ibatis 之分页
iBatis分页是采用游标滚动的方式来实现的，不支持物理分页，这种方式在大数据量的情况下往往会造成内存溢出、响应速度较慢。因此一般都采用手写SQL语句实现数据库物理分页。
找到ibatis执行sql的地方，截获sql并重新组装sql，为ibatis引入物理分页机制，效率相对较高。
列表集合获取：使用Spring ibatis(SqlMapClientTemplate)实现.
总记录数获取：使用Spring JdbcTemplate 实现.
Ibatis sql执行者，截取sql语句并重新组装
package com.ibatis;
import java.sql.Connection;
import java.sql.SQLException;
import com.ibatis.sqlmap.engine.execution.SqlExecutor;
import com.ibatis.sqlmap.engine.mapping.statement.RowHandlerCallback;
import com.ibatis.sqlmap.engine.scope.RequestScope;
public class SQLExecutor extends SqlExecutor {
private Dialect dialect = null;
public Dialect getDialect() {
return dialect;
}
public void setDialect(Dialect dialect) {
this.dialect = dialect;
}
@Override
public void executeQuery(RequestScope request, Connection conn, String sql,
Object[] parameters, int skipResults, int maxResults,
RowHandlerCallback callback) throws SQLException {
if ((skipResults != NO_SKIPPED_RESULTS || maxResults != NO_MAXIMUM_RESULTS)) {
sql = dialect.getLimitString(sql, skipResults, maxResults);
skipResults = NO_SKIPPED_RESULTS;
maxResults = NO_MAXIMUM_RESULTS;
}
super.executeQuery(request, conn, sql, parameters, skipResults,maxResults, callback);
}
}
Ibatis 动态SQL语句、参数类
package com.ibatis;
import com.ibatis.sqlmap.engine.impl.ExtendedSqlMapClient;
import com.ibatis.sqlmap.engine.mapping.parameter.ParameterMap;
import com.ibatis.sqlmap.engine.mapping.sql.Sql;
import com.ibatis.sqlmap.engine.mapping.statement.MappedStatement;
import com.ibatis.sqlmap.engine.scope.RequestScope;
public class SQL {
private ExtendedSqlMapClient sqlMapClient = null;
private String statementName = null;
private Object parameterObject = null;
private RequestScope request = null;
public SQL(ExtendedSqlMapClient sqlMapClient, String statementName,
Object parameterObject) {
this.sqlMapClient = sqlMapClient;
this.statementName = statementName;
this.parameterObject = parameterObject;
this.request = newRequestScope(this.sqlMapClient, this.statementName,this.parameterObject);
}
private RequestScope newRequestScope(ExtendedSqlMapClient sqlMapClient,String statementName, Object parameterObject) {
RequestScope request = new RequestScope();
MappedStatement stmt = sqlMapClient.getMappedStatement(statementName);
request.setStatement(stmt);
Sql sql = stmt.getSql();
request.setSql(sql);
ParameterMap parameterMap = sql.getParameterMap(request,parameterObject);
request.setParameterMap(parameterMap);
return request;
}
public String getSql() {
return request.getSql().getSql(request, parameterObject);
}
public Object[] getParameters() {
return request.getParameterMap().getParameterObjectValues(request,parameterObject);
}
}
方言接口
package com.ibatis.dialect;
public interface Dialect {
public abstract String getCountString(String sql);
public abstract String getLimitString(String sql, int startRow, int maxRow);
}
Oracle 方言实现类
package com.ibatis.dialect;
public class OracleDialect implements Dialect {
public String getCountString(String sql) {
StringBuffer sql_ = new StringBuffer();
sql_.append("select count(1) as count from ( ").append(sql).append(" )");
return sql_.toString();
}
public String getLimitString(String sql, int startRow, int maxRow) {
StringBuffer sql_ = new StringBuffer();
sql_.append("select * from ( select t1.*, rownum rownum_ from ( ");
sql_.append(sql);
sql_.append(" ) t1 where rownum <= "+maxRow+") where rownum_ > "+startRow+"");
return sql_.toString();
}
}
分页实体类
package com.commons;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Page implements java.io.Serializable {
private static final long serialVersionUID = 1L;
/** 当前页数 * */
private int pageNo = 1;
/** 每页显示的记录数 * */
private int pageSize = 20;
/** 总记录 * */
private int totalCount;
/** 总页数* */
private int totalPage;
private boolean hasNext = false;
private int nextPage;
private boolean hasPre = false;
private int prePage;
/** 页面数据List * */
private List items;
/** 参数 Map * */
private Map<String, Object> params = new HashMap<String, Object>();
/** URL 参数* */
private String urlParam;
public Page() {
}
public Page(List items, int pageNo, int pageSize, int totalCount) {
this.pageNo = pageNo;
this.totalCount = totalCount;
this.pageSize = pageSize;
this.items = items;
}
public void addParam(String name, Object value) {
if (name != null && !name.equals("") && value != null && !value.equals("")) {
if (params.size() == 0) {
urlParam = name + "=" + value;
} else {
urlParam = "&" + name + "=" + value;
}
params.put(name, value);
}
}
public int getPageNo() {
return pageNo;
}
public void setPageNo(int pageNo) {
this.pageNo = pageNo;
}
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int getTotalCount() {
return totalCount;
}
public void setTotalCount(int totalCount) {
this.totalCount = totalCount;
}
public int getTotalPage() {
if (totalCount == 0)
return 0;
totalPage = totalCount / pageSize;
if (totalCount % pageSize > 0) {
totalPage++;
}
return totalPage;
}
public void setTotalPage(int totalPage) {
this.totalPage = totalPage;
}
/** 是否有下一页 */
public boolean isHasNext() {
this.hasNext = (pageNo + 1 <= getTotalPage());
return hasNext;
}
public int getNextPage() {
if (isHasNext())
nextPage = pageNo + 1;
else
nextPage = totalPage;
return nextPage;
}
public void setNextPage(int nextPage) {
this.nextPage = nextPage;
}
/** 是否有上一页 */
public boolean isHasPre() {
this.hasPre = (pageNo - 1 >= 1);
return hasPre;
}
public int getPrePage() {
if (isHasPre())
prePage = pageNo - 1;
else
prePage = pageNo;
return prePage;
}
public void setPrePage(int prePage) {
this.prePage = prePage;
}
public List getItems() {
return items;
}
public void setItems(List items) {
this.items = items;
}
public Map<String, Object> getParams() {
return params;
}
public void setParams(Map<String, Object> params) {
this.params = params;
}
public void setUrlParam(String urlParam) {
this.urlParam = urlParam;
}
public String getUrlParam() {
return this.urlParam;
}
}
基础 DAO接口
package com.commons;
import java.util.List;
import org.springframework.jdbc.core.JdbcOperations;
public interface IBaseDao {
/**
* JDBC 执行类
* @date Jan 12, 2011
* @return
*/
JdbcOperations getJdbcTemplate();
/**
* 单个对象获取
* @date Jan 12, 2011
* @param statementName
* @param parameterObject 参数值对象
* @return
*/
Object getObject(String statementName,Object parameterObject);
/**
* 集合对象获取
* @date Jan 12, 2011
* @param statementName
* @param parameterObject 参数值对象
* @return
*/
List list(String statementName,Object parameterObject);
/**
* 分页对象获取
* @date Jan 12, 2011
* @param statementName
* @param page 分页值对象
* @return
*/
Page list(String statementName,Page page);