javaweb实战之商城项目开发（三）

package com.dao;import com.model.Pager;import com.util.SessionUtil;import com.util.SystemContext;import org.apache.ibatis.session.SqlSession;import java.util.HashMap;import java.util.List;import java.util.Map;/** * Created by nl101 on 2016/2/23. */public class BaseDao<T> {  /**   * 根据id取出一个T类型   * @param id 要取出T类型的id   * @return   */  public T load(Class<T> tc,int id){    SqlSession session = SessionUtil.getSession();    T t = null;    try {      t = session.selectOne(tc.getName()+".load",id);    } finally {      SessionUtil.closeSession(session);    }    return t;  }  /**   * 添加一个T类型   * @param t 要添加的T类型   * @return true成功   */  public boolean add(T t){    int isAdd = 0;    SqlSession session = SessionUtil.getSession();    try {      isAdd = session.insert(t.getClass().getName()+".add",t);      session.commit();//提交    } catch (Exception e) {      session.rollback();//提交失败则回滚    }finally {      SessionUtil.closeSession(session);    }    return isAdd>0;  }  /**   *根据id删除T类型   * @param id 要删除T的id   * @return true成功   */  public boolean delete(Class<T> t,int id){    int isDelete = 0;    SqlSession session = SessionUtil.getSession();    try {      isDelete = session.delete(t.getName()+".delete",id);      session.commit();    } catch (Exception e) {      session.rollback();//失败返回      System.out.println("删除用户失败");      e.printStackTrace();    }finally {      SessionUtil.closeSession(session);    }    return isDelete>0;  }  /**   *更新T类型   * @param t 要更新的用户   * @return true成功   */  public boolean update(T t){    int isUpdate = 0;    SqlSession session = SessionUtil.getSession();    try {      isUpdate = session.delete(t.getClass().getName()+".update",t);      session.commit();    } catch (Exception e) {      session.rollback();//失败返回      System.out.println("更新用户失败");      e.printStackTrace();    }finally {      SessionUtil.closeSession(session);    }    return isUpdate>0;  }  /**   * 根据指定条件分页查询   * @param maps 指定条件集合   * @return   */  public Pager<T> find(Class<T> t,Map<String,Object> maps){    int pageStart = SystemContext.getPageStart();//分页起始    int pageSize = SystemContext.getPageSize();//分页大小    Pager<T> pagers = new Pager<>();    maps.put("pageStart",pageStart);    maps.put("pageSize",pageSize);    SqlSession session = SessionUtil.getSession();    List<T> datas = null;    try {      datas = session.selectList(t.getName()+".find",maps);//获取记录      pagers.setDatas(datas);      pagers.setPageSize(pageSize);      pagers.setPageStart(pageStart);      int totalRecord = session.selectOne(t.getName()+".findcount",maps);//获取记录总数      pagers.setTotalRecord(totalRecord);      pagers.setPageIndex(pageStart/pageSize+1);    } finally {      SessionUtil.closeSession(session);    }    return pagers;  }  /**   * 根据指定条件取出部分数据   * @param maps 指定条件集合   * @return   */  public Pager<T> list(Class<T> t,Map<String,Object> maps){    Pager<T> pagers = new Pager<>();    SqlSession session = SessionUtil.getSession();    List<T> datas = null;    try {      datas = session.selectList(t.getName()+".list",maps);//获取记录      pagers.setDatas(datas);      pagers.setTotalRecord(datas.size());    } finally {      SessionUtil.closeSession(session);    }    return pagers;  }}

public class UserDao extends BaseDao<User>{  /**   * 根据id取出一个用户   * @param id 要取出用户的id   * @return   */  public User load(int id){    return super.load(User.class,id);  }/* 其他函数就不一一贴出来了,都是类似的写法*/}

  public class Address {  private int id;  private String name;  private String phone;  private String postcode;  //直接给user对象,来代替user_id  private User user;    `````````}

<!--加载一个地址-->  <!--这里需要表连接,取出User,又连接保证取出的地址不为空,并且为重复属性id取别名-->  <select id="load" parameterType="int" resultMap="addressMap">     select *,t1.id AS 'a_id' from address t1 RIGHT JOIN user t2 ON           (t1.user_id = t2.id) WHERE t1.id=#{id};  </select>

<resultMap id="addressMap" type="Address" autoMapping="true">    <!--把结果中的a_id映射为id,其他的autoMapping = true会自动匹配-->    <id column="a_id" property="id"/>    <!--取出关联属性-->    <association property="user" javaType="User" >    <!--把user_id映射为user的id-->      <id column="user_id" property="id"/>      <result column="username" property="username"/>      <result column="nickname" property="nickname"/>      <result column="type" property="type"/>    </association>  </resultMap>

package com.dao;import com.model.Address;public class AddressDao extends BaseDao<Address> {  public static void main(String[] args) {    AddressDao addressDao = new AddressDao();    Address address = addressDao.load(1);    System.out.println(address.toString());  }  /**   * 加载一个地址   * @param id 要加载地址的id   * @return 返回要加载的地址,null则加载失败   */  public Address load(int id){    return super.load(Address.class,id);  }}

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapper    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"    "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.model.Address">  <!--当数据库中的字段信息和对象的属性不一致时需要通过resultMap来映射 -->  <resultMap id="addressMap" type="Address" autoMapping="true">    <!--把结果中的a_id映射为id,其他的autoMapping = true会自动匹配-->    <id column="a_id" property="id"/>    <!--取出关联属性-->    <association property="user" javaType="User" >      <!--把user_id映射为user的id-->      <id column="user_id" property="id"/>      <result column="username" property="username"/>      <result column="nickname" property="nickname"/>      <result column="type" property="type"/>    </association>  </resultMap>  <!--加载一个地址-->  <!--这里需要表连接,取出User,又连接保证取出的地址不为空,并且为重复属性id取别名-->  <select id="load" parameterType="int" resultMap="addressMap">    select *,t1.id AS 'a_id' from address t1 RIGHT JOIN user t2 ON (t1.user_id = t2.id) WHERE t1.id=#{id};  </select>  <!--增加一个地址-->  <insert id="add" parameterType="Address">    insert into address values (null,#{name},#{phone},#{postcode},${user_id})  </insert>  <!--删除一个地址-->  <delete id="delete" parameterType="int">    DELETE FROM address WHERE id=#{id}  </delete>  <!--修改一个地址-->  <update id="update" parameterType="Address">    UPDATE address SET name=#{name},phone=#{phone},postcode=#{postcode} where id=#{id}  </update>  <!--找出指定用户所有的地址-->  <select id="list" parameterType="Map" resultMap="addressMap">    SELECT *,t1.id AS 'a_id' FROM address t1 RIGHT JOIN user t2 ON (t1.user_id=t2.id) WHERE t1.user_id=#{user_id}  </select></mapper>

package com.dao;import com.model.Address;import com.model.Pager;import java.util.HashMap;import java.util.Map;/** * Created by nl101 on 2016/2/23. */public class AddressDao extends BaseDao<Address> {  public static void main(String[] args) {    AddressDao addressDao = new AddressDao();    Pager<Address> pagers = addressDao.list(1);    System.out.println(pagers.getDatas().size());  }  /**   * 加载一个地址   * @param id 要加载地址的id   * @return 返回要加载的地址,null则加载失败   */  public Address load(int id){    return super.load(Address.class,id);  }  /**   * 添加一个地址   * @param address 要添加的地址   * @param user_id 要添加的地址对应的user_id   * @return true成功   */  public boolean add(Address address,int user_id){    UserDao userDao = new UserDao();    if (userDao.load(user_id)==null){      return false;    }    return super.add(address);  }  /**   * 删除一个地址   * @param id 要删除地址对应的id   * @return true删除成功   */  public boolean delete(int id){    return super.delete(Address.class,id);  }  /**   * 更新一个地址   * @param address 要更新的地址   * @return true更新成功   */  public boolean update(Address address){    return super.update(address);  }  /**   * 根据用户id取出该用户所有地址   * @param user_id   * @return   */  public Pager<Address> list(int user_id){    Map<String,Object> maps = new HashMap<>();    maps.put("user_id",user_id);    return super.list(Address.class,maps);  }}