MyBatis3-实现MyBatis分页
此文章中的例子是沿用上一篇文章http://www.cnblogs.com/EasonJim/p/7055499.html的Spring MVC集成的例子改装的。
MyBatis分页有以下方式实现：
一、内存分页，使用RowBounds类，但这种方式不推荐，基本不用，所以此方式集成省略。
二、自定义实现，代码量比较少，简单，比较灵活。以下为具体的集成步骤：
1、在User.xml中加入select节点，并组装分页SQL
<select id="getUserArticlesByLimit" parameterType="int" resultMap="resultUserArticleList">
select user.id,user.userName,user.userAddress,article.id as aid,article.title,article.content from user,article where user.id=article.userid and user.id=#{arg0} limit #{arg1},#{arg2}
</select>
注意：上面的写法中select节点的parameterType属性为int类型，而此时是由于当前业务的SQL语句就是全部都是int型的，当对于多类型时，这种属性就不能这么设置了。具体的在多参数中会进行讲解。
2、在IUserOperation.java中加入Mapping对应的方法
public List<Article> getUserArticlesByLimit(int id,int start,int limit);
3、修改UserController.java中获取数据的方法，改成分页方法，并传入指定参数
package com.jsoft.testmybatis.controller;
import java.util.List;
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.jsoft.testmybatis.inter.IUserOperation;
import com.jsoft.testmybatis.models.Article;
@Controller
@RequestMapping("/article")
public class UserController {
@Autowired
IUserOperation userMapper;
@RequestMapping("/list")
public ModelAndView listall(HttpServletRequest request,HttpServletResponse response){
List<Article> articles=userMapper.getUserArticlesByLimit(1,0,2);
ModelAndView mav=new ModelAndView("/article/list");
mav.addObject("articles",articles);
return mav;
}
}
意思是获取用户1的数据，从第0行开始的2条数据。
4、运行测试
mvn tomcat7:run
三、通过自定义插件的形式实现分页，也是最好的，也叫做分页拦截器。实现步骤如下：
插件支持MySQL和Oracle两种数据库，通过方法名关键字ListPage去匹配，有才进行分页处理，并且不用在Mapping中写分页代码。
1、在User.xml中添加查询语句
<!-- 插件式分页查询测试 -->
<select id="selectArticleListPage" resultMap="resultUserArticleList">
select user.id,user.userName,user.userAddress,article.id as aid,article.title,article.content from user,article where user.id=article.userid and user.id=#{userid}
</select>
2、在IUserOperation.java中添加接口
public List<Article> selectArticleListPage(
@Param("page")
PageInfo page,
@Param("userid")
int userid);
3、以下是插件实现的三个类
PageInfo.java:
package com.jsoft.testmybatis.util;
import java.io.Serializable;
public class PageInfo implements Serializable {
private static final long serialVersionUID = 587754556498974978L;
// pagesize ，每一页显示多少
private int showCount = 3;
// 总页数
private int totalPage;
// 总记录数
private int totalResult;
// 当前页数
private int currentPage;
// 当前显示到的ID, 在mysql limit 中就是第一个参数.
private int currentResult;
private String sortField;
private String order;
public int getShowCount() {
return showCount;
}
public void setShowCount(int showCount) {
this.showCount = showCount;
}
public int getTotalPage() {
return totalPage;
}
public void setTotalPage(int totalPage) {
this.totalPage = totalPage;
}
public int getTotalResult() {
return totalResult;
}
public void setTotalResult(int totalResult) {
this.totalResult = totalResult;
}
public int getCurrentPage() {
return currentPage;
}
public void setCurrentPage(int currentPage) {
this.currentPage = currentPage;
}
public int getCurrentResult() {
return currentResult;
}
public void setCurrentResult(int currentResult) {
this.currentResult = currentResult;
}
public String getSortField() {
return sortField;
}
public void setSortField(String sortField) {
this.sortField = sortField;
}
public String getOrder() {
return order;
}
public void setOrder(String order) {
this.order = order;
}
}
ReflectHelper.java：
package com.jsoft.testmybatis.util;
import java.lang.reflect.Field;
public class ReflectHelper {
public static Field getFieldByFieldName(Object obj, String fieldName) {
for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
try {
return superClass.getDeclaredField(fieldName);
} catch (NoSuchFieldException e) {
}
}
return null;
}
/**
* Obj fieldName的获取属性值.
*
* @param obj
* @param fieldName
* @return
* @throws SecurityException
* @throws NoSuchFieldException
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
public static Object getValueByFieldName(Object obj, String fieldName) throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
Field field = getFieldByFieldName(obj, fieldName);
Object value = null;
if (field != null) {
if (field.isAccessible()) {
value = field.get(obj);
} else {
field.setAccessible(true);
value = field.get(obj);
field.setAccessible(false);
}
}
return value;
}
/**
* obj fieldName设置的属性值.
*
* @param obj
* @param fieldName
* @param value
* @throws SecurityException
* @throws NoSuchFieldException
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
public static void setValueByFieldName(Object obj, String fieldName, Object value) throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
Field field = obj.getClass().getDeclaredField(fieldName);
if (field.isAccessible()) {
field.set(obj, value);
} else {
field.setAccessible(true);
field.set(obj, value);
field.setAccessible(false);
}
}
}
PagePlugin.java：
package com.jsoft.testmybatis.util;
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 javax.xml.bind.PropertyException;
import org.apache.ibatis.scripting.xmltags.ForEachSqlNode;
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.session.Configuration;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.TypeHandlerRegistry;
@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class, Integer.class }) })
public class PagePlugin implements Interceptor {
private static String dialect = "";
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 {
Connection connection = (Connection) ivk.getArgs()[0];
String sql = boundSql.getSql();
String countSql = "select count(0) from (" + sql + ") myCount";
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();
int count = 0;
if (rs.next()) {
count = rs.getInt(1);
}
rs.close();
countStmt.close();
PageInfo page = null;
if (parameterObject instanceof PageInfo) {
page = (PageInfo) parameterObject;
page.setTotalResult(count);
} else if (parameterObject instanceof Map) {
Map<String, Object> map = (Map<String, Object>) parameterObject;
page = (PageInfo) map.get("page");
if (page == null)
page = new PageInfo();
page.setTotalResult(count);
} else {
Field pageField = ReflectHelper.getFieldByFieldName(parameterObject, "page");
if (pageField != null) {
page = (PageInfo) ReflectHelper.getValueByFieldName(parameterObject, "page");
if (page == null)
page = new PageInfo();
page.setTotalResult(count);
ReflectHelper.setValueByFieldName(parameterObject, "page", page);
} else {
throw new NoSuchFieldException(parameterObject.getClass().getName());
}
}
String pageSql = generatePageSql(sql, page);
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, PageInfo page) {
if (page != null && (dialect != null || !dialect.equals(""))) {
StringBuffer pageSql = new StringBuffer();
if ("mysql".equals(dialect)) {
pageSql.append(sql);
pageSql.append(" limit " + page.getCurrentResult() + "," + page.getShowCount());
} else if ("oracle".equals(dialect)) {
pageSql.append("select * from (select tmp_tb.*,ROWNUM row_id from (");
pageSql.append(sql);
pageSql.append(") tmp_tb where ROWNUM<=");
pageSql.append(page.getCurrentResult() + page.getShowCount());
pageSql.append(") where row_id>");
pageSql.append(page.getCurrentResult());
}
return pageSql.toString();
} else {
return sql;
}
}
public Object plugin(Object arg0) {
// TODO Auto-generated method stub
return Plugin.wrap(arg0, this);
}
public void setProperties(Properties p) {
dialect = p.getProperty("dialect");
if (dialect == null || dialect.equals("")) {
try {
throw new PropertyException("dialect property is not found!");
} catch (PropertyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
pageSqlId = p.getProperty("pageSqlId");
if (dialect == null || dialect.equals("")) {
try {
throw new PropertyException("pageSqlId property is not found!");
} catch (PropertyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
4、在Configuration.xml中配置插件
<?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>
<typeAliases>
<typeAlias alias="PageInfo" type="com.jsoft.testmybatis.util.PageInfo" />
</typeAliases>
<plugins>
<plugin interceptor="com.jsoft.testmybatis.util.PagePlugin">
<property name="dialect" value="mysql" />
<property name="pageSqlId" value=".*ListPage.*" />
</plugin>
</plugins>
</configuration>
注意：这个插件定义了一个规则，也就是在mapper中SQL语句的id必须包含ListPage才能被拦截。否则将不会分页处理。
5、在UserController.java中添加测试的Controller
@RequestMapping("/pagelist")
public ModelAndView pageList(HttpServletRequest request, HttpServletResponse response) {
int currentPage = request.getParameter("page") == null ? 1 : Integer.parseInt(request.getParameter("page"));
int pageSize = 3;
if (currentPage <= 0) {
currentPage = 1;
}
int currentResult = (currentPage - 1) * pageSize;
System.out.println(request.getRequestURI());
System.out.println(request.getQueryString());
PageInfo page = new PageInfo();
page.setShowCount(pageSize);
page.setCurrentResult(currentResult);
List<Article> articles = userMapper.selectArticleListPage(page, 1);
System.out.println(page);
int totalCount = page.getTotalResult();
int lastPage = 0;
if (totalCount % pageSize == 0) {
lastPage = totalCount % pageSize;
} else {
lastPage = 1 + totalCount / pageSize;
}
if (currentPage >= lastPage) {
currentPage = lastPage;
}
String pageStr = "";
pageStr = String.format("<a href=\"%s\">上一页</a> <a href=\"%s\">下一页</a>", request.getRequestURI() + "?page=" + (currentPage - 1), request.getRequestURI() + "?page=" + (currentPage + 1));
// 制定视图，也就是list.jsp
ModelAndView mav = new ModelAndView("/article/pagelist");
mav.addObject("articles", articles);
mav.addObject("pageStr", pageStr);
return mav;
}
6、页面文件pagelist.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" isELIgnored="false"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<c:forEach items="${articles}" var="item">
${item.id }--${item.title }--${item.content }<br />
</c:forEach>
<div style="padding:20px;">${pageStr}</div>
</body>
</html>
7、测试结果：
测试工程：https://github.com/easonjim/5_java_example/tree/master/mybatis/test7
