mybatis与数据库连接过程

菜鸟发文 请大神多多指导

1.准被一个maven项目

2.先导入jar包

3.配置mybatis核心文件

4.把连接数据库的配置项抽离出来

5.编写实体类

6.编写接口

7.编写mapper映射文件

8.把相同SQL session 方法抽离 进行封装

9.配置打印文件log4j

10最后进行测试

1.配置所需的jar包

也就是pom文件

<?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.bdqn</groupId>
    <artifactId>BasicDao01</artifactId>
    <version>1.0-SNAPSHOT</version>
    <!--导入jar包-->
    <dependencies>
        <!--导入mybatis包-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.2.8</version>
        </dependency>
        <!--导入MySQL包-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.28</version>
        </dependency>
        <!--导入测试包-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>
        <!--导入log4j包-->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.12</version>
        </dependency>
    </dependencies>
    <!--扫描所有.xml文件-->
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>

                    <include>**/*.xml</include>

2.配置核心文件

取名为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">
<!--根节点-->
<configuration>
    <!--引入properties文件-->
    <properties resource="database.properties"></properties>
<!--修改mybatis运行时的行为方式-->
    <settings>
        <!--配置log4j日志-->
    <setting name="logImpl" value="LOG4J"></setting>
    </settings>
    <!--配置别名-->
    <typeAliases>
        <package name="com.bdqn.entity"></package>
    </typeAliases>
   <!--配置运行时环境-->
    <environments default="development">
        <environment id="development">
            <!--配置事务管理器-->
            <transactionManager type="JDBC"></transactionManager>
            <!--配置数据源-->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"></property>
                <property name="url" value="${jdbc.url}"></property>
                <property name="username" value="${jdbc.username}"></property>
                <property name="password" value="${jdbc.password}"></property>
            </dataSource>
        </environment>
    </environments>
    <!--配置映射文件 mappers映射器-->
    <mappers>
      <mapper resource="com/bdqn/dao/UserMapper.xml"></mapper>
    </mappers>

</configuration>

3.把所需要的连接数据库的配置抽离出来 

取名为 database.properties

记住 在设置密码时一定要注意 要加.jdbc什么

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/tcmp
jdbc.username=root
jdbc.password=admin

4.进行实体类的编写

我以用户的实体为例子

在这里我取名为User

public class User {
    private Integer id;
    private String userName,password,nickName;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", userName='" + userName + '\'' +
                ", password='" + password + '\'' +
                ", nickName='" + nickName + '\'' +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    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 String getNickName() {
        return nickName;
    }

    public void setNickName(String nickName) {
        this.nickName = nickName;
    }
}

5.进行接口绑定的编写

我取名为UserMapper

注意这里我用了求和方法和查询所有方法

public interface UserMapper {
    /*count 求和方法接口*/
    public Integer queryCountUser();
    /*查询所有用户方法接口*/
    public List<User>queryAllUsers();
}

6.进行mapper映射文件的编写

我取名为UserMapper.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文件的路径没有.xml-->
<mapper namespace="com.bdqn.dao.UserMapper">
    <resultMap id="UserMap" type="User">
        <id property="id" column="id"></id>
        <result property="userName" column="user_name"></result>
        <result property="nickName" column="nick_name"></result>
    </resultMap>
    <!--count 求和方法sql语句返回类型为Integer类型-->
    <select id="queryCountUser" resultType="Integer">
        SELECT COUNT(1) FROM t_user
    </select>
    <!--查询所有用户方法 因为表中的列名和实体类的名字不一样所以需要映射 用到result map 返回为一个泛型list集合-->
    <select id="queryAllUsers" resultMap="UserMap" >
SELECT * FROM t_user
    </select>
</mapper>

7.把所需要的SQL session抽离封装单独起一个工具类以便我们在测试时进行很好的调用

这里我取名为 MyBatisUtil类

public class MybatisUtil {
    /*声明工厂*/
    private static SqlSessionFactory sqlSessionFactory;
    /*静态代码块只执行一次*/
      static{
          String source="mybatis-config.xml";
          /*获取输入流*/
        try {
            InputStream inputStream= Resources.getResourceAsStream(source);
            /*创建一个工厂 sqlSessionFactory*/
            sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /*打开一个SQL session*/
    public static SqlSession createSqlSession (){
      return sqlSessionFactory.openSession();
    }
    /*关闭连接释放资源*/
    public void close(SqlSession sqlSession){
        if (sqlSession!=null){
            sqlSession.close();
        }
    }
}

8.进行测试    

public class TestUser {

    /*测试求和方法*/
    private SqlSession sqlSession=null;
    Integer count;
    @Test
    public void queryCount(){
        sqlSession= MybatisUtil.createSqlSession();
        count=sqlSession.getMapper(UserMapper.class).queryCountUser();
        if (count!=null){
            System.out.println(count);
        }
    }
    /*测试查询所有用户方法*/
    @Test
    public void queryAllUsers(){
        List<User>list;
        sqlSession=MybatisUtil.createSqlSession();
        list=sqlSession.getMapper(UserMapper.class).queryAllUsers();
        if (list!=null){
            for (User user : list) {
                System.out.println(user);
            }
        }
    }
}

9.配置log4j打印文件

log4j.rootLogger=DEBUG,CONSOLE,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
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
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  

 10.最后进行测试