使用Jorm处理特殊字段

> 引言
有时候我们有这样的需求，对象有一个属性可能有多个值，需要在数据库中作为一个字段存储

还是以User为例，career存储多个职业

> 建表
以MySQL为例，执行下面的sql建立数据表
CREATE TABLE `t_user` (               
        `id` int(11) NOT NULL,              
        `name` varchar(50) DEFAULT NULL,    
        `sex` char(4) DEFAULT NULL,         
        `age` int(11) DEFAULT NULL,         
        `career` varchar(100) DEFAULT NULL, 
        PRIMARY KEY (`id`)                  
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

> 代码
实体类 User.java
@Entity(table = "t_user")
@PK(value = "id")
public class User implements Serializable {

    /** desc */
    private static final long serialVersionUID = -4750351638245912867L;

    @Id
    private int id;

    private String name;

    private String sex;

    private Integer age;

    @Basic(processor=DefinedFieldProcessor.class)
    private String[] career;

    @NoColumn
    private int kvalue;

    public JawaUser() {
        super();
    }

    public JawaUser(String name, String sex, Integer age, String[] career) {
        super();
        this.name = name;
        this.sex = sex;
        this.age = age;
        this.career = career;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

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

    public Integer getAge() {
        return age;
    }

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

    public String[] getCareer() {
        return career;
    }

    public void setCareer(String[] career) {
        this.career = career;
    }

    public int getKvalue() {
        return kvalue;
    }

    public void setKvalue(int kvalue) {
        this.kvalue = kvalue;
    }

    public String toString() {
        return "User [age=" + age + ", career=" + Arrays.toString(career)
                + ", id=" + id + ", kvalue=" + kvalue + ", name=" + name
                + ", sex=" + sex + "]";
    }
}


属性字段处理类 DefinedFieldProcessor.java

import java.lang.reflect.Field;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.javaclub.jorm.Session;
import org.javaclub.jorm.common.CommonUtil;
import org.javaclub.jorm.common.Reflections;
import org.javaclub.jorm.jdbc.process.FieldProcessor;

public class DefinedFieldProcessor implements FieldProcessor {

    public Object insert(Session session, Object entity, Field field) {
        String[] crs = (String[]) Reflections.getFieldValue(entity, field);
        if(!CommonUtil.isEmpty(crs)) {
            StringBuilder sbf = new StringBuilder();
            for (int i = 0; i < crs.length; i++) {
                if(i > 0) {
                    sbf.append(",");
                }
                sbf.append(crs[i]);
            }
            return sbf.toString();
        }
        return "";
    }

    public void load(Session session, Object entity, Field field, ResultSet rs,
            int idx) throws SQLException {
        String str = rs.getString(idx);
        String[] crs = str.split(",");
        Reflections.setFieldValue(entity, field, crs);
    }

}

> 测试

import org.javaclub.jorm.Jorm;
import org.javaclub.jorm.Session;
import org.javaclub.jorm.common.Numbers;
import org.javaclub.jorm.common.Strings;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

public class FieldProcessorTest {

    static Session session;

    @BeforeClass
    public static void setUpBeforeClass() {
        session = Jorm.getSession();
    }

    @AfterClass
    public static void destroy() {
        Jorm.free();
    }

    @Test
    public void test_save() {

        session.clean(User.class);
        User u;
        for (int i = 0; i < 100; i++) {
            String sex = (i % 2 == 0 ? "男" : "女");
            String[] cr = {};
            if(i % 3 == 0) {
                cr = new String[] {Strings.fixed(2), Strings.random(5), Strings.fixed(6)};
            } else if(i % 3 == 1) {
                cr = new String[] {Strings.fixed(2), Strings.random(5)};
            } else {
                cr = new String[] {Strings.fixed(2)};
            }
            u = new User(Strings.fixed(6), sex, Numbers.random(100), cr);
            session.save(u);
        }

        for (int i = 0; i < 10; i++) {
            u = session.read(User.class, i + 1);
            System.out.println(u);
        }
    }
}

Jorm项目地址：http://javaclub.sourceforge.net/jorm.html