Mybatis中的一对一查询

前期准备

建立用户信息user和账户表account，并设置外键

建立账户account和用户user实体类

public class User implements Serializable {
    private Integer id;
    private String nam;
    private String sex;
    private String address;
    private Integer age;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", nam='" + nam + '\'' +
                ", sex='" + sex + '\'' +
                ", address='" + address + '\'' +
                ", age=" + age +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getNam() {
        return nam;
    }

    public void setNam(String nam) {
        this.nam = nam;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

public class Account implements Serializable {
    private Integer id;
    private Integer uid;
    private Double money;

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", uid=" + uid +
                ", money=" + money +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public Double getMoney() {
        return money;
    }

    public void setMoney(Double money) {
        this.money = money;
    }
}

一对一查询目标：查询账户表中所有信息，以及对应的用户信息。

查询方式一：

定义AccountUser类，如下：

public class AccountUser extends Account{
    private String nam;
    private String address;

    @Override
    public String toString() {
        return super.toString() + "AccountUser{" +
                "nam='" + nam + '\'' +
                ", address='" + address + '\'' +
                '}';
    }

    public String getNam() {
        return nam;
    }

    public void setNam(String nam) {
        this.nam = nam;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

定义IAccountDao接口

重新定义配置文件IAccountDao.xml

测试：

 查询方式二：

在账户实体类中添加User属性，并重新生成 toString() 方法

定义IAccountDao接口方法：

重新定义配置文件 IAccountDao.xml：

测试：