参数在前台通过对象的形式传递到后台,在后台,可以用@RequestBody注解通过Map或JSONObject接收(太麻烦,既要从Map中取值,取完值后又要封装到Map),也可以用@RequestParam注解通过具体的属性接收。在dao层可以通过Map将参数传递到mapper.xml,也可以用@Param注解将具体的属性值传递到Mapper.xml。

@RequestParam语法:

语法:@RequestParam(value=”参数名”,required=”true/false”,defaultValue=””)

1、value:参数名,

2、required:是否包含该参数,默认为true,表示该请求路径中必须包含该参数,如果不包含就报错。

示例:如果像下面这样写,当你清空(点击X号)省市区划时,会触发change事件,

<el-select v-model="listQuery.provinceCode" style="width: 160px;" placeholder="请选择省" @change="provinceChange" filterable clearable>
            <el-option v-for="item in provinceList" :key="item.id" :label="item.chiShortName"
                       :value="item.id" />
          </el-select>

provinceChange方法:

//根据省查询市
    provinceChange(value) {
      console.log(value)
      if (this.listQuery.cityCode != undefined) {
        this.listQuery.cityCode = '';
      };
      if (this.listQuery.areaCode != undefined) {
        this.listQuery.areaCode = '';
      };
      const query = { 'pid': value }
      area.selectCityByPid(query).then(response => {
        console.log(response)
        this.cityList = response.data;
      });
    },

由于pid值为空,故会报错。

@RequestMapping("/selectCity")
    public Result findAreasByPCity(@RequestParam(name = "pid") String pid) {
        return areaCodeService.findCityByPid(pid);
    }

故修改如下:

@RequestMapping("/selectCity")
    public Result findAreasByPCity(@RequestParam(name = "pid", required = false) String pid) {
        return areaCodeService.findCityByPid(pid);
    }

3、defaultValue:默认参数值,如果没有传该参数,就使用默认值

 @RequestParam(name = "page", defaultValue = "1") int pageIndex,

在写接口时:加或不加@RequestParam注解的区别:

加@RequestParam为必传,因为required值默认是true,所以默认必传。可以通过@RequestParam(required = false)设置为非必传。

不加@RequestParam为非必传。

实例如下:

@PostMapping("/list")
    @ResponseBody
    public Result getCompanyInfoList(@RequestParam Integer page, Integer limit, String enterpiseType,
                                     String enterpriseName, String enterpiseCode, String organizationCode) {
        Result rs = new Result();
        try{

            PageHelper.startPage(page, limit);
            List<Map<String, Object>> select = enterpriseService.queryEnterpriseList(enterpiseType, enterpriseName, enterpiseCode, organizationCode, 0, limit);
            PageInfo p = new PageInfo<>(select);
            rs.setData(p);
            rs.setCode(ResultCode.SUCCESS);

        }catch (Exception e){
            rs.setCode(ResultCode.FAILURE);
            logger.error(e.getMessage());
        }
        return rs;
    }

只有page为必传,其他都为非必传。

前端代码:

前端传递给后台一个对象。

data() {
    return {
      listQuery: {
        page: 1,
        limit: 20,
        dataCode: null,
        dataName: null,
        // enterpriseId: null,
        enterpriseType: null
      },
  },
getList() {
      this.listLoading = true
      dataSet.getList(this.listQuery).then(response => {
        if (response.success) {
          this.list = response.data
          this.total = response.total
        } else {
          this.$message.error("数据集合信息获取失败")
        }
      }).catch(error => {
        console.log(error)
        this.$message.error("发生内部错误,请联系管理员")
      }).finally(() => {
        this.listLoading = false
      })
    },
getList(query) {
    return request({
      url: '/dataSet/list',
      method: 'post',
      params: query
    })
  },

后台代码:

controller:

controller用@RequestParam注解接收单个属性

@RestController
@RequestMapping("api/dataSet")
@Validated
public class DataSetController {
    private static Logger logger = LoggerFactory.getLogger(DataSetController.class);

    @Autowired
    private DataSetService dataSetService;
    @PostMapping("/list")
    public Result getDataSetList(
            @RequestParam(required = false) String dataCode,
            @RequestParam(required = false) String dataName,
            @RequestParam(name = "page", defaultValue = "1") int pageIndex,
            @RequestParam(name = "limit", defaultValue = "10") int length
    ) {
        return dataSetService.getDataSetList(dataCode, dataName, pageIndex, length);
    }
}

也可以用Map或JSONObject接收前端传递过来的整个对象

@RestController
@RequestMapping(
"api/dataSet") @Validated public class DataSetController { private static Logger logger = LoggerFactory.getLogger(DataSetController.class); @Autowired private DataSetService dataSetService; @PostMapping("/list") public Result getDataSetList(@RequestBody Map map ) {
      String dataCode = (String) map.get("dataCode");
      String dataName = (String) map.get("dataName");
      Integer pageIndex = (Integer) map.get("pageIndex");
      Integer length = (Integer) map.get("length");
      return dataSetService.getDataSetList(dataCode, dataName, pageIndex, length); } }
@RestController
@RequestMapping("api/dataSet")
@Validated
public class DataSetController {
    private static Logger logger = LoggerFactory.getLogger(DataSetController.class);

    @Autowired
    private DataSetService dataSetService;
    @PostMapping("/list")
    public Result getDataSetList(@RequestBody JSONObject map ) {
      String dataCode = map.getString("dataCode");
      String dataName = map.getString("dataName");
      Integer pageIndex = map.getIntValue("pageIndex");
      Integer length = map.getIntValue("length");
      return dataSetService.getDataSetList(dataCode, dataName, pageIndex, length); } }

service:

service中可以将参数封装到Map中再传递到dao层,即使是controller层用Map接收,service层中也要从Map中取值。

public Result getDataSetList(String dataCode, String dataName, int pageIndex, int length) {
Map map = new HashMap();
map.put("dataCode", dataCode);
map.put("dataName", dataName);
PageHelper.startPage(pageIndex, length);
List<Map> dataSetList = dataSetMapper.selectDataSetList(map);
PageInfo pageInfo = new PageInfo(dataSetList);
return Result.operating("数据集合查询成功", true, Result.SUCCESS, pageInfo.getList(), (int) pageInfo.getTotal(), pageInfo.getPages());
}

service中也可以直接将参数分别传递到dao层

public Result getDataSetList(String dataCode, String dataName, int pageIndex, int length) {
    PageHelper.startPage(pageIndex, length);
    List<Map> dataSetList = dataSetMapper.selectDataSetList(dataCode,dataName);
    PageInfo pageInfo = new PageInfo(dataSetList);
    return Result.operating("数据集合查询成功", true, Result.SUCCESS, pageInfo.getList(), (int) pageInfo.getTotal(), pageInfo.getPages());
}

dao层:

官方介绍如果你的映射方法接受多个参数,就可以使用这个注解自定义每个参数的名字。否则在默认情况下,除RowBounds以外的参数会以 "param" 加参数位置被命名。例如 #{param1}#{param2}。如果使用了 @Param("person"),参数就会被命名为 #{person}

@Param(该注解属于MyBatis)作为Dao层的注解,作用是用于传递参数,从而可以与SQL中的的字段名相对应,一般在2=<参数数<=5时使用最佳。

使用方式:

1.传递单个参数时,不需要使用@Param,因为传进去一个值,也只有一个参数与之匹配(当然也可以用@Param)。

2.传递多个参数时,使用@Param可以进行参数的绑定(当然也可以不用,可以封装JavaBean或者使用Map传值)。

@Param注解的作用是给参数命名,参数命名后就能根据名字得到参数值,正确的将参数传入sql语句中。

(1)、如果service中将参数封装到Map中再传递到dao层,则dao层用Map

public interface DataSetMapper extends Mapper<DataSet> {
    List<Map> selectDataSetList(Map map);
}

(2)、如果service中直接将参数分别传递到dao层,则用@Param注解接收

public interface DataSetMapper extends Mapper<DataSet> {
    List<Map> selectDataSetList(@Param("dataCode") String dataCode,@Param("dataName") String dataName); }

mapper.xml:

<select id="selectDataSetList" resultType="java.util.Map">
SELECT
t1.id AS "dataId",
t1.data_code AS "dataCode",
t1.data_name AS "dataName",
t1.remark AS "remark",
t2.id AS "enterpriseDataSetId",
t3.id AS "enterpriseId",
t3.enterprise_name AS "enterpriseName"
FROM
sys_data_set t1
LEFT JOIN sys_enterprise_data_set t2 ON t1.id = t2.data_id
LEFT JOIN sys_enterprise t3 ON t2.enterprise_id = t3.id
WHERE 1=1 AND t1.status=0
<if test="dataCode!=null and dataCode!=''">
AND t1.data_code LIKE '%'||#{dataCode}||'%'
</if>
<if test="dataName!=null and dataName!=''">
AND t1.data_name LIKE '%'||#{dataName}||'%'
</if>
<if test="enterpriseId!=null and enterpriseId!=''">
AND t3.del_flag = 0
AND t3.id=#{enterpriseId}
</if>
ORDER BY t1.id DESC
</select>

使用@Param给参数命名为其他名字

List<Menu> getMenuList(@Param("menuId") Integer parentId);

mapper.xml

<select id="getMenuList" resultMap="result_SysMenu_Map">
        select * from sys_menu
        <if test="menuId != null and  menuId !=''  ">where parent_id=#{menuId}</if>
        <if test="menuId == null or  menuId ==''  ">where parent_id =0</if>
        order by order_num
    </select>

(3)、不使用@Param注解时,最好传递 Javabean。在SQL语句里就可以直接引用JavaBean的属性,而且只能引用JavaBean存在的属性。

Mapper接口方法:

public int getUsersDetail(User user);

对应Sql Mapper.xml文件:

<!--这里直接引用对象属性即可,不需要对象.属性的方式--> 
<select id="getUserDetail" statementType="CALLABLE" resultMap="baseMap">
          Exec WebApi_Get_CustomerList #{userid}
</select>

 

posted on 2020-10-30 16:04  周文豪  阅读(13757)  评论(0编辑  收藏  举报