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servlet中如何存放、传递、调用数据库中字段类型不同的数据集的问题----及不同类型对象的存取
比如我的一个表（AA）里有三个字段，ID，NAME，CONTENT；
字段类型分别为：int,varchar,ntext;----------及字段类型不同；
问：
我想通过一个servlet调用出表AA里的n条数据集，然后在jsp端一条一条纪录的显示出来，该如何处理？及如何将不同类型的多条对象先存放于某个集合，再能一一取出来？？
请详细说明最好能举例示意。
----针对相同类型的对象，我采用的是将各字段存入数组，然后将该数组代表的每个记录集通过循环放入Vector;不知此方法是否妥当，应该有更简便通用的方法吧？！
困扰几天了，谢谢了！:)
字段类型分别为：int,varchar,ntext;----------及字段类型不同；
问：
我想通过一个servlet调用出表AA里的n条数据集，然后在jsp端一条一条纪录的显示出来，该如何处理？及如何将不同类型的多条对象先存放于某个集合，再能一一取出来？？
请详细说明最好能举例示意。
----针对相同类型的对象，我采用的是将各字段存入数组，然后将该数组代表的每个记录集通过循环放入Vector;不知此方法是否妥当，应该有更简便通用的方法吧？！
困扰几天了，谢谢了！:)
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cleverfish 2002-04-08
谢谢各位，尤其是：pengji(彭乃超)，我也找到了一些方法。结账！
chrischen79 2002-04-05
楼上的代码我粗粗的看了一下，重点看一下public Vector select(String strQuery)这个method就可以了。
pengji 2002-04-05
package com.hzs.order;
import java.io.IOException;
import java.sql.*;
import java.util.Vector;
import java.util.*;
public class DBHandle {
// Field
private Vector result = new Vector();
private Connection conn = null;
// Construct
public DBHandle() {
}
// Connect to database
public void connect() throws DBException, IOException {
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection("jdbc:oracle:thin:system/828112@192.9.200.50:1521:mydb");
} catch(ClassNotFoundException E) {
throw new DBException("Connnect: " + String.valueOf(E.getMessage()));
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
public void transaction() throws DBException, IOException {
try {
conn.setAutoCommit(false);
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
// Executes a SQL statement that returns a single ResultSet.
public Vector select(String strQuery) throws DBException, IOException {
result = new Vector();
try {
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(strQuery);
ResultSetMetaData rsmd = rs.getMetaData();
int FieldNum = rsmd.getColumnCount();
while (rs.next()) {
for (int i = 1; i <= FieldNum; i ++)
result.addElement(rs.getString(i));
}
rs.close();
stmt.close();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
return result;
}
// Executes an SQL INSERT, UPDATE or DELETE statement.
public int update(String strUpdate) throws DBException, IOException {
int stmtInt=-1;
try {
Statement stmt = conn.createStatement();
stmtInt = stmt.executeUpdate(strUpdate);
stmt.close();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
return stmtInt;
}
// commit
public void commit() throws DBException, IOException {
try {
conn.commit();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
// rollback
public void rollback() throws DBException, IOException {
try {
conn.rollback();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
// close
public void close() throws DBException, IOException {
try {
conn.close();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
public static String toChinese(String strValue) {
try {
if (strValue == null)
return null;
else
return new String(strValue.getBytes("8859_1"), "gb2312");
} catch(Exception e) {
return null;
}
}
public static float toFloat(String str){
return Float.parseFloat(str);
}
}
package com.hzs.order;
public class DBException extends Exception {
public DBException(String desc) {
super(desc);
}
}
import java.io.IOException;
import java.sql.*;
import java.util.Vector;
import java.util.*;
public class DBHandle {
// Field
private Vector result = new Vector();
private Connection conn = null;
// Construct
public DBHandle() {
}
// Connect to database
public void connect() throws DBException, IOException {
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection("jdbc:oracle:thin:system/828112@192.9.200.50:1521:mydb");
} catch(ClassNotFoundException E) {
throw new DBException("Connnect: " + String.valueOf(E.getMessage()));
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
public void transaction() throws DBException, IOException {
try {
conn.setAutoCommit(false);
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
// Executes a SQL statement that returns a single ResultSet.
public Vector select(String strQuery) throws DBException, IOException {
result = new Vector();
try {
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(strQuery);
ResultSetMetaData rsmd = rs.getMetaData();
int FieldNum = rsmd.getColumnCount();
while (rs.next()) {
for (int i = 1; i <= FieldNum; i ++)
result.addElement(rs.getString(i));
}
rs.close();
stmt.close();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
return result;
}
// Executes an SQL INSERT, UPDATE or DELETE statement.
public int update(String strUpdate) throws DBException, IOException {
int stmtInt=-1;
try {
Statement stmt = conn.createStatement();
stmtInt = stmt.executeUpdate(strUpdate);
stmt.close();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
return stmtInt;
}
// commit
public void commit() throws DBException, IOException {
try {
conn.commit();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
// rollback
public void rollback() throws DBException, IOException {
try {
conn.rollback();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
// close
public void close() throws DBException, IOException {
try {
conn.close();
} catch(SQLException E) {
throw new DBException("SQLException: " + String.valueOf(E.getMessage()));
} catch(Exception E) {
throw new DBException("Exception: " + String.valueOf(E.getMessage()));
}
}
public static String toChinese(String strValue) {
try {
if (strValue == null)
return null;
else
return new String(strValue.getBytes("8859_1"), "gb2312");
} catch(Exception e) {
return null;
}
}
public static float toFloat(String str){
return Float.parseFloat(str);
}
}
package com.hzs.order;
public class DBException extends Exception {
public DBException(String desc) {
super(desc);
}
}
cleverfish 2002-04-04
哪位大虾给个示例好吗？？
cleverfish 2002-04-03
to pengji(彭乃超):谢谢提醒！这方法是不是就是所谓的UserBean?!
另，和用hastable的区别、利弊是什么？
另，和用hastable的区别、利弊是什么？
cleverfish 2002-04-03
chenyuan_tongji(chenyuan_tongji) 的回答较贴近我问的意思，
还有没有详细点的，需要补充的？继续！
还有没有详细点的，需要补充的？继续！
pengji 2002-04-03
可以用VECTOR,也可以自己做一个类里面方一条记录,并设置相应的GET,SET方法,当从数据库中取出几条记录就生成几个实例,最后放如一个VECTOR也可以的!
chrischen79 2002-04-03
如果是为了输出在页面上，则可以使用hashtable，用数据库表的filed name做key，相应的值用getString取出来作为value。
zjp009 2002-04-03
比如一个RECORD中有int,varchar,ntext，则：
...
while( oRst.next() )
{
iInt = oRst.getInt("...");
str1 = oRst.getString("...");
str2 = oRst.getString("...");
...
}
对于使用VECTOR来存储是可以的。
...
while( oRst.next() )
{
iInt = oRst.getInt("...");
str1 = oRst.getString("...");
str2 = oRst.getString("...");
...
}
对于使用VECTOR来存储是可以的。
cleverfish 2002-04-03
谁能提供一个简单、完整的示例吗！！！！谢谢！谢谢！
pengji 2002-04-03
优点数据封装更清晰,一条记录是一个CLASS实例,缺点是效率比较底!