MyBatis 最简单的分页

package isxiatian.mybatis.plugin; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Properties; import org.apache.ibatis.builder.StaticSqlSource; import org.apache.ibatis.executor.Executor; import org.apache.ibatis.executor.parameter.ParameterHandler; import org.apache.ibatis.mapping.BoundSql; import org.apache.ibatis.mapping.MappedStatement; import org.apache.ibatis.mapping.ParameterMapping; import org.apache.ibatis.mapping.SqlCommandType; import org.apache.ibatis.mapping.SqlSource; 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; import org.apache.ibatis.session.ResultHandler; import org.apache.ibatis.session.RowBounds; import org.apache.log4j.Logger; import isxiatian.mybatis.plugin.parser.MySqlParser; import isxiatian.mybatis.plugin.parser.Parser; /** * Mybatis - 通用分页拦截器 * @author xia * */ @Intercepts(@Signature(type = Executor.class, method = "query", args = { MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class })) public class PageHelper implements Interceptor,ParserData { private static final Logger LOGGER = Logger.getLogger(PageHelper.class); @SuppressWarnings("rawtypes") private static final ThreadLocal<Page> localPage = new ThreadLocal<Page>(); private static Parser parser = null; /** * 开始分页 * * @param pageNum * @param pageSize */ public static <E> Page<E> startPage(int pageNum, int pageSize,Class<E> resultType) { Page<E> page=new Page<E>(pageNum, pageSize); localPage.set(page); return page; } public static <E> Page<E> startPage(int pageNum, int pageSize,String orderby,Class<E> resultType) { Page<E> page=new Page<E>(pageNum, pageSize,orderby); localPage.set(page); return page; } public static <E> Page<E> startPage(int pageNum, int pageSize,String orderby,OrderByType orderByType,Class<E> resultType) { Page<E> page =new Page<E>(pageNum, pageSize,orderby,orderByType); localPage.set(page); return page; } @SuppressWarnings({ "rawtypes", "unchecked" }) @Override public Object intercept(Invocation invocation) throws Throwable { //获取Page Page page=localPage.get(); if ( page == null || page.getPageSize() <= 0) { return invocation.proceed(); } //忽略Mybatis自带的内存分页 RowBounds rowBounds=(RowBounds)invocation.getArgs()[2]; invocation.getArgs()[2] = RowBounds.DEFAULT; MappedStatement mappedStatement = (MappedStatement)invocation.getArgs()[0]; Object parameter = invocation.getArgs()[1]; //不是查询跳过 if(mappedStatement.getSqlCommandType() != SqlCommandType.SELECT) return invocation.proceed(); Configuration configuration = mappedStatement.getConfiguration(); BoundSql boundSql = mappedStatement.getBoundSql(parameter); //获取连接 Connection connection=mappedStatement.getConfiguration().getEnvironment().getDataSource().getConnection(); //重设分页参数里的总页数等 setPageParameter(boundSql.getSql(), connection, mappedStatement, boundSql, page); //越界则取最后一页 if(page.getEndRow()>page.getPages()*page.getPageSize()) { page.setPageNum(page.getPages()); page.setStartRow((page.getPageNum()-1)*page.getPageSize()); page.setEndRow(page.getPageNum()*page.getPageSize()); } //获取参数 列表 List<ParameterMapping> newParameterMappings =parser.setParameterKeys(configuration, boundSql.getParameterMappings(), page); //获取 分页sql String newSql=parser.getPageSql(boundSql.getSql(),page); StaticSqlSource sqlsource = new StaticSqlSource(configuration,newSql,newParameterMappings); //替换ms invocation.getArgs()[0]=newMappedStatement(mappedStatement,sqlsource,SUFFIX_PAGE); //获取参数 数值 Map<String, Object> map = setPageParameter(mappedStatement,parameter,mappedStatement.getBoundSql(parameter)); Map<String, Object> newMap=parser.setParameterValues(map, page); int i=1; //防止使用 sql 使用 下标作为参数 报错 for (ParameterMapping parameterMapping : newParameterMappings) { newMap.put("param"+i++, newMap.get(parameterMapping.getProperty())); } //替换参数 invocation.getArgs()[1]=newMap; Object result = invocation.proceed(); page.setResult((List)result); localPage.remove(); //还原 invocation.getArgs()[0]=mappedStatement; invocation.getArgs()[1]=parameter; invocation.getArgs()[2]=rowBounds; return result; } /** * 获取总记录数 * * @param sql * @param connection * @param mappedStatement * @param boundSql * @param page */ @SuppressWarnings("rawtypes") private void setPageParameter(String sql, Connection connection, MappedStatement mappedStatement, BoundSql boundSql, Page page) { // 记录总记录数 String countSql = parser.getCountSql(sql); PreparedStatement countStmt = null; ResultSet rs = null; try { countStmt = connection.prepareStatement(countSql); BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(), countSql, boundSql.getParameterMappings(), boundSql.getParameterObject()); setParameters(countStmt, mappedStatement, countBS, boundSql.getParameterObject()); rs = countStmt.executeQuery(); int totalCount = 0; if (rs.next()) { totalCount = rs.getInt(1); } page.setTotal(totalCount); int totalPage = totalCount / page.getPageSize() + ((totalCount % page.getPageSize() == 0) ? 0 : 1); page.setPages(totalPage); } catch (SQLException e) { LOGGER.error("Ignore this exception", e); } finally { try { rs.close(); } catch (SQLException e) { LOGGER.error("Ignore this exception", e); } try { countStmt.close(); } catch (SQLException e) { LOGGER.error("Ignore this exception", e); } } } /** * 代入参数值 * * @param ps * @param mappedStatement * @param boundSql * @param parameterObject * @throws SQLException */ private void setParameters(PreparedStatement ps, MappedStatement mappedStatement, BoundSql boundSql, Object parameterObject) throws SQLException { ParameterHandler parameterHandler = new DefaultParameterHandler(mappedStatement, parameterObject, boundSql); parameterHandler.setParameters(ps); } /** * 创建 MappedStatement * @param ms * @param sqlSource * @param suffix MappedStatement id * @return MappedStatement */ private MappedStatement newMappedStatement(MappedStatement ms, SqlSource sqlSource,String suffix) { String id = ms.getId() + suffix; MappedStatement.Builder builder = new MappedStatement.Builder(ms.getConfiguration(), id, sqlSource, ms.getSqlCommandType()); builder.resource(ms.getResource()); builder.fetchSize(ms.getFetchSize()); builder.statementType(ms.getStatementType()); builder.keyGenerator(ms.getKeyGenerator()); if (ms.getKeyProperties() != null && ms.getKeyProperties().length != 0) { StringBuilder keyProperties = new StringBuilder(); for (String keyProperty : ms.getKeyProperties()) { keyProperties.append(keyProperty).append(","); } keyProperties.delete(keyProperties.length() - 1, keyProperties.length()); builder.keyPropert