分页功能源代码

public void setTotalRows(int totalRows) {
this.totalRows = totalRows;
}
public void setStartRow(int startRow) {
this.startRow = startRow;
query.setMaxResults(20); // query.setFetchSize(20);
List list = query.list();
Hibernate中，抽象类org.hibernate.dialect.Dialect指定了所有底层数据库的对外统一接口，通过针对不同数据库提供相应的Dialect实现，数据库之间的差异性得以消除，从而为上层机制提供了透明的、数据库无关的存储层基础。对于分页机制而言，Dialect中定义了一个方法如下：
Criteria criteria = session.createCriteria(TUser.class);
criteria.add(Expression.eq("age", "20"));
//从检索结果中获取第100条记录开始的20条记录
criteria.setFirstResult(100);
public String getLimitString(String sql, boolean hasOffset) {
return new StringBuffer( sql.length()+20 )
.append(sql)
.append( hasOffset ? " limit ?, ?" : " limit ?")
if (currentPage > totalPages) {
criteria.setFetchSize(20);
通过Query.setFirstResult和Query.setMaxResults方法也可以设定分页范围，如：
Query query = session.createQuery("from TUser");
query.setFirstResult(100);
currentPage = 1;
startRow = 0;
}
public void previous() {
if (currentPage == 1) {
return;
}
currentPage--;
startRow = (currentPage - 1) * pageSize;
private int startRow; //当前页在数据库中的起始行
public page(int _totalRows) {
totalRows = _totalRows;
totalPages=totalRows/pageSize;
int mod=totalRows%pageSize;
currentPage = totalPages;
startRow = (currentPage - 1) * pageSize;
}
public void refresh(int _currentPage) {
currentPage = _currentPage;
}
public void next() {
if (currentPage < totalPages) {
currentPage++;
}
startRow = (currentPage - 1) * pageSize;
}
public void last() {
public class page {
private int totalRows; //总行数
private int pageSize = 10; //每页显示的行数
private int currentPage; //当前页号
private int totalPages; //总页数
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int getTotalRows() {
return totalRows;
}
public void first() {
isForUpdate = true;
}
StringBuffer pagingSelect = new StringBuffer( sql.length()+100 );
if (hasOffset) {
pagingSelect.append("select * from ( select row_.*, rownum rownum_ from ( ");
}
else {
pagingSelect.append("select * from ( ");
}
pagingSelect.append(sql);
if (hasOffset) {
pagingSelect.append(" ) row_ where rownum <= ?) where rownum_ > ?");
sqlsql = sql.trim();
boolean isForUpdate = false;
if ( sql.toLowerCase().endsWith(" for update") ) {
sqlsql = sql.substring( 0, sql.length()-11 );
/**
* Add a LIMIT clause to the given SQL SELECT
*
* @return the modified SQL
*/
public String getLimitString(String querySelect, boolean hasOffset) {
if ( offset > 0 ) {
throw new UnsupportedOperationException( "sql server has no offset" );
}
return new StringBuffer( querySelect.length()+8 )
return getLimitString( querySelect, offset>0 );
}
此方法用于在现有Select语句基础上，根据各个数据库自身特性，构造对应的记录返回限定子句。如MySQL中对应的记录限定子句为Limit，Oracle中，通过rownum子句实现。MySQLDialect中的getLimitString实现：
}
else {
pagingSelect.append(" ) where rownum <= ?");
}
if ( isForUpdate ) {
pagingSelect.append( " for update" );
}
if(mod>0){
totalPages++;
}
currentPage = 1;
startRow = 0;
}
public int getStartRow() {
return startRow;
}
public int getTotalPages() {
return totalPages;
}
public int getCurrentPage() {
return currentPage;
}
public int getPageSize() {
return pageSize;
}
.append(querySelect)
.insert( getAfterSelectInsertPoint(querySelect), " top " + limit )
.toString();
}
通过SQLServer特有的top子句实现。HSQLDialect中的getLimitString实现：
.toString();
}
MySQLDialect.getLimitString方法的实现实际上是在给定的Select语句后追加MySQL所提供的专有SQL子句limit来实现。
Oracle9Dialect中的getLimitString实现：
public String getLimitString(String sql, boolean hasOffset) {
public String getLimitString(String sql, boolean hasOffset) {
return new StringBuffer( sql.length() + 10 )
.append( sql )
.insert( sql.toLowerCase().indexOf( "select" ) + 6, hasOffset ? " limit ? ?" : " top ?" )
private String a_title;
private String a_body;