mybatise自定义插件或者叫mybatise拦截器，动态修改sql语句

package com.teamsun.net.common.utils;

import java.lang.reflect.Constructor;

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.mapping.MappedStatement.Builder;

import org.apache.ibatis.mapping.SqlSource;

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;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import com.github.miemiedev.mybatis.paginator.OffsetLimitInterceptor;

import com.github.miemiedev.mybatis.paginator.dialect.Dialect;

import com.github.miemiedev.mybatis.paginator.domain.PageBounds;

import com.github.miemiedev.mybatis.paginator.support.PropertiesHelper;

@Intercepts({ @Signature(type = Executor.class, method = "query", args = {

MappedStatement.class, Object.class, RowBounds.class,

ResultHandler.class }) })

public class MyBatisePlugin implements Interceptor {

private static Logger logger = LoggerFactory

.getLogger(OffsetLimitInterceptor.class);

static int MAPPED_STATEMENT_INDEX = 0;// 这是对应上面的args的序号

static int PARAMETER_INDEX = 1;

static int ROWBOUNDS_INDEX = 2;

static int RESULT_HANDLER_INDEX = 3;

String dialectClass;// 在mybatise-config的配制属性，可多个

@Override

public Object intercept(Invocation invocation) throws Throwable {

final Executor executor = (Executor) invocation.getTarget();

final Object[] queryArgs = invocation.getArgs();

final MappedStatement ms = (MappedStatement) queryArgs[MAPPED_STATEMENT_INDEX];

final Object parameter = queryArgs[PARAMETER_INDEX];

final RowBounds rowBounds = (RowBounds) queryArgs[ROWBOUNDS_INDEX];

final PageBounds pageBounds = new PageBounds(rowBounds);

final Dialect dialect;

try {

Class clazz = Class.forName(dialectClass);// 这是在mybatise-config里配制，就是设置你选用了哪种数据库，mysql

// or oracle

Constructor constructor = clazz.getConstructor(

MappedStatement.class, Object.class, PageBounds.class);

dialect = (Dialect) constructor.newInstance(new Object[] { ms,

parameter, pageBounds });

} catch (Exception e) {

throw new ClassNotFoundException("Cannot create dialect instance: "

+ dialectClass, e);

}

final BoundSql boundSql = ms.getBoundSql(parameter);// 获得查询语句对像

GlobalUser globalUser = GlobalUser.getGlobalUser();// 获得线程中的全局用户信息

if (globalUser != null) {

System.out.println("user:_______"

+ globalUser.getUser().getUserid());

String sql = boundSql.getSql();// 获得查询语句

System.out.println("orginsql_________________:" + sql);

sql = sql + " where userid='" + globalUser.getUser().getUserid()

+ "'";// 改变查询语句

BoundSql newBoundSql = new BoundSql(ms.getConfiguration(), sql,

boundSql.getParameterMappings(),

boundSql.getParameterObject());// 重新new一个查询语句对像

MappedStatement newMs = copyFromMappedStatement(ms,

new BoundSqlSqlSource(newBoundSql));// 把新的查询放到statement里

queryArgs[MAPPED_STATEMENT_INDEX] = newMs;

}

String methonName = invocation.getMethod().getName();

System.out.println("methodName__________:" + methonName);

return invocation.proceed();

}

@Override

public Object plugin(Object target) {

return Plugin.wrap(target, this);// 这些莫认调用

}

@Override

public void setProperties(Properties properties) {

// TODO Auto-generated method stub

PropertiesHelper propertiesHelper = new PropertiesHelper(properties);

String dialectClass = propertiesHelper

.getRequiredString("dialectClass");

setDialectClass(dialectClass);// 这个方法主要就是获得mybatis-config里的配制

// 比如：<!-- <plugin

// interceptor="com.teamsun.net.common.utils.MyBatisePlugin">

// <property name="dialectClass"

// value="com.github.miemiedev.mybatis.paginator.dialect.OracleDialect"

// />

// </plugin> -->

// 上面是在mybatise-config的配制

}

public void setDialectClass(String dialectClass) {

logger.debug("dialectClass: {} ", dialectClass);

this.dialectClass = dialectClass;

}

private MappedStatement copyFromMappedStatement(MappedStatement ms,

SqlSource newSqlSource) {

Builder builder = new MappedStatement.Builder(ms.getConfiguration(),

ms.getId(), newSqlSource, ms.getSqlCommandType());

builder.resource(ms.getResource());

builder.fetchSize(ms.getFetchSize());

builder.statementType(ms.getStatementType());

builder.keyGenerator(ms.getKeyGenerator());

if (ms.getKeyProperties() != null && ms.getKeyProperties().length > 0) {

builder.keyProperty(ms.getKeyProperties()[0]);

}

// setStatementTimeout()

builder.timeout(ms.getTimeout());

// setStatementResultMap()

builder.parameterMap(ms.getParameterMap());

// setStatementResultMap()

builder.resultMaps(ms.getResultMaps());

builder.resultSetType(ms.getResultSetType());

// setStatementCache()

builder.cache(ms.getCache());

builder.flushCacheRequired(ms.isFlushCacheRequired());

builder.useCache(ms.isUseCache());

return builder.build();

}

public static class BoundSqlSqlSource implements SqlSource {

private BoundSql boundSql;

public BoundSqlSqlSource(BoundSql boundSql) {

this.boundSql = boundSql;

}

public BoundSql getBoundSql(Object parameterObject) {

return boundSql;

}

}

}

我这里主要是修改了 intercept，我的目的是动态修改查询语句，写好这个后，在mybatise-config里配一下就可以，类似paginator的分页插件，配制如下：

<!-- 分页插件 -->

<plugins>

<plugin

interceptor="com.github.miemiedev.mybatis.paginator.OffsetLimitInterceptor">

<property name="dialectClass"

value="com.github.miemiedev.mybatis.paginator.dialect.OracleDialect" />

</plugin>

<!-- <plugin

interceptor="com.teamsun.net.common.utils.MyBatisePlugin">

<property name="dialectClass"

value="com.github.miemiedev.mybatis.paginator.dialect.OracleDialect" />

</plugin> -->

</plugins>

注意这个plugins不是随便义，要放到typeAliases后面，mappers节点前面

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