MyBatis笔记----mybatis分页

Posted 2020-09-08 Stay Hungry, Stay Foolish

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mybatis版本3.4以下

结构

spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://www.springframework.org/schema/beans"
        xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-4.3.xsd">
<!--   自动扫描加载注解的包 -->
<context:component-scan base-package="com.ij34.bean"/>
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> 
<property name="prefix" value="/WEB-INF/view/"></property>
<property name="suffix" value=".jsp" ></property>
</bean>

</beans>

com.ij34.mybatis

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
            http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context-4.3.xsd"
            default-autowire="byName" default-lazy-init="false"> 
    <!-- Showcase\'s CustomFreemarkerManager example -->
  <bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource">
     <property name="driverClassName" value="com.mysql.jdbc.Driver"></property> 
     <property name="url" value="jdbc:mysql://localhost:3306/mybatis"></property> 
     <property name="username" value="root"></property> 
     <property name="password" value="123456"></property> 
  </bean> 
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
      <property name="dataSource" ref="dataSource" />
    </bean>
  <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
      <property name="dataSource" ref="dataSource"></property>
      <property name="configLocation" value="classpath:com/ij34/mybatis/mybatis-config.xml"></property>
      <property name="mapperLocations" value="classpath:com/ij34/mybatis/UserMapper.xml"></property>
  </bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.ij34.model"></property>
    <property name="sqlSessionFactory" ref="sqlSessionFactory" />  
</bean>
</beans>

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>
<typeAliases>
<typeAlias type="com.ij34.model.Article" alias="Article"/>
<typeAlias type="com.ij34.model.User" alias="User"/>
<typeAlias type="com.ij34.pages.PageInfo" alias="PageInfo"/>
</typeAliases>
  <plugins>
        <plugin interceptor="com.ij34.pages.PagePlugin">
            <property name="dialect" value="mysql" />
            <property name="pageSqlId" value=".*ListPage.*" />
        </plugin>
    </plugins>
</configuration>

UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

  <mapper  namespace="com.ij34.model.UserMapper">
<resultMap type="Article" id="resultAticleList">
  <id property="id" column="aid"/>
  <result property="title" column="title"/>
  <result property="content" column="content"/>
  <association property="user" javaType="User">
  <id property="id" column="id"/>
  <result property="name" column="name"/>
  <result property="age" column="age"/>
  </association>
  </resultMap>
   <select id="selectarticle" parameterType="int" resultMap="resultAticleList">
  select users.id,users.name,users.age,article.id aid,article.title,article.content from users,article
  where users.id=article.userid and users.id=#{id}
  </select>
  
  <select id="ListPage" resultMap="resultAticleList">
  select users.id,users.name,users.age,article.id aid,article.title,article.content from users,article
  where users.id=article.userid and users.id=#{userid}
  </select>
  
  </mapper>

com.ij34.model

User.java

package com.ij34.model;

public class User {
  private int id;
  private String name;
  private int age;


  public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public int getAge() {
    return age;
}

public void setAge(int age) {
    this.age = age;
}
public String toString() {
    return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
}


}

View Code

Article.java

package com.ij34.model;

public class Article {
  private int id;
  private User user;
  private String title;
  private String content;
  
public String getContent() {
    return content;
}
public void setContent(String content) {
    this.content = content;
}
public int getId() {
    return id;
}
public void setId(int id) {
    this.id = id;
}
public User getUser() {
    return user;
}
public void setUser(User user) {
    this.user = user;
}
public String getTitle() {
    return title;
}
public void setTitle(String title) {
    this.title = title;
}

  
}

View Code

UserMapper.java

package com.ij34.model;

import java.util.List;

import org.apache.ibatis.annotations.Param;

import com.ij34.pages.PageInfo;

public interface UserMapper {
      
    public List<Article> selectarticle(int id);   
    public List<Article> ListPage(@Param("page") PageInfo page,@Param("userid") int userid);
}

View Code

com.ij34.pages

参考网上的分页插件

PageInfo.java

package com.ij34.pages;

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 = 9;
    //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;
    }
    
    
}

PagePlugin.java

@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }) })

要用3.4以下版本，可以参考官方

package com.ij34.pages;

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.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;

@Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.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();
            }
        }
    }


}

ReflectHelper.java

package com.ij34.pages;

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;  
    }  
  

    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;  
    }  
  
 
    public static void setValueByFieldName(Object obj, String fieldName,  
            Object value) throws SecurityException, NoSuchFieldException,  
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