mybatis MappedStatement类中有个方法getBoundSql()返回对象是BoundSql ，怎么用我自己的BoundSql对象来替换这个方法的返回？
[code="java"]
public BoundSql getBoundSql(Object parameterObject) {
BoundSql boundSql = sqlSource.getBoundSql(parameterObject);
List parameterMappings = boundSql.getParameterMappings();
if (parameterMappings == null || parameterMappings.size() <= 0) {
boundSql = new BoundSql(configuration, boundSql.getSql(), parameterMap.getParameterMappings(), parameterObject);
}
// check for nested result maps in parameter mappings (issue #30)
for (ParameterMapping pm : boundSql.getParameterMappings()) {
String rmId = pm.getResultMapId();
if (rmId != null) {
ResultMap rm = configuration.getResultMap(rmId);
if (rm != null) {
hasNestedResultMaps |= rm.hasNestedResultMaps();
}
}
}
return boundSql;
}
[/code]
要实现修改返回值为类需求，一般要和原来的类实现相同的接口，这个时候在自己的类内部持有原来的类，用“装饰者”或者“代理”这一类的模式，实现自己的功能。
StatementHandler statementHandler = (StatementHandler) invocation
.getTarget();
MetaObject metaStatementHandler = MetaObject
.forObject(statementHandler, DEFAULT_OBJECT_FACTORY, DEFAULT_OBJECT_WRAPPER_FACTORY);
MappedStatement mappedStatement = (MappedStatement) metaStatementHandler.getValue("delegate.mappedStatement");
BoundSql boundSql = (BoundSql) metaStatementHandler.getValue("delegate.boundSql");
BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(), boundSql ,
boundSql.getParameterMappings(), boundSql.getParameterObject());
package com.ztesoft.common.mybatis.plugin;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;
import org.apache.ibatis.executor.parameter.ParameterHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
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.reflection.MetaObject;
import org.apache.ibatis.reflection.factory.DefaultObjectFactory;
import org.apache.ibatis.reflection.factory.ObjectFactory;
import org.apache.ibatis.reflection.wrapper.DefaultObjectWrapperFactory;
import org.apache.ibatis.reflection.wrapper.ObjectWrapperFactory;
import org.apache.ibatis.scripting.defaults.DefaultParameterHandler;
import org.apache.ibatis.session.RowBounds;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.ztesoft.common.mybatis.Dialect;
import com.ztesoft.dto.Page;
@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }) })
public class PageInterceptor implements Interceptor {
// 日志对象
protected static Logger logger = LoggerFactory
.getLogger(PageInterceptor.class);
private static final ObjectFactory DEFAULT_OBJECT_FACTORY = new DefaultObjectFactory();
private static final ObjectWrapperFactory DEFAULT_OBJECT_WRAPPER_FACTORY = new DefaultObjectWrapperFactory();
private String dialect=null;
/*
* (non-Javadoc)
*
* @see
* org.apache.ibatis.plugin.Interceptor#intercept(org.apache.ibatis.plugin
* .Invocation)
*/
@Override
public Object intercept(Invocation invocation) throws Throwable {
StatementHandler statementHandler = (StatementHandler) invocation
.getTarget();
MetaObject metaStatementHandler = MetaObject
.forObject(statementHandler, DEFAULT_OBJECT_FACTORY, DEFAULT_OBJECT_WRAPPER_FACTORY);
MappedStatement mappedStatement = (MappedStatement) metaStatementHandler.getValue("delegate.mappedStatement");
BoundSql boundSql = (BoundSql) metaStatementHandler.getValue("delegate.boundSql");
RowBounds rowBounds = (RowBounds) metaStatementHandler
.getValue("delegate.rowBounds");
Connection connection = (Connection) invocation.getArgs()[0];
if (rowBounds == null || rowBounds == RowBounds.DEFAULT) {
// DefaultParameterHandler defaultParameterHandler = (DefaultParameterHandler) metaStatementHandler
// .getValue("delegate.parameterHandler");
// Object parameterObject = defaultParameterHandler.getParameterObject();
// if(parameterObject instanceof Page){
// Page<?> page=(Page<?>)parameterObject;
// //设置查询总条数的sql
// setTotalSql(boundSql,metaStatementHandler,page);
// // 重设分页参数里的总页数等
// setPageParameter(boundSql.getSql(), connection, mappedStatement, boundSql, page);
// return invocation.proceed();
// }else{
return invocation.proceed();
// }
}else{
Page<?> page=(Page<?>)rowBounds;
// Object sidx = parameterMap.get("_sidx");
// Object sord = parameterMap.get("_sord");
// String originalSql = (String) metaStatementHandler
// .getValue("delegate.boundSql.sql");
// if (sidx != null && sord != null) {
// originalSql = originalSql + " order by " + sidx + " " + sord;
// }
//设置查询总条数的sql
setTotalSql(boundSql.getSql(), connection, mappedStatement, boundSql, page);
// 重设分页参数里的总页数等
setPageParameter(boundSql,metaStatementHandler,page);
return invocation.proceed();
}
}
/**
* 设置分页查询语句
* @param boundSql
* @param metaStatementHandler
* @param page
* @throws InstantiationException
* @throws IllegalAccessException
* @throws ClassNotFoundException
*/
public void setPageParameter(BoundSql boundSql,MetaObject metaStatementHandler,Page<?> page) throws InstantiationException, IllegalAccessException, ClassNotFoundException{
Dialect dialect=(Dialect) Class.forName(this.dialect).newInstance();
metaStatementHandler.setValue("delegate.boundSql.sql", dialect
.getLimitString(boundSql.getSql(), page.getStart(),
page.getLimit()));
metaStatementHandler.setValue("delegate.rowBounds.offset",
RowBounds.NO_ROW_OFFSET);
metaStatementHandler.setValue("delegate.rowBounds.limit",
RowBounds.NO_ROW_LIMIT);
if (logger.isDebugEnabled()) {
logger.debug("生成分页SQL : " + boundSql.getSql());
}
}
/*
* (non-Javadoc)
*
* @see org.apache.ibatis.plugin.Interceptor#plugin(java.lang.Object)
*/
@Override
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
/**
* 从数据库里查询总的记录数并计算总页数，回写进分页参数<code>PageParameter</code>,这样调用者就可用通过 分页参数
* <code>PageParameter</code>获得相关信息。
*
* @param sql
* @param connection
* @param mappedStatement
* @param boundSql
* @param page
*/
private void setTotalSql(String sql, Connection connection, MappedStatement mappedStatement,
BoundSql boundSql, Page<?> page) {
// 记录总记录数
String countSql = "select count(0) total from (" + sql + ")";
PreparedStatement countStmt = null;
ResultSet rs = null;
try {
countStmt = connection.prepareStatement(countSql);
BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(), countSql,
boundSql.getParameterMappings(), boundSql.getParameterObject());
setParameters(countStmt, mappedStatement, countBS, boundSql.getParameterObject());
rs = countStmt.executeQuery();
int totalCount = 0;
if (rs.next()) {
totalCount = rs.getInt(1);
}
page.setTotalCount(totalCount);
// int totalPage = totalCount / page.getPageSize() + ((totalCount % page.getPageSize() == 0) ? 0 : 1);
// page.setTotalPage(totalPage);
} catch (SQLException e) {
logger.error("Ignore this exception", e);
} finally {
try {
rs.close();
} catch (SQLException e) {
logger.error("Ignore this exception", e);
}
try {
countStmt.close();
} catch (SQLException e) {
logger.error("Ignore this exception", e);
}
}
}
/**
* 对SQL参数(?)设值
*
* @param ps
* @param mappedStatement
* @param boundSql
* @param parameterObject
* @throws SQLException
*/
private void setParameters(PreparedStatement ps, MappedStatement mappedStatement, BoundSql boundSql,
Object parameterObject) throws SQLException {
ParameterHandler parameterHandler = new DefaultParameterHandler(mappedStatement, parameterObject, boundSql);
parameterHandler.setParameters(ps);
}
/*
* (non-Javadoc)
*
* @see
* org.apache.ibatis.plugin.Interceptor#setProperties(java.util.Properties)
*/
/**
* 设置注册拦截器时设定的属性
*/
public void setProperties(Properties properties) {
this.dialect = properties.getProperty("dialect");
}
}