- 目录和依赖
-
- 相关配置
- 增删改查操作
- 测试类:
- 一些注意点
目录和依赖
![](https://img.laitimes.com/img/__Qf2AjLwojIjJCLyojI0JCLiAzNfRHLGZkRGZkRfJ3bs92YsYTMfVmepNHLwMGVORTV61EeRpHW4Z0MMBjVtJWd0ckW65UbM5WOHJWa5kHT20ESjBjUIF2X0hXZ0xCMx81dvRWYoNHLrdEZwZ1Rh5WNXp1bwNjW1ZUba9VZwlHdssmch1mclRXY39CXldWYtlWPzNXZj9mcw1ycz9WL49zZuBnLhhjNwcTZklzM4QWYiJDN4cjYzQDM4YzYwYTM4IjMxgzLc52YucWbp5GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.png)
<dependencies>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-log4j12 -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>2.0.0-alpha1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
</dependencies>
<!--在build中配置resources,来防止我们资源导出失败的问题-->
<build>
<resources>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
</resources>
</build>
数据表:
相关配置
1.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">
<configuration>
<!--引入外部配置文件-->
<properties resource="db.properties"/>
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
<setting name="cacheEnabled" value="true"/>
<setting name="logImpl" value="STDOUT_LOGGING"/>
</settings>
<typeAliases>
<typeAlias type="com.hou.pojo.User" alias="User"></typeAlias>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<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>
<!--绑定接口-->
<mappers>
<mapper class="com.hou.mapper.UserMapper"></mapper>
</mappers>
</configuration>
2.log4j.properties
log4j.rootLogger=debug, stdout, R
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=example.log
log4j.appender.R.MaxFileSize=100KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=5
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n
3.ehcache.xml
<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd"
updateCheck="false">
<!--
diskStore:为缓存路径,ehcache分为内存和磁盘两级,此属性定义磁盘的缓存位置。参数解释如下:
user.home – 用户主目录
user.dir – 用户当前工作目录
java.io.tmpdir – 默认临时文件路径
-->
<diskStore path="java.io.tmpdir/Tmp_EhCache"/>
<!--
defaultCache:默认缓存策略,当ehcache找不到定义的缓存时,则使用这个缓存策略。只能定义一个。
-->
<!--
name:缓存名称。
maxElementsInMemory:缓存最大数目
maxElementsOnDisk:硬盘最大缓存个数。
eternal:对象是否永久有效,一但设置了,timeout将不起作用。
overflowToDisk:是否保存到磁盘,当系统当机时
timeToIdleSeconds:设置对象在失效前的允许闲置时间(单位:秒)。仅当eternal=false对象不是永久有效时使用,可选属性,默认值是0,也就是可闲置时间无穷大。
timeToLiveSeconds:设置对象在失效前允许存活时间(单位:秒)。最大时间介于创建时间和失效时间之间。仅当eternal=false对象不是永久有效时使用,默认是0.,也就是对象存活时间无穷大。
diskPersistent:是否缓存虚拟机重启期数据 Whether the disk store persists between restarts of the Virtual Machine. The default value is false.
diskSpoolBufferSizeMB:这个参数设置DiskStore(磁盘缓存)的缓存区大小。默认是30MB。每个Cache都应该有自己的一个缓冲区。
diskExpiryThreadIntervalSeconds:磁盘失效线程运行时间间隔,默认是120秒。
memoryStoreEvictionPolicy:当达到maxElementsInMemory限制时,Ehcache将会根据指定的策略去清理内存。默认策略是LRU(最近最少使用)。你可以设置为FIFO(先进先出)或是LFU(较少使用)。
clearOnFlush:内存数量最大时是否清除。
memoryStoreEvictionPolicy:可选策略有:LRU(最近最少使用,默认策略)、FIFO(先进先出)、LFU(最少访问次数)。
FIFO,first in first out,这个是大家最熟的,先进先出。
LFU, Less Frequently Used,就是上面例子中使用的策略,直白一点就是讲一直以来最少被使用的。如上面所讲,缓存的元素有一个hit属性,hit值最小的将会被清出缓存。
LRU,Least Recently Used,最近最少使用的,缓存的元素有一个时间戳,当缓存容量满了,而又需要腾出地方来缓存新的元素的时候,那么现有缓存元素中时间戳离当前时间最远的元素将被清出缓存。
-->
<defaultCache
eternal="false"
maxElementsInMemory="10000"
overflowToDisk="false"
diskPersistent="false"
timeToIdleSeconds="1800"
timeToLiveSeconds="259200"
memoryStoreEvictionPolicy="LRU"/>
<!-- 在mybatis中使用二级缓存-->
<cache
name="cloud_user"
eternal="false"
maxElementsInMemory="5000"
overflowToDisk="false"
diskPersistent="false"
timeToIdleSeconds="1800"
timeToLiveSeconds="1800"
memoryStoreEvictionPolicy="LRU"/>
</ehcache>
db.properties
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3308/data1?userSSL=true&userUnicode=true&characterEncoding=UTF-8
username=heziyi
password=123456
mybatis配置:
//sqlSessionFactory --> sqlSession
public class MybatisUtils {
private static SqlSessionFactory sqlSessionFactory;
static {
try {
//使用mybatis第一步:获取sqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession(true);
}
}
增删改查操作
pojo:
@Data
public class User implements Serializable {
private int id;
private String name;
private String pwd;
public User(int id, String name, String pwd) {
this.id = id;
this.name = name;
this.pwd = pwd;
}
}
mapper和接口:
public interface UserMapper {
User queryUserByid(@Param("id") int id);
}
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.hou.mapper.UserMapper">
<cache type="org.mybatis.caches.ehcache.EhcacheCache"/>
<select id="queryUserByid" resultType="User">
select * from data1.user where id = #{id}
</select>
<update id="updateUser" parameterType="User">
update data1.user set name=#{name}, pwd=#{pwd} where id=#{id}
</update>
</mapper>
测试类:
public class MyTest {
@Test
public void addBlog(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
SqlSession sqlSession1 = MybatisUtils.getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = userMapper.queryUserByid(1);
System.out.println(user);
sqlSession.close();
UserMapper userMapper1 = sqlSession1.getMapper(UserMapper.class);
User user1 = userMapper1.queryUserByid(1);
System.out.println(user1);//User(id=1, name=你好, pwd=345678)
System.out.println(user==user1);//true
User u3 = userMapper1.queryUserByid(2);
System.out.println(u3);
sqlSession1.close();
}
}
运行结果: