java操作数据库增删改查的小工具2--TxQueryRunner

小编 2026-07-13 阅读:1974 评论:0

　　当涉及到多表查询时,如数据库中有两张表分别为t_person和t_address,表结构如下...

　　当涉及到多表查询时,如数据库中有两张表分别为t_person和t_address,表结构如下:

其中t_person的外键为t-address的主键aid,

新建两个javaBean类,Person 和 Address;设置属性名与数据库列名一致:

public class Person {    private String pid;    private String pname;    private int age;    private String sex;    private Address address;    //把Address作为Person的一个属性引入    public Address getAddress() {        return address;    }    public void setAddress(Address address) {        this.address = address;    }    public String getPid() {        return pid;    }    public void setPid(String pid) {        this.pid = pid;    }    public String getPname() {        return pname;    }    public void setPname(String pname) {        this.pname = pname;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    @Override    public String toString() {        return "Person [pid=" + pid + ", pname=" + pname + ", age=" + age                + ", sex=" + sex + ", address=" + address + "]";    }        }

public class Address {    private String aid;    private String province;    private String city;    private String district;    private String street;    public String getAid() {        return aid;    }    public void setAid(String aid) {        this.aid = aid;    }    public String getProvince() {        return province;    }    public void setProvince(String province) {        this.province = province;    }    public String getCity() {        return city;    }    public void setCity(String city) {        this.city = city;    }    public String getDistrict() {        return district;    }    public void setDistrict(String district) {        this.district = district;    }    public String getStreet() {        return street;    }    public void setStreet(String street) {        this.street = street;    }    @Override    public String toString() {        return "Address [aid=" + aid + ", province=" + province + ", city="                + city + ", district=" + district + ", street=" + street + "]";    }        }

测试方法如何下:

/**     * 一行结果集中包含了两张表的列     * 使用MapHandler来处理     * 1. 把结果集封装到map中     * 2. 使用map生成Person对象     * 3. 使用map生成address对象     * 4. 把两个实体对象建立关系     * @throws SQLException     */    @Test    public void testQuery6() throws SQLException {        String sql = "SELECT * FROM t_person p, t_address a WHERE p.aid=a.aid AND p.pid=?";        QueryRunner qr = new TxQueryRunner();        /*         * 1. 得到Map         */        Map map = qr.query(sql, new MapHandler(), "aaa");        /*         * 2. 把Map中部分数据封装到Person中         */        Person p = CommonUtils.toBean(map, Person.class);        /*         * 3. 把Map中部分数据封装到Address中         */        Address addr = CommonUtils.toBean(map, Address.class);        /*         * 4. 建立两个实体的关系         */        p.setAddress(addr);                System.out.println(p);    }