手把手带你实现基础的Mybatis分页查询

灰太狼 2024-03-08 09:06 44阅读 0赞

> 使用pageHelper分页插件的分页方式可看这个文章：[使用PageHelper实现分页查询（详细）\_筱晰的博客-CSDN博客][PageHelper_-CSDN]

#### 1、引入依赖 ####

<properties>
            <maven.compiler.source>8</maven.compiler.source>
            <maven.compiler.target>8</maven.compiler.target>
            <spring-boot.version>2.6.13</spring-boot.version>
            <druid.version>1.2.16</druid.version>
        </properties>
    
        <dependencyManagement>
            <dependencies>
                
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-dependencies</artifactId>
                    <version>${spring-boot.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
    
        <dependencies>
            <dependency>
                <groupId>com.mysql</groupId>
                <artifactId>mysql-connector-j</artifactId>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <scope>provided</scope>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
    
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>${druid.version}</version>
            </dependency>
    
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>3.0.2</version>
            </dependency>
        </dependencies>

### 2、配置yml ###

server:
      port: 8080
    
    spring:
      datasource:
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://localhost:3306/ssm?characterEncoding=UTF-8&serverTimezone=GMT%2B8
        username: root
        password: root
        type: com.alibaba.druid.pool.DruidDataSource
    
    mybatis-plus:
      configuration:
        log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
        map-underscore-to-camel-case: true

#### 3、编写mapper ####

实体类：

@Data
    @TableName("tz_user")
    public class User {
        private Long id;
        private String name;
        private int age;
    }

> 分页查询，前端需要获得两个结果。**一个是pageTotal即结果总数，另一个是rows即查询到的分页列表**。因此这里需要两个sql语句查询。

mapper类：![61ef2d829dde4f32a89acacb4417557f.png][]

> 查询分页数据需要**页码**和**当前页查询数**，因此查询参数如下：
> 
> ![ba5fe794ed094b61a4195880947c706c.png][]
> 
> 这里的**getIndex（）**方法是因为mybatis获取参数是**通过实体类的get方法获取**，而index代表的含义就是当前的页码实际所在位数（即我要查第2页，每页查2个，那么index就是2）.用在sql语句limit限制里。

**maper.xml:**

<select id="pageList" resultType="com.xin.entity.pojo.User">
            select id,name,age from tz_user
                <where>
                    <if test="name != null and name !='' ">
                        and name like concat('%',#{name},'%')
                    </if>
                    <if test="age != '' and age != null">
                        and age = #{age}
                    </if>
                </where>
            limit #{index} , #{pageSize}
        </select>
        
        <select id="countTotal" resultType="java.lang.Integer">
            select count(1) from tz_user
            <where>
                <if test="name != null and name !='' ">
                    and name like concat('%',#{name},'%')
                </if>
                <if test="age != '' and age != null">
                    and age = #{age}
                </if>
            </where>
        </select>

写完之后即可进行测试。

[PageHelper_-CSDN]: https://blog.csdn.net/m0_48736673/article/details/124805124?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522169503511516800225589671%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request_id=169503511516800225589671&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~top_positive~default-1-124805124-null-null.142%5Ev94%5EchatsearchT3_1&utm_term=pagehelper&spm=1018.2226.3001.4187
[61ef2d829dde4f32a89acacb4417557f.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/08/b6225a308ad84d028c8a5f5326b0519b.png
[ba5fe794ed094b61a4195880947c706c.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/08/c2a81d2ee460422b89ec1a85f9b217a0.png