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MyBatis系列：（4）分页查询
Emp.java
package com.rk.entity;
public class Emp {
private Integer id;
private String name;
private Double sal;
public Emp(){}
public Emp(Integer id, String name, Double sal) {
this.id = id;
this.name = name;
this.sal = sal;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Double getSal() {
return sal;
}
public void setSal(Double sal) {
this.sal = sal;
}
}mybatis.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>
<!-- 加载类路径下的属性文件 -->
<properties resource="db.properties"/>
<!-- 设置类型别名 -->
<typeAliases>
<typeAlias type="com.rk.entity.Emp" alias="emp"/>
</typeAliases>
<!-- 设置一个默认的连接环境信息 -->
<environments default="mysql_development">
<environment id="mysql_development">
<!-- mybatis使用jdbc事务管理方式 -->
<transactionManager type="JDBC"/>
<!-- mybatis使用连接池方式来获取连接 -->
<dataSource type="POOLED">
<!-- 配置与数据库交互的4个必要属性 -->
<property name="driver" value="http://www.mamicode.com/${mysql.driver}"/>
<property name="url" value="http://www.mamicode.com/${mysql.url}"/>
<property name="username" value="http://www.mamicode.com/${mysql.username}"/>
<property name="password" value="http://www.mamicode.com/${mysql.password}"/>
</dataSource>
</environment>
<!-- 连接环境信息，取一个任意唯一的名字 -->
<environment id="oracle_development">
<!-- mybatis使用jdbc事务管理方式 -->
<transactionManager type="jdbc"/>
<!-- mybatis使用连接池方式来获取连接 -->
<dataSource type="pooled">
<!-- 配置与数据库交互的4个必要属性 -->
<property name="driver" value="http://www.mamicode.com/${oracle.driver}"/>
<property name="url" value="http://www.mamicode.com/${oracle.url}"/>
<property name="username" value="http://www.mamicode.com/${oracle.username}"/>
<property name="password" value="http://www.mamicode.com/${oracle.password}"/>
</dataSource>
</environment>
</environments>
<!-- 加载映射文件-->
<mappers>
<mapper resource="com/rk/entity/EmpMapper.xml"/>
</mappers>
</configuration>db.properties
mysql.driver=com.mysql.jdbc.Driver mysql.url=jdbc:mysql://127.0.0.1:3306/testdb mysql.username=root mysql.password=root oracle.driver=oracle.jdbc.driver.OracleDriver oracle.url=jdbc:oracle:thin:@127.0.0.1:1521:orcl oracle.username=scott oracle.password=tiger
EmpMapper.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">
<!-- namespace属性是名称空间，必须唯一 -->
<mapper namespace="com.rk.entity.Emp">
<!-- resultMap标签:映射实体与表
type属性：表示实体全路径名
id属性：为实体与表的映射取一个任意的唯一的名字
-->
<resultMap type="emp" id="empMap">
<!-- id标签:映射主键属性
result标签：映射非主键属性
property属性:实体的属性名
column属性：表的字段名
-->
<id property="id" column="id"/>
<result property="name" column="name"/>
<result property="sal" column="sal"/>
</resultMap>
<!--
insert标签：要书写insert这么一个sql语句
id属性：为insert这么一个sql语句取一个任意唯一的名字
parameterType:要执行的dao中的方法的参数，如果是类的话，必须使用全路径类
-->
<insert id="add" parameterType="emp">
insert into emp(id,name,sal) values(#{id},#{name},#{sal})
</insert>
<select id="paginationAll" parameterType="map" resultType="emp">
select id,name,sal from emp limit #{pstart},#{psize}
</select>
<select id="pagination" parameterType="map" resultType="emp">
select id,name,sal from emp where name like #{pname} limit #{pstart},#{psize}
</select>
</mapper>MyBatisUtils.java
package com.rk.utils;
import java.io.IOException;
import java.io.Reader;
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;
public class MyBatisUtils {
private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
private static SqlSessionFactory sqlSessionFactory;
static{
try {
Reader reader = Resources.getResourceAsReader("mybatis.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
private MyBatisUtils() {}
public static SqlSession getSqlSession(){
SqlSession sqlSession = threadLocal.get();
if(sqlSession == null){
sqlSession = sqlSessionFactory.openSession();
threadLocal.set(sqlSession);
}
return sqlSession;
}
public static void closeSqlSession(){
SqlSession sqlSession = threadLocal.get();
if(sqlSession != null){
sqlSession.close();
threadLocal.remove();
}
}
public static void main(String[] args) {
Connection conn = MyBatisUtils.getSqlSession().getConnection();
System.out.println(conn!=null ? "连接成功" : "连接失败");
}
}EmpDao.java
package com.rk.dao;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.session.SqlSession;
import com.rk.entity.Emp;
import com.rk.utils.MyBatisUtils;
public class EmpDao {
/**
* 添加员工
*/
public void add(Emp emp){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlSession();
int i = sqlSession.insert(Emp.class.getName() + ".add", emp);
System.out.println("本次操作影响"+i+"行数据");
sqlSession.commit();
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
}
/**
* 分页查询所有员工
*/
public List<Emp> paginationAll(int start,int size){
SqlSession sqlSession = null;
List<Emp> list = null;
try {
Map<String, Integer> map = new HashMap<String, Integer>();
map.put("pstart", start);
map.put("psize", size);
sqlSession = MyBatisUtils.getSqlSession();
list = sqlSession.selectList(Emp.class.getName() + ".paginationAll",map);
sqlSession.commit();
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
return list;
}
/**
* 根据姓名，分页查询所有员工
*/
public List<Emp> pagination(String name,int start,int size){
SqlSession sqlSession = null;
List<Emp> list = null;
try {
Map<String, Object> map = new HashMap<String, Object>();
map.put("pname", "%" + name + "%");
map.put("pstart", start);
map.put("psize", size);
sqlSession = MyBatisUtils.getSqlSession();
list = sqlSession.selectList(Emp.class.getName() + ".pagination",map);
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
sqlSession.commit();
MyBatisUtils.closeSqlSession();
}
return list;
}
public static void main(String[] args) {
EmpDao dao = new EmpDao();
// for(int i=0;i<20;i++){
// Emp emp = new Emp(30+i, "Tom" + i, 200D+i);
// dao.add(emp);
// }
//List<Emp> list = dao.paginationAll(0, 5);
List<Emp> list = dao.pagination("Tom",0, 5);
if(list != null && list.size()>0){
for(Emp emp : list){
System.out.println( emp.getName() + ":"+emp.getSal());
}
}
}
}MyBatis系列：（4）分页查询
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