我一般都在线上,只是隐身而已,你随时可以呼我
可惜不是你,陪我到最后
实在没办法，我就只好写了一个封装了数据库，并实现Map方法的类
累死我了...忙乎了一个上午..平时被Spring宠惯了，面对异常处理我还真不记得怎么办了。
程序代码：import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.SQLSyntaxErrorException;
import java.sql.Statement;
import java.sql.PreparedStatement;
import java.util.Collection;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* DerByCollection类，用数据库存放高耗内存文件
*
* @author vlinux
*
* @param <E>
* 只接受实现了 的类
*/
public class DerByMap<K, E extends implements Map<K, E> {
private String databaseName;// 数据库名
private static long index = 0;// 编号，每创建一个DerByCollection类就自增一次，避免数据库名重复相互干扰
private static Set<String> databaseNameSet = new HashSet<String>();// 创建过的数据库名称集合，避免数据库名重复相互干扰
private Connection conn = null;
private long unitSize;// blob字段的大小,单位byte
/**
* 创建DerByCollection集合类
*
* @param databaseName
* 集合类的数据库名
*/
public DerByMap(String databaseName, long unitSize) {
this.databaseName = databaseName;
this.unitSize = unitSize;
if (databaseNameSet.contains(databaseName)) {
throw new RuntimeException("数据库名已存在");
}// if检查databaseName是否已经存在
try {
init();
} catch (SQLException sqle) {
sqle.printStackTrace();
// throw new RuntimeException("数据库初始化失败:" + sqle.getMessage());
}// try init
}
/**
* 创建DerByCollection集合类
*/
public DerByMap(long unitSize) {
this(("DerbyColl" + index++), unitSize);// 默认的数据库名DerbyColl加上index
}
/**
* 初始化数据库
*/
protected void init() throws SQLException {
String databaseURL = "jdbc:derby:" + databaseName + ";create=true";// create=true表示当数据库不存在时就创建它
try {
conn = DriverManager.getConnection(databaseURL);
} catch (SQLException sqle) {
close();// 不管怎么样，一旦出现异常，首先关闭数据库再说
}// try create conn
Statement stmt = null;
try {
stmt = conn.createStatement();
try {
stmt.execute("drop table t_data");// 先删除数据库表
} catch (SQLSyntaxErrorException sqlsee) {
// do nothing
}// try能捕获到这个异常，说明数据库表尚未存在，故这个异常可以不理会
stmt.execute("create table t_data (id varchar(20), data blob("
+ unitSize + "))");// 创建表
} finally {
try {
stmt.close();
} catch (Exception e) {
//
}// try close stmt
}// try stmt
}
/**
* 关闭数据库
*/
public void close() {
try {
conn.close();
} catch (Exception e) {
//
}
}
public void clear() {
Statement stmt = null;
try {
stmt.execute("delete from t_data");// 清空表中所有数据
} catch (SQLException sqle) {
sqle.printStackTrace();
} finally {
try {
stmt.close();
} catch (Exception e) {
//
}//try
}//try
}
public boolean containsKey(Object key) {
PreparedStatement pstmt = null;
ResultSet rs = null;
boolean returnValue = false;
try {
pstmt = conn.prepareStatement("select * from t_data where id = ?");
pstmt.setString(1, key.toString());
rs = pstmt.executeQuery();
returnValue = rs.next();
} catch (SQLException sqle) {
sqle.printStackTrace();
returnValue = false;
} finally {
try {
rs.close();
} catch (Exception e) {
//
}// try close rs
try {
pstmt.close();
} catch (Exception e) {
//
}// try close pstmt
}
return returnValue;
}
public boolean containsValue(Object value) {
throw new RuntimeException("该方法还没被实现");
}
public Set<java.util.Map.Entry<K, E>> entrySet() {
throw new RuntimeException("该方法还没被实现");
}
@SuppressWarnings("unchecked")
public E get(Object key) {
PreparedStatement pstmt = null;
ResultSet rs = null;
ObjectInputStream ois = null;
E returnValue = null;
try {
pstmt = conn.prepareStatement("select * from t_data where id = ?");
pstmt.setString(1, key.toString());
rs = pstmt.executeQuery();
if( rs.next() ) {
ois = new ObjectInputStream(rs.getBlob("data").getBinaryStream());
returnValue = (E) ois.readObject();
}//if
} catch (SQLException sqle) {
sqle.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
} catch (ClassNotFoundException cnfe) {
cnfe.printStackTrace();
} finally {
try {
ois.close();
} catch (Exception e) {
//
}// try close rs
try {
rs.close();
} catch (Exception e) {
//
}// try close rs
try {
pstmt.close();
} catch (Exception e) {
//
}// try close pstmt
}
return returnValue;
}
public boolean isEmpty() {
return this.size()==0?true:false;
}
public Set<K> keySet() {
throw new RuntimeException("该方法还没被实现");
}
public E put(K key, E value) {
PreparedStatement pstmt = null;
ObjectInputStream ois = null;
ByteArrayOutputStream bos = null;
ObjectOutputStream oos = null;
ByteArrayInputStream bis = null;
E returnValue = null;
try {
pstmt = conn.prepareStatement("insert into t_data (id, data) values(?,?)");
pstmt.setString(1, key.toString());
bos = new ByteArrayOutputStream();
oos = new ObjectOutputStream(bos);
oos.writeObject(value);
bis = new ByteArrayInputStream(bos.toByteArray());
pstmt.setBinaryStream(2, bis);
pstmt.execute();
} catch (SQLException sqle) {
sqle.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
} finally {
try {
ois.close();
} catch (Exception e) {
//
}// try close ois
try {
bos.close();
} catch (Exception e) {
//
}// try close bos
try {
oos.close();
} catch (Exception e) {
//
}// try close oos
try {
bis.close();
} catch (Exception e) {
//
}// try close bis
try {
pstmt.close();
} catch (Exception e) {
//
}// try close pstmt
}
return returnValue;
}
public void putAll(Map<? extends K, ? extends E> m) {
throw new RuntimeException("该方法还没被实现");
}
public E remove(Object key) {
E returnValue = get(key);
if( null == returnValue ) {
return null;
}//if首先获取该数据，然后再删除...该死的remove方法...
PreparedStatement pstmt = null;
try {
pstmt = conn.prepareStatement("delete from t_data where id = ?");
pstmt.setString(1, key.toString());
pstmt.execute();
} catch (SQLException sqle) {
sqle.printStackTrace();
} finally {
try {
pstmt.close();
} catch (Exception e) {
//
}//try
}//try
return null;
}
public int size() {
Statement stmt = null;
ResultSet rs = null;
int size = 0;
try {
stmt = conn.createStatement();
rs = stmt.executeQuery("select count(*) from t_data");
rs.next();
size = rs.getInt(1);
} catch (SQLException sqle) {
sqle.printStackTrace();
} finally {
try {
rs.close();
} catch (Exception e) {
//
}//try
try {
stmt.close();
} catch (Exception e) {
//
}//try
}//try
return size;
}
public Collection<E> values() {
throw new RuntimeException("该方法还没被实现");
}
@Override
protected void finalize() {
close();
}
}[[it] 本帖最后由 神vLinux飘飘 于 2008-2-27 12:18 编辑 [/it]]
