mybatis呢是一个orm数据库框架，非常适合新人学，门槛相对较低

本人呢曾经是先做的hibernate，后接触的mybatis，接触mabatis前我比较抵触，为啥呢，

当时喜欢hibernate的POJO，直接注解实体映射数据库表对象，要增删改造直接get(id),save(entity),delete(entity),update(entity),显得非常方便；

而且又支持hql的查询

但是，久而久之，很多数据库性能方面的问题会暴露出来，你必须直接优化sql语句，那么hibernate的弊端就出现了

虽然mybatis需要手写sql语句，其实也挺不错，字段映射就OK了，多写写sql也是有好处滴

那有的人会问了，什么时候用hibernate，什么时候用mybatis呢？

回答曰：看项目呗，如果项目挺大，那就是mybatis，如果项目相对较小，是个后台管理系统，对数据的查询量不是特别多，那就用hibernate呗

或者干脆每个项目都用mybatis都行啊~！

除此之外，也有部分企业使用的自己开发的orm框架，连数据源都是自己的，那这样当然最好

好吧，废话有点多，咱写代码的还是直接贴码吧：

（头几篇博文不会使用maven，后面的ssm整合会使用maven来进行管理）

工程结构：

asm-3.3.1.jar

cglib-2.2.2.jar

commons-logging-1.1.1.jar

javassist-3.17.1-GA.jar

log4j-1.2.17.jar

log4j-api-2.0-beta9.jar

log4j-core-2.0-beta9.jar

mybatis-3.2.3.jar

mysql-connector-java-5.1.7-bin.jar

slf4j-api-1.7.5.jar

slf4j-log4j12-1.7.5.jar

 

SqlMapConfig.xml，这个可以理解为连接mybatis和数据库的媒介，以及一些mybatis配置都在这个文件里

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User.xml 这个文件就是正对user实体进行的相关查询，命名同User.java

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      20         21         SELECT * FROM USER WHERE id = #{id}22     23     24     25     26     
      27     
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      34         select * from user where name like '%${value}%'35     36     37     38     
      41     
      
       42     43     
       49      
       50         
       
        51             select LAST_INSERT_ID()52         
       53         54         insert into user(name,age,sex) values(#{name},#{age},#{sex})55     
      56     57     
      58     59     
      
       60        delete from user where id=#{id}61     
      62     63     
      66     
      
       67        update user set name=#{name},age=#{age},sex=#{sex}  where id=#{id}68     
      69     70 71 
     

User.java

1 package com.mybatis001.bean; 2  3 public class User { 4  5     private int id; 6     private String name; 7     private int age; 8     private String sex; 9     10     public User() {11         super();12     }13 14     public User(String name, int age, String sex) {15         super();16         this.name = name;17         this.age = age;18         this.sex = sex;19     }20     21     public int getId() {22         return id;23     }24     public void setId(int id) {25         this.id = id;26     }27     public String getName() {28         return name;29     }30     public void setName(String name) {31         this.name = name;32     }33     public int getAge() {34         return age;35     }36     public void setAge(int age) {37         this.age = age;38     }39     public String getSex() {40         return sex;41     }42     public void setSex(String sex) {43         this.sex = sex;44     }45     46     @Override47     public String toString() {48         return "User [id=" + id + ", name=" + name + ", age=" + age + ", sex="49                 + sex + "]";50     }51     52 }

UserDao.java

1 package com.mybatis001.dao; 2  3 import java.util.List; 4  5 import com.mybatis001.bean.User; 6  7 public interface UserDao { 8      9     public User findUserById(int id) throws Exception;10     11     public List
     
       findUserList(String name) throws Exception;12     13     public Integer insertUser(User user) throws Exception;14     15     public void deleteUser(int id) throws Exception;16     17     public void updateUser(User user) throws Exception;18     19 }
     

UserDaoImpl.java

1 package com.mybatis001.dao.impl; 2  3 import java.util.List; 4  5 import org.apache.ibatis.session.SqlSession; 6 import org.apache.ibatis.session.SqlSessionFactory; 7  8 import com.mybatis001.bean.User; 9 import com.mybatis001.dao.UserDao;10 11 public class UserDaoImpl implements UserDao {12 13     // 注入SqlSessionFactory14     private SqlSessionFactory sqlSessionFactory;15 16     public UserDaoImpl(SqlSessionFactory sqlSessionFactory) {17         this.sqlSessionFactory = sqlSessionFactory;18     }19 20     @Override21     public User findUserById(int id) throws Exception {22 23         // 根据SqlSessionFactory创建SqlSession24 25         SqlSession sqlSession = sqlSessionFactory.openSession();26 27         // 通过sqlSession查询用户信息(发起数据库操作)28         // 第一个参数statement：指定mapper映射文件中statement的id，指定 时需要前边加上statement所属的命名空间29         // 第二个参数parameter，指定 输入参数30         // selectOne返回的是单条记录，如果select返回多条记录(list集合)，使用selectOne会报错31         // 根据映射文件中的resultType指定输出类型32         User user = sqlSession.selectOne("test.findUserById", id);33         return user;34     }35 36     @Override37     public List
     
       findUserList(String name) throws Exception {38         SqlSession sqlSession = sqlSessionFactory.openSession();39         List
      
        userList = sqlSession.selectList("test.findUserList", name);40         return userList;41     }42 43     @Override44     public Integer insertUser(User user) throws Exception {45         SqlSession sqlSession = sqlSessionFactory.openSession();46         int lastUserId = sqlSession.insert("test.insertUser", user);47         48         sqlSession.commit();49         sqlSession.close();50         return lastUserId;51     }52 53     @Override54     public void deleteUser(int id) throws Exception {55         SqlSession sqlSession = sqlSessionFactory.openSession();56         sqlSession.delete("test.deleteUser", id);57         sqlSession.commit();58         sqlSession.close();59     }60 61     @Override62     public void updateUser(User user) throws Exception {63         SqlSession sqlSession = sqlSessionFactory.openSession();64         sqlSession.update("test.updateUser", user);65         sqlSession.commit();66         sqlSession.close();67     }68 69 }
      
     

测试：

1 package com.test.mybatis001; 2  3  4 import java.io.InputStream; 5 import java.util.List; 6  7 import org.apache.ibatis.io.Resources; 8 import org.apache.ibatis.session.SqlSessionFactory; 9 import org.apache.ibatis.session.SqlSessionFactoryBuilder;10 import org.junit.Before;11 import org.junit.Test;12 13 import com.mybatis001.bean.User;14 import com.mybatis001.dao.UserDao;15 import com.mybatis001.dao.impl.UserDaoImpl;16 17 public class UserDaoImplTest {18 19     // 会话工厂20     private SqlSessionFactory sqlSessionFactory;21 22     @Before23     public void setUp() throws Exception {24         // 加载配置文件25         String resource = "SqlMapConfig.xml";26         InputStream inputStream = Resources.getResourceAsStream(resource);27 28         // 根据mytais的配置创建SqlSessionFactory29         sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);30     }31 32     @Test33     public void testFindUserById() throws Exception {34         UserDao userDao = new UserDaoImpl(sqlSessionFactory);35         User user = userDao.findUserById(1001);36 //        System.out.println(user.toString());37         38         List
     
       userList = userDao.findUserList("lee");39         40         if (!userList.isEmpty()) {41             for (User u : userList) {42                 System.out.println(u.toString());43             }44         }45     }46     47     @Test48     public void insertUser() throws Exception {49         UserDao userDao = new UserDaoImpl(sqlSessionFactory);50         51         User u1 = new User("nathan.lee.salvatore", 18, "男");52         User u2 = new User("nathan", 22, "男");53         User u3 = new User("leechenxiang", 20, "男");54         User u4 = new User("李晨翔", 19, "男");55         56         userDao.insertUser(u1);57         userDao.insertUser(u2);58         userDao.insertUser(u3);59         userDao.insertUser(u4);60     }61 62     @Test63     public void deleteUser() throws Exception {64         UserDao userDao = new UserDaoImpl(sqlSessionFactory);65         userDao.deleteUser(1013);66     }67     68     @Test69     public void updateUser() throws Exception {70         UserDao userDao = new UserDaoImpl(sqlSessionFactory);71         User user = new User("李斯涵", 1, "女");72         user.setId(1001);73         userDao.updateUser(user);74     }75 }
     

 

 

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