessionFactory对象

       this.sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);

    }

 

    @Test

    public void testQueryUserById() throws Exception {

       // 4. 创建SqlSession对象

       SqlSession sqlSession = sqlSessionFactory.openSession();

 

       // 5. 执行SqlSession对象执行查询，获取结果User

       // 第一个参数是User.xml的statement的id，第二个参数是执行sql需要的参数；

       Object user = sqlSession.selectOne("queryUserById", 1);

 

       // 6. 打印结果

       System.out.println(user);

 

       // 7. 释放资源

       sqlSession.close();

    }

}

9.测试成功

DEBUG [main] - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.

DEBUG [main] - PooledDataSource forcefully closed/removed all connections.

DEBUG [main] - PooledDataSource forcefully closed/removed all connections.

DEBUG [main] - PooledDataSource forcefully closed/removed all connections.

DEBUG [main] - PooledDataSource forcefully closed/removed all connections.

DEBUG [main] - Opening JDBC Connection

DEBUG [main] - Created connection 107915280.

DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@66ea810]

DEBUG [main] - ==>  Preparing: SELECT * FROM user WHERE id = ?

DEBUG [main] - ==> Parameters: 10(Integer)

DEBUG [main] - <==      Total: 1

User [id=10, username=张三, sex=1, birthday=2014-07-10, address=北京市]