在线教育day-04 EasyExcel 课程管理

EasyExcel

简介

数据导入 减轻录入工作量 数据导出 统计信息归档 数据传输 异构系统之间数据传输

特点 使用简单、节省内存 从磁盘上一行行读取数据 逐个解析 将一行的解析结果以观察者的模式通知处理

1. 引入依赖

<dependencies>

    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>easyexcel</artifactId>
        <version>2.1.7</version>
    </dependency>

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>1.7.5</version>
    </dependency>

    <dependency>
        <groupId>org.apache.xmlbeans</groupId>
        <artifactId>xmlbeans</artifactId>
        <version>3.1.0</version>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.10</version>
    </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>

</dependencies>
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2. 创建一个实体类

实体类中的字段对应exel表的列名

@Data
public class ExcelStudentData {

    @ExcelProperty("姓名")
    private String name;

    @ExcelProperty("生日")
    private Date birthday;

    @ExcelProperty("薪资")
    private Double salary;

    /**
     * 忽略这个字段
     */
    @ExcelIgnore
    private String password;
}
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写Excel

public class ExcelWriteTest {

    /**
     * 最简单的写
     */
    @Test
    public void simpleWrite07() {

        String fileName = "d:/excel/01-simpleWrite-07.xlsx";
        // 这里 需要指定写用哪个class去写，然后写到第一个sheet，名字为模板 然后文件流会自动关闭
        EasyExcel.write(fileName, ExcelStudentData.class).sheet("模板").doWrite(data());
    }

    @Test
    public void simpleWrite03() {

        String fileName = "d:/excel/01-simpleWrite-03.xls";
        // 如果这里想使用03 则 传入excelType参数即可
        EasyExcel.write(fileName, ExcelStudentData.class).excelType(ExcelTypeEnum.XLS).sheet("模板").doWrite(data());
    }

    private List<ExcelStudentData> data(){
        List<ExcelStudentData> list = new ArrayList<>();

        //算上标题，做多可写65536行
        //超出：java.lang.IllegalArgumentException: Invalid row number (65536) outside allowable range (0..65535)
        for (int i = 0; i < 65535; i++) {
            ExcelStudentData data = new ExcelStudentData();
            data.setName("Helen" + i);
            data.setBirthday(new Date());
            data.setSalary(0.56);
            data.setPassword("123"); //即使设置也不会被导出
            list.add(data);
        }

        return list;
    }

}
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1. 指定写入列与自定义格式转换

为列配置index属性

@Data
public class ExcelStudentData {

    @ExcelProperty(value = "姓名")
    private String name;

    @DateTimeFormat("yyyy年MM月dd日HH时mm分ss秒")
    @ExcelProperty(value = "生日")
    private Date birthday;

    @NumberFormat("#.##%")//百分比表示，保留两位小数
    @ExcelProperty(value = "薪资")
    private Double salary;

    /**
     * 忽略这个字段
     */
    @ExcelIgnore
    private String password;
}
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读Excel

1. 创建监听器

@Slf4j
public class ExcelStudentDataListener extends AnalysisEventListener<ExcelStudentData> {

    /**
     * 每隔5条存储数据库，实际使用中可以3000条，然后清理list ，方便内存回收
     */
    private static final int BATCH_COUNT = 5;
    List<ExcelStudentData> list = new ArrayList<>();

    /**
     * 这个每一条数据解析都会来调用
     *
     * @param data
     *            one row value. Is is same as {@link AnalysisContext#readRowHolder()}
     * @param context
     */
    @Override
    public void invoke(ExcelStudentData data, AnalysisContext context) {
        log.info("解析到一条数据:{}", data);
        list.add(data);
        // 达到BATCH_COUNT了，需要去存储一次数据库，防止数据几万条数据在内存，容易OOM
        if (list.size() >= BATCH_COUNT) {
            log.info("存数据库");
            // 存储完成清理 list
            list.clear();
        }
    }

    /**
     * 所有数据解析完成了 都会来调用
     *
     * @param context
     */
    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {

        log.info("所有数据解析完成！");
    }

}
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2. 测试

public class ExcelReadTest {

    /**
     * 最简单的读
     */
    @Test
    public void simpleRead07() {

        String fileName = "d:/excel/01-simpleWrite-07.xlsx";
        // 这里默认读取第一个sheet
        EasyExcel.read(fileName, ExcelStudentData.class, new ExcelStudentDataListener()).sheet().doRead();
    }
    }
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课程管理列表

监听器

@Slf4j
@AllArgsConstructor
@NoArgsConstructor
public class ExcelSubjectDataListener extends AnalysisEventListener<ExcelSubjectData> {
    /**
     * 加上这是一个DAO，当然有业务逻辑这个也可以是一个service，当然如果不用存储这个对象没用
     */
    private SubjectMapper subjectMapper;

    /**
     * 根据分类名称查询这个一级分类是否存在
     * @param title
     * @return
     */
    private Subject getByTitle(String title) {

        QueryWrapper<Subject> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("title", title);
        queryWrapper.eq("parent_id", "0");//一级分类
        return subjectMapper.selectOne(queryWrapper);
    }

    /**
     * 根据分类名称和父id查询这个二级分类是否存在
     * @param title
     * @return
     */
    private Subject getSubByTitle(String title, String parentId) {

        QueryWrapper<Subject> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("title", title);
        queryWrapper.eq("parent_id", parentId);
        return subjectMapper.selectOne(queryWrapper);
    }

    /**
     * 遍历每一行的记录 这里每一条数据解析都会来调用
     * @param excelSubjectData
     * @param analysisContext
     */
    @Override
    public void invoke(ExcelSubjectData excelSubjectData, AnalysisContext analysisContext) {

        log.info("解析到一条记录: {}", excelSubjectData);
        //处理读取出来的数据
        String levelOneTitle = excelSubjectData.getLevelOneTitle();//一级标题
        String levelTwoTitle = excelSubjectData.getLevelTwoTitle();//二级标题

        //判断一级分类是否重复
        Subject subjectLevelOne = this.getByTitle(levelOneTitle);
        String parentId = null;
        if (subjectLevelOne == null){
            //将一级分类存入数据库
            Subject subject = new Subject();
            subject.setParentId("0");
            subject.setTitle(levelOneTitle);//一级分类名称
            subjectMapper.insert(subject);
            parentId = subject.getId();
        }else {
            parentId = subjectLevelOne.getId();
        }

        //判断二级分类是否重复
        Subject subjectLevelTwo = this.getSubByTitle(levelTwoTitle, parentId);
        if (subjectLevelTwo == null){
            //将二级分类存入数据库
            Subject subject = new Subject();
            subject.setTitle(levelTwoTitle);
            subject.setParentId(parentId);
            subjectMapper.insert(subject);//添加
        }
    }

    /**
     * 所有数据解析完成了，都会来调用
     * @param analysisContext
     */
    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {
        log.info("所有数据解析完成！");
    }

}
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SubjectCOntroller

@CrossOrigin
@Api(description = "课程类别管理")
@RestController
@RequestMapping("/admin/edu/subject")
@Slf4j
public class SubjectController {

    @Autowired
    private SubjectService subjectService;

    @ApiOperation(value = "Excel批量导入课程类别数据")
    @PostMapping("import")
    public R batchImport(
            @ApiParam(value = "Excel文件", required = true)
            @RequestParam("file") MultipartFile file) {

        try {
            InputStream inputStream = file.getInputStream();
            subjectService.batchImport(inputStream);
            return R.ok().message("批量导入成功");
        } catch (Exception e) {
            log.error(ExceptionUtils.getMessage(e));
            throw new GuliException(ResultCodeEnum.EXCEL_DATA_IMPORT_ERROR);
        }
    }
}
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service

@Transactional(rollbackFor = Exception.class)
@Override
public void batchImport(InputStream inputStream) {

    // 这里 需要指定读用哪个class去读，然后读取第一个sheet 文件流会自动关闭
    EasyExcel.read(inputStream, ExcelSubjectData.class, new ExcelSubjectDataListener(baseMapper))
        .excelType(ExcelTypeEnum.XLS).sheet().doRead();

}
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前端

import.vue

<template>
  <div class="app-container">
    <el-form label-width="120px">

      <el-form-item label="信息描述">

        <el-tag type="info">excel模版说明</el-tag>
        <el-tag>
          <i class="el-icon-download"/>
          <a :href="defaultExcelTemplate">点击下载模版</a>
        </el-tag>

      </el-form-item>

      <el-form-item label="选择Excel">
        <el-upload
          ref="upload"
          :auto-upload="false"
          :on-exceed="fileUploadExceed"
          :on-success="fileUploadSuccess"
          :on-error="fileUploadError"
          :limit="1"
          action="http://127.0.0.1:8001/admin/edu/subject/import"
          name="file"
          accept="application/vnd.ms-excel">
          <el-button
            slot="trigger"
            size="small"
            type="primary">选取文件</el-button>
          <el-button
            :disabled="importBtnDisabled"
            style="margin-left: 10px;"
            size="small"
            type="success"
            @click="submitUpload()">导入</el-button>
        </el-upload>

      </el-form-item>
    </el-form>
  </div>
</template>

<script>
export default {
  data() {
    return {
      defaultExcelTemplate: process.env.OSS_PATH + '/excel/课程分类列表模板.xls', // 默认Excel模板
      importBtnDisabled: false // 导入按钮是否禁用
    }
  },

  methods: {

    // 执行上传
    submitUpload() {
      this.importBtnDisabled = true // 禁用按钮
      this.$refs.upload.submit() // 手动表单提交
    },

    // 当选择文件超出约定数量时触发
    fileUploadExceed() {
      this.$message.warning('只能选取一个文件')
    },

    // 上传成功的回调
    fileUploadSuccess(response) {
      if (response.success) {
        this.importBtnDisabled = false // 启用按钮
        this.$message.success(response.message)
        this.$refs.upload.clearFiles() // 清空文件列表
      } else {
        this.$message.error('上传失败! （非20000）')
      }
    },

    // 上传失败的回调
    fileUploadError() {
      this.importBtnDisabled = false // 启用按钮
      this.$message.error('上传失败! （http失败）')
      this.$refs.upload.clearFiles() // 清空文件列表
    }
  }
}
</script>
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list.vue

<template>
  <div class="app-container">
    <el-input
      v-model="filterText"
      placeholder="输入查询条件"
      style="margin-bottom:30px;" />

    <el-tree
      ref="subjectTree"
      :data="subjectList"
      :props="defaultProps"
      :filter-node-method="filterNode"
      style="margin-top:10px;" />

  </div>
</template>

<script>
import subjectApi from '@/api/subject'
export default {

  data() {
    return {
      filterText: '', // 过滤文本
      subjectList: [], // 数据列表
      defaultProps: {// 属性列表数据属性的key
        children: 'children',
        label: 'title'
      }
    }
  },

  // 监听 filterText的变化
  watch: {
    filterText(val) {
      this.$refs.subjectTree.filter(val)// 调用tree的filter方法
    }
  },

  created() {
    this.fetchNodeList()
  },

  methods: {
    // 获取远程数据
    fetchNodeList() {
      subjectApi.getNestedTreeList().then(response => {
        this.subjectList = response.data.items
      })
    },

    // 过滤节点
    filterNode(value, data) {
      if (!value) return true
      return data.title.toLowerCase().indexOf(value.toLowerCase()) !== -1 // 忽略大小写
    }
  }
}
</script>

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subject.js

import request from '@/utils/request'

export default {
  getNestedTreeList() {
    return request({
      url: '/admin/edu/subject/nested-list',
      method: 'get'
    })
  }
}
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分类列表展示

vo

@Data
public class SubjectVo implements Serializable {

    private static final long serialVersionUID = 1L;

    private String id;
    private String title;
    private Integer sort;
    private List<SubjectVo> children = new ArrayList<>();
}
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controller

@ApiOperation(value = "嵌套数据列表")
@GetMapping("nested-list")
public R nestedList(){
    List<SubjectVo> subjectVoList = subjectService.nestedList();
    return R.ok().data("items", subjectVoList);
}
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实现

@Override
public List<SubjectVo> nestedList() {
    return baseMapper.selectNestedListByParentId("0");
}
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SubjectMapper.java

List<SubjectVo> selectNestedListByParentId(String parentId);
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SubjectMapper.xml

<resultMap id="nestedSubject" type="com.atguigu.guli.service.edu.entity.vo.SubjectVo">
    <id property="id" column="id"/>
    <result property="title" column="title"/>
    <result property="sort" column="sort" />
    <collection property="children"
                ofType="com.atguigu.guli.service.edu.entity.vo.SubjectVo"
                select="selectNestedListByParentId"
                column="id"/>
</resultMap>

<select id="selectNestedListByParentId" resultMap="nestedSubject">
    select id, sort, title from edu_subject where parent_id = #{parentId}
</select>
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如果报错Invalid bound statement (not found):

解决：

在pom中配置

<build>
    
    <!-- 项目打包时会将java目录中的*.xml文件也进行打包 -->
    <resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.xml</include>
            </includes>
            <filtering>false</filtering>
        </resource>
    </resources>
</build>
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配置文件中配置

mybatis-plus:
  mapper-locations: classpath:com/atguigu/guli/service/edu/mapper/xml/*.xml
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