ibatis的探索和应用，实现ibatis的CRUD功能，ibatis的优缺点

一、ibatis简介：ibatis是apache的一个开源项目，一个ORMapping解决方案，iBatis最大的特点就是小巧，上手快。如果不需要大多的功能，iBatis是能满足你的要求又是够灵活的最简单的解决方案。

二、搭建环境：

首先，添加jar包：分别是oracle的jar包，和iBatis的jar包，iBatis的jar包可以在网上直接下载，必须带有SqlMapClient类的jar包才行；

2,接下来，创建数据库Student,包含字段sid,sname,major.birth,score

3,建立SqlMapConfig,xml用于连接数据库的

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE sqlMapConfig PUBLIC "-//ibatis.apache.org//DTD SQL Map Config 2.0//EN""http://ibatis.apache.org/dtd/sql-map-config-2.dtd"><SqlMapConfig><properties resource ="com/itcast/SqlMap.properties"/><transactionManager type="JDBC"><dataSource type="SIMPLE"><property name="${driver}" value="JDBC.Driver"/><property name="${url}" value="JDBC.ConnectionURL"/><property name="${username}" value="JDBC.Username"/><property name="${password}" value="JDBC.Password"/></dataSource></transactionManager><properties resource ="com/itcast/Student.xml"/></SqlMapConfig>

上面的driver,url,username,password是不是很熟悉，jdbc中的老朋友

再配完上面的SqlMapConfig，那还要给对应的driver,url,username,password赋值啊，创建一个SqlMap.properties文件，写入

driver=oracle.jdbc.driver.OracleDriver
url=jdbc\:oracle\:thin\:@192.168.2.144\:8080\:1521\:orcl
username=aaa
password=123

3，完成上述，就可以建立Student实体类了，Get/Set一下

4，创建接口类IStudentDAO，完成CRUD操作

package com.itcast;import java.util.List;public interface IStudentDAO {public void addStudent(Student student);public void addStudentBySequence(Student student);public void deleteStudentById(int id);public void updateStudentById(Student student);public List<Student> queryAllStudent();public List<Student> queryStudentByName(String name);public Student queryStudentById(int id);}

5，创建Student.xml文件封装sql语句，这里也是体现ibatis高效简便的地方

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE sqlMapConfig PUBLIC "-//ibatis.apache.org//DTD SQL Map Config 2.0//EN""http://ibatis.apache.org/dtd/sql-map-config-2.dtd"><SqlMap><typeAlias alias="Student" type="com.itcast.Student"/><!--这里的id是对应到类中的，resultClass是返回值类型 --><select id="selectAllStudent" resultClass="Student">select * from  student</select><select id="selectStudentById" parameterClass="int" resultClass ="Student">select *from studentwheresid="#sid"</select><!--插入,parameterClass参数的类型，#夹着表示这是一个需要传入的数据，而且最好是与插入的表列名想一致 --><insert id="insertStudent" parameterClass ="Student">insert into Student(sid,  sname,   major,   birth,  score)Values   (#sid#,#sname#,#smajor#,#birth#,#score#)</insert><!-- 这里的#sid#，#夹着表示这是一个需要传入的数据，相当于占位符没有意义，parameterClass参数的类型 --><deleteid="deleteStudentById" parameterClass="int">delete    fromStudent wheresid = #sid#</delete><!--parameterClass中的Student不区分大小写--><update id="updateStudentById" parameterClass="Student">updateStudentsetsname=#sname#,major=#major#,score=#score#,birth=#birth#where sid=#sid#</update><!--模糊查询，%$sname$% --><select id="selectStudentByName" parameterClass="String" resultClass="Student">selectsid,sname,major,birth,scorefromStudentwheresnamelike'%$sname$%'</select><!-- sql主键生成方式首先，要创建一个sql序列，create sequenceStudentPKSquence start with 1 increment by 1; --><insert id="insertStudentBySequence"parameterClass="Student"><selectKeyresultClass="int"keyProperty="sid">selectStudentPKSequence.nextValfromdual</selectKey>insertintoStudent(sid,  sname,   major,   birth,  score)Values   (#sid#,#sname#,#smajor#,#birth#,#score#)</insert></SqlMap>

对应的实现类IStudentDAOImpl,

package com.itcast;import java.io.Reader;import java.sql.SQLException;import java.util.List;import com.ibatis.sqlmap.client.SqlMapClient;public class IStudentDAOImpl implements IStudentDAO {private static SqlMapClient sqlMapClient = null;static {try{//获取数据库连接数据Reader reader = com.ibatis.common.resources.Resources.getResourceAsReader("com.itcast.SqlMapConfig.xml");}catch(Exception e){e.printStackTrace();}}public void addStudent(Student student) {try {sqlMapClient.insert("insertStudent",student);} catch (SQLException e) {e.printStackTrace();}}public void addStudentBySequence(Student student) {try {sqlMapClient.insert("insertStudentBySequence",student);} catch (SQLException e) {e.printStackTrace();}}public void deleteStudentById(int id) {try {sqlMapClient.insert("deleteStudentById",id);} catch (SQLException e) {e.printStackTrace();}}public List<Student> queryAllStudent() {List<Student> studentList = null;try {//这里selectAllStudent就是Student.xml中的id，必须一一对应的studentList = sqlMapClient.queryForList("selectAllStudent");} catch (SQLException e) {e.printStackTrace();}return studentList;}public Student queryStudentById(int id) {Student student = null;try {student = (Student) sqlMapClient.queryForObject("selectStudentById");} catch (SQLException e) {e.printStackTrace();}return student;}public List<Student> queryStudentByName(String name) {List<Student> studentList = null;try {//这里selectAllStudent就是Student.xml中的id，必须一一对应的studentList = sqlMapClient.queryForList("selectStudentByName",name);} catch (SQLException e) {e.printStackTrace();}return studentList;}public void updateStudentById(Student student) {try { sqlMapClient.update("updateStudentById",student);} catch (SQLException e) {e.printStackTrace();}}}

综上，ibatis的CRUD已经结束了。

下面说下iBatis的优缺点吧：

与JDBC相比较，优点：

1）减少代码量61%；2）简单，架构级性能增强；3）sql语句与程序代码分离，（这是它最明显的优势）

4）简化项目中的分工；5）增强了可移植性；

缺点：1）sql需要自己写；2）参数数量只能一个，parameterClass