Mysql实例MyBatis 如何写配置文件和简单使用

<?xml version="1.0" encoding="UTF-8" ?> 
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" 
"http://mybatis.org/dtd/mybatis-3-config.dtd"> 
<configuration> 
  <typeAliases> 
    <!-- 配置类型的别名 --> 
    <typeAlias alias="User" type="cn.hncu.domain.User" /> 
  </typeAliases> 
  <environments default="development"> 
    <environment id="development"> 
      <transactionManager type="JDBC" /> 
      <dataSource type="POOLED"> 
        <property name="driver" value="com.mysql.jdbc.Driver" /> 
        <property name="url" value="jdbc:mysql://127.0.0.1:3306/mybatis?characterEncoding=UTF-8" /> 
        <property name="username" value="hncu" /> 
        <property name="password" value="1234" /> 
        <property name="poolMaximumActiveConnections" value="5"/> 
      </dataSource> 
    </environment> 
  </environments> 
  <mappers> 
    <mapper resource="cn/hncu/domain/User.xml"></mapper> 
    <mapper resource="cn/hncu/domain/User2.xml"></mapper> 
  </mappers> 
</configuration> 

package cn.hncu.utils; 
 
import java.io.IOException; 
import java.io.InputStream; 
import java.sql.Connection; 
 
import org.apache.ibatis.io.Resources; 
import org.apache.ibatis.session.SqlSession; 
import org.apache.ibatis.session.SqlSessionFactory; 
import org.apache.ibatis.session.SqlSessionFactoryBuilder; 
 
import com.mysql.jdbc.interceptors.SessionAssociationInterceptor; 
 
 
public class SqlSessionUtils { 
  private static SqlSessionFactory sessionFactory=null;//DataSource--pool 
  static{ 
    try { 
      InputStream in=Resources.getResourceAsStream("mybatis-config.xml");//加载配置文件 
      sessionFactory=new SqlSessionFactoryBuilder().build(in); 
      /* 
       * 这里给出一种不需要使用Resources类加载文件的办法(利用ClassLoader以底层加载配置文件) 
        sessionFactory=new SqlSessionFactoryBuilder().build(SqlSessionUtils.class.getClassLoader().getResourceAsStream("mybatis-config.xml")); 
       */ 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } 
  } 
   
  public static SqlSessionFactory getSessionFactory(){ 
    return sessionFactory; 
  } 
  public static SqlSession getSqlSession(){ 
    return sessionFactory.openSession(); 
  } 
  public static void main(String[] args) { 
    //mybatis在池中控制的是连接的数量 
    for(int i=0;i<10;i++){ 
      SqlSession s=getSqlSession(); 
      System.out.println(s); 
      Connection con=s.getConnection(); 
      System.out.println("con: "+con); 
    } 
  } 
} 

package cn.hncu.domain; 
 
public class User { 
  private String id; 
  private String name; 
  private String pwd; 
  public String getId() { 
    return id; 
  } 
  public void setId(String id) { 
    this.id = id; 
  } 
  public String getName() { 
    return name; 
  } 
  public void setName(String name) { 
    this.name = name; 
  } 
  public String getPwd() { 
    return pwd; 
  } 
  public void setPwd(String pwd) { 
    this.pwd = pwd; 
  } 
  @Override 
  public String toString() { 
    return "User [id=" + id + ", name=" + name + ", pwd=" + pwd + "]"; 
  } 
   
} 

package cn.hncu.domain; 
 
import java.util.List; 
 
public interface UserMapper { 
  public List<User> all(); 
  public List<User> user2(String string); 
  public List<User> user3(User user); 
} 

package cn.hncu.domain; 
 
import java.util.List; 
 
public interface UserMapper { 
  public List<User> all(); 
  public List<User> user2(String string); 
  public List<User> user3(User user); 
} 

package cn.hncu.demo; 
 
import java.util.HashMap; 
import java.util.List; 
import java.util.Map; 
 
import org.apache.ibatis.session.SqlSession; 
import org.junit.Test; 
 
import cn.hncu.domain.User; 
import cn.hncu.domain.UserMapper; 
import cn.hncu.utils.SqlSessionUtils; 
 
public class Demo1 { 
  @Test 
  public void test1(){ 
    //先获取SqlSession 
    SqlSession s=SqlSessionUtils.getSqlSession(); 
    List<User> list=s.selectList("users.all");//返回结果用list封装,参数用id来指定使用映射文件中的哪一段,<select>或<insert>等sql操作 
//   List<User> list=s.selectList("all");//省略命名空间----如果名称(id)冲突,则必须使用命名空间来进行识别 
    //System.out.println(list); 
    for(User u:list){ 
      System.out.println(u); 
    } 
  } 
  <span style="color:#ff0000;">//使用接口方式操作数据库(推荐使用这种方式,更平安) 
  /*步骤 
   * 1.写一个接口:UserMapper,接口中的抽象方法名必须和<select>的属性id值相同,即一个抽象方法代表一段操作 
   * 2.把User2.xml中的命名空间改成接口的完全类名 
   * 3.在测试代码中(又dao层的java),用"s.getMapper()"获得一个代理类对象,使用该对象调用某个方法,即执行某段操作 
   */</span> 
   
  @Test//面向接口的方式,以下调用的都是: User2.xml 
  public void test2(){ 
    //先获取SqlSession 
    SqlSession s=SqlSessionUtils.getSqlSession(); 
    UserMapper m=s.getMapper(UserMapper.class);//获得一个代理对象 
    List<User>list=m.all(); 
    System.out.println(list); 
  } 
  ///////////////test3()演示条件查询中的单条件查询,调用User2.xml/////////////////// 
   
  @Test//传统方式 
  public void test3_1(){ 
    SqlSession s=SqlSessionUtils.getSqlSession(); 
//   List<User> users=s.selectList("cn.hncu.domain.UserMapper.all"); 
    List<User> users=s.selectList("user2","2");//返回结果用List封装,内部的元素文件类型由映射文件配置 
    System.out.println(users); 
  } 
  @Test//面向接口方式 
  public void test3_2(){ 
    SqlSession s=SqlSessionUtils.getSqlSession(); 
    UserMapper u=s.getMapper(UserMapper.class); 
    List<User> users=u.user2("3"); 
    System.out.println(users); 
  } 
   
  ///////////////////多条件查询(条件查询最好用对象封装条件)////////////// 
  @Test 
  public void test4(){ 
    SqlSession s=SqlSessionUtils.getSqlSession(); 
     
    UserMapper u=s.getMapper(UserMapper.class); 
    User user=new User(); 
    user.setId("4"); 
    user.setName("二蛋"); 
    List<User> users=u.user3(user); 
    System.out.println(users); 
  } 
  @Test 
  public void test5(){//返回结果用map 
    SqlSession s=SqlSessionUtils.getSqlSession(); 
    System.out.println(s); 
    List<Map<String,Object>> users=s.selectList("user4"); 
    for(Map<String,Object> user:users){ 
      System.out.println(user); 
    } 
  } 
  @Test//把输入参数设为map 
  public void test6(){ 
    SqlSession s=SqlSessionUtils.getSqlSession(); 
    Map<String, Object> map=new HashMap<String,Object>(); 
    map.put("id", "5"); 
    map.put("name", "小奇"); 
    List<Map<String,Object>> users=s.selectList("user5",map); 
    for(Map<String,Object> user:users){ 
      System.out.println(user); 
    } 
  } 
} 

<?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"> 
<!-- 当前配置文件专用展示面向接口的操作方式 --> 
<!--  
<mapper namespace="cn.hncu.domain.UserMapper"> 
  <select id="all" resultType="cn.hncu.domain.User"> 
    select * from users 
  </select> 
</mapper> 
--> 
<mapper namespace="cn.hncu.domain.UserMapper"> 
<!-- 使用了类型别名 --> 
  <select id="all" resultType="User"> 
    select * from users 
  </select> 
   
  <!--条件查询之单条件查询,下面的sql语句的参数可以随便写 --> 
  <select id="user2" resultType="User" parameterType="string"> 
    select * from users where id=#{xx} 
  </select> 
  <!--条件查询之多条件查询,下面的sql语句的参数必须要和值对象的属性名一致(要用if条件式判断参数是否为空) --> 
  <select id="user3" resultType="User" parameterType="string"> 
    select * from users where id=#{id} 
    <if test="name!=null"> 
      and name=#{name} 
    </if> 
  </select> 
  <!-- 把查询结果封装成List<Map<>> --> 
  <select id="user4" resultType="map"> 
    select * from users 
  </select> 
  <!-- 把输入参数封装成map类型 --> 
  <select id="user5" resultType="hashmap" parameterType="hashmap"> 
    select * from users where id=#{id} 
    <if test="name!=null"> 
      and name=#{name} 
    </if> 
  </select> 
</mapper>