Mybatis应用

工具类MyBatisUtils

在上一篇博客中 通过sqlsession 中 写了一个就简单的查询方法 并输出测试  我们发现 几乎所有的增删该查 都会调用 sqlsession 这样得到代码十分的冗余 所有在这里我们将这些公共的代码 都提到了一个公共的静态类既方便理解也方便后期的维护

 1 package cn.wh.util;
 2 
 3 import org.apache.ibatis.session.SqlSession;
 4 import org.apache.ibatis.session.SqlSessionFactory;
 5 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 6 
 7 import java.io.IOException;
 8 import java.io.InputStream;
 9 public class MybatisUtil {
10         static String path="mybatis-config.xml";
11         static InputStream is;
12         static SqlSessionFactory factory;
13     static {
14         try {
15             is = org.apache.ibatis.io.Resources.getResourceAsStream(path);
16             factory=new  SqlSessionFactoryBuilder().build(is);
17         } catch (IOException e) {
18             e.printStackTrace();
19         }
20     }
21     public static SqlSession getSqlSession() {
22         return factory.openSession();
23     }
24 }
View Code

下面我写一个简单的案例 来书写一下这个MyBatisUtils的使用（接口和小配置的XML文件这里就不展示了 只是展示一下MyBatisUtils的使用）

1  @Test //使用工具类 MybatisUtil
2     public void  MybatisUtil(){
3         SqlSession sqlSession = MybatisUtil.getSqlSession();
4         User user= sqlSession.selectOne("SelectUser");
5         System.out.println(user.getUname()+"=");
6     }
View Code

这里我们仅仅用了三行代码就实现了这个查询 还是比较便于开发的

getMapper()

getMapper的作用，获取到接口，直接通过点的方式调用方法，以免直接手打的方式写错方法名，（强类型的方式）

 

   public  void  FirstList(){
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        IUserDao mapper = sqlSession.getMapper(IUserDao.class);
        Map<String ,Object> map=new HashMap<String ,Object>() ;
        //Key千万一定要和实体类对应
        map.put("uname","1");
        map.put("upwd","1");
        List<User> users = mapper.conditionFirst(map);
        System.out.println(users.size());
    }

 

在mybatis中 有一些智能标签 

他分为 where ,if ,choose ,foreach的array方式 ,foreach的list方式 ,foreach的list自定义类型方式

下面我书写两个例子

 

 1   <!--智能标签forearch 数组-->
 2     <select id="conditionByforearch" resultMap="MessageResult">
 3      SELECT * from user 
 4      <where>
 5          uid in
 6          <foreach collection="array" item="myid" open="(" close=")" separator=",">
 7           #{myid}
 8          </foreach>
 9      </where>
10     </select>
11     <!--智能标签forearch 集合-->
12     <select id="conditionByforearchList" resultMap="MessageResult">
13         SELECT * from user
14         <where>
15             uid in
16             <foreach collection="list" item="myid" open="(" close=")" separator=",">
17                 #{myid}
18             </foreach>
19         </where>
20     </select>
21     <!--智能标签forearch 自定义集合-->
22     <select id="conditionByforearchListSecond" resultMap="MessageResult">
23         SELECT * from user
24         <where>
25             uid in
26             <foreach collection="list" item="user" open="(" close=")" separator=",">
27                 #{user.uid}
28             </foreach>
29         </where>
30     </select>
View Code

 

测试类

 1   @Test //智能标签 forearch 数组
 2     public  void  conditionByforearch(){
 3         SqlSession sqlSession = MybatisUtil.getSqlSession();
 4         IUserDao mapper = sqlSession.getMapper(IUserDao.class);
 5         int [] bookid={1,2};
 6         List<User> condition = mapper.conditionByforearch(bookid);
 7         for (User item:condition
 8              ) {
 9             System.out.println(item.getUname());
10         }
11     }
12     @Test //智能标签 forearch 集合
13     public  void  conditionByforearchList(){
14         SqlSession sqlSession = MybatisUtil.getSqlSession();
15         IUserDao mapper = sqlSession.getMapper(IUserDao.class);
16      List<Integer> list=new ArrayList<>();
17             list.add(1);
18         List<User> condition = mapper.conditionByforearchList(list);
19         for (User item:condition
20                 ) {
21             System.out.println(item.getUname());
22         }
23     }
24     @Test //智能标签 forearch 集合自定义
25     public  void  SecondconditionByforearchList(){
26         SqlSession sqlSession = MybatisUtil.getSqlSession();
27         IUserDao mapper = sqlSession.getMapper(IUserDao.class);
28         List<User> list=new ArrayList<User>();
29         User user=new User();
30         user.setUid(1);
31         list.add(user);
32         User user1=new User();
33         user1.setUid(2);
34         list.add(user1);
35         List<User> condition = mapper.conditionByforearchListSecond(list);
36         for (User item:condition
37              ) {
38             System.out.println(item.getUname());
39         }
40 
41     }
View Code

这些智能标签大大增加了我们的开发速度，从而也减少我们的代码数量

多表关联查询（有一点难理解 整整弄了半天  ）

先看一下实体类吧

 

 1 package cn.wh.entity;
 2 
 3 import java.util.ArrayList;
 4 import java.util.List;
 5 
 6 public class UserType {
 7     private Integer typeid;
 8     private  String typeName;
 9     private  Integer uid;
10 
11     private List<User> users=new ArrayList<User>();
12 
13     public List<User> getUsers() {
14         return users;
15     }
16 
17     public void setUsers(List<User> users) {
18         this.users = users;
19     }
20 
21     public Integer getTypeid() {
22         return typeid;
23     }
24 
25     public void setTypeid(Integer typeid) {
26         this.typeid = typeid;
27     }
28 
29     public String getTypeName() {
30         return typeName;
31     }
32 
33     public void setTypeName(String typeName) {
34         this.typeName = typeName;
35     }
36 
37     public Integer getUid() {
38         return uid;
39     }
40 
41     public void setUid(Integer uid) {
42         this.uid = uid;
43     }
44 }
View Code

 

一共两个实体类这是第二个

 1 package cn.wh.entity;
 2 
 3 public class User {
 4 
 5     // 用户id
 6     private int uid;
 7     // 用户名
 8     private String uname;
 9     //密码
10     private  String upwd;
11     //手机
12     private  String phone;
13 
14     private  UserType  userType;
15 
16     public UserType getUserType() {
17         return userType;
18     }
19 
20     public void setUserType(UserType userType) {
21         this.userType = userType;
22     }
23 
24     public String getUpwd() {
25         return upwd;
26     }
27 
28     public void setUpwd(String upwd) {
29         this.upwd = upwd;
30     }
31 
32     public String getPhone() {
33         return phone;
34     }
35 
36     public void setPhone(String phone) {
37         this.phone = phone;
38     }
39 
40 
41     public int getUid() {
42         return uid;
43     }
44     public void setUid(int uid) {
45         this.uid = uid;
46     }
47     public String getUname() {
48         return uname;
49     }
50     public void setUname(String uname) {
51         this.uname = uname;
52     }
53 }
View Code

 

 

第一套方式

 

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE mapper
 3         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 <mapper namespace="cn.wh.dao.IUserType">
 6     <resultMap type="cn.wh.entity.UserType" id="UserType">
 7         <id column="typeid" jdbcType="INTEGER" property="typeid"/>
 8         <result column="typeName" jdbcType="VARCHAR" property="typeName" />
 9 
10 
11         <collection property="users" ofType="cn.wh.entity.User">
12             <id column="uid" jdbcType="INTEGER" property="uid"/>
13             <result column="uname" jdbcType="VARCHAR" property="uname" />
14         </collection>
15     </resultMap>
16 
17     <resultMap type="cn.wh.entity.UserType" id="UserType1">
18         <id column="typeid" jdbcType="INTEGER" property="typeid"/>
19         <result column="typeName" jdbcType="VARCHAR" property="typeName" />
20         <collection property="users" ofType="cn.wh.entity.User" select="ss" column="typeid">
21         </collection>
22     </resultMap>
23 <select id="listType" resultMap="UserType">
24 select user.uid from usertype,user
25 where user.typeid=usertype.typeid
26 and user.uid='1'
27 
28 
29 </select>
30     <select id="UserTypecondition" resultMap="UserType1">
31          SELECT typeid from  usertype
32         where typeid='1'
33     </select>
34     <select id="ss" resultType="cn.wh.entity.User">
35         SELECT * from user
36         where typeid='1'
37   </select>
38 </mapper>
View Code

 

测试类

 1     @Test
 2  public  void  userTypeList(){
 3         SqlSession sqlSession = MybatisUtil.getSqlSession();
 4         IUserType mapper = sqlSession.getMapper(IUserType.class);
 5         UserType userType = mapper.listType();
 6         System.out.println(userType.getUsers().size());
 7     }
 8     //查询单一条 有条件 (一对多)
 9     @Test
10     public  void  userTypeListcondition(){
11         SqlSession sqlSession = MybatisUtil.getSqlSession();
12         IUserType mapper = sqlSession.getMapper(IUserType.class);
13         UserType userType = mapper.UserTypecondition(1);
14         List<User> users = userType.getUsers();
15         System.out.println(users);
16         for (User item:users
17              ) {
18             System.out.println(item.getUpwd());
19         }
20 }
View Code

第二种方式

 

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE mapper
 3         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 <mapper namespace="cn.wh.dao.IUser">
 6 
 7     <resultMap id="Users" type="cn.wh.entity.User">
 8         <id column="uid" jdbcType="INTEGER" property="uid"/>
 9         <result column="uname" jdbcType="VARCHAR" property="uname" />
10         <association property="userType" javaType="cn.wh.entity.UserType">
11             <id column="typeid" jdbcType="INTEGER" property="typeid"/>
12             <result column="typeName" jdbcType="VARCHAR" property="typeName" />
13         </association>
14     </resultMap>
15     <resultMap id="manyUsers" type="cn.wh.entity.User">
16         <id column="uid" jdbcType="INTEGER" property="uid"/>
17         <result column="uname" jdbcType="VARCHAR" property="uname" />
18         <association property="userType" javaType="cn.wh.entity.UserType" column="uid" select="ss">
19         </association>
20     </resultMap>
21 <!--多对一-->
22     <select id="findeUser" resultMap="Users">
23     SELECT * from user,usertype where user.typeid=usertype.typeid and user.uid=#{uid}
24     </select>
25     <!--多对多-->
26     <select id="findempmany" resultMap="manyUsers">
27           SELECT uid from user
28         where typeid='1'
29     </select>
30     <select id="ss" resultType="cn.wh.entity.UserType">
31          SELECT * from  usertype
32         where typeid='1'
33     </select>
34 
35 </mapper>
View Code

 

测试类

 1     //多对一
 2    @Test
 3     public  void manyTOne(){
 4         SqlSession sqlSession = MybatisUtil.getSqlSession();
 5         IUser mapper = sqlSession.getMapper(IUser.class);
 6         User user = mapper.findeUser(2);
 7 
 8         System.out.println(user.getUname()+"=");
 9     }
10     //多对多
11     @Test
12     public  void manyTomany(){
13         SqlSession sqlSession = MybatisUtil.getSqlSession();
14         IUser mapper = sqlSession.getMapper(IUser.class);
15         User user = mapper.findempmany(1);
16         System.out.println(user.getUserType().getUid());
17     }
View Code

 

posted @ 2018-07-05 10:10  HelloWord404  阅读(210)  评论(0)  编辑  收藏  举报