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mybatis-09-缓存

2019-02-03 18:20:00【个人日记】457人已围观

简介查询的数据放入内存中,查询更快

缓存

一级缓存

此缓存只是在当前会话(SqlSession)有用

当数据只读取而不改变,则缓存不会消失

如果数据改变,例如使用commit,则当前会话将缓存全部被清除

二级缓存 *

此缓存在当前命名空间(namespace)有用

一级缓存默认开启,二级缓存需要在全局文件中配置

<?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
    <!-- 开启二级缓存 -->
    <settings>
        <setting name="cacheEnabled" value="true"/>
    </settings>
    <environments default="development">
        <environment id="development">
            <!-- 使用JDBC技术 -->
            <transactionManager type="JDBC"/>
            <!-- 数据库连接池,mybatis连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/order?useUnicode=true&amp;characterEncoding=utf8&amp;useSSL=true"/>
                <property name="username" value="root"/>
                <property name="password" value="1538933906"/>
            </dataSource>
        </environment>
    </environments>
    <!-- 配置映射文件 -->
    <mappers>
        <mapper resource="orderMapper.xml"/>
        <mapper resource="userMapper.xml"/>
    </mappers>
</configuration>

    <settings>
        <setting name="cacheEnabled" value="true"/>
    </settings>

以上配置需要在全局文件中配置

配置时应该注意顺序,mapper配置应该在最后,设置settings放在开头,数据库environments放在中间

但是缓存需要在磁盘或内存中储存对象信息,所以需要缓存的对象需要实现序列化

User对象应该实现序列化

package com.huangxin.order.model;
import java.io.Serializable;
import java.util.List;
         //实现序列化接口
public class User implements Serializable {
    private Integer id;
    private String userName;
    private String userTelephone;
    private String userSex;
    private List<Orders> orders;
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", userName='" + userName + '\'' +
                ", userTelephone='" + userTelephone + '\'' +
                ", userSex='" + userSex + '\'' +
                ", orders=" + orders +
                '}';
    }
    public List<Orders> getOrders() {
        return orders;
    }
    public void setOrders(List<Orders> orders) {
        this.orders = orders;
    }
    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 getUserTelephone() {
        return userTelephone;
    }
    public void setUserTelephone(String userTelephone) {
        this.userTelephone = userTelephone;
    }
    public String getUserSex() {
        return userSex;
    }
    public void setUserSex(String userSex) {
        this.userSex = userSex;
    }
}