SpringBoot速成（12）文章分类P15-P20

1.新增文章分类

1.Postman登录不上，可以从头registe->login一个新的成员:注意，跳转多个url时，post/get/patch记得修改成controller类中对应方法上写的

2.postman运行成功：

但表中不更新：细节有问题：

c是小写

拼写错误

3.sql层报错，已运行到mapper层->controller层没有对参数校验

参数校验：

1.pojo层

2.controller层

运行后 ：

代码展示：

pojo:

package com.itheima.springbootconfigfile.pojo;import jakarta.validation.constraints.NotEmpty;
import lombok.Data;import java.time.LocalDateTime;
@Data
public class Category {private Integer id;//主键ID@NotEmptyprivate String categoryName;//分类名称@NotEmptyprivate String categoryAlias;//分类别名private Integer createUser;//创建人IDprivate LocalDateTime createTime;//创建时间private LocalDateTime updateTime;//更新时间@Overridepublic String toString() {return "Category{" +"id=" + id +", categoryName='" + categoryName + '\'' +", categoryAlias='" + categoryAlias + '\'' +", createUser=" + createUser +", createTime=" + createTime +", updateTime=" + updateTime +'}';}public Category() {}public Category(Integer id, String categoryName, String categoryAlias, Integer createUser, LocalDateTime createTime, LocalDateTime updateTime) {this.id = id;this.categoryName = categoryName;this.categoryAlias = categoryAlias;this.createUser = createUser;this.createTime = createTime;this.updateTime = updateTime;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getCategoryName() {return categoryName;}public void setCategoryName(String categoryName) {this.categoryName = categoryName;}public String getCategoryAlias() {return categoryAlias;}public void setCategoryAlias(String categoryAlias) {this.categoryAlias = categoryAlias;}public Integer getCreateUser() {return createUser;}public void setCreateUser(Integer createUser) {this.createUser = createUser;}public LocalDateTime getCreateTime() {return createTime;}public void setCreateTime(LocalDateTime createTime) {this.createTime = createTime;}public LocalDateTime getUpdateTime() {return updateTime;}public void setUpdateTime(LocalDateTime updateTime) {this.updateTime = updateTime;}
}

controller:

package com.itheima.springbootconfigfile.controller;import com.itheima.springbootconfigfile.pojo.Category;
import com.itheima.springbootconfigfile.pojo.Result;
import com.itheima.springbootconfigfile.service.CategoryService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;//文章分类
@RestController
@RequestMapping("/category")
public class CategoryController {@Autowiredprivate CategoryService categoryService;//新增文章分类@PostMapping("/add")public Result add(@RequestBody @Validated Category category){categoryService.add(category);return  Result.success();}}

categoryServiceIMpl:

package com.itheima.springbootconfigfile.service.impl;import com.itheima.springbootconfigfile.mapper.CategoryMapper;
import com.itheima.springbootconfigfile.pojo.Category;
import com.itheima.springbootconfigfile.service.CategoryService;
import com.itheima.springbootconfigfile.utils.ThreadLocalUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.time.LocalDateTime;
import java.util.Map;@Service
public class CategoryServiceImpl implements CategoryService {@Autowiredprivate CategoryMapper categoryMapper;@Overridepublic void add(Category category) {category.setCreateTime(LocalDateTime.now());category.setUpdateTime(LocalDateTime.now());Map<String,Object> map= ThreadLocalUtil.get();Integer userId= (Integer) map.get("id");category.setCreateUser(userId);//连接user表中的id，即userId=createUser=idcategoryMapper.add(category);}
}

categoryMapper:

package com.itheima.springbootconfigfile.mapper;import com.itheima.springbootconfigfile.pojo.Category;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;@Mapper
public interface CategoryMapper {@Insert("insert into category (categoryName,categoryAlias,createUser,createTime,updateTime) values (#{categoryName},#{categoryAlias},#{createUser},now(),now())")void add(Category category);
}

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2.文章分类列表（显示当前用户已有的所有文章分类）

代码展示：

controller：

 //文章分类列表@GetMapping()public  Result<List<Category>> list(){List<Category> cs=categoryService.list();return Result.success(cs);}

categoryServiceImpl:

 @Overridepublic List<Category> list() {Map<String,Object> map=ThreadLocalUtil.get();Integer userId= (Integer) map.get("id");return categoryMapper.list(userId);}

categoryMapper:

  @Select("select * from category where createUser=#{userId}")List<Category> list(Integer userId);

 createUser和userId:

运行：

优化：时间表达不是常规表达

对属性的限制可加在controller类的方法的参数上 或 实体类上

修改：

@Data
public class Category {private Integer id;//主键ID@NotEmptyprivate String categoryName;//分类名称@NotEmptyprivate String categoryAlias;//分类别名private Integer createUser;//创建人ID@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")private LocalDateTime createTime;//创建时间@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")private LocalDateTime updateTime;//更新时间

运行：

回忆下User类对属性的注解：

@Data
public class User {
    @NotNull
    private Integer id;//主键ID
    private String username;//用户名
    @JsonIgnore
    //当前对象转变为json字符串时，忽略password，最终的json 字符串就无password这个属性
    private String password;//密码
    @NotEmpty
    @Pattern(regexp = "^\\S{1,10}$")
    private String nickname;//昵称
    @NotEmpty
    @Email
    private String email;//邮箱

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3.获取文章分类详情 

代码展示：

controller:

  //获取文章详情@GetMapping("/detail")public Result<Category> detail(Integer id){Category c=categoryService.findById(id);return Result.success(c);}

categoryServiceImpl:

  @Overridepublic Category findById(Integer id) {Category c =categoryMapper.findById(id);return c;}

categoryMapper:

   @Select("select * from category where id=#{id}")Category findById(Integer id);

运行： 

可优化：category表和user表是联通的，但该方法没要求必须是本用户才可以查询文章分类详情，即可以查到其他用户的文章分类

但若以文章分类是公共的，也可以不限制

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4.更新文章分类 

代码展示：

//更新文章分类
@PutMapping("update")
public Result update(@RequestBody @Validated Category category){categoryService.update(category);return Result.success();
}

 @Overridepublic void update(Category category) {category.setUpdateTime(LocalDateTime.now());categoryMapper.update(category);}

 @Update("update category set categoryName=#{categoryName},categoryAlias=#{categoryAlias},updateTime=#{updateTime} where id=#{id}")void update(Category category);

 @NotNullprivate Integer id;//主键ID

运行：

postman修改后，idea重新运行才会成功

可优化：createUser=userId

思考：

为什么不能这样写：

@PutMapping("update")
public Result<Category> update(Integer id){Category c= categoryService.update(id);return Result.success(c);
}

 运行报错：

问题的核心在于 CategoryMapper.update 方法的返回类型不被 MyBatis 支持。MyBatis 对于 update、delete、insert 等操作的返回类型通常是 int，表示影响的行数，而不是返回一个 POJO 类型。 

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5.BUG修改 

bug描述：

第4中在category类增加了

再运行1.add，报错：