SpringBoot中的查询以及分页查询操作

1.查询用户操作

1.1dao层文件

    //通过用户名查询
    User queryUserByUserName(String userName);

    //通过id进行查询
    User queryById(Integer id);

1.2service层

    /*查询用户ByName*/
    public User queryUserByUserName(String userName){
        return userMapper.queryUserByUserName(userName);
    }

    /*查询用户ById*/
    public User queryUserById(Integer id){
        return userMapper.queryById(id);
    }

1.3controller层

 @GetMapping("/user/{userName}")
    public User queryUserByUserName(@PathVariable String userName){
        return  userService.queryUserByUserName(userName);
    }
    @GetMapping("/user/id/{id}")
    public User queryUserById(@PathVariable Integer id){
        return userService.queryUserById(id);
    }

2.分页查询

2.1新建分页类UserQuery

package org.example.springboot.query;

public class UserQuery {
    private Integer pageNum=1;//当前页
    private Integer pageSize=10;//每页显示的数量
    //条件参数
    private String userName;

    public Integer getPageNum() {
        return pageNum;
    }

    public void setPageNum(Integer pageNum) {
        this.pageNum = pageNum;
    }

    public Integer getPageSize() {
        return pageSize;
    }

    public void setPageSize(Integer pageSize) {
        this.pageSize = pageSize;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }
}

2.2dao层文件（这里是查询的对象是User,方法中的传入的类是UserQuery）

//通过条件分页查询
    List<User> queryUserByParams(UserQuery userQuery);

2.3service层文件(这里返回的是pageinfo对象)

 /*分页查询*/
    public PageInfo<User> queryUserByParams(UserQuery userQuery){
        return new PageInfo<User>(userMapper.queryUserByParams(userQuery));
    }

2.4controller层对象

 @GetMapping("/user/list")
    public PageInfo<User> queryUserByParams(UserQuery userQuery){
        return userService.queryUserByParams(userQuery);
    }