mybatis Executor插件加载源码

qinling072

//插件扩展实现类：
org.apache.ibatis.session.Configuration
//具体方法：

protected ExecutorType defaultExecutorType = ExecutorType.SIMPLE;  
public Executor newExecutor(Transaction transaction, ExecutorType executorType) {
executorType = executorType == null ? defaultExecutorType : executorType;
executorType = executorType == null ? ExecutorType.SIMPLE : executorType;
Executor executor;
if (ExecutorType.BATCH == executorType) {
executor = new BatchExecutor(this, transaction);
} else if (ExecutorType.REUSE == executorType) {
executor = new ReuseExecutor(this, transaction);
} else {
executor = new SimpleExecutor(this, transaction);
}
if (cacheEnabled) {
executor = new CachingExecutor(executor);
}
executor = (Executor) interceptorChain.pluginAll(executor);
return executor;
}

　　Executor接口：

public interface Executor {
ResultHandler NO_RESULT_HANDLER = null;
int update(MappedStatement ms, Object parameter) throws SQLException;
List query(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler) throws SQLException;
List<BatchResult> flushStatements() throws SQLException;
void commit(boolean required) throws SQLException;
void rollback(boolean required) throws SQLException;
CacheKey createCacheKey(MappedStatement ms, Object parameterObject, RowBounds rowBounds);
boolean isCached(MappedStatement ms, CacheKey key);
void clearLocalCache();
void deferLoad(MappedStatement ms, MetaObject resultObject, String property, CacheKey key);
Transaction getTransaction();
void close(boolean forceRollback);
boolean isClosed();
}

　　插件继承和扩展：

implements Interceptor

@Intercepts( { @Signature(type = Executor.class, method = "query", args = {
MappedStatement.class, Object.class, RowBounds.class,
ResultHandler.class }) })
　　具体实例：

package com.xuanwu.sms.smstask.webmanager.common.crud.plugins;
import java.lang.reflect.Field;
import java.util.Properties;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
@Intercepts( { @Signature(type = Executor.class, method = "query", args = {
MappedStatement.class, Object.class, RowBounds.class,
ResultHandler.class }) })
public class PaginationInterceptor implements Interceptor {
public Object intercept(Invocation invocation) throws Throwable {
MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];
Object parameter = invocation.getArgs()[1];
mappedStatement.getSqlSource().getBoundSql(parameter);
BoundSql boundSql = mappedStatement.getBoundSql(parameter);
if (boundSql == null || boundSql.getSql() == null || "".equals(boundSql.getSql())) {
return null;
}
String newSql = "select * from (" + boundSql.getSql() + ") t";
Class<?> cla =boundSql.getClass();
Field field = cla.getDeclaredField("sql");
field.setAccessible(true);
field.set(boundSql, newSql);
String test = boundSql.getSql();
return invocation.proceed();
}
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
public void setProperties(Properties properties) {
String dialectClass = properties.getProperty("dialectClass");
try {
Object dialect = (Object) Class.forName(dialectClass).newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}