Mybatis框架搭建与简单查询详解

public class User {
 @Override
 public String toString() {
 return "User [id=" + id + ", username=" + username + ", sex=" + sex
 + ", address=" + address + ", birthday=" + birthday + "]";
 }
 private int id;
 private String username;
 private String sex;
 private String address;
 private Date birthday;
 public int getId() {
 return id;
 }
 public void setId(int id) {
 this.id = id;
 }
 public String getUsername() {
 return username;
 }
 public void setUsername(String username) {
 this.username = username;
 }
 public String getSex() {
 return sex;
 }
 public void setSex(String sex) {
 this.sex = sex;
 }
 public String getAddress() {
 return address;
 }
 public void setAddress(String address) {
 this.address = address;
 }
 public Date getBirthday() {
 return birthday;
 }
 public void setBirthday(Date birthday) {
 this.birthday = birthday;
 }
}

<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!-- 和spring整合后 environments配置将废除-->
<environments default="development">
<environment id="development">
<!-- 使用jdbc事务管理-->
<transactionManager type="JDBC" />
<!-- 数据库连接池-->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />
<property name="username" value="root" />
<property name="password" value="123456" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="sqlmap/User.xml"></mapper>
</mappers>
</configuration>

# Global logging configuration，建议开发环境中要用debug
log4j.rootLogger=DEBUG, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

<?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">
<!-- namespace命名空间，为了对sql语句进行隔离，方便管理 ，mapper开发dao方式，使用namespace有特殊作用 -->
<mapper namespace="test">
<!-- 在mapper.xml文件中配置很多的sql语句，执行每个sql语句时，封装为MappedStatement对象
mapper.xml以statement为单位管理sql语句
 -->
 <!-- 根据id查询用户信息 -->
 <!-- 
 id：唯一标识 一个statement
 #{}：表示 一个占位符，如果#{}中传入简单类型的参数，#{}中的名称随意
 parameterType：输入 参数的类型，通过#{}接收parameterType输入 的参数
 resultType：输出结果 类型，不管返回是多条还是单条，指定单条记录映射的pojo类型
 -->
 <select id="findUserById" parameterType="int" resultType="cn.qkp.mybatis.po.User"> 
 SELECT * FROM USER WHERE id=#{id}
 </select>
</mapper>

private SqlSessionFactory sqlsessionfactory;//存储SqlSessionFactory 对象
@Before
 public void star() throws Exception{
 //设置配置路径，mybitis是以SqlMapConfig.xml为主路径。因为SqlMapConfig中的mapper关联了user.xml
 //因为在config根目录下，所以可以直接引用而不用带config
 String resource = "SqlMapConfig.xml";
 //SqlMapConfig.xml读给输入流，使用mybitis的Resources类下的getResourceAsStream实现
 InputStream inputStream = Resources.getResourceAsStream(resource);
 //创建Mybitis的SqlSessionFactory工厂类
 sqlsessionfactory = new SqlSessionFactoryBuilder().build(inputStream);
 }
 @Test
 public void test(){
 //通过工厂类打开数据接口
 SqlSession sqlsession = sqlsessionfactory.openSession();
 //设置接收对象
 User user = null;
 try {
 //查询数据selectOne为查询一条的方法第一个参数是user.xml中的namespace.id；第二个参数是user配置文件中的#{id}
 user = sqlsession.selectOne("test.findUserById", 1);
 } catch (Exception e) {
 // TODO: handle exception
 }finally{
 sqlsession.close();//读完要关闭sqlsession
 }
 System.out.println(user);//打印输出
 }

<select id="selectByName" parameterType="String" resultType="cn.qkp.po.User">
select * from User where username like '%${value}%'
</select>

@Test
 public void star2(){
 SqlSession sqlsession = sqlsessionfactory.openSession();
 List<User> user = sqlsession.selectList("test.selectByName", "小明");
 sqlsession.close();
 System.out.println(user.get(0));
 }