一步步学Mybatis-实现多表联合查询(4)

  上一章节中我们已经完成了对单表的CRUD操作,接下来今天这一讲讲述的是关于Mybatis在多表查询时候的应用,毕竟实际业务中也是多表的联合查询比较多嘛~

还记得最一开始我们新建过一张Website表吗,在那张表里有个VisitorId字段,,表示访问者访问过哪些网站,现在我们先按照上一张中的要求把关于Website的JavaBean实体先建立出来。

还是在david.mybatis.model包下面新建一个Website类,用来持久化数据之用,重写下相应toString()方法,方便测试程序之用。

package david.mybatis.model;import java.text.SimpleDateFormat;import java.util.Date;public class Website {private int id;private String name;private int visitorId;private int status;private Date createTime;private Visitor visitor;public Website() {// TODO Auto-generated constructor stubcreateTime = new Date();visitor = new Visitor();}public Website(String name, int visitorId) {this.name = name;this.visitorId = visitorId;visitor = new Visitor();status = 1;createTime = new Date();}public int getId() {return id;}public void setId(int id) {this.id = id;}public Visitor getVisitor() {return visitor;}public void setVisitor(Visitor visitor) {this.visitor = visitor;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getStatus() {return status;}public void setStatus(int status) {this.status = status;}public Date getCreateTime() {return createTime;}public void setCreateTime(Date createTime) {this.createTime = createTime;}public int getVisitorId() {int id = 0;if (visitor == null)id = visitorId;elseid = visitor.getId();return id;}public void setVisitorId(int visitorId) {this.visitorId = visitorId;}@Overridepublic String toString() {StringBuilder sb = new StringBuilder(String.format(“Website=> {Id:%d, Name:%s, CreateTime:%s}\r\n”, id, name,new SimpleDateFormat(“yyyy-MM-dd HH:mm:ss”).format(createTime)));if (visitor != null)sb.append(String.format(“Visitor=> %s”, visitor.toString()));return sb.toString();}}人生至少要有两次冲动,一为奋不顾身的爱情,一为说走就走的旅行。

一步步学Mybatis-实现多表联合查询(4)

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