标签：aop切面 owb poi ack because 项目开发 .exe private out
项目背景：项目开发中数据库使用了读写分离，所有查询语句走从库，除此之外走主库。
最简单的办法其实就是建两个包，把之前数据源那一套配置copy一份，指向另外的包，但是这样扩展很有限，所有采用下面的办法。
参考了两篇文章如下：
http://blog.csdn.net/zl3450341/article/details/20150687
http://www.blogjava.net/hoojo/archive/2013/10/22/405488.html
这两篇文章都对原理进行了分析，下面只写自己的实现过程其他不再叙述。
实现思路是：
第一步，实现动态切换数据源：配置两个DataSource，配置两个SqlSessionFactory指向两个不同的DataSource，两个SqlSessionFactory都用一个SqlSessionTemplate，同时重写Mybatis提供的SqlSessionTemplate类，最后配置Mybatis自动扫描。
第二步，利用aop切面，拦截dao层所有方法，因为dao层方法命名的特点，比如所有查询sql都是select开头，或者get开头等等，拦截这些方法，并把当前数据源切换至从库。
spring中配置如下：
主库数据源配置：
1 <bean id="masterDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> 2 <property name="driverClass" value="${master_mysql_jdbc_driver}" /> 3 <property name="jdbcUrl" value="${master_mysql_jdbc_url}" /> 4 <property name="user" value="${master_mysql_jdbc_user}" /> 5 <property name="password" value="${master_mysql_jdbc_password}" /> 6 </bean>
从库数据源配置：
1 <bean id="masterDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> 2 <property name="driverClass" value="${slave_mysql_jdbc_driver}" /> 3 <property name="jdbcUrl" value="${slave_mysql_jdbc_url}" /> 4 <property name="user" value="${slave_mysql_jdbc_user}" /> 5 <property name="password" value="${slave_mysql_jdbc_password}" /> 6 </bean>
主库SqlSessionFactory配置：
1 <bean id="masterSqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> 2 <property name="dataSource" ref="masterDataSource" /> 3 <property name="mapperLocations" value="classpath:com/sincetimes/slg/dao/*.xml"/> 4 </bean>
从库SqlSessionFactory配置：
1 <bean id="slaveSqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> 2 <property name="dataSource" ref="slaveDataSource" /> 3 <property name="mapperLocations" value="classpath:com/sincetimes/slg/dao/*.xml"/> 4 </bean>
两个SqlSessionFactory使用同一个SqlSessionTemplate配置：
1 <bean id="MasterAndSlaveSqlSessionTemplate" class="com.sincetimes.slg.framework.core.DynamicSqlSessionTemplate"> 2 <constructor-arg index="0" ref="masterSqlSessionFactory" /> 3 <property name="targetSqlSessionFactorys"> 4 <map> 5 <entry value-ref="masterSqlSessionFactory" key="master"/> 6 <entry value-ref="slaveSqlSessionFactory" key="slave"/> 7 </map> 8 </property> 9 </bean>
配置Mybatis自动扫描dao
1 <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> 2 <property name="basePackage" value="com.sincetimes.slg.dao" /> 3 <property name="sqlSessionTemplateBeanName" value="MasterAndSlaveSqlSessionTemplate" /> 4 </bean>
自己重写了SqlSessionTemplate代码如下：
1 package com.sincetimes.slg.framework.core; 2 3 import static java.lang.reflect.Proxy.newProxyInstance; 4 import static org.apache.ibatis.reflection.ExceptionUtil.unwrapThrowable; 5 import static org.mybatis.spring.SqlSessionUtils.closeSqlSession; 6 import static org.mybatis.spring.SqlSessionUtils.getSqlSession; 7 import static org.mybatis.spring.SqlSessionUtils.isSqlSessionTransactional; 8 9 import java.lang.reflect.InvocationHandler; 10 import java.lang.reflect.Method; 11 import java.sql.Connection; 12 import java.util.List; 13 import java.util.Map; 14 15 import org.apache.ibatis.exceptions.PersistenceException; 16 import org.apache.ibatis.executor.BatchResult; 17 import org.apache.ibatis.session.Configuration; 18 import org.apache.ibatis.session.ExecutorType; 19 import org.apache.ibatis.session.ResultHandler; 20 import org.apache.ibatis.session.RowBounds; 21 import org.apache.ibatis.session.SqlSession; 22 import org.apache.ibatis.session.SqlSessionFactory; 23 import org.mybatis.spring.MyBatisExceptionTranslator; 24 import org.mybatis.spring.SqlSessionTemplate; 25 import org.springframework.dao.support.PersistenceExceptionTranslator; 26 import org.springframework.util.Assert; 27 28 import com.sincetimes.slg.framework.util.SqlSessionContentHolder; 29 30 31 /** 32 * 33 * TODO 重写SqlSessionTemplate 34 * @author ccg 35 * @version 1.0 36 * Created 2017年4月21日 下午3:15:15 37 */ 38 public class DynamicSqlSessionTemplate extends SqlSessionTemplate { 39 40 private final SqlSessionFactory sqlSessionFactory; 41 private final ExecutorType executorType; 42 private final SqlSession sqlSessionProxy; 43 private final PersistenceExceptionTranslator exceptionTranslator; 44 45 private Map<Object, SqlSessionFactory> targetSqlSessionFactorys; 46 private SqlSessionFactory defaultTargetSqlSessionFactory; 47 48 public void setTargetSqlSessionFactorys(Map<Object, SqlSessionFactory> targetSqlSessionFactorys) { 49 this.targetSqlSessionFactorys = targetSqlSessionFactorys; 50 } 51 52 public Map<Object, SqlSessionFactory> getTargetSqlSessionFactorys(){ 53 return targetSqlSessionFactorys; 54 } 55 56 public void setDefaultTargetSqlSessionFactory(SqlSessionFactory defaultTargetSqlSessionFactory) { 57 this.defaultTargetSqlSessionFactory = defaultTargetSqlSessionFactory; 58 } 59 60 public DynamicSqlSessionTemplate(SqlSessionFactory sqlSessionFactory) { 61 this(sqlSessionFactory, sqlSessionFactory.getConfiguration().getDefaultExecutorType()); 62 } 63 64 public DynamicSqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType) { 65 this(sqlSessionFactory, executorType, new MyBatisExceptionTranslator(sqlSessionFactory.getConfiguration() 66 .getEnvironment().getDataSource(), true)); 67 } 68 69 public DynamicSqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType, 70 PersistenceExceptionTranslator exceptionTranslator) { 71 72 super(sqlSessionFactory, executorType, exceptionTranslator); 73 74 this.sqlSessionFactory = sqlSessionFactory; 75 this.executorType = executorType; 76 this.exceptionTranslator = exceptionTranslator; 77 78 this.sqlSessionProxy = (SqlSession) newProxyInstance( 79 SqlSessionFactory.class.getClassLoader(), 80 new Class[] { SqlSession.class }, 81 new SqlSessionInterceptor()); 82 83 this.defaultTargetSqlSessionFactory = sqlSessionFactory; 84 } 85 86 @Override 87 public SqlSessionFactory getSqlSessionFactory() { 88 89 SqlSessionFactory targetSqlSessionFactory = targetSqlSessionFactorys.get(SqlSessionContentHolder.getContextType()); 90 if (targetSqlSessionFactory != null) { 91 return targetSqlSessionFactory; 92 } else if (defaultTargetSqlSessionFactory != null) { 93 return defaultTargetSqlSessionFactory; 94 } else { 95 Assert.notNull(targetSqlSessionFactorys, "Property ‘targetSqlSessionFactorys‘ or ‘defaultTargetSqlSessionFactory‘ are required"); 96 Assert.notNull(defaultTargetSqlSessionFactory, "Property ‘defaultTargetSqlSessionFactory‘ or ‘targetSqlSessionFactorys‘ are required"); 97 } 98 return this.sqlSessionFactory; 99 } 100 101 @Override 102 public Configuration getConfiguration() { 103 return this.getSqlSessionFactory().getConfiguration(); 104 } 105 106 public ExecutorType getExecutorType() { 107 return this.executorType; 108 } 109 110 public PersistenceExceptionTranslator getPersistenceExceptionTranslator() { 111 return this.exceptionTranslator; 112 } 113 114 /** 115 * {@inheritDoc} 116 */ 117 public <T> T selectOne(String statement) { 118 return this.sqlSessionProxy.<T> selectOne(statement); 119 } 120 121 /** 122 * {@inheritDoc} 123 */ 124 public <T> T selectOne(String statement, Object parameter) { 125 return this.sqlSessionProxy.<T> selectOne(statement, parameter); 126 } 127 128 /** 129 * {@inheritDoc} 130 */ 131 public <K, V> Map<K, V> selectMap(String statement, String mapKey) { 132 return this.sqlSessionProxy.<K, V> selectMap(statement, mapKey); 133 } 134 135 /** 136 * {@inheritDoc} 137 */ 138 public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey) { 139 return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey); 140 } 141 142 /** 143 * {@inheritDoc} 144 */ 145 public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey, RowBounds rowBounds) { 146 return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey, rowBounds); 147 } 148 149 /** 150 * {@inheritDoc} 151 */ 152 public <E> List<E> selectList(String statement) { 153 return this.sqlSessionProxy.<E> selectList(statement); 154 } 155 156 /** 157 * {@inheritDoc} 158 */ 159 public <E> List<E> selectList(String statement, Object parameter) { 160 return this.sqlSessionProxy.<E> selectList(statement, parameter); 161 } 162 163 /** 164 * {@inheritDoc} 165 */ 166 public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds) { 167 return this.sqlSessionProxy.<E> selectList(statement, parameter, rowBounds); 168 } 169 170 /** 171 * {@inheritDoc} 172 */ 173 public void select(String statement, ResultHandler handler) { 174 this.sqlSessionProxy.select(statement, handler); 175 } 176 177 /** 178 * {@inheritDoc} 179 */ 180 public void select(String statement, Object parameter, ResultHandler handler) { 181 this.sqlSessionProxy.select(statement, parameter, handler); 182 } 183 184 /** 185 * {@inheritDoc} 186 */ 187 public void select(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler) { 188 this.sqlSessionProxy.select(statement, parameter, rowBounds, handler); 189 } 190 191 /** 192 * {@inheritDoc} 193 */ 194 public int insert(String statement) { 195 return this.sqlSessionProxy.insert(statement); 196 } 197 198 /** 199 * {@inheritDoc} 200 */ 201 public int insert(String statement, Object parameter) { 202 return this.sqlSessionProxy.insert(statement, parameter); 203 } 204 205 /** 206 * {@inheritDoc} 207 */ 208 public int update(String statement) { 209 return this.sqlSessionProxy.update(statement); 210 } 211 212 /** 213 * {@inheritDoc} 214 */ 215 public int update(String statement, Object parameter) { 216 return this.sqlSessionProxy.update(statement, parameter); 217 } 218 219 /** 220 * {@inheritDoc} 221 */ 222 public int delete(String statement) { 223 return this.sqlSessionProxy.delete(statement); 224 } 225 226 /** 227 * {@inheritDoc} 228 */ 229 public int delete(String statement, Object parameter) { 230 return this.sqlSessionProxy.delete(statement, parameter); 231 } 232 233 /** 234 * {@inheritDoc} 235 */ 236 public <T> T getMapper(Class<T> type) { 237 return getConfiguration().getMapper(type, this); 238 } 239 240 /** 241 * {@inheritDoc} 242 */ 243 public void commit() { 244 throw new UnsupportedOperationException("Manual commit is not allowed over a Spring managed SqlSession"); 245 } 246 247 /** 248 * {@inheritDoc} 249 */ 250 public void commit(boolean force) { 251 throw new UnsupportedOperationException("Manual commit is not allowed over a Spring managed SqlSession"); 252 } 253 254 /** 255 * {@inheritDoc} 256 */ 257 public void rollback() { 258 throw new UnsupportedOperationException("Manual rollback is not allowed over a Spring managed SqlSession"); 259 } 260 261 /** 262 * {@inheritDoc} 263 */ 264 public void rollback(boolean force) { 265 throw new UnsupportedOperationException("Manual rollback is not allowed over a Spring managed SqlSession"); 266 } 267 268 /** 269 * {@inheritDoc} 270 */ 271 public void close() { 272 throw new UnsupportedOperationException("Manual close is not allowed over a Spring managed SqlSession"); 273 } 274 275 /** 276 * {@inheritDoc} 277 */ 278 public void clearCache() { 279 this.sqlSessionProxy.clearCache(); 280 } 281 282 /** 283 * {@inheritDoc} 284 */ 285 public Connection getConnection() { 286 return this.sqlSessionProxy.getConnection(); 287 } 288 289 /** 290 * {@inheritDoc} 291 * @since 1.0.2 292 */ 293 public List<BatchResult> flushStatements() { 294 return this.sqlSessionProxy.flushStatements(); 295 } 296 297 /** 298 * Proxy needed to route MyBatis method calls to the proper SqlSession got from Spring‘s Transaction Manager It also 299 * unwraps exceptions thrown by {@code Method#invoke(Object, Object...)} to pass a {@code PersistenceException} to 300 * the {@code PersistenceExceptionTranslator}. 301 */ 302 private class SqlSessionInterceptor implements InvocationHandler { 303 public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { 304 final SqlSession sqlSession = getSqlSession( 305 DynamicSqlSessionTemplate.this.getSqlSessionFactory(), 306 DynamicSqlSessionTemplate.this.executorType, 307 DynamicSqlSessionTemplate.this.exceptionTranslator); 308 try { 309 Object result = method.invoke(sqlSession, args); 310 if (!isSqlSessionTransactional(sqlSession, DynamicSqlSessionTemplate.this.getSqlSessionFactory())) { 311 // force commit even on non-dirty sessions because some databases require 312 // a commit/rollback before calling close() 313 sqlSession.commit(true); 314 } 315 return result; 316 } catch (Throwable t) { 317 Throwable unwrapped = unwrapThrowable(t); 318 if (DynamicSqlSessionTemplate.this.exceptionTranslator != null && unwrapped instanceof PersistenceException) { 319 Throwable translated = DynamicSqlSessionTemplate.this.exceptionTranslator 320 .translateExceptionIfPossible((PersistenceException) unwrapped); 321 if (translated != null) { 322 unwrapped = translated; 323 } 324 } 325 throw unwrapped; 326 } finally { 327 closeSqlSession(sqlSession, DynamicSqlSessionTemplate.this.getSqlSessionFactory()); 328 } 329 } 330 } 331 332 }
SqlSessionContentHolder类代码如下：
1 package com.sincetimes.slg.framework.util; 2 3 public abstract class SqlSessionContentHolder { 4 5 public final static String SESSION_FACTORY_MASTER = "master"; 6 public final static String SESSION_FACTORY_SLAVE = "slave"; 7 8 private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>(); 9 10 public static void setContextType(String contextType) { 11 contextHolder.set(contextType); 12 } 13 14 public static String getContextType() { 15 return contextHolder.get(); 16 } 17 18 public static void clearContextType() { 19 contextHolder.remove(); 20 } 21 }
最后就是写切面去对dao所有方法进行处理了，代码很简单如下：
1 package com.sincetimes.slg.framework.core; 2 3 import org.aspectj.lang.JoinPoint; 4 import org.aspectj.lang.annotation.Aspect; 5 import org.aspectj.lang.annotation.Before; 6 import org.aspectj.lang.annotation.Pointcut; 7 8 import com.sincetimes.slg.framework.util.SqlSessionContentHolder; 9 10 @Aspect 11 public class DynamicDataSourceAspect { 12 13 @Pointcut("execution( * com.sincetimes.slg.dao.*.*(..))") 14 public void pointCut(){ 15 16 } 17 @Before("pointCut()") 18 public void before(JoinPoint jp){ 19 String methodName = jp.getSignature().getName(); 20 //dao方法查询走从库 21 if(methodName.startsWith("query") || methodName.startsWith("get") || methodName.startsWith("count") || methodName.startsWith("list")){ 22 SqlSessionContentHolder.setContextType(SqlSessionContentHolder.SESSION_FACTORY_SLAVE); 23 }else{ 24 SqlSessionContentHolder.setContextType(SqlSessionContentHolder.SESSION_FACTORY_MASTER); 25 } 26 } 27 28 }
标签：aop切面 owb poi ack because 项目开发 .exe private out
原文地址：http://www.cnblogs.com/FlyHeLanMan/p/6744171.html
