Mybatis拦截器分页

落日映苍穹つ 2022-09-21 13:23 185阅读 0赞

这里做的是以ByPage结尾的，使用mysql数据库  
一、page类：

package com.ming.util;
    
    /** * 分页对应的实体类 */
    public class Page { 
        /** * 总条数 */
        private int totalNumber;
        /** * 当前第几页 */
        private int currentPage;
        /** * 总页数 */
        private int totalPage;
        /** * 每页显示条数 */
        private int pageNumber = 5;
        /** * 数据库中limit的参数，从第几条开始取 */
        private int dbIndex;
        /** * 数据库中limit的参数，一共取多少条 */
        private int dbNumber;
    
        /** * 根据当前对象中属性值计算并设置相关属性值 */
        public void count() {
            // 计算总页数
            int totalPageTemp = this.totalNumber / this.pageNumber;
            int plus = (this.totalNumber % this.pageNumber) == 0 ? 0 : 1;
            totalPageTemp = totalPageTemp + plus;
            if(totalPageTemp <= 0) {
                totalPageTemp = 1;
            }
            this.totalPage = totalPageTemp;
    
            // 设置当前页数
            // 总页数小于当前页数，应将当前页数设置为总页数
            if(this.totalPage < this.currentPage) {
                this.currentPage = this.totalPage;
            }
            // 当前页数小于1设置为1
            if(this.currentPage < 1) {
                this.currentPage = 1;
            }
    
            // 设置limit的参数
            this.dbIndex = (this.currentPage - 1) * this.pageNumber;
            this.dbNumber = this.pageNumber;
        }
    
        public int getTotalNumber() {
            return totalNumber;
        }
    
        public void setTotalNumber(int totalNumber) {
            this.totalNumber = totalNumber;
            this.count();
        }
    
        public int getCurrentPage() {
            return currentPage;
        }
    
        public void setCurrentPage(int currentPage) {
            this.currentPage = currentPage;
        }
    
        public int getTotalPage() {
            return totalPage;
        }
    
        public void setTotalPage(int totalPage) {
            this.totalPage = totalPage;
        }
    
        public int getPageNumber() {
            return pageNumber;
        }
    
        public void setPageNumber(int pageNumber) {
            this.pageNumber = pageNumber;
            this.count();
        }
    
        public int getDbIndex() {
            return dbIndex;
        }
    
        public void setDbIndex(int dbIndex) {
            this.dbIndex = dbIndex;
        }
    
        public int getDbNumber() {
            return dbNumber;
        }
    
        public void setDbNumber(int dbNumber) {
            this.dbNumber = dbNumber;
        }
    }

二、拦截器

package com.ming.interceptor;
    
    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 com.ming.util.Page;
    
    /** * * 拦截器签名:要拦截的目标类型是StatementHandler（注意：type只能配置成接口类型）， * 拦截的方法是名称为prepare参数为Connection类型的方法 * */
    @Intercepts({ @Signature(type = StatementHandler.class, method = "prepare", args = { Connection.class }) })
    public class PageInterceptor1 implements Interceptor {
    
        public Object intercept(Invocation invocation) throws Throwable {
            // 拦截获取statement处理类
            StatementHandler statementHandler = (StatementHandler) invocation.getTarget();
            // 把statement处理类交给MetaObject代理类代理
            MetaObject metaObject = MetaObject.forObject(statementHandler, SystemMetaObject.DEFAULT_OBJECT_FACTORY,
                    SystemMetaObject.DEFAULT_OBJECT_WRAPPER_FACTORY);
            MappedStatement mappedStatement = (MappedStatement) metaObject.getValue("delegate.mappedStatement");
            String id = mappedStatement.getId();
            //以ByPage结尾的才操作
            if (id.matches(".+ByPage$")) {
                BoundSql boundSql = statementHandler.getBoundSql();
                String sql = boundSql.getSql();
                String countSql = "select count(*) from (" + sql + ")a";
                // 获取connection
                Connection connection = (Connection) invocation.getArgs()[0];
                // 通过connection获取prepareStatement
                PreparedStatement countStatement = connection.prepareStatement(countSql);
                // 获取参数处理类
                ParameterHandler parameterHandler = (ParameterHandler) metaObject.getValue("delegate.parameterHandler");
                // 通过参数处理类 把参数设置进去
                parameterHandler.setParameters(countStatement);
                // 开始查询
                ResultSet rs = countStatement.executeQuery();
                // 获取传过来的参数
                Map<?, ?> parameter = (Map<?, ?>) boundSql.getParameterObject();
                // 获取page参数
                Page page = (Page) parameter.get("page");
                if (rs.next()) {
                    // 为page设置查询出来的所有数据条数
                    page.setTotalNumber(rs.getInt(1));
                }
                // 改造后带分页查询的SQL语句
                String pageSql = sql + " limit " + page.getDbIndex() + "," + page.getDbNumber();
                // 代理类设置改装好sql语句
                metaObject.setValue("delegate.boundSql.sql", pageSql);
            }
            return invocation.proceed();
        }
    
        public Object plugin(Object target) {
            //不合条件的 直接放行
            return Plugin.wrap(target, this);
        }
    
        public void setProperties(Properties properties) {
        }
    
    }

小例子下载地址：