jpa 多对多关系的实现注解形式

1， 表结构

　　1）设备表 VTM_DEVICE_INFO

create table VTM_DEVICE_INFO
(
  ID                 INTEGER not null,
  SN                 VARCHAR2(32) not null,
  STATUS             INTEGER,
  MEMO               VARCHAR2(256),
  DEVICE_NO          INTEGER,
  START_TIME         TIMESTAMP(6),
  END_TIME           TIMESTAMP(6),
  FACTORY            INTEGER,
  DEVICE_IN_DATE     TIMESTAMP(6),
  ISAFEDOOR_POSITION INTEGER,
  AUDIT_FLAG         VARCHAR2(1)
);
alter table VTM_DEVICE_INFO
  add constraint PK_VTM_DEVICE_INFO primary key (ID);

　　2）模块表 VTM_MODULE_DEFINE

create table VTM_MODULE_DEFINE
(
  ID          INTEGER not null,
  MODULE_NAME VARCHAR2(50) not null
);
alter table VTM_MODULE_DEFINE
  add constraint PK_VTM_MODULE_DEFINE primary key (ID);

　　3）设备模块关系表 VTM_DEVICE_MODULE

create table VTM_DEVICE_MODULE
(
  DEVICE_ID INTEGER not null,
  MODULE_ID INTEGER not null
)
;
alter table VTM_DEVICE_MODULE
  add constraint FK_VTM_DEVI_REF_DEVIC_VTM_DEVI foreign key (DEVICE_ID)
  references VTM_DEVICE_INFO (ID);
alter table VTM_DEVICE_MODULE
  add constraint FK_VTM_DEVI_REF_DEVIC_VTM_MODU foreign key (MODULE_ID)
  references VTM_MODULE_DEFINE (ID);

　　4）初始化模块表数据

insert into VTM_MODULE_DEFINE (ID, MODULE_NAME) values (1, '读卡器');
insert into VTM_MODULE_DEFINE (ID, MODULE_NAME) values (2, '密码键盘');
insert into VTM_MODULE_DEFINE (ID, MODULE_NAME) values (3, '取款模块');
insert into VTM_MODULE_DEFINE (ID, MODULE_NAME) values (4, '存款模块');

　　5）数据库中要到的序列

create sequence DEVICE_INFO_SEQ
minvalue 1
maxvalue 9999999999
start with 101
increment by 1
cache 20;

create sequence DEVICE_MODULE_SEQ
minvalue 1
maxvalue 9999999999
start with 1
increment by 1
cache 20;

　　设备表 与 模块表 之间是多对多的关系，关系表为 设备模块表

2，实体类采用注解的形式，体现他们之间的关系

package opstools.vtm.device.entity;

import java.io.Serializable;
import java.util.Date;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.ManyToOne;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;/**
 * 设备实体类
 * @author yangw
 */
@Entity
@Table(name = "VTM_DEVICE_INFO")
@SequenceGenerator(name = "deviceInfoSeq", sequenceName = "DEVICE_INFO_SEQ")
public class DeviceInfo implements Serializable {

    private static final long serialVersionUID = -6964820074623402896L;

    @Id
    @Column(name="ID")
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "deviceInfoSeq")
    private Integer deviceId;          //设备Id
    
    @Column
    private String sn;                 //序号
    @Column
    private Integer status;          //设备使用状态
    
    @Column
    private Integer branchId;
    
    @Column
    private String memo;             //备注信息
    @Column
    private Integer deviceNo;        //设备型号

    @Temporal(TemporalType.TIMESTAMP)
    @Column
    private Date startTime;         //开始使用时间
    @Temporal(TemporalType.TIMESTAMP)
    @Column
    private Date endTime;            //设备终止时间
    @Column
    private Integer factory;        //设备厂商
    @Temporal(TemporalType.TIMESTAMP)
    @Column
    private Date deviceInDate;        //设备增加时间
    @Column
    private Integer isafedoorPosition;    //开门方向
    @Column
    private Integer auditFlag;        //审核标志

    @ManyToMany(cascade=CascadeType.PERSIST)     
    @JoinTable(name = "VTM_DEVICE_MODULE", joinColumns = {@JoinColumn(name = "deviceId")},inverseJoinColumns=@JoinColumn(name="MODULE_ID"))
    private Set<ModuleDefine> moduleDefine;  
    
      //get set 省略
}

package opstools.vtm.device.entity;

import java.io.Serializable;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;

/**
 * 设备模块表
 * @author yangw
 */
@Entity
@Table(name = "VTM_MODULE_DEFINE")
@SequenceGenerator(name = "moduleDefineSeq", sequenceName = "MODULE_DEFINE_SEQ")
public class ModuleDefine implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @Column(name="ID")
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "moduleDefineSeq")
    private Integer moduleId;          //模块Id
    
    @Column
    private String moduleName;         //模块名称

    @ManyToMany(mappedBy = "moduleDefine")  
    private Set<DeviceInfo> deviceInfo;  
    
    //省略 get set 这个类可能不需要再写@ManyToMany来维护关系，因为这个表的数据是初始化好的，不需要修改， 具体没有测试.
    
}

3, dao层的实现，就是将 设备添加到数据库

@Override
    public void createDeviceInfo(DeviceInfo deviceInfo) {
        super.create(deviceInfo);    
    }

4，service层的实现，将模块信息设置到设备类的属性中.

@Override
    public void createDeviceInfo(DeviceInfo deviceInfo, Integer[] moduleIds) {
        if(moduleIds!=null){
            
            Set<ModuleDefine> defineSet=deviceInfo.getModuleDefine();
            if(defineSet==null){
                defineSet=new HashSet<ModuleDefine>();
            }
            for(int i=0;i<moduleIds.length;i++){
                ModuleDefine define=new ModuleDefine();
                define.setModuleId(moduleIds[i]);
                defineSet.add(define);
            }
            deviceInfo.setModuleDefine(defineSet);
            
        }
        
        deviceInfoDao.createDeviceInfo(deviceInfo);    
        
    }

5,action层的简单实现

    @Override
    public void submitPage(String pageName) throws Exception {
        
        deviceInfo.setStartTime(DateSupportUtils.str2second(startTime));
        deviceInfo.setEndTime(DateSupportUtils.str2second(endTime));
        
        if(pageName.equals(PAGE_CREATE)){
            deviceInfo.setDeviceInDate(new Date());
            deviceInfoService.createDeviceInfo(deviceInfo,moduleIds);
        }
        else if(pageName.equals(PAGE_UPDATE)){
            deviceInfoService.updateDeviceInfo(deviceInfo);
        }
    }

6，界面jsp页面，简单给大家看看.

<%@ page language="java" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %> 

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
    <head>
        <title>${pageTitle}</title>
        <s:include value="../../../include/page.jsp"/>
        <style type="shett"></style>
        <script type="text/javascript" >
        　　

//这里的代码是级联获取下拉框数据，省略掉，可以参考上一篇处理json的代码</script>
    </head>
    <body onload="Page.init('${pageError}','${pageMessage}',${isSubmit})">
        <div id="title">${pageTitle}</div>
        <s:form id="MYFORM" action="%{pageAction}" method="post" theme="simple">
        <input type="hidden" value="0" name="deviceInfo.status"/>
        <input type="hidden" value="0" name="deviceInfo.auditFlag"/>
        <div id="content">
            <table>
                
             //下面一种标签只列出来了一个
                <tr>
                    <th width="13%">开始使用时间:</th>
                    <td width="35%"><div>
                        <input name="startTime" value="<s:date name="deviceInfo.startTime" format="yyyy-MM-dd HH:mm:ss"/>" class="Wdate" onfocus="WdatePicker({isShowClear:false,dateFmt:'yyyy-MM-dd HH:mm:ss',readOnly:true})"/>
                    </div></td>
                 
                </tr>
                <tr>
                    
                    <th width="17%">设备厂商:</th>
                    <td width="35%"><s:select name="deviceInfo.factory" id="deviceFactory"
                            list="deviceFactoryList" 
                            listKey="realValue"
                            listValue="displayValue"
                            headerKey=""
                            headerValue="请选择"/>
                        </td>
                  
                </tr>
                <tr>
                    <th width="17%">模块:</th>
                    <td width="35%" >
                        <div>
                        <s:checkboxlist name="moduleIds" cssClass="checkbox"
                            list="moduleList"
                            listKey="realValue"
                            listValue="displayValue"
                            >
                            
                        </s:checkboxlist>
                        </div>
                    </td>
                </tr>
                <tr>
                    <th width="13%">备注信息:</th>
                    <td width="35%" colspan="3" ><div>
                        <s:textarea name="deviceInfo.memo"  onblur="Check.checkLength(this,256)"/>
                    </div></td>
                </tr>
            </table>
        </div>
        <div id="operator">
            <div class="left"></div>
            <div class="middle" onclick="Page.submit()">提交</div>
            <div class="right"></div>
            <div class="left"></div>
            <div class="middle" onclick="Page.close()">关闭</div>
            <div class="right"></div>
        </div>
        </s:form>
    </body>
</html>