Java simply implements SpringMVC+MyBatis paging plug-in

1. Encapsulate the paging Page class

package com.framework.common.page.impl;
 
import java.io.Serializable;
 
import com.framework.common.page.IPage;
/**
 * 
 * 
 *
 */
public abstract class BasePage implements IPage, Serializable {
 
  /**
   * 
   */
  private static final long serialVersionUID = -3623448612757790359L;
   
  public static int DEFAULT_PAGE_SIZE = 20;
  private int pageSize = DEFAULT_PAGE_SIZE;
  private int currentResult;
  private int totalPage;
  private int currentPage = 1;
  private int totalCount = -1;
 
  public BasePage(int currentPage, int pageSize, int totalCount) {
    this.currentPage = currentPage;
    this.pageSize = pageSize;
    this.totalCount = totalCount;
  }
 
  public int getTotalCount() {
    return this.totalCount;
  }
 
  public void setTotalCount(int totalCount) {
    if (totalCount < 0) {
      this.totalCount = 0;
      return;
    }
    this.totalCount = totalCount;
  }
 
  public BasePage() {
  }
 
  public int getFirstResult() {
    return (this.currentPage - 1) * this.pageSize;
  }
 
  public void setPageSize(int pageSize) {
    if (pageSize < 0) {
      this.pageSize = DEFAULT_PAGE_SIZE;
      return;
    }
    this.pageSize = pageSize;
  }
 
  public int getTotalPage() {
    if (this.totalPage <= 0) {
      this.totalPage = (this.totalCount / this.pageSize);
      if ((this.totalPage == 0) || (this.totalCount % this.pageSize != 0)) {
        this.totalPage += 1;
      }
    }
    return this.totalPage;
  }
 
  public int getPageSize() {
    return this.pageSize;
  }
 
  public void setPageNo(int currentPage) {
    this.currentPage = currentPage;
  }
 
  public int getPageNo() {
    return this.currentPage;
  }
 
  public boolean isFirstPage() {
    return this.currentPage <= 1;
  }
 
  public boolean isLastPage() {
    return this.currentPage >= getTotalPage();
  }
 
  public int getNextPage() {
    if (isLastPage()) {
      return this.currentPage;
    }
    return this.currentPage + 1;
  }
 
  public int getCurrentResult() {
    this.currentResult = ((getPageNo() - 1) * getPageSize());
    if (this.currentResult < 0) {
      this.currentResult = 0;
    }
    return this.currentResult;
  }
 
  public int getPrePage() {
    if (isFirstPage()) {
      return this.currentPage;
    }
    return this.currentPage - 1;
  }
 
 
}

package com.framework.common.page.impl;
 
import java.util.List;
/**
 * 
 * 
 *
 */
public class Page extends BasePage {
 
  /**
   * 
   */
  private static final long serialVersionUID = -970177928709377315L;
 
  public static ThreadLocal<Page> threadLocal = new ThreadLocal<Page>();
 
  private List<?> data; 
   
  public Page() {
  }
 
  public Page(int currentPage, int pageSize, int totalCount) {
    super(currentPage, pageSize, totalCount);
  }
 
  public Page(int currentPage, int pageSize, int totalCount, List<?> data) {
    super(currentPage, pageSize, totalCount);
    this.data = data;
  }
 
  public List<?> getData() {
    return data;
  }
 
  public void setData(List<?> data) {
    this.data = data;
  }
   
 
}

2. Encapsulate the paging plug-in

package com.framework.common.page.plugin;
 
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 javax.xml.bind.PropertyException;
 
import org.apache.commons.lang3.StringUtils;
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.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.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 com.framework.common.page.impl.Page;
import com.framework.common.utils.ReflectUtil;
/**
 * 
 * 
 *
 */
@Intercepts({ @org.apache.ibatis.plugin.Signature(type = org.apache.ibatis.executor.statement.StatementHandler.class, method = "prepare", args = { Connection.class }) })
public class PagePlugin implements Interceptor {
 
  private String dialect = "";
  private String pageSqlId = "";
 
  @Override
  public Object intercept(Invocation invocation) throws Throwable {
    if (invocation.getTarget() instanceof RoutingStatementHandler) {
      BaseStatementHandler delegate = (BaseStatementHandler) ReflectUtil
          .getValueByFieldName(
              (RoutingStatementHandler) invocation.getTarget(),
              "delegate");
      MappedStatement mappedStatement = (MappedStatement) ReflectUtil
          .getValueByFieldName(delegate,
              "mappedStatement");
 
      Page page = Page.threadLocal.get();
      if (page == null) {
        page = new Page();
        Page.threadLocal.set(page);
      }
 
      if (mappedStatement.getId().matches(".*(" + this.pageSqlId + ")$") && page.getPageSize() > 0) {
        BoundSql boundSql = delegate.getBoundSql();
        Object parameterObject = boundSql.getParameterObject();
 
        String sql = boundSql.getSql();
        String countSqlId = mappedStatement.getId().replaceAll(pageSqlId, "Count");
        MappedStatement countMappedStatement = null;
        if (mappedStatement.getConfiguration().hasStatement(countSqlId)) {
          countMappedStatement = mappedStatement.getConfiguration().getMappedStatement(countSqlId);
        }
        String countSql = null;
        if (countMappedStatement != null) {
          countSql = countMappedStatement.getBoundSql(parameterObject).getSql();
        } else {
          countSql = "SELECT COUNT(1) FROM (" + sql + ") T_COUNT";
        }
         
        int totalCount = 0;
        PreparedStatement countStmt = null;
        ResultSet resultSet = null;
        try {
          Connection connection = (Connection) invocation.getArgs()[0];
          countStmt = connection.prepareStatement(countSql);
          BoundSql countBoundSql = new BoundSql(mappedStatement.getConfiguration(), countSql, boundSql.getParameterMappings(), parameterObject);
           
          setParameters(countStmt, mappedStatement, countBoundSql, parameterObject);
           
          resultSet = countStmt.executeQuery();
          if(resultSet.next()) {
            totalCount = resultSet.getInt(1);
          }
        } catch (Exception e) {
          throw e;
        } finally {
          try {
            if (resultSet != null) {
              resultSet.close();
            }
          } finally {
            if (countStmt != null) {
              countStmt.close();
            }
          }
        }
         
        page.setTotalCount(totalCount);
         
        ReflectUtil.setValueByFieldName(boundSql, "sql", generatePageSql(sql,page));
      }
    }
 
    return invocation.proceed();
  }
   
 
  /** 
   * 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()); 
        } 
      } 
    } 
  } 
   
  /** 
   * 根据数据库方言，生成特定的分页sql 
   * @param sql 
   * @param page 
   * @return 
   */
  private String generatePageSql(String sql,Page page){ 
    if(page!=null && StringUtils.isNotBlank(dialect)){ 
      StringBuffer pageSql = new StringBuffer(); 
      if("mysql".equals(dialect)){ 
        pageSql.append(sql); 
        pageSql.append(" LIMIT "+page.getCurrentResult()+","+page.getPageSize()); 
      }else if("oracle".equals(dialect)){ 
        pageSql.append("SELECT * FROM (SELECT TMP_TB.*,ROWNUM ROW_ID FROM ("); 
        pageSql.append(sql); 
        pageSql.append(") AS TMP_TB WHERE ROWNUM <= "); 
        pageSql.append(page.getCurrentResult()+page.getPageSize()); 
        pageSql.append(") WHERE ROW_ID > "); 
        pageSql.append(page.getCurrentResult()); 
      } 
      return pageSql.toString(); 
    }else{ 
      return sql; 
    } 
  } 
 
  @Override
  public Object plugin(Object target) {
    return Plugin.wrap(target, this);
  }
 
  @Override
  public void setProperties(Properties properties) {
    try {
      if (StringUtils.isEmpty(this.dialect = properties
          .getProperty("dialect"))) {
        throw new PropertyException("dialect property is not found!");
      }
      if (StringUtils.isEmpty(this.pageSqlId = properties
          .getProperty("pageSqlId"))) {
        throw new PropertyException("pageSqlId property is not found!");
      }
    } catch (PropertyException e) {
      e.printStackTrace();
    }
  }
 
}

3. MyBatis configuration file: mybatis-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD SQL Map Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
  <plugins>
    <plugin interceptor="com.framework.common.page.plugin.PagePlugin">
      <property name="dialect" value="mysql" />
      <property name="pageSqlId" value="ByPage" />
    </plugin>
  </plugins>
</configuration>

4. Paging interception Device

package com.framework.common.page.interceptor;
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.apache.commons.lang3.math.NumberUtils;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
 
import com.framework.common.page.impl.Page;
/**
* 
* 14 *
*/
public class PageInterceptor extends HandlerInterceptorAdapter {
 
 @Override
 public void postHandle(HttpServletRequest request,
     HttpServletResponse response, Object handler,
     ModelAndView modelAndView) throws Exception {
   super.postHandle(request, response, handler, modelAndView);
   Page page = Page.threadLocal.get();
   if (page != null) {
     request.setAttribute("page", page);
   }
   Page.threadLocal.remove();
 }
 
 @Override
 public boolean preHandle(HttpServletRequest request,
     HttpServletResponse response, Object handler) throws Exception {
   String pageSize = request.getParameter("pageSize");
   String pageNo = request.getParameter("pageNo");
   Page page = new Page();
   if (NumberUtils.isNumber(pageSize)) {
     page.setPageSize(NumberUtils.toInt(pageSize));
   }
   if (NumberUtils.isNumber(pageNo)) {
     page.setPageNo(NumberUtils.toInt(pageNo));
   }
   Page.threadLocal.set(page);
   return true;
 }
 
}

5.Spring configuration

<!-- ===================================================================
- Load property file
- =================================================================== -->
<context:property-placeholder location="classpath:application.properties" />
 
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
  <property name="dataSource" ref="dataSource" />
  <property name="configLocation" value="classpath:mybatis-config.xml" />
  <property name="mapperLocations">
    <list>
      <value>classpath:/com/framework/mapper/**/*Mapper.xml</value>
    </list>
  </property>
</bean>
 
<!-- ===================================================================
- 通过扫描的模式，扫描目录下所有的dao， 根据对应的mapper.xml为其生成代理类
- =================================================================== -->
<bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
  <property name="basePackage" value="com.framework.dao" />
  <property name="processPropertyPlaceHolders" value="true" />
  <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
</bean>

6.SpringMVC configuration interceptor

<!-- 分页拦截器 -->
  <bean id="pageInterceptor" class="com.framework.common.page.interceptor.PageInterceptor"></bean>
   
  <!-- 配置拦截器 -->
  <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping">
    <property name="interceptors">
      <list>
        <ref bean="pageInterceptor" />
      </list>
    </property>
  </bean>

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