spring+mybatis 物理分页

新项目用的spring mvc 和 mybatis 分页。研究了一下，集众家之长然后形成现在的项目。我把分页部分剥离出来与大家分享。如有不妥的地方欢迎交流拍砖。

单独做了一个小项目，放到了下载区，如果有用到的朋友可以去下载。

本项目采用了拦截器，就是mybaits自带的plus功能。将每次select操作都进行拦截。

项目架构如下：



1：首先从cotroller层出发，啥也不说，上代码。这个最实惠

package com.flydreamer.controller;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import com.flydreamer.logic.UserService;
import com.flydreamer.page.Page;
import com.flydreamer.page.PageContext;
import com.flydreamer.util.web.HandlerResult;

@Controller
@RequestMapping("/user.do")
public class UserController {

@Autowired
private UserService userService;

@RequestMapping(params = ("method=list"))
public ModelAndView listAll(HttpServletRequest request,HttpServletResponse response) {

//可以将分页参数获取封装，已达到更好的复用效果。
//page=2&pageSize=10&totalPages=19&totalRows=188
String pagec = request.getParameter("page");
String pageSize = request.getParameter("pageSize");
String totalPages = request.getParameter("totalPages");
String totalRows = request.getParameter("totalRows");

//方法1：将分页参数直接放到mapper接口函数参数中，也可在对象中定义名字为page的属性，反射一样可以得到
//后台连接直接获取
//Page page = new Page();

//方法2：不用进行map传参，用ThreadLocal进行传参,方便没有侵入性
PageContext page = PageContext.getContext();

//请自行验证
if(null == pagec)
{
page.setCurrentPage(1);
page.setPageSize(10);
}
else{
page.setCurrentPage(Integer.parseInt(pagec));
page.setPageSize(Integer.parseInt(pageSize));
page.setTotalPages(Integer.parseInt(totalPages));
page.setTotalRows(Integer.parseInt(totalRows));
}
page.setPagination(true);

//      方法1用
//      Map map = new HashMap();
//      map.put("page", page);
//      HandlerResult rs = userService.list(map);

//方法2用
HandlerResult rs = userService.list();

ModelAndView mv = new ModelAndView("/views/show.jsp");
mv.addObject("userList", rs.getResultObj());
mv.addObject("page",page);
return mv;
}

}

简要说明：本文采用两种方式将page对象传入到拦截器中。第一种方式是采用参数传值，不管是用map还是在统一参数对象中名称为page的属性都可以在分页拦截器中得到page的值。第二种方式是用ThreadLocal，对service层没有侵入性。比较方便。

2：Service层代码。没啥可说的上代码

package com.flydreamer.logic;

import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.flydreamer.orm.mapper.UsersMapper;
import com.flydreamer.util.web.HandlerResult;

@Service
public class UserService {

@Autowired
private UsersMapper usersMappser;

/**
* 统一Service出口，方便管理
* @param map
* @return
*/
public HandlerResult list(Map map){

HandlerResult rs = new HandlerResult();

rs.setResultObj(usersMappser.list(map));

return rs;
}

/**
* 采用本地线程的方式分页
* @return
*/
public HandlerResult list(){

HandlerResult rs = new HandlerResult();

rs.setResultObj(usersMappser.list2());

return rs;
}

public UsersMapper getUsersMappser() {
return usersMappser;
}

public void setUsersMappser(UsersMapper usersMappser) {
this.usersMappser = usersMappser;
}
}

3：mybatis接口

package com.flydreamer.orm.mapper;

import java.util.List;
import java.util.Map;

import com.flydreamer.orm.SqlMapper;

public interface UsersMapper extends SqlMapper{

public List list(Map para);

public List list2();
}

4：page的拦截器

package com.flydreamer.interceptor;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Properties;

import org.apache.ibatis.builder.xml.dynamic.ForEachSqlNode;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.logging.Log;
import org.apache.ibatis.logging.LogFactory;
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.mapping.SqlSource;
import org.apache.ibatis.mapping.MappedStatement.Builder;
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.session.Configuration;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.TypeHandlerRegistry;

import com.flydreamer.page.Dialect;
import com.flydreamer.page.MySql5Dialect;
import com.flydreamer.page.OracleDialect;
import com.flydreamer.page.Page;
import com.flydreamer.page.PageContext;
import com.flydreamer.page.ReflectHelper;

//只拦截select部分
@Intercepts({@Signature(type=Executor.class,method="query",args={ MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class })})
public class PaginationInterceptor implements Interceptor{

private final static Log log = LogFactory.getLog(PaginationInterceptor.class);

Dialect dialect = new MySql5Dialect();

public Object intercept(Invocation invocation) throws Throwable {

MappedStatement mappedStatement=(MappedStatement)invocation.getArgs()[0];
Object parameter = invocation.getArgs()[1];
BoundSql boundSql = mappedStatement.getBoundSql(parameter);
String originalSql = boundSql.getSql().trim();
RowBounds rowBounds = (RowBounds)invocation.getArgs()[2];

Object parameterObject = boundSql.getParameterObject();
if(boundSql==null || boundSql.getSql()==null || "".equals(boundSql.getSql()))
return null;
//分页参数--上下文传参
Page page = null;
PageContext context=PageContext.getContext();

//map传参每次都将currentPage重置,先判读map再判断context
if(parameterObject!=null)
page = (Page)ReflectHelper.isPage(parameterObject,"page");

//分页参数--context参数里的Page传参
if(page==null && context.isPagination()==true)
{
page = context;
}

//后面用到了context的东东
if(page!=null && page.isPagination()==true)
{
int totpage=page.getTotalRows();
//得到总记录数
if (totpage==0)
{
StringBuffer countSql  = new StringBuffer(originalSql.length()+100 );
countSql.append("select count(1) from (").append(originalSql).append(") t");
Connection connection=mappedStatement.getConfiguration().getEnvironment().getDataSource().getConnection()  ;
PreparedStatement countStmt = connection.prepareStatement(countSql.toString());
BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(),countSql.toString(),boundSql.getParameterMappings(),parameterObject);
setParameters(countStmt,mappedStatement,countBS,parameterObject);
ResultSet rs = countStmt.executeQuery();
if (rs.next()) {
totpage = rs.getInt(1);
}
rs.close();
countStmt.close();
connection.close();
}

//分页计算
page.init(totpage,page.getPageSize(),page.getCurrentPage());

if(rowBounds == null || rowBounds == RowBounds.DEFAULT){
rowBounds= new RowBounds(page.getPageSize()*(page.getCurrentPage()-1),page.getPageSize());

}

//分页查询 本地化对象 修改数据库注意修改实现
String pagesql=dialect.getLimitString(originalSql, rowBounds.getOffset(), rowBounds.getLimit());
invocation.getArgs()[2] = new RowBounds(RowBounds.NO_ROW_OFFSET, RowBounds.NO_ROW_LIMIT);
BoundSql newBoundSql = new BoundSql(mappedStatement.getConfiguration(), pagesql,boundSql.getParameterMappings(),boundSql.getParameterObject());
MappedStatement newMs = copyFromMappedStatement(mappedStatement,new BoundSqlSqlSource(newBoundSql));

invocation.getArgs()[0]= newMs;
}

return invocation.proceed();

}
public static class BoundSqlSqlSource implements SqlSource {
BoundSql boundSql;

public BoundSqlSqlSource(BoundSql boundSql) {
this.boundSql = boundSql;
}

public BoundSql getBoundSql(Object parameterObject) {
return boundSql;
}
}
public Object plugin(Object arg0) {
return Plugin.wrap(arg0, this);
}
public void setProperties(Properties arg0) {

}

/**
* 对SQL参数(?)设值,参考org.apache.ibatis.executor.parameter.DefaultParameterHandler
* @param ps
* @param mappedStatement
* @param boundSql
* @param parameterObject
* @throws SQLException
*/
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 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());
builder.keyProperty(ms.getKeyProperty());
builder.timeout(ms.getTimeout());
builder.parameterMap(ms.getParameterMap());
builder.resultMaps(ms.getResultMaps());
builder.cache(ms.getCache());
MappedStatement newMs = builder.build();
return newMs;
}

}

简要说明：刚刚忘记了，有一些查询操作是不需要分页的。可以自行修改拦截器中代码部分，加个判断啥的。

5：spring 配置

<bean id="paginationInterceptor" class="com.flydreamer.interceptor.PaginationInterceptor"></bean>

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource" />

<property name="plugins">
<ref bean="paginationInterceptor"/>
</property>
</bean>

大致就是这样了。完整的可运行项目已放到这里。最近CSDN没有分了，收1分，各位童鞋见谅了~