MyBatis分页插件--有测试代码哦，可以抄袭哦

也许分页插件是你最为感兴趣的东西，那好我们开完成一个分页插件。

好长的代码，hold住哦。 博主今天累了，改天再和你们解释一下这个插件的设计思想。

package com.learn.mybatis.plugin;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Map;
import java.util.Properties;

import org.apache.ibatis.executor.parameter.ParameterHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
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.SystemMetaObject;
import org.apache.ibatis.scripting.defaults.DefaultParameterHandler;
import org.apache.ibatis.session.Configuration;

/**
 *
 * @author ykzhen2015
 */
@Intercepts({
    @Signature(type = StatementHandler.class,
            method = "prepare",
            args = {Connection.class})})
public class PagingPlugin implements Interceptor {

    private Integer defaultPage;
    private Integer defaultPageSize;
    private Boolean defaultUseFlag;
    private Boolean defaultCheckFlag;

    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        StatementHandler stmtHandler = getUnProxyObject(invocation);
        MetaObject metaStatementHandler = SystemMetaObject.forObject(stmtHandler);
        String sql = (String) metaStatementHandler.getValue("delegate.boundSql.sql");
        //不是select语句.
        if (!this.checkSelect(sql)) {
            return invocation.proceed();
        }
        BoundSql boundSql = (BoundSql) metaStatementHandler.getValue("delegate.boundSql");
        Object parameterObject = boundSql.getParameterObject();
        PageParams pageParams = null;
        if (parameterObject instanceof Map) {
        	Map parameterMap = (Map) parameterObject;
        	pageParams = (PageParams) parameterMap.get("$pageParams");
        } else if (parameterObject instanceof PageParams) {
        	pageParams = (PageParams) parameterObject;
        }
        if (pageParams == null) {
        	throw new Exception("没有获得分页参数！！，请正确使用分页参数！！");
        }
        //获取参数.
        Integer pageNum = pageParams.getPage() == null? this.defaultPage : pageParams.getPage();
        Integer pageSize = pageParams.getPageSize() == null? this.defaultPageSize : pageParams.getPageSize();
        Boolean useFlag = pageParams.getUseFlag() == null? this.defaultUseFlag : pageParams.getUseFlag();
        Boolean checkFlag = pageParams.getCheckFlag() == null? this.defaultCheckFlag : pageParams.getCheckFlag();
        if (!useFlag) {  //不使用分页插件.
            return invocation.proceed();
        }
        int total = this.getTotal(invocation, metaStatementHandler, boundSql);
        pageParams.setTotal(total);
        //计算总页数.
        int totalPage = total % pageSize == 0 ? total / pageSize : total / pageSize + 1;
        pageParams.setTotalPage(totalPage);
        //检查当前页码的有效性.
        this.checkPage(checkFlag, pageNum, totalPage);
        //修改sql
        this.changeSQL(metaStatementHandler, boundSql, pageNum, pageSize);
        //执行查询，得到最后的结果.
        Object data = invocation.proceed();
//        PageDataPO pageData = this.dealPageData(data, pageTotal, total, pageSize, pageNum);
        return data;
    }

    /**
     * 判断是否sql语句.
     * @param sql
     * @return
     */
    private boolean checkSelect(String sql) {
        String trimSql = sql.trim();
        int idx = trimSql.toLowerCase().indexOf("select");
        return idx == 0;
    }

    /**
     * 检查当前页码的有效性.
     * @param checkFlag
     * @param pageNum
     * @param pageTotal
     * @throws Throwable
     */
    private void checkPage(Boolean checkFlag, Integer pageNum, Integer pageTotal) throws Throwable  {
        if (checkFlag) {
            //检查页码page是否合法.
            if (pageNum > pageTotal) {
                throw new Exception("查询失败，查询页码【" + pageNum + "】大于总页数【" + pageTotal + "】！！");
            }
        }
    }

    /**
     * 修改当前查询的SQL
     * @param metaStatementHandler
     * @param boundSql
     * @param page
     * @param pageSize
     */
    private void changeSQL(MetaObject metaStatementHandler, BoundSql boundSql, int page, int pageSize) {
        //获取当前需要执行的SQL
        String sql = (String) metaStatementHandler.getValue("delegate.boundSql.sql");
        /**
         * TODO 这里使用的是MySQL其他数据库需要修改.
         * 根据你的数据库，修改分页的SQL
         */
        String newSql = "select * from (" + sql + ") $_paging_table limit " + (page - 1) * pageSize + ", " + pageSize;
        //修改当前需要执行的SQL
        metaStatementHandler.setValue("delegate.boundSql.sql", newSql);
    }

    /**
     * 获取综述.
     *
     * @param ivt Invocation
     * @param metaStatementHandler statementHandler
     * @param boundSql sql
     * @return sql查询总数.
     * @throws Throwable 异常.
     */
    private int getTotal(Invocation ivt, MetaObject metaStatementHandler, BoundSql boundSql) throws Throwable {
        //获取当前的mappedStatement
        MappedStatement mappedStatement = (MappedStatement) metaStatementHandler.getValue("delegate.mappedStatement");
        //配置对象
        Configuration cfg = mappedStatement.getConfiguration();
        //当前需要执行的SQL
        String sql = (String) metaStatementHandler.getValue("delegate.boundSql.sql");
        /**
        * TODO 如果是其他的数据库需要按你数据库的SQL规范改写.
        * 改写为统计总数的SQL
        */
        String countSql = "select count(*) as total from (" + sql + ") $_paging";
        //获取拦截方法参数，我们知道是Connection对象.
        Connection connection = (Connection) ivt.getArgs()[0];
        PreparedStatement ps = null;
        int total = 0;
        try {
            //预编译统计总数SQL
            ps = connection.prepareStatement(countSql);
            //构建统计总数SQL
            BoundSql countBoundSql = new BoundSql(cfg, countSql, boundSql.getParameterMappings(), boundSql.getParameterObject());
            //构建MyBatis的ParameterHandler用来设置总数Sql的参数。
            ParameterHandler handler = new DefaultParameterHandler(mappedStatement, boundSql.getParameterObject(), countBoundSql);
            //设置总数SQL参数
            handler.setParameters(ps);
            //执行查询.
            ResultSet rs = ps.executeQuery();
            while (rs.next()) {
                total = rs.getInt("total");
            }
        } finally {
            //这里不能关闭Connection否则后续的SQL就没法继续了。
            if (ps != null && ps.isClosed()) {
                ps.close();
            }
        }
        System.err.println("总条数：" + total);
        return total;
    }

    /**
     * 从代理对象中分离出真实对象.
     *
     * @param ivt --Invocation
     * @return 非代理StatementHandler对象
     */
    private StatementHandler getUnProxyObject(Invocation ivt) {
        StatementHandler statementHandler = (StatementHandler) ivt.getTarget();
        MetaObject metaStatementHandler = SystemMetaObject.forObject(statementHandler);
        // 分离代理对象链(由于目标类可能被多个拦截器拦截，从而形成多次代理，通过循环可以分离出最原始的的目标类)
        Object object = null;
        while (metaStatementHandler.hasGetter("h")) {
            object = metaStatementHandler.getValue("h");
        }
        if (object == null) {
            return statementHandler;
        }
        return (StatementHandler) object;
    }

    @Override
    public Object plugin(Object statementHandler) {
        return Plugin.wrap(statementHandler, this);
    }

    @Override
    public void setProperties(Properties props) {
        String strDefaultPage = props.getProperty("default.page", "1");
        String strDefaultPageSize = props.getProperty("default.pageSize", "50");
        String strDefaultUseFlag = props.getProperty("default.useFlag", "false");
        String strDefaultCheckFlag = props.getProperty("default.checkFlag", "false");
        this.defaultPage = Integer.parseInt(strDefaultPage);
        this.defaultPageSize = Integer.parseInt(strDefaultPageSize);
        this.defaultUseFlag = Boolean.parseBoolean(strDefaultUseFlag);
        this.defaultCheckFlag = Boolean.parseBoolean(strDefaultCheckFlag);
    }

}

注意：在代码注解的地方有些地方有TODO,这里我采用的是MySQL修改语句，如果你是其他数据库需要在哪里修改为对应数据库的SQL语句。

有了这个插件，还不行哦，还要配置一下：

     <plugins>
        <plugin interceptor="com.learn.mybatis.plugin.PagingPlugin">
            <!--默认第1页-->
            <property name="default.page" value="1" />
            <!--默认每页20条-->
            <property name="default.pageSize" value="20" />
            <!--默认不启用分页插件-->
            <property name="default.useFlag" value="false" />
            <!--默认不检查页码-->
            <property name="default.checkFlag" value="false" />
        </plugin>
    </plugins>

这样在MyBatis上下文就可以引用这个插件了。

这里的配置：

  • default.page -- 缺省页码的时候，采用第1页
  • default.pageSize -- 缺省每页多少条配置的时候，才有每页20条
  • default.useFlag -- 查询是否启用分页插件，如果为false则不启用。
  • default.checkFlag -- 查询是否检查page当前页有效。如最大页码是2，程序传递为3，如此项为true，则抛出异常提示错误。如果为false则不抛出异常

以上的默认参数都可以通过这个类进行改变：

package com.learn.mybatis.plugin;

/**
 *
 * @author ykzhen2015
 */
public class PageParams {

	private Integer page;
	private Integer pageSize;
	private Boolean useFlag;
	private Boolean checkFlag;
	private Integer total;
	private Integer totalPage;

	public Integer getPage() {
		return page;
	}

	public void setPage(Integer page) {
		this.page = page;
	}

	public Integer getPageSize() {
		return pageSize;
	}

	public void setPageSize(Integer pageSize) {
		this.pageSize = pageSize;
	}

	public Boolean getUseFlag() {
		return useFlag;
	}

	public void setUseFlag(Boolean useFlag) {
		this.useFlag = useFlag;
	}

	public Boolean getCheckFlag() {
		return checkFlag;
	}

	public void setCheckFlag(Boolean checkFlag) {
		this.checkFlag = checkFlag;
	}

	public Integer getTotal() {
		return total;
	}

	public void setTotal(Integer total) {
		this.total = total;
	}

	public Integer getTotalPage() {
		return totalPage;
	}

	public void setTotalPage(Integer totalPage) {
		this.totalPage = totalPage;
	}

}

当以下属性被设置会有这样的效果：

  • page  --插件默认设置default.page作废，采取这个值
  • pageSize --插件默认设置default.pageSize作废，采取这个值
  • useFlag --插件默认设置default.useFlag作废，采取这个值
  • checkFlag --插件默认设置default.checkFlag作废，采取这个值

而：

total  ——代表总条数，插件回自动帮我们回填

totalPage ——代表总页数，插件回自动帮我们回填

有了这个类，我们来举例如何使用它，我们先定义Mapper接口。

package com.learn.mybatis.chapter1.mapper;

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

import org.apache.ibatis.annotations.Param;

import com.learn.mybatis.chapter1.po.TRole;
import com.learn.mybatis.plugin.PageParams;
import com.learn.mybatis.plugin.TestParams;

public interface RoleMapper {
    public TRole getRole(Long id);

    public List<TRole> selectAllRole(TestParams pageParams);

    public List<TRole> selectRoleByMap(Map<String, Object> params);

      //"$pageParams"这个键不能修改
     public List<TRole> selectRoleByMap(@Param("roleName") String roleName, @Param("$pageParams") PageParams pageParams);
}



好，这里有三个select开头的方法，参数分别为POJO, map和MyBatis的注解型。这三种类型这个插件都可以适用。


让我们看看POJO---TestParams,它继承了PageParams


package com.learn.mybatis.plugin;

public class TestParams extends PageParams {

	String roleName;

	public String getRoleName() {
		return roleName;
	}

	public void setRoleName(String roleName) {
		this.roleName = roleName;
	}
}



这时候我们看看roleMapper.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.learn.mybatis.chapter1.mapper.RoleMapper">
    <select id="getRole" parameterType="long" resultType="com.learn.mybatis.chapter1.po.TRole">
        select id, role_name as roleName, note from t_role where id=#{id}
    </select>

   <select id="selectAllRole" parameterType="com.learn.mybatis.plugin.TestParams" resultType="com.learn.mybatis.chapter1.po.TRole">
        select id, role_name as roleName, note from t_role
        <where>
        <if test="roleName != null">
        role_name like concat('%', #{roleName}, '%')
        </if>
        </where>
    </select>

    <select id="selectRoleByMap" parameterType="map" resultType="com.learn.mybatis.chapter1.po.TRole">
        select id, role_name as roleName, note from t_role
        <where>
        <if test="roleName != null">
        role_name like concat('%', #{roleName}, '%')
        </if>
        </where>
    </select>

    <select id="selectRoleByKey"  resultType="com.learn.mybatis.chapter1.po.TRole">
        select id, role_name as roleName, note from t_role
        <where>
        <if test="roleName != null">
        role_name like concat('%', #{roleName}, '%')
        </if>
        </where>
    </select>
</mapper>


可以看好，三个select都有方法了。


我们用main方法测试一下：


public static void main(String[] args) {
        testParams();
        testPOJO();
        testMap();

    }

    public static void testPOJO() {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtil.getSqlSessionFactroy().openSession();
            RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class);
            TestParams params = new TestParams();
            params.setUseFlag(true);
            params.setCheckFlag(false);
            params.setPage(2);
            params.setPageSize(5);
            params.setRoleName("test");
            List<TRole> pageData = roleMapper.selectAllRole(params);
            System.err.println("#######################测试POJO##################");
            System.err.println("总页数：" + params.getTotalPage());
            System.err.println("总条数：" + params.getTotal());
        } finally {
            sqlSession.close();
        }
    }

    public static void testMap() {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtil.getSqlSessionFactroy().openSession();
            RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class);
            Map<String, Object> paramMap = new HashMap<String, Object>();
            PageParams pageParams = new PageParams();
            pageParams.setUseFlag(true);
            pageParams.setCheckFlag(false);
            pageParams.setPage(2);
            pageParams.setPageSize(5);
            paramMap.put("roleName", "test");
           paramMap.put("$pageParams", pageParams);//"$pageParams"这个键不能修改
            List<TRole> pageData2 = roleMapper.selectRoleByMap(paramMap);
            System.err.println("#######################测试Map##################");
            System.err.println("总页数：" + pageParams.getTotalPage());
            System.err.println("总条数：" + pageParams.getTotal());
        } finally {
            sqlSession.close();
        }
    }

    public static void testParams() {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtil.getSqlSessionFactroy().openSession();
            RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class);
            PageParams pageParams2 = new PageParams();
            pageParams2.setUseFlag(true);
            pageParams2.setCheckFlag(true);
            pageParams2.setPage(2);
            pageParams2.setPageSize(5);
            List<TRole> pageData3 = roleMapper.selectRoleByMap("test", pageParams2);
            System.err.println("#######################测试@Param##################");
            System.err.println("总页数：" + pageParams2.getTotalPage());
            System.err.println("总条数：" + pageParams2.getTotal());
        } finally {
            sqlSession.close();
        }
    }


好，他们都执行相同的查询，并且打印了总页数和总条数，会不会成功呢？我们看看打印的日志：


run:
DEBUG 2016-06-16 21:03:46,208 org.apache.ibatis.logging.LogFactory: Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
DEBUG 2016-06-16 21:03:46,818 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2016-06-16 21:03:46,834 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2016-06-16 21:03:46,834 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2016-06-16 21:03:46,834 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2016-06-16 21:03:47,583 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Opening JDBC Connection
DEBUG 2016-06-16 21:03:48,646 org.apache.ibatis.datasource.pooled.PooledDataSource: Created connection 2042495840.
DEBUG 2016-06-16 21:03:48,646 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Setting autocommit to false on JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:03:48,662 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==>  Preparing: select count(*) as total from (select id, role_name as roleName, note from t_role WHERE role_name like concat('%', ?, '%')) $_paging
DEBUG 2016-06-16 21:03:48,802 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==> Parameters: test(String)
DEBUG 2016-06-16 21:03:48,896 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: <==      Total: 1
总条数：11
DEBUG 2016-06-16 21:03:48,896 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==>  Preparing: select * from (select id, role_name as roleName, note from t_role WHERE role_name like concat('%', ?, '%')) $_paging_table limit 5, 5
DEBUG 2016-06-16 21:03:48,912 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==> Parameters: test(String)
DEBUG 2016-06-16 21:03:48,927 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: <==      Total: 5
#######################测试@Param##################
总页数：3
总条数：11
DEBUG 2016-06-16 21:03:48,927 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Resetting autocommit to true on JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:03:48,927 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Closing JDBC Connection [com.mysql.jdbc.JDBC4Connectio[email protected]]
DEBUG 2016-06-16 21:03:48,943 org.apache.ibatis.datasource.pooled.PooledDataSource: Returned connection 2042495840 to pool.
DEBUG 2016-06-16 21:03:48,943 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Opening JDBC Connection
DEBUG 2016-06-16 21:03:48,943 org.apache.ibatis.datasource.pooled.PooledDataSource: Checked out connection 2042495840 from pool.
DEBUG 2016-06-16 21:03:48,943 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Setting autocommit to false on JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:03:48,943 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==>  Preparing: select count(*) as total from (select id, role_name as roleName, note from t_role WHERE role_name like concat('%', ?, '%')) $_paging
DEBUG 2016-06-16 21:03:48,958 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==> Parameters: test(String)
DEBUG 2016-06-16 21:03:48,958 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: <==      Total: 1
总条数：11
DEBUG 2016-06-16 21:03:48,958 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==>  Preparing: select * from (select id, role_name as roleName, note from t_role WHERE role_name like concat('%', ?, '%')) $_paging_table limit 5, 5
DEBUG 2016-06-16 21:03:48,958 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==> Parameters: test(String)
DEBUG 2016-06-16 21:03:48,974 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: <==      Total: 5
#######################测试POJO##################
总页数：3
总条数：11
DEBUG 2016-06-16 21:03:48,974 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Resetting autocommit to true on JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:03:48,974 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Closing JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:03:48,974 org.apache.ibatis.datasource.pooled.PooledDataSource: Returned connection 2042495840 to pool.
DEBUG 2016-06-16 21:03:48,974 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Opening JDBC Connection
DEBUG 2016-06-16 21:03:48,974 org.apache.ibatis.datasource.pooled.PooledDataSource: Checked out connection 2042495840 from pool.
DEBUG 2016-06-16 21:03:48,974 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Setting autocommit to false on JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:03:48,990 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==>  Preparing: select count(*) as total from (select id, role_name as roleName, note from t_role WHERE role_name like concat('%', ?, '%')) $_paging
DEBUG 2016-06-16 21:03:48,990 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==> Parameters: test(String)
总条数：11
DEBUG 2016-06-16 21:03:48,990 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: <==      Total: 1
DEBUG 2016-06-16 21:03:48,990 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==>  Preparing: select * from (select id, role_name as roleName, note from t_role WHERE role_name like concat('%', ?, '%')) $_paging_table limit 5, 5
DEBUG 2016-06-16 21:03:48,990 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==> Parameters: test(String)
DEBUG 2016-06-16 21:03:49,005 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: <==      Total: 5
#######################测试Map##################
总页数：3
总条数：11
DEBUG 2016-06-16 21:03:49,005 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Resetting autocommit to true on JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:03:49,005 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Closing JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:03:49,005 org.apache.ibatis.datasource.pooled.PooledDataSource: Returned connection 2042495840 to pool.
成功构建 (总时间: 5 秒)



好，我们看到，我们的分页参数的总条数和总页数被回填了。而且我们可以通过useFlag属性来控制是否启用分页，这样对于select count(*) from t_role这样的语句我们通过设置参数，就可以不启用这个分页功能了。


此外还有检查页码的功能，只要设置了属性，checkFlag插件会为我们检查这个页码的正确性，让我们看看：


public static void testException() {
        SqlSession sqlSession = null;
        try {
            sqlSession = MyBatisUtil.getSqlSessionFactroy().openSession();
            RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class);
            TestParams params = new TestParams();
            params.setUseFlag(true);
            params.setCheckFlag(true);//检查页码正确性
            params.setPage(5);//故意超过最大页数
            params.setPageSize(5);
            params.setRoleName("test");
            List<TRole> pageData = roleMapper.selectAllRole(params);
            System.err.println("#######################测试POJO##################");
            System.err.println("总页数：" + params.getTotalPage());
            System.err.println("总条数：" + params.getTotal());
        } finally {
            sqlSession.close();
        }
    }


params.setCheckFlag(true);//检查页码正确性


注意这里设置了需要检验


params.setPage(5);//故意超过最大页数


这样让他超过了最大的页数。


我们测试它，得到日志：


run:
DEBUG 2016-06-16 21:09:22,123 org.apache.ibatis.logging.LogFactory: Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
DEBUG 2016-06-16 21:09:22,341 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2016-06-16 21:09:22,341 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2016-06-16 21:09:22,341 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2016-06-16 21:09:22,341 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2016-06-16 21:09:22,732 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Opening JDBC Connection
DEBUG 2016-06-16 21:09:23,482 org.apache.ibatis.datasource.pooled.PooledDataSource: Created connection 1033490990.
DEBUG 2016-06-16 21:09:23,482 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Setting autocommit to false on JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:09:23,513 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==>  Preparing: select count(*) as total from (select id, role_name as roleName, note from t_role WHERE role_name like concat('%', ?, '%')) $_paging
DEBUG 2016-06-16 21:09:23,669 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: ==> Parameters: test(String)
DEBUG 2016-06-16 21:09:23,794 org.apache.ibatis.logging.jdbc.BaseJdbcLogger: <==      Total: 1
总条数：11
DEBUG 2016-06-16 21:09:23,810 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Resetting autocommit to true on JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:09:23,810 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Closing JDBC Connection [[email protected]]
DEBUG 2016-06-16 21:09:23,826 org.apache.ibatis.datasource.pooled.PooledDataSource: Returned connection 1033490990 to pool.
Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException:
### Error querying database.  Cause: java.lang.reflect.UndeclaredThrowableException
### The error may exist in com\learn\mybatis\chapter1\sqlmap\role.xml
### The error may involve com.learn.mybatis.chapter1.mapper.RoleMapper.selectAllRole-Inline
### The error occurred while setting parameters
### Cause: java.lang.reflect.UndeclaredThrowableException
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:122)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:113)
	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:122)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:64)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53)
	at com.sun.proxy.$Proxy3.selectAllRole(Unknown Source)
	at com.learn.mybatis.chapter1.main.MyBatisExample.testException(MyBatisExample.java:33)
	at com.learn.mybatis.chapter1.main.MyBatisExample.main(MyBatisExample.java:18)
Caused by: java.lang.reflect.UndeclaredThrowableException
	at com.sun.proxy.$Proxy4.prepare(Unknown Source)
	at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:76)
	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:61)
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:303)
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:154)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:102)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:82)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:120)
	... 7 more
Caused by: java.lang.Exception: 查询失败，查询页码【5】大于总页数【3】！！
	at com.learn.mybatis.plugin.PagingPlugin.checkPage(PagingPlugin.java:105)
	at com.learn.mybatis.plugin.PagingPlugin.intercept(PagingPlugin.java:73)
	at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:61)
	... 15 more
C:\Users\ykzhen\AppData\Local\NetBeans\Cache\8.1\executor-snippets\run.xml:53: Java returned: 1
构建失败 (总时间: 2 秒)



我们看到了，异常，并且指明超过了最大总页数
				


				
时间： 2024-10-30 12:50:08 

		


		


	

	
	

		


		
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