分页规范

为了统一部门内开发中分页方式的统一，以下是分页传参、处理、响应结果封装的规范

1.请求参数

请求参数主要两个对象，一个是和数据库表结构对应的实体对象(最好采用自定义成DTO用于传参，因为查询很可能涉及复杂条件或关联查询)；另一个是分页信息对象，对象存放2个必要参数和2个非必要参数，必要参数是limit每页总条数，offset当页起始位置，非必要参数为sort需要排序的字段名，order排序方式(默认ASC)

/** * 分页数据封装类. */public class Page implements java.io.Serializable {private static final long serialVersionUID = -5823482162101235168L;public static final String ORDER_ASC = "ASC";public static final String ORDER_DESC = "DESC";private int offset;private int limit;private String sort;private String order = ORDER_ASC;public Page() {this(0, Integer.MAX_VALUE);}public Page(int offset, int limit) {this.offset = offset;this.limit = limit;}public Page(int offset, int limit, String sort, String order) {this.offset = offset;this.limit = limit;this.sort = sort;this.order = order;}public int getOffset() {return offset;}public void setOffset(int offset) {this.offset = offset;}public int getLimit() {return limit;}public void setLimit(int limit) {this.limit = limit;}public String getSort() {return sort;}public void setSort(String sort) {this.sort = sort;}public String getOrder() {return order;}public void setOrder(String order) {this.order = order;}public int getOffsetLimit() {return this.offset + this.limit;}public String toString() {return "[Page: " + offset + ", " + limit + ", " + sort + ", " + order + "]";}}

2.查询组装

先组装查询条件，若没有组装工具需要自己拼接时需注意拼接不要使用string做拼接，应使用StringBuffer，原因string拼接时每一次变动都会产生新的对象

SELECT count(*) as count from TABLENAME WHERE A=?
SELECT TABLENAME WHERE A=? ORDER BY ? ? limit ?,?
3.结果封装
将查询结果封装到如下对象中
import java.util.Collection;import java.util.Collections;import java.util.HashMap;import java.util.Map;/** * 数据列表返回格式封装实体 * @param <T> 数据列表类型 */public class DataGrid<T> implements java.io.Serializable {private static final long serialVersionUID = -4353059775338989141L;// 总数量private Integer numRows;// 当前分页记录列表private Collection<T> items;// 标识字段private String identified = "id";// 统计信息private Map<String, Object> stats = new HashMap<String, Object>();public DataGrid() {}public DataGrid(Collection<T> items) {this(items, items.size());}public DataGrid(Collection<T> items, Integer numRows) {this.items = items;this.numRows = numRows;}public DataGrid(Collection<T> items, Integer numRows, String identified) {this(items, items.size());this.identified = identified;}public Integer getNumRows() {return numRows;}public void setNumRows(Integer numRows) {this.numRows = numRows;}public Collection<T> getItems() {return items;}public void setItems(Collection<T> items) {this.items = items;}public String getIdentified() {return identified;}public void setIdentified(String identified) {this.identified = identified;}public Map<String, Object> getStats() {return stats;}public void setStats(Map<String, Object> stats) {this.stats = stats;}/** * 增加统计信息 * @param name * @param value */public void addStat(String name, Object value) {this.stats.put(name, value);}/** * 返回一个空的数据列表。 * @return */public static <T> DataGrid<T> empty() {Collection<T> items = Collections.emptyList();return new DataGrid<T>(items);}}
4.lifery示例

public Object listLog(ResourceRequest request) {try {DispatchLog dispatchLog = new DispatchLogImpl();dispatchLog = (DispatchLog) ModelUtil.getModel(dispatchLog, request, null);Long startTime = ParamUtil.getLong(request, "startTime");Long endTime = ParamUtil.getLong(request, "endTime");int limit = ParamUtil.getInteger(request, "limit");int offset = ParamUtil.getInteger(request, "offset");Date startDateRes = null;Date endDateRes = null;if (startTime != null) {startDateRes = new java.util.Date(startTime);}if (endTime != null) {endDateRes = new java.util.Date(endTime);}DataGrid<DispatchLog> dataGrid = dispatchLogServiceUtil.list(getCompanyId(request), dispatchLog.getDevId(), dispatchLog.getIfSuccess(), dispatchLog.getActiveName(), dispatchLog.getCreateTime(),startDateRes,endDateRes,limit,offset);return new JsonResponse(true,JSON.toJSONString(dataGrid));} catch (Exception e) {return new JsonResponse(false, e.getMessage());}}

package com.flame.dispatcher.manger;import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.Date;import java.util.List;import com.alibaba.fastjson.JSON;import com.flame.dispatcher.service.dispatchlog.model.DispatchLog;import com.flame.dispatcher.service.dispatchlog.model.impl.DispatchLogImpl;import com.flame.dispatcher.util.DataGrid;import com.flame.jkzx.service.rulesversion.service.RulesVersionLocalServiceUtil;import com.liferay.portal.kernel.exception.SystemException;public class DispatchLogServiceUtil {/** * 获取列表 *  * @param id * @param searchable * @return */public DataGrid<DispatchLog> list(Long companyId,Long devId,String ifSuccess,String activeName,Date createTime,Date startTime,Date endTime,int limit,int offset) throws SystemException {DataGrid<DispatchLog> dataGrid = new DataGrid<DispatchLog>();List<DispatchLog> logs = new ArrayList<DispatchLog>();try {StringBuffer buffer = new StringBuffer();buffer.append("where");buffer.append(" fdl.companyId="+companyId);if (devId != null&& devId !=0)buffer.append(" and fdl.devId="+devId);if (ifSuccess != null && ifSuccess.length()>0)buffer.append(" and fdl.ifSuccess='"+ifSuccess+"'");if (activeName != null && activeName.length()>0)buffer.append(" and fdl.activeName like '"+activeName+"%'");if (startTime != null)buffer.append(" and fdl.createTime >='"+new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(startTime)+"'");if (endTime != null)buffer.append(" and fdl.createTime <='"+new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(endTime)+"'");String sql = "select fdl.id_,fdl.devId,fdl.companyId,fdl.direId,fdl.activeName,fdl.createTime,fdl.direType,fdl.ifSuccess,fdl.message from flame_dispatch_log fdl inner join flame_dispatch_group_detail fdgd on fdl.devId=fdgd.id_  "+buffer+" ORDER BY fdl.id_ asc limit "+offset+","+limit;List list = RulesVersionLocalServiceUtil.executeQuery(sql);if (list != null && list.size() > 0) {for (Object obj : list) {Object[] dto = (Object[]) obj;DispatchLog org = new DispatchLogImpl();org.setId(Long.parseLong(dto[0]+""));org.setDevId(Long.parseLong(dto[1]+""));org.setCompanyId(Long.parseLong(dto[2]+""));org.setDireId(Long.parseLong(dto[3]+""));org.setActiveName(dto[4].toString());org.setCreateTime((Date) dto[5]);org.setDireType(dto[6].toString());org.setIfSuccess(dto[7].toString());org.setMessage(dto[8].toString());logs.add(org);}}String sqlCount = "SELECT count(*) as count from flame_dispatch_log fdl inner join flame_dispatch_group_detail fdgd on fdl.devId=fdgd.id_ "+buffer;List list2 = RulesVersionLocalServiceUtil.executeQuery(sqlCount);int count = 0;if (list2 != null && list2.size() > 0) {for (Object obj : list2) {count=Integer.valueOf(obj.toString());break;}}dataGrid.setItems(logs);dataGrid.setNumRows(count);} catch (Exception e) {System.out.println(e);dataGrid.setItems(new ArrayList<DispatchLog>());dataGrid.setNumRows(0);return dataGrid;}return dataGrid;}}