Mybatis第三讲——关联一对一（1）

Dear 丶 2022-03-17 15:25 149阅读 0赞

[Mybatis第二讲——熟悉使用XML配置SQL映射器][Mybatis_XML_SQL]

这讲主要是针对两张表，一张学生信息表t\_student，一张地址表t\_address：

![20190225095606356.png][]

![20190225095620641.png][]

t\_student中的addressId字段对应于t\_address中的id，但是两张表之间并没有物理上的关联。我们只是人为的把字段添加上去了而已。

工程结构：

![20190225094744990.png][]

与第二讲相比，增加了model下的Address.java 文件：

package com.java1234.model;
    
    public class Address {
    
    	private Integer id;
    	private String sheng;
    	private String shi;
    	private String qu;
    	
    	
    	public Integer getId() {
    		return id;
    	}
    	public void setId(Integer id) {
    		this.id = id;
    	}
    	public String getSheng() {
    		return sheng;
    	}
    	public void setSheng(String sheng) {
    		this.sheng = sheng;
    	}
    	public String getShi() {
    		return shi;
    	}
    	public void setShi(String shi) {
    		this.shi = shi;
    	}
    	public String getQu() {
    		return qu;
    	}
    	public void setQu(String qu) {
    		this.qu = qu;
    	}
    	@Override
    	public String toString() {
    		return "Address [id=" + id + ", sheng=" + sheng + ", shi=" + shi + ", qu=" + qu + "]";
    	}
    	
    	
    }

StudentMapper.java中新增接口:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lvbmdidXRpbmd4aWRl_size_16_color_FFFFFF_t_70][]

StudentMapper.xml中新增如下代码段：

<resultMap type="Address" id="addressResult">
    	 <result property="id" column="id"/>
    		<result property="sheng" column="sheng"/>
    		<result property="shi" column="shi"/>
    		<result property="qu" column="qu"/> 
    	</resultMap>
    	
    	<resultMap type="Student" id="StudentResult">
    		<id property="id" column="id"/>
    		<result property="name" column="name"/>
    		<result property="age" column="age"/>
    		
    		
    		
    		<association property="address" resultMap="addressResult"/>
    	</resultMap> 
    	
    	<select id="getAllStudents" resultMap="StudentResult">
    	select * from t_student 
    	</select>
    	
    	<select id="findStudentWithAddress" resultMap="StudentResult" parameterType="Integer">
    	select * from t_student t1,t_address t2 where t1.addressId=t2.id and t2.id=#{id} 
    	</select>

测试：

![20190225095438171.png][]

输出结果：

![20190225095505274.png][]

[Mybatis_XML_SQL]: https://blog.csdn.net/yongbutingxide/article/details/86538422
[20190225095606356.png]: /images/20220317/221c377d2a244831ae65b590983ac7ad.png
[20190225095620641.png]: /images/20220317/0f7791fd850b43d280120d143c6a0bc5.png
[20190225094744990.png]: /images/20220317/ffacd88e51474ee88e280196b52646e3.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lvbmdidXRpbmd4aWRl_size_16_color_FFFFFF_t_70]: /images/20220317/f2d5cc021d9c469ebfa52012fa0390c1.png
[20190225095438171.png]: /images/20220317/80b615a7966b4e7b9121aa18e5a266b9.png
[20190225095505274.png]: /images/20220317/c46f22eac81941e29196f976c6763efb.png