MyBatis分页拦截 MyBatis

一、MyBatis配置

mybatis-config

二、分页封装类

public interface Dialect { public static enum Type { MYSQL { public String getValue() { return "mysql"; } }, SQLSERVER { public String getValue() { return "sqlserver"; } }, ORACLE { public String getValue() { return "oracle"; } }; public abstract String getValue(); } // 获取分页的查询SQL public String getPaginationSql(String sql, int offset, int limit); }

三、分页方言 1.oracle

public class OracleDialect implements Dialect { public String getPaginationSql(String sql, int offset, int limit) { return "select * from (select rownum rn, t.* from (" + sql + ") t where rownum <= " + (offset + limit) + ") t1 where t1.rn > " + offset; } }

2. mysql

public class MySQL5Dialect implements Dialect { public String getPaginationSql(String sql, int offset, int limit) { return sql + " limit " + offset + "," + limit; } }

3.SqlServer

public class SqlServerDialect implements Dialect { public String getPaginationSql(String sql, int pageNo, int pageSize) { return "select top " + pageSize + " from (" + sql + ") t where t.id not in (select top " + (pageNo - 1) * pageSize + " t1.id from (" + sql + ") t1)"; } }

四、MyBatis分页拦截器
【MyBatis分页拦截】

@Intercepts({ @Signature(type = Executor.class, method = "query", args = { MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class }) }) public class PageInterceptor implements Interceptor { static int MAPPED_STATEMENT_INDEX = 0; static int PARAMETER_INDEX = 1; static int ROWBOUNDS_INDEX = 2; static int RESULT_HANDLER_INDEX = 3; public Object intercept(Invocation invocation) throws Throwable { processIntercept(invocation.getArgs()); return invocation.proceed(); } public void processIntercept(Object[] queryArgs) throws ConfigurationException { // 当前环境 MappedStatement，BoundSql，及sql取得 MappedStatement mappedStatement = (MappedStatement)queryArgs[MAPPED_STATEMENT_INDEX]; // 请求的对象 Object parameter = queryArgs[PARAMETER_INDEX]; // 分页信息 RowBounds rowBounds = (RowBounds)queryArgs[ROWBOUNDS_INDEX]; int offset = rowBounds.getOffset(); int limit = rowBounds.getLimit(); //如果分页信息为null,则rowBounds默认为rowBounds.offset=0,rowBounds.limit=Integer.MAX_VALUE,所以这里作下判断 if (offset != 0 || limit != Integer.MAX_VALUE) { Dialect dialect = getDialect(mappedStatement.getConfiguration()); BoundSql boundSql = mappedStatement.getBoundSql(parameter); String sql = boundSql.getSql().trim(); sql = dialect.getPaginationSql(sql, offset, limit); offset = 0; // 这里没有增加的话导致后面分页查询不出来 limit = Integer.MAX_VALUE; queryArgs[ROWBOUNDS_INDEX] = new RowBounds(offset, limit); BoundSql newBoundSql = new BoundSql(mappedStatement.getConfiguration(), sql, boundSql.getParameterMappings(), boundSql.getParameterObject()); MappedStatement newMs = copyFromMappedStatement(mappedStatement, new BoundSqlSqlSource(newBoundSql)); queryArgs[MAPPED_STATEMENT_INDEX] = newMs; } } private Dialect getDialect(Configuration configuration) throws ConfigurationException { Dialect.Type databaseType = null; try { databaseType = Dialect.Type.valueOf(configuration.getVariables().getProperty("dialect").toUpperCase()); } catch (Exception e) { throw new ConfigurationException("the value of the dialect property in mybatis-config.xml is not defined : " + configuration.getVariables().getProperty("dialect")); }Dialect dialect = null; switch (databaseType) { case MYSQL: dialect = new MySQL5Dialect(); case SQLSERVER: dialect = new SqlServerDialect(); case ORACLE: dialect = new OracleDialect(); }return dialect; } private MappedStatement copyFromMappedStatement(MappedStatement ms, SqlSource newSqlSource) { Builder builder = new Builder(ms.getConfiguration(), ms.getId(), newSqlSource, ms.getSqlCommandType()); builder.resource(ms.getResource()); builder.fetchSize(ms.getFetchSize()); builder.statementType(ms.getStatementType()); builder.keyGenerator(ms.getKeyGenerator()); // builder.keyProperty(ms.getKeyProperty()); builder.timeout(ms.getTimeout()); builder.parameterMap(ms.getParameterMap()); builder.resultMaps(ms.getResultMaps()); builder.resultSetType(ms.getResultSetType()); builder.cache(ms.getCache()); builder.flushCacheRequired(ms.isFlushCacheRequired()); builder.useCache(ms.isUseCache()); return builder.build(); } public class BoundSqlSqlSource implements SqlSource { BoundSql boundSql; public BoundSqlSqlSource(BoundSql boundSql) { this.boundSql = boundSql; }public BoundSql getBoundSql(Object parameterObject) { return boundSql; } } public Object plugin(Object arg0) { return Plugin.wrap(arg0, this); } public void setProperties(Properties properties) { } }

说明:本人于 ITEYE创建于2014年,现转移到CSDN