企业官网建设流程全解析

一 领域模型

package org.fkit.domain; import java.io.Serializable; /** * CREATE TABLE `tb_user` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `name` VARCHAR(18) DEFAULT NULL, `sex` CHAR(2) DEFAULT NULL, `age` INT(11) DEFAULT NULL, PRIMARY KEY (`id`) ) */ public class User implements Serializable{ private static final long serialVersionUID = 1L; private Integer id; private String name; private String sex; private Integer age; public User() { super(); // TODO Auto-generated constructor stub } public User( String name, String sex, Integer age) { super(); this.name = name; this.sex = sex; this.age = age; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } @Override public String toString() { return "User [id=" + id + ", name=" + name + ", sex=" + sex + ", age=" + age + "]"; } }

二 会话工厂

package org.fkit.factory; import java.io.InputStream; 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 FKSqlSessionFactory { private static SqlSessionFactory sqlSessionFactory = null; // 初始化创建SqlSessionFactory对象 static{ try (// 读取mybatis-config.xml文件 InputStream is = Resources.getResourceAsStream("mybatis-config.xml"); ){ sqlSessionFactory = new SqlSessionFactoryBuilder() .build(is); } catch (Exception e) { e.printStackTrace(); } } // 获取SqlSession对象的静态方法 public static SqlSession getSqlSession(){ return sqlSessionFactory.openSession(); } // 获取SqlSessionFactory的静态方法 public static SqlSessionFactory getSqlSessionFactory() { return sqlSessionFactory; } }

三 mapper

package org.fkit.mapper; import org.apache.ibatis.annotations.CacheNamespace; import org.apache.ibatis.annotations.Delete; import org.apache.ibatis.annotations.Options; import org.apache.ibatis.annotations.Select; import org.apache.ibatis.cache.decorators.LruCache; import org.fkit.domain.User; @CacheNamespace(eviction=LruCache.class,flushInterval=60000,size=512, readWrite=true) public interface UserMapper { // 根据id查询User @Select("SELECT * FROM TB_USER WHERE id = #{id}") @Options(useCache=true) User selectUserById(Integer id); // 根据id删除User @Delete("DELETE FROM TB_USER WHERE id = #{id}") void deleteUserById(Integer id); }

四 配置文件

1 db.properties

driver=com.mysql.jdbc.Driver url=jdbc:mysql://127.0.0.1:3306/mybatis username=root password=123456

2 log4j.xml

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd"> <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/"> <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender"> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%5p [%t] %m%n" /> </layout> </appender> <logger name="org.fkit.mapper"> <level value="DEBUG" /> </logger> <root> <level value="ERROR" /> <appender-ref ref="STDOUT" /> </root> </log4j:configuration>

3 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"> <!-- XML 配置文件包含对 MyBatis 系统的核心设置 --> <configuration> <properties resource="db.properties"/> <!-- 指定 MyBatis 所用日志的具体实现 --> <settings> <setting name="logImpl" value="LOG4J"/> <!-- 开启二级缓存 --> <setting name="cacheEnabled" value="true"/> </settings> <environments default="mysql"> <!-- 环境配置，即连接的数据库。 --> <environment id="mysql"> <!-- 指定事务管理类型，type="JDBC"指直接简单使用了JDBC的提交和回滚设置 --> <transactionManager type="JDBC"/> <!-- dataSource指数据源配置，POOLED是JDBC连接对象的数据源连接池的实现。 --> <dataSource type="POOLED"> <property name="driver" value="${driver}"/> <property name="url" value="${url}"/> <property name="username" value="${username}"/> <property name="password" value="${password}"/> </dataSource> </environment> </environments> <!-- mappers告诉了MyBatis去哪里找持久化类的映射文件 --> <mappers> <mapper class="org.fkit.mapper.UserMapper"/> </mappers> </configuration>

五 测试

package org.fkit.test; import org.apache.ibatis.session.SqlSession; import org.fkit.domain.User; import org.fkit.factory.FKSqlSessionFactory; import org.fkit.mapper.UserMapper; public class ATwoLevelCacheTest { public static void main(String[] args) { // 使用工厂类获得SqlSession对象 SqlSession sqlSession1 = FKSqlSessionFactory.getSqlSession(); // 获得UserMapping对象 UserMapper um = sqlSession1.getMapper(UserMapper.class); // 查询id为1的User对象，会执行select语句 User user = um.selectUserById(1); System.out.println(user); // 关闭一级缓存 sqlSession1.close(); // 重新获取一级缓存 SqlSession sqlSession2 = FKSqlSessionFactory.getSqlSession(); // 再次获得UserMapping对象 um = sqlSession2.getMapper(UserMapper.class); // 再次查询id为1的User对象，虽然现在使用的是一个新的SqlSession对象,但是二级缓存中缓存了数据，所以不会执行再次select语句 User user2 = um.selectUserById(1); System.out.println(user2); // 关闭SqlSession对象 sqlSession2.close(); } }

六 测试结果

DEBUG [main] ==> Preparing: SELECT * FROM TB_USER WHERE id = ? DEBUG [main] ==> Parameters: 1(Integer) DEBUG [main] <== Total: 1 User [id=1, name=cakin, sex=男, age=18] DEBUG [main] Cache Hit Ratio [org.fkit.mapper.UserMapper]: 0.5 User [id=1, name=cakin, sex=男, age=18]