ibatis多对一表关联映射的解决过程
1、问题：当查询新闻的时候我们一般情况下需要新闻的类型以及作者的信息。根据表设计的规范我们要把文章，文章类型，作者信息分别设计成一张表，其中文章中分别存在指向文章类型和作者信息的外键。我们的问题就是怎么使用ibatis把表空间数据映射为java的实体类属性。
2、表DDL，
用户表
CREATE TABLE `users` (
`id` int(11) NOT NULL auto_increment,
`username` varchar(25) default NULL,
’password` varchar(32) default NULL,
`gender` int(11) default '1',
`birth` date default NULL,
`user_type` int(11) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;
文章类型表
CREATE TABLE `article_class` (
`acid` int(11) NOT NULL auto_increment,
`name` varchar(25) default NULL,
`class_desc` varchar(255) default NULL,
PRIMARY KEY (`acid`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;
文章表
CREATE TABLE `article` (
`aid` int(11) NOT NULL auto_increment,
`title` varchar(36) default NULL,
`content` text,
`classid` int(11) default NULL,
`userid` int(11) default NULL,
PRIMARY KEY (`aid`),
KEY `classid` (`classid`),
KEY `userid` (`userid`),
CONSTRAINT `article_ibfk_1` FOREIGN KEY (`classid`) REFERENCES `article_class` (`acid`),
CONSTRAINT `article_ibfk_2` FOREIGN KEY (`userid`) REFERENCES `users` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;
3、实体类
import java.sql.Date;public class User {private Integer id;private String username;private String password;private int gender;private Date birth;private int userType = 1;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public int getGender() {return gender;}public void setGender(int gender) {this.gender = gender;}public Date getBirth() {return birth;}public void setBirth(Date birth) {this.birth = birth;}public int getUserType() {return userType;}public void setUserType(int user_type) {this.userType = user_type;}}文章类型类public class ArticleClass {private Integer id;private String name;private String desc;public ArticleClass() {}public ArticleClass(int id) {this.id = id;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getDesc() {return desc;}public void setDesc(String desc) {this.desc = desc;}}文章类public class Article {private Integer id;//private int classid;//private int userid;private String title;private String content;private ArticleClass articleClass;private User user;public Article() {}/*public int getClassid() {return classid;}public void setClassid(int classid) {this.classid = classid;}public int getUserid() {return userid;}public void setUserid(int userid) {this.userid = userid;}*/public Article(String title, String content) {this.title = title;this.content = content;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getTitle() {return title;}public void setTitle(String title) {this.title = title;}public String getContent() {return content;}public void setContent(String content) {this.content = content;}public ArticleClass getArticleClass() {return articleClass;}public void setArticleClass(ArticleClass articleClass) {this.articleClass = articleClass;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}}