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MyBatis 入门（一）
MyBatis
mybatis和hibernate都属于orm(对象与关系映射) 框架
mybatis的优点：
1.sql-mapping ：操作更自由，可控性高，执行效率更高
2.轻量，学习更容易
3.维护和修改容易
mybatis使用场合：
在不需要太多复杂的功能，且需要性能更高，并且希望更灵活可以使用mybatis
什么时候不宜使用mybatis:
对象持久化对程序完全透明时，使用hibernate
当数据有移植需求且需要支持多种数据库是
当应用程序要求完全动态sql时
没有使用关系数据库时
使用mybatis需要使用到架包：
下载架包
下面开始我么第一个mybatis练习：、
1.建一个项目：
2.配置mybatis-config.xml (帮助文档 里面可以查找到 )
3.建一个实体类
4.创建一个mapper文件 (可以在帮助文档里面查看)
5.创建dao 封装类
6.测试
先上代码：
mybatis-config.xml:
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE configuration 3 PUBLIC "-//mybatis.org//DTD Config 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-config.dtd"> 5 <configuration> 6 <settings> 7 <setting name="cacheEnabled" value="true"/> 8 9 </settings>10 <!-- -->11 <environments default="development">12 <environment id="development">13 <!-- 事务处理方式 -->14 <transactionManager type="JDBC"/>15 <!-- 数据源 ：提供数据库连接池 -->16 <dataSource type="POOLED">17 <!-- 驱动 -->18 <property name="driver" value="oracle.jdbc.driver.OracleDriver"/>19 <!-- -->20 <property name="url" value="jdbc:oracle:thin:@localhost:1521:xe"/>21 <property name="username" value="super_user"/>22 <property name="password" value="abc123"/>23 </dataSource>24 </environment>25 </environments>26 27 28 <!-- 映射文件，可以配置多个 -->29 <mappers>30 <mapper resource="dao/grade.xml"/>31 32 </mappers>33 34 35 </configuration>
grade.xml:
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE mapper 3 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 5 <mapper namespace="dao.MyBatis01Dao"> 6 <cache eviction="FIFO" flushInterval="60000" size="512" readOnly="true"/> 7 <!-- parameterType="int" 指定传入参数类型 id最好与接口里面的方法名一致--> 8 <select id="testgetGrade" resultType="entity.Grade"> 9 select * from grade where gradeid=1 10 </select> 11 <resultMap type="entity.Grade" id="gradeMap"> 12 13 </resultMap> 14 <select id="testBatis1" parameterType="int" resultMap="gradeMap"> 15 select * from grade where gradeid>=#{gradeid} 16 </select> 17 <select id="seleTrend" parameterType="entity.Grade" resultType="entity.Grade"> 18 select * from grade where 1=1 19 <if test ="gradeid != null"> 20 <![CDATA[ 21 and gradeid<= #{gradeid} 22 ]]> 23 24 </if> 25 <if test ="gradename != null"> 26 <!-- 模糊查询 --> 27 <![CDATA[ 28 and gradename like ‘%${gradename}%‘ 29 ]]> 30 </if> 31 32 33 </select> 34 35 <insert id="insertGrade" parameterType="entity.Grade" flushCache="true" > 36 insert into grade values(#{gradeid},#{gradename}) 37 38 </insert> 39 <insert id="insertGradeBySeq" parameterType="entity.Grade" flushCache="true"> 40 <selectKey keyProperty="gradeid" resultType="int" order="BEFORE"> 41 select seq_gradeindex.nextVal from dual 42 </selectKey> 43 insert into grade values(#{gradeid},#{gradename}) 44 45 </insert> 46 <delete id="delGrade" parameterType="entity.Grade" flushCache="true" > 47 delete grade where gradeid=#{gradeid} 48 49 </delete> 50 <update id="upGrade" parameterType="entity.Grade" flushCache="true" > 51 update grade set gradename=#{gradename} where gradeid=#{gradeid} 52 53 </update> 54 55 56 57 <!-- 动态查询 --> 58 <select id="testTrendSele1" parameterType="entity.Student" resultType="entity.Student"> 59 select * from student where 1=1 60 <if test="stuno != null"> 61 <![CDATA[ 62 and stuno<=#{stuno} 63 ]]> 64 65 </if> 66 <if test="name != null"> 67 <![CDATA[ 68 and name like ‘%${name}%‘ 69 ]]> 70 </if> 71 <if test="gradeid != null"> 72 <![CDATA[ 73 and gradeid>=#{gradeid} 74 ]]> 75 </if> 76 77 </select> 78 <!-- MyBatis where 查询 --> 79 <select id="testTrendSeleByWhere" parameterType="entity.Student" resultType="entity.Student"> 80 select * from student 81 <where> 82 <if test="stuno != null"> 83 <![CDATA[ 84 and stuno<=#{stuno} 85 ]]> 86 87 </if> 88 <if test="name != null"> 89 <![CDATA[ 90 and name like ‘%${name}%‘ 91 ]]> 92 </if> 93 <if test="gradeid != null"> 94 <![CDATA[ 95 and gradeid>=#{gradeid} 96 ]]> 97 </if> 98 </where> 99 100 </select>101 <!-- choose查询 -->102 <select id="testTrendSeleByChoose" parameterType="entity.Student" resultType="entity.Student">103 104 select * from student where 1=1105 <choose>106 <when test="stuno != null">107 <![CDATA[108 and stuno<=#{stuno}109 ]]>110 </when>111 <when test="name != null">112 <![CDATA[113 and name like ‘%${name}%‘114 ]]>115 </when>116 <otherwise>117 <![CDATA[118 and gradeid>=#{gradeid}119 ]]>120 </otherwise>121 </choose>122 123 </select>124 <!-- set 动态更新 -->125 <update id="testTrendSeleBySet" parameterType="entity.Grade">126 update grade127 <set>128 <if test="gradename != null">129 gradename=#{gradename}130 </if>131 132 </set>133 where gradeid=#{gradeid}134 135 </update>136 137 </mapper>
dao.GradeDaoImpl:
1 package dao.impl; 2 3 import java.io.Reader; 4 import java.util.List; 5 6 import junit.framework.TestCase; 7 import org.apache.ibatis.io.Resources; 8 import org.apache.ibatis.session.SqlSession; 9 import org.apache.ibatis.session.SqlSessionFactory; 10 import org.apache.ibatis.session.SqlSessionFactoryBuilder; 11 import org.junit.Test; 12 13 import util.MyBatisUtil; 14 15 import dao.MyBatis01Dao; 16 import entity.Grade; 17 import entity.Student; 18 19 public class GradeImplDao extends TestCase implements MyBatis01Dao{ 20 21 22 String resource="mybatis-config.xml"; 23 Reader reader=null; 24 SqlSessionFactory factory=null; 25 SqlSession session=null; 26 /** 27 * 测试 有参方法 28 */ 29 30 public void testV(){ 31 try { 32 //session=(new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource))).openSession(); 33 //MyBatis01Dao con=session.getMapper(MyBatis01Dao.class); 34 //con.testBatis1(5); 35 36 //testBatis1(2); 37 // Grade grade=new Grade(); 38 // grade.setGradeid(7); 39 // grade.setGradename(""); 40 //delGrade(grade); 41 //insertGrade(grade); 42 //upGrade(grade); 43 //seleTrend(grade); 44 Student student=new Student(25,"ab%d",2); 45 //testTrendSele1(student); 46 testTrendSeleByChoose(student); 47 //testTrendSeleByWhere(student); 48 //testTrendSeleBySet(student); 49 } catch (Exception e) { 50 // TODO: handle exception 51 e.printStackTrace(); 52 } 53 finally{ 54 //session.close(); 55 } 56 57 } 58 /** 59 * 第一个mybatis查询 60 */ 61 62 public void testgetGrade(){ 63 try { 64 //读取配置文件 65 reader=Resources.getResourceAsReader(resource); 66 SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder(); 67 //创建sqlsessionfactory 68 factory=builder.build(reader); 69 session=factory.openSession(); 70 //读取 71 List grade=session.selectList("testgetGrade"); 72 System.out.println(grade); 73 } catch (Exception e) { 74 // TODO: handle exception 75 e.printStackTrace(); 76 }finally{ 77 session.close(); 78 79 } 80 81 82 } 83 84 /** 85 * 传入一个参数查询 seleGradeByPara 86 */ 87 public void testBatis1(int id){ 88 try { 89 //创建并且打开session 90 session=(new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource))).openSession(); 91 //设置参数 92 List grade=session.selectList("testBatis1",id); 93 System.out.println(grade); 94 } catch (Exception e) { 95 e.printStackTrace(); 96 }finally{ 97 //关闭 98 session.close(); 99 100 }101 }102 103 104 105 106 /**107 * 新增108 */109 @Override110 public void insertGrade(Grade grade) {111 try {112 //打开113 session=(new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource))).openSession();114 //新增115 session.insert("insertGrade",grade);116 session.commit();117 //显示118 System.out.println(session.selectList("testBatis1",1)); 119 } catch (Exception e) {120 // TODO: handle exception121 e.printStackTrace();122 }finally{123 session.close();124 }125 126 }127 128 /**129 * 删除指定130 * @param grade131 */132 public void delGrade(Grade grade){133 try {134 session=(new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource))).openSession();135 session.delete("delGrade",grade);136 session.commit();137 System.out.println(session.selectList("testBatis1",1)); 138 139 } catch (Exception e) {140 // TODO: handle exception141 e.printStackTrace();142 }finally{143 session.close();144 }145 146 }147 /**148 * 更新149 * @param grade150 */151 public void upGrade(Grade grade){152 try {153 session=(new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource))).openSession();154 session.update("upGrade",grade);155 session.commit();156 System.out.println(session.selectList("testBatis1",1)); 157 } catch (Exception e) {158 // TODO: handle exception159 e.printStackTrace();160 }finally{161 session.close();162 }163 }164 165 /**166 * 动态查询167 * @param grade168 */169 public void seleTrend(Grade grade){170 try {171 session=(new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource))).openSession();172 173 System.out.println(session.selectList("seleTrend", grade));174 175 } catch (Exception e) {176 // TODO: handle exception177 e.printStackTrace();178 }finally{179 session.close();180 }181 182 }183 184 /**185 * 测试更新186 */187 public void testForUpdate(){188 try {189 session=new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource)).openSession();190 Grade grade=new Grade();191 grade.setGradename("研究院");192 session.insert("insertGradeBySeq",grade);193 session.commit();194 } catch (Exception e) {195 // TODO: handle exception196 e.printStackTrace();197 session.rollback();198 }finally{199 session.close();200 201 }202 203 }204 205 @Override206 public void testTrendSele1(Student student) {207 try {208 //System.out.println("111111111");209 session=(new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource))).openSession();210 List students=session.selectList("testTrendSele1",student);211 for(int i=0;i<students.size();i++){212 System.out.println(students.get(i));213 214 215 }216 217 218 } catch (Exception e) {219 e.printStackTrace();220 }221 finally{222 if(session != null)223 session.close();224 }225 }226 227 @Override228 public void testTrendSeleByWhere(Student student) {229 // TODO Auto-generated method stub230 try {231 session=new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource)).openSession();232 //代替 where 1=1 where字句233 List students=session.selectList("testTrendSeleByWhere",student);234 for(int i=0;i<students.size();i++){235 System.out.println(students.get(i));236 237 238 }239 } catch (Exception e) {240 e.printStackTrace();241 }242 finally{243 session.close();244 }245 }246 247 @Override248 public void testTrendSeleByChoose(Student student) {249 // TODO Auto-generated method stub250 try {251 session=MyBatisUtil.getSession();252 //choose： 只查询 其中一个条件，从上到下执行253 List students=session.selectList("testTrendSeleByChoose",student);254 for(int i=0;i<students.size();i++){255 System.out.println(students.get(i));256 257 258 }259 MyBatisUtil.closeSession();260 session=MyBatisUtil.getSession();261 List students2=session.selectList("testTrendSeleByChoose",student);262 System.out.println("---------"+(students==students2)+"----------");263 264 } catch (Exception e) {265 e.printStackTrace();266 }267 finally{268 MyBatisUtil.closeSession();269 }270 271 272 }273 274 @Override275 public void testTrendSeleBySet(Student student) {276 // TODO Auto-generated method stub277 try {278 session=new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource)).openSession();279 Grade grade=new Grade();280 grade.setGradeid(2);281 grade.setGradename("一年级");282 session.update("testTrendSeleBySet", grade);283 session.commit();284 System.out.println("success!");285 } catch (Exception e) {286 e.printStackTrace();287 session.rollback();288 }289 finally{290 MyBatisUtil.closeSession();291 }292 293 294 }295 296 297 @Test298 public void testname() {299 System.out.println("11111");300 }301 302 303 304 }
entity.Grade
1 package entity; 2 3 import java.io.Serializable; 4 import java.util.HashSet; 5 import java.util.Set; 6 /** 7 * 年级实体类 8 * @author Administrator 9 *10 */11 public class Grade implements Serializable{12 //年级编号13 private Integer gradeid;14 //年级15 private String gradename;16 17 @Override18 public String toString() {19 // TODO Auto-generated method stub20 return gradeid+"\t"+gradename;21 }22 23 public Grade(){}24 25 26 public Integer getGradeid() {27 return gradeid;28 }29 public void setGradeid(Integer gradeid) {30 this.gradeid = gradeid;31 }32 public String getGradename() {33 return gradename;34 }35 public void setGradename(String gradename) {36 this.gradename = gradename;37 }38 39 40 41 }
config配置文件中：
主要配置了数据库连接信息
以及映射文件的位置信息
mapper配置文件：
配置了各种sql语句，与config关联起来需要在config里面写上这句代码：
<mappers>
<mapper resource="dao/grade.xml"/>
</mappers>
mybatis支持哪些操作：
增 删 改 查
实现普通查询：
1.配置mapper
<mapper namespace="dao接口包"/>
<select id="testgetGrade" resultType="entity.Grade">
select * from grade where gradeid=1
</select>
解释：
id:我们在dao.impl里面去操作数据库时，指定sql语句就根据id指定,id尽量与接口提供的方法同名（后面讲getMapper()可以看出作用 ）
resultType：返回值类型，支持各种类型
2.在dao里面写代码：
mybatis也是基于session的
1、声明一个sqlSessionFactory对象、SqlSession对象、Reader对象
2、读取配置文件
//指定config路径
String resource="mybatis-config.xml";
//读取配置文件
reader=Resources.getResourceAsReader(resource);
//声明sqlsessionfactorybuilder
SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder();
//创建sqlsessionfactory
factory=builder.build(reader);
//开启sqlsession
session=factory.openSession();
//读取
List grade=session.selectList("testgetGrade");
//打印
System.out.println(grade);
暂时介绍select方法；
selectlist方法返回的是一个list集合
上面的代码里面包含了，查询，删除，修改，新增，动态查询，缓存的方法，结合帮助文档可以看明白
下次做详细深入的总结
MyBatis 入门（一）
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