MyBatis-Plus分页接口实现教程：Spring Boot中如何编写分页查询
1. 添加 MyBatis-Plus 依赖
在 pom.xml 文件中添加 MyBatis-Plus 的依赖：
xml
<!--mybatis-plus-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.5.3.1</version>
</dependency>Springboot只能使用3.1.5及以下版本！！！
2. 配置分页插件
在 Spring Boot 的配置类中添加分页插件的配置：
java
import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
//@MapperScan("com.example.demo.mapper")
public class MybatisPlusConfig {
/**
* 新增分页拦截器，并设置数据库类型为mysql
*
* @return
*/
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
return interceptor;
}
}3. 创建服务层接口
创建一个服务层接口，用于定义分页查询的方法：
java
@Service
public class UserServiceImpl implements UserService {
@Autowired
private UserMapper userMapper;
@Override
public Result listPageUser(@RequestParam Integer page, @RequestParam Integer pageSize) {
//分页参数
Page<UserEntity> rowPage = new Page<>(page, pageSize);
//queryWrapper组装查询where条件
LambdaQueryWrapper<UserEntity> queryWrapper = new LambdaQueryWrapper<>();
rowPage = userMapper.selectPage(rowPage, queryWrapper);
return Result.success("数据列表", rowPage);
}
}4. 创建控制器
创建一个控制器，用于处理 HTTP 请求并调用服务层的分页查询方法：
java
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserServiceImpl userServiceImpl;
@PostMapping("/listPage")
@Operation(summary = "列表分页")
public Result listPageUser(@RequestParam Integer page, @RequestParam Integer pageSize) {
return userServiceImpl.listPageUser(page, pageSize);
}
}5. 运行应用并测试
启动 Spring Boot 应用，并通过 Postman 或其他 API 测试工具发送 POST 请求到 /user/listPage 端点，传递 page 和 pageSize 参数，即可测试分页查询功能。
6.全部代码
java
import com.alibaba.excel.EasyExcel;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.common.req.IdParam;
import com.example.common.resp.Result;
import com.example.system.entity.UserEntity;
import com.example.system.mapper.UserMapper;
import com.example.system.resp.LoginResp;
import com.example.system.service.UserService;
import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.tags.Tag;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Objects;
/**
* <p>
* 用户表 前端控制器
* </p>
*
* @author he
* @since 2024-03-23
*/
@Tag(name = "用户")
@RestController
@RequestMapping("/userEntity")
public class UserController {
@Autowired
private UserMapper userMapper;
@Autowired
private UserService userService;
private final String id = "User_id";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
@Operation(summary = "列表")
@PostMapping("/list")
public Result listUser() {
return Result.success("数据列表", userService.list());
}
@Operation(summary = "存在")
@PostMapping("/exist")
public Result existUser(@RequestBody @Validated IdParam param) {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq(id.toLowerCase(Locale.ROOT), param.getId());
long count = userService.count(wrapper);
if (count == 0) return Result.success("ID不存在", false);
return Result.success("ID已存在", true);
}
@Operation(summary = "保存")
@PostMapping("/insert")
public Result insertUser(@RequestBody @Validated UserEntity param) {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq(id.toLowerCase(Locale.ROOT), param.getId());
if (userService.count(wrapper) != 0) return Result.failure("ID已存在", sdf.format(new Date()));
if (userService.save(param)) return Result.success("保存成功", sdf.format(new Date()));
return Result.failure("保存失败", sdf.format(new Date()));
}
@Operation(summary = "删除")
@PostMapping("/delete")
public Result deleteUser(@RequestBody @Validated IdParam param) {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq(id.toLowerCase(Locale.ROOT), param.getId());
if (userService.count(wrapper) == 0) return Result.failure("ID不存在", param.getId());
if (userService.remove(wrapper)) return Result.success("删除成功", param.getId());
return Result.failure("删除失败", param.getId());
}
@Operation(summary = "修改")
@PostMapping("/update")
public Result updateUser(@RequestBody @Validated UserEntity param) {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq(id.toLowerCase(Locale.ROOT), param.getId());
if (userService.count(wrapper) == 0) return Result.failure("ID不存在", sdf.format(new Date()));
if (userService.updateById(param)) return Result.success("修改成功", sdf.format(new Date()));
return Result.failure("修改失败", sdf.format(new Date()));
}
@Operation(summary = "查询")
@PostMapping("/select")
public Result selectUser(@RequestBody @Validated IdParam param) {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq(id.toLowerCase(Locale.ROOT), param.getId());
if (userService.count(wrapper) == 0) return Result.failure("ID不存在", param.getId());
return Result.success(userService.getOne(wrapper));
}
@Operation(summary = "查询byAcc")
@PostMapping("/selectByAcc/{param}")
public Result selectUserByAcc(@PathVariable @Validated String param) {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
String acc = "User_acc";
wrapper.eq(acc.toLowerCase(Locale.ROOT), param);
if (userService.count(wrapper) == 0) return Result.failure("账号不存在", sdf.format(new Date()));
return Result.success(userService.getOne(wrapper));
}
@Operation(summary = "列表分页")
@PostMapping("/listPage")
public Result listPageUser(@RequestParam Integer page, @RequestParam Integer pageSize) {
//分页参数
Page<UserEntity> rowPage = new Page(page, pageSize);
//queryWrapper组装查询where条件
LambdaQueryWrapper<UserEntity> queryWrapper = new LambdaQueryWrapper<>();
rowPage = userMapper.selectPage(rowPage, queryWrapper);
return Result.success("数据列表", rowPage);
}
@Operation(summary = "导出数据")
@PostMapping("exportExcel")
public void exportExcelUser(HttpServletResponse response) throws IOException {
response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
response.setCharacterEncoding("utf-8");
String fileName = URLEncoder.encode("轮播图", StandardCharsets.UTF_8).replaceAll("\\+", "%20");
List<UserEntity> list = userService.list();
response.setHeader("Content-disposition", "attachment;filename*=" + fileName + ".xlsx");
EasyExcel.write(response.getOutputStream(), UserEntity.class).sheet("轮播图").doWrite(list);
}
@Operation(summary = "导入数据")
@PostMapping("/importExcel")
public Result importExcelUser(MultipartFile file) {
try {
//获取文件的输入流
InputStream inputStream = file.getInputStream();
List<UserEntity> list = EasyExcel.read(inputStream) //调用read方法
//注册自定义监听器，字段校验可以在监听器内实现
//.registerReadListener(new UserListener())
.head(UserEntity.class) //对应导入的实体类
.sheet(0) //导入数据的sheet页编号，0代表第一个sheet页，如果不填，则会导入所有sheet页的数据
.headRowNumber(1) //列表头行数，1代表列表头有1行，第二行开始为数据行
.doReadSync();//开始读Excel，返回一个List<T>集合，继续后续入库操作
//模拟导入数据库操作
for (UserEntity entity : list) {
userService.saveOrUpdate(entity);
}
return Result.success("导入成功", sdf.format(new Date()));
} catch (IOException exception) {
throw new RuntimeException(exception);
}
}
}