mybatis怎么进行使用，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。
1.数据源DataSource
计算
安全
数据库
网络和加速
企业服务
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<!-- 数据源配置, 使用 BoneCP 数据库连接池 -->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
<!-- 数据源驱动类可不写，Druid默认会自动根据URL识别DriverClass -->
<property name="driverClassName" value="${jdbc.driver}" />
<!-- 基本属性 url、user、password -->
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<!-- config.decrypt=true生效 必须配置 filters的value包含config -->
<property name="connectionProperties" value="druid.stat.slowSqlMillis=5000;config.decrypt=true;config.decrypt.key=${jdbc.publicKey}"/>
<!-- 配置初始化大小、最小、最大 -->
<property name="initialSize" value="${jdbc.pool.init}" />
<property name="minIdle" value="${jdbc.pool.minIdle}" />
<property name="maxActive" value="${jdbc.pool.maxActive}" />
<!-- 配置获取连接等待超时的时间 -->
<property name="maxWait" value="60000" />
<!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 -->
<property name="timeBetweenEvictionRunsMillis" value="60000" />
<!-- 配置一个连接在池中最小生存的时间，单位是毫秒 -->
<property name="minEvictableIdleTimeMillis" value="300000" />
<property name="validationQuery" value="${jdbc.testSql}" />
<property name="testWhileIdle" value="true" />
<property name="testOnBorrow" value="false" />
<property name="testOnReturn" value="false" />
<!-- 打开PSCache，并且指定每个连接上PSCache的大小（Oracle使用）
<property name="poolPreparedStatements" value="true" />
<property name="maxPoolPreparedStatementPerConnectionSize" value="20" /> -->
<!-- 配置监控统计拦截的filters -->
<property name="filters" value="config,stat,mergeStat,wall" />
</bean>
<!-- 数据源配置, 使用应用服务器的数据库连接池
<jee:jndi-lookup id="dataSource" jndi-name="java:comp/env/jdbc/umanager" />-->
<!-- 数据源配置, 不使用连接池
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="${jdbc.driver}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</bean>-->
</beans>2.mapper.xml文件
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="configLocation" value="classpath:META-INF/com/unilife/mybatis-config.xml" />
<property name="mapperLocations" value="classpath:META-INF/com/unilife/**/sqlmap/**/*.xml"/>
</bean>3.Dao类的实例化
方法一：原生方法的实例化
自定义一个BaseDao抽象类实现SqlSessionDaoSupport并注入sqlSessionFactory，通过namespace+id找到mapper.xml文件
方法二：spring-mytabis动态代理生成实例化
<!-- 扫描basePackage下所有以@MyBatisDao注解的接口 -->
<bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
<property name="basePackage" value="com.unilife"/>
<property name="annotationClass" value="com.unilife.annotation.UMemberBatisDao"/>
</bean>4.分页插件
4.1自定义分页插件
<plugins>
<plugin interceptor="com.unilife.commons.utils.PagePlugin">
<property name="dialect" value="mysql" />
<property name="pageSqlId" value=".*ByPage" />
</plugin>
</plugins>
package com.unilife.commons.utils;
import com.unilife.commons.dto.Page;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.executor.statement.BaseStatementHandler;
import org.apache.ibatis.executor.statement.RoutingStatementHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.ParameterMode;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.property.PropertyTokenizer;
import org.apache.ibatis.scripting.xmltags.ForEachSqlNode;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.TypeHandlerRegistry;
import org.springframework.util.StringUtils;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Properties;
@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }) })
public class PagePlugin implements Interceptor {
private String dialect = ""; // 数据库方言
private String pageSqlId = ""; // mapper.xml中需要拦截的ID(正则匹配)
@Override
public Object intercept(Invocation ivk) throws Throwable {
if (ivk.getTarget() instanceof RoutingStatementHandler) {
RoutingStatementHandler statementHandler = (RoutingStatementHandler) ivk
.getTarget();
BaseStatementHandler delegate = (BaseStatementHandler) ReflectHelper
.getValueByFieldName(statementHandler, "delegate");
MappedStatement mappedStatement = (MappedStatement) ReflectHelper
.getValueByFieldName(delegate, "mappedStatement");
if (mappedStatement.getId().matches(pageSqlId)) { // 拦截需要分页的SQL
BoundSql boundSql = delegate.getBoundSql();
Object parameterObject = boundSql.getParameterObject();// 分页SQL<select>中parameterType属性对应的实体参数，即Mapper接口中执行分页方法的参数,该参数不得为空
if (parameterObject == null) {
throw new NullPointerException("parameterObject尚未实例化！");
} else {
Connection connection = (Connection) ivk.getArgs()[0];
String sql = boundSql.getSql();
String countSql = "select count(0) from (" + sql
+ ") tmp_count"; // 记录统计
PreparedStatement countStmt = connection
.prepareStatement(countSql);
BoundSql countBS = new BoundSql(
mappedStatement.getConfiguration(), countSql,
boundSql.getParameterMappings(), parameterObject);
/*
* 此处特殊处理foreach的参数
*/
Field metaParamsField = ReflectHelper.getFieldByFieldName(
boundSql, "metaParameters");
if (metaParamsField != null) {
MetaObject mo = (MetaObject) ReflectHelper
.getValueByFieldName(boundSql, "metaParameters");
ReflectHelper.setValueByFieldName(countBS,
"metaParameters", mo);
}
setParameters(countStmt, mappedStatement, countBS,
parameterObject);
ResultSet rs = countStmt.executeQuery();
int count = 0;
if (rs.next()) {
count = rs.getInt(1);
}
rs.close();
countStmt.close();
// System.out.println(count);
Page page = null;
if (parameterObject instanceof Page) { // 参数就是Page实体
page = (Page) parameterObject;
page.setEntityOrField(true); // 见com.flf.entity.Page.entityOrField
// // 注释
page.setTotalResult(count);
} else { // 参数为某个实体，该实体拥有Page属性
Field pageField = ReflectHelper.getFieldByFieldName(
parameterObject, "page");
if (pageField != null) {
page = (Page) ReflectHelper.getValueByFieldName(
parameterObject, "page");
if (page == null)
page = new Page();
page.setEntityOrField(false); // 见com.flf.entity.Page.entityOrField
// 注释
page.setTotalResult(count);
ReflectHelper.setValueByFieldName(parameterObject,
"page", page); // 通过反射，对实体对象设置分页对象
} else {
throw new NoSuchFieldException(parameterObject
.getClass().getName() + "不存在 page 属性！");
}
}
String pageSql = generatePageSql(sql, page);
ReflectHelper.setValueByFieldName(boundSql, "sql", pageSql); // 将分页sql语句反射回BoundSql.
}
}
}
return ivk.proceed();
}
@Override
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
/**
* 对SQL参数(?)设值,参考org.apache.ibatis.executor.parameter.
* DefaultParameterHandler
*
* @param ps
* @param mappedStatement
* @param boundSql
* @param parameterObject
* @throws SQLException
*/
private void setParameters(PreparedStatement ps,
MappedStatement mappedStatement, BoundSql boundSql,
Object parameterObject) throws SQLException {
ErrorContext.instance().activity("setting parameters")
.object(mappedStatement.getParameterMap().getId());
List<ParameterMapping> parameterMappings = boundSql
.getParameterMappings();
if (parameterMappings != null) {
Configuration configuration = mappedStatement.getConfiguration();
TypeHandlerRegistry typeHandlerRegistry = configuration
.getTypeHandlerRegistry();
MetaObject metaObject = parameterObject == null ? null
: configuration.newMetaObject(parameterObject);
for (int i = 0; i < parameterMappings.size(); i++) {
ParameterMapping parameterMapping = parameterMappings.get(i);
if (parameterMapping.getMode() != ParameterMode.OUT) {
Object value;
String propertyName = parameterMapping.getProperty();
PropertyTokenizer prop = new PropertyTokenizer(propertyName);
if (parameterObject == null) {
value = null;
} else if (typeHandlerRegistry
.hasTypeHandler(parameterObject.getClass())) {
value = parameterObject;
} else if (boundSql.hasAdditionalParameter(propertyName)) {
value = boundSql.getAdditionalParameter(propertyName);
} else if (propertyName
.startsWith(ForEachSqlNode.ITEM_PREFIX)
&& boundSql.hasAdditionalParameter(prop.getName())) {
value = boundSql.getAdditionalParameter(prop.getName());
if (value != null) {
value = configuration.newMetaObject(value)
.getValue(
propertyName.substring(prop
.getName().length()));
}
} else {
value = metaObject == null ? null : metaObject
.getValue(propertyName);
}
TypeHandler typeHandler = parameterMapping.getTypeHandler();
if (typeHandler == null) {
throw new ExecutorException(
"There was no TypeHandler found for parameter "
+ propertyName + " of statement "
+ mappedStatement.getId());
}
typeHandler.setParameter(ps, i + 1, value,
parameterMapping.getJdbcType());
}
}
}
}
/**
* 根据数据库方言，生成特定的分页sql
*
* @param sql
* @param page
* @return
*/
private String generatePageSql(String sql, Page page) {
if (page != null && StringUtils.hasLength(dialect)) {
StringBuffer pageSql = new StringBuffer();
if ("mysql".equals(dialect)) {
pageSql.append(sql);
if (StringUtils.hasLength(page.getSort())) {
pageSql.append(" ORDER BY " + page.getSort());
if (StringUtils.hasLength(page.getSort())) {
pageSql.append(" " + page.getOrder());
}
}
pageSql.append(" limit " + page.getCurrentResult() + ","
+ page.getShowCount());
} else if ("oracle".equals(dialect)) {
pageSql.append("select * from (select tmp_tb.*,ROWNUM row_id from (");
pageSql.append(sql);
pageSql.append(") tmp_tb where ROWNUM<=");
pageSql.append(page.getCurrentResult() + page.getShowCount());
pageSql.append(") where row_id>");
pageSql.append(page.getCurrentResult());
if (StringUtils.hasLength(page.getSort())) {
pageSql.append(" ORDER BY " + page.getSort());
if (StringUtils.hasLength(page.getSort())) {
pageSql.append(" " + page.getOrder());
}
}
}
return pageSql.toString();
} else {
return sql;
}
}
@Override
public void setProperties(Properties properties) {
dialect = properties.getProperty("dialect");
pageSqlId = properties.getProperty("pageSqlId");
}
}
class ReflectHelper {
/**
* 获取obj对象fieldName的Field
*
* @param obj
* @param fieldName
* @return
*/
public static Field getFieldByFieldName(Object obj, String fieldName) {
for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass
.getSuperclass()) {
try {
return superClass.getDeclaredField(fieldName);
} catch (NoSuchFieldException e) {
}
}
return null;
}
/**
* 获取obj对象fieldName的属性值
*
* @param obj
* @param fieldName
* @return
* @throws SecurityException
* @throws NoSuchFieldException
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
public static Object getValueByFieldName(Object obj, String fieldName)
throws SecurityException, NoSuchFieldException,
IllegalArgumentException, IllegalAccessException {
Field field = getFieldByFieldName(obj, fieldName);
Object value = null;
if (field != null) {
if (field.isAccessible()) {
value = field.get(obj);
} else {
field.setAccessible(true);
value = field.get(obj);
field.setAccessible(false);
}
}
return value;
}
/**
* 设置obj对象fieldName的属性值
*
* @param obj
* @param fieldName
* @param value
* @throws SecurityException
* @throws NoSuchFieldException
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
public static void setValueByFieldName(Object obj, String fieldName,
Object value) throws SecurityException, NoSuchFieldException,
IllegalArgumentException, IllegalAccessException {
Field field = obj.getClass().getDeclaredField(fieldName);
if (field.isAccessible()) {
field.set(obj, value);
} else {
field.setAccessible(true);
field.set(obj, value);
field.setAccessible(false);
}
}
}4.2 开源分页插件
com.github.pagehelper
5.补充，可以通过mybatis-config.xml进行configuration对象的配置
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原文链接：https://my.oschina.net/u/1458864/blog/3095841
