利用mybatis拦截器实现分页
package cn.com.common.ssm.engine.utils;
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.Map;
import java.util.Properties;
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.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.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.slf4j.Logger;
import org.slf4j.LoggerFactory;
import cn.com.common.ssm.engine.mapper.Page;
@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }) })
public class PagePlugin<T> implements Interceptor {
private static Logger logger = LoggerFactory.getLogger(PagePlugin.class);
private static String pageSqlId = "";
@SuppressWarnings("unchecked")
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)) {
BoundSql boundSql = delegate.getBoundSql();
Object parameterObject = boundSql.getParameterObject();
if (parameterObject == null) {
throw new NullPointerException("parameterObject error");
} else {
Page<T> page = null;
if (parameterObject instanceof Page) {
page = (Page<T>) parameterObject;
} else if(parameterObject instanceof Map){
Map<String, Object> map = (Map<String, Object>)parameterObject;
if(map.get("page") instanceof Page){
page = (Page<T>)map.get("page");
if(page == null)
page = new Page<T>();
}else{
throw new NoSuchFieldException("PageInfo not instanceof com.panshi.basic.tools.PageInfo");
}
}else {
Field pageField = ReflectHelper.getFieldByFieldName(
parameterObject, "page");
if (pageField != null) {
page = (Page<T>) ReflectHelper.getValueByFieldName(
parameterObject, "page");
if (page == null)
page = new Page<T>();
ReflectHelper.setValueByFieldName(parameterObject,
"page", page);
} else {
throw new NoSuchFieldException(parameterObject
.getClass().getName());
}
}
int rowCount = 0; //总记录数
if(page.getCount()==0){ //不重复查询总数
Connection connection = (Connection) ivk.getArgs()[0];
String sql = boundSql.getSql();
int fromIndex = sql.indexOf("from");
fromIndex = fromIndex>-1?fromIndex:sql.indexOf("FROM");
String countSql = "select count(0) "+sql.substring(fromIndex);
// System.out.println("总数sql 语句:"+countSql);
PreparedStatement countStmt = connection
.prepareStatement(countSql);
BoundSql countBS = new BoundSql(
mappedStatement.getConfiguration(), countSql,
boundSql.getParameterMappings(), parameterObject);
setParameters(countStmt, mappedStatement, countBS,
parameterObject);
ResultSet rs = countStmt.executeQuery();
if (rs.next()) {
rowCount = rs.getInt(1);
}
rs.close();
countStmt.close();
}else{
rowCount = page.getCount();
}
page.setCount(rowCount);
// page.compute(page.getNum(), rowCount); //==================计算分页
String pageSql = generatePageSql(boundSql.getSql(), page);
logger.debug("生成的SQL为: " + pageSql);
// System.out.println("page sql:"+pageSql);
ReflectHelper.setValueByFieldName(boundSql, "sql", pageSql);
}
}
}
return ivk.proceed();
}
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());
}
}
}
}
private String generatePageSql(String sql, Page page) {
if (page != null) {
StringBuffer pageSql = new StringBuffer();
pageSql.append(sql);
pageSql.append(" limit " + page.getStart() + ","
+ page.getLength());
return pageSql.toString();
} else {
return sql;
}
}
public Object plugin(Object arg0) {
return Plugin.wrap(arg0, this);
}
public void setProperties(Properties p) {
pageSqlId = p.getProperty("pageSqlId");
}
}
mybatis-config.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<plugins>
<plugin interceptor="cn.com.common.ssm.engine.utils.PagePlugin">
<property name="pageSqlId" value=".*Page.*" />
</plugin>
</plugins>
</configuration>
/**
* @file Page.java
* @date 2016年8月4日
* @version 1.0.0
*
* Copyright (c) 2016 Yeexun Information Tech, Inc. All Rights Reserved.
*/
package cn.com.common.ssm.engine.mapper;
import java.util.List;
/**
*
*
* @author yong.zhou
* @version 1.0.0, 2016年8月4日 下午12:02:42
*/
public class Page<T> {
private int count; //记录总数
private int pageCount;
private int length = 10; //页大小
private int start = 0; //下标启始位置
private List<T> data;
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
this.pageCount = (count % length > 0) ? (count / length + 1) : (count / length);
}
public int getPageCount() {
return pageCount;
}
public void setPageCount(int pageCount) {
this.pageCount = pageCount;
}
public int getLength() {
return length;
}
public void setLength(int length) {
this.length = length;
}
public List<T> getData() {
return data;
}
public void setData(List<T> data) {
this.data = data;
}
public int getStart() {
return start;
}
public void setStart(int start) {
this.start = start;
}
}
