MyBaits 入门之MyBatis环境搭建(第一篇)

mybatis 简介

mybatis的前身叫ibatis，本是apache的一个开源项目, 2010年这个项目由apache software foundation 迁移到了google code，并且改名为mybatis。

mybatis是支持普通sql查询，存储过程和高级映射的优秀持久层框架。mybatis消除了几乎所有的jdbc代码和参数的手工设置以及结果集的检索。mybatis使用简单的xml或注解用于配置和原始映射，将接口和java的pojos（plan old java objects，普通的java对象）映射成数据库中的记录。

下面分步骤给搭建介绍mybatis 环境搭建。

1)在工程下引入mybatis-3.4.1.jar包，再引入数据库（mysql,mssql..）包.

2)在src下新建一个配置文件conf.xml

<?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>
<!-- 引入外部配置文件 -->
 <properties resource="jdbc.properties" />
 <!-- 配置mybatis运行环境 -->
 <environments default="development">
 <environment id="development">
  <!-- type="jdbc" 代表使用jdbc的提交和回滚来管理事务 -->
  <transactionmanager type="jdbc" />  
  <!-- mybatis提供了3种数据源类型，分别是：pooled,unpooled,jndi -->
  <!-- pooled 表示支持jdbc数据源连接池 -->
  <!-- unpooled 表示不支持数据源连接池 -->
  <!-- jndi 表示支持外部数据源连接池 -->
  <datasource type="pooled">
  <property name="driver" value="${driver}" />
  <property name="url" value="${url}" />
  <property name="username" value="${username}" />
  <property name="password" value="${password}" />
  </datasource>
 </environment>
 </environments> 
 <mappers>
 <mapper resource="usermapper.xml"/>
 </mappers> 
</configuration>

这里是通过外部配置文件来存储数据库存信息的，所以加入一个jdbc.properties的数据库存信息

driver=com.microsoft.sqlserver.jdbc.sqlserverdriver
url=jdbc:sqlserver://127.0.0.1;databasename=test
username=sa
password=123456

3)建立一个映射文件 usermapper.xml

<?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="hw.com.ser.iuser">
 <!-- 查询全部用户 -->
 <select id="queryusers" resulttype="hw.com.pojo.user">
  select * from ms_user
 </select>
 <selectid="queryuserbyid" resulttype="hw.com.pojo.user" parametertype="int">
  select * from ms_user where id=#{id}
 </select> 
</mapper>

(这里要注意的是，namespace属性，因为，此实例是通过接口映射的方式，所以，namespace属性一点要写成接口的路径)附图：

4)建一个映射接口类

package hw.com.ser;
import java.util.list;
import hw.com.pojo.user;
public interface iuser {
 public list<user> queryusers();
 public user queryuserbyid(int id);
}

5）建立一个sqlsessionfactory

package hw.com.util;
import java.io.ioexception;
import java.io.inputstream;
import java.io.inputstreamreader;
import java.io.reader;
import java.util.properties;
import org.apache.ibatis.io.resources;
import org.apache.ibatis.session.sqlsession;
import org.apache.ibatis.session.sqlsessionfactory;
import org.apache.ibatis.session.sqlsessionfactorybuilder;
public class sqlsessionfactoryutil {
 private static sqlsessionfactory sqlsessionfactory = null;
 private static final class class_lock = sqlsessionfactoryutil.class;
 private sqlsessionfactoryutil() {
 }
 public static sqlsessionfactory initsqlsessionfactory() {
 string resource = "conf.xml";
 inputstream inputstream = null;
 try {
  inputstream = resources.getresourceasstream(resource);  
 } catch (ioexception e) {
  e.printstacktrace();
 }
 synchronized (class_lock) {
  if (sqlsessionfactory == null) {
  sqlsessionfactory = new sqlsessionfactorybuilder().build(inputstream);
  }
 }
 return sqlsessionfactory;
 }
 public static sqlsession opensqlsession(){
 if(sqlsessionfactory==null){
  initsqlsessionfactory();
 }
 return sqlsessionfactory.opensession();
 }
}

6)建一个pojo

package hw.com.pojo;
import java.util.date;
public class user {
 private string id;
 private string username;
 private string userpwd;
 private int deptmentid;
 private string usertruename;
 private string email;
 private int learncenterid;
 private date createdate;
 private date lastmodifydate;
 private int userstatus;
 public user() {
 super();
 // todo auto-generated constructor stub
 }
 public string getid() {
 return id;
 }
 public void setid(string id) {
 id = id;
 }
 public string getusername() {
 return username;
 }
 public void setusername(string username) {
 username = username;
 }
 public string getuserpwd() {
 return userpwd;
 }
 public void setuserpwd(string userpwd) {
 userpwd = userpwd;
 }
 public int getdeptmentid() {
 return deptmentid;
 }
 public void setdeptmentid(int deptmentid) {
 deptmentid = deptmentid;
 }
 public string getusertruename() {
 return usertruename;
 }
 public void setusertruename(string usertruename) {
 usertruename = usertruename;
 }
 public string getemail() {
 return email;
 }
 public void setemail(string email) {
 email = email;
 }
 public int getlearncenterid() {
 return learncenterid;
 }
 public void setlearncenterid(int learncenterid) {
 learncenterid = learncenterid;
 }
 public date getcreatedate() {
 return createdate;
 }
 public void setcreatedate(date createdate) {
 createdate = createdate;
 }
 public date getlastmodifydate() {
 return lastmodifydate;
 }
 public void setlastmodifydate(date lastmodifydate) {
 lastmodifydate = lastmodifydate;
 }
 public int getuserstatus() {
 return userstatus;
 }
 public void setuserstatus(int userstatus) {
 userstatus = userstatus;
 }
 @override
 public string tostring() {
 return "user [id=" + id + ", username=" + username + ", userpwd=" + userpwd + ", deptmentid=" + deptmentid
  + ", usertruename=" + usertruename + ", email=" + email + ", learncenterid=" + learncenterid
  + ", createdate=" + createdate + ", lastmodifydate=" + lastmodifydate + ", userstatus=" + userstatus
  + "]";
 }
}

7) 在main方法下做测试

package hw.com.day1.main;
import java.util.list;
import org.apache.ibatis.session.sqlsession;
import hw.com.pojo.user;
import hw.com.ser.iuser;
import hw.com.util.sqlsessionfactoryutil;
public class usertest {
 public static void main(string[] args) { 
 sqlsession sqlsession=null;
 try {
  sqlsession=sqlsessionfactoryutil.opensqlsession();
  iuser iuser=sqlsession.getmapper(iuser.class);
  list<user> users=iuser.queryusers();
  if(users.size()>0){
  for (user user : users) {
   system.out.println(user.tostring());
  }
  }
 } catch (exception e) {
  e.printstacktrace();
 }
 }
}