准备先把以前写的持久层及表示层框架写完再写loonframework-game包(实际上是想自己业余建站用,用现成的框架太无聊,重复发明轮子的最
大意义就在于解闷……),在2005年时写过一个开头,由于自己没有整理文档,现在拿起来就觉得代码很乱,又懒于写文档,于是把一些心得类的东西整理一
下,用以备忘。
在此持久层框架中,我将持久化过程分为两个松耦合模块,第一模块封装jdbc操作,隐藏Connection及相关事务,处理driver差异后执行标准CRUD并释放资源,于第二模块进行实体映射操作。
但
和Spring
JdbcTemplate等jdbc封装略有不同的是,我除了直接将结果集转为List和实体返回外,还引入了一个类似CachedRowSet但非继承
CachedRowSet或ResultSet的结果集cache实体(没有提供诸如CachedRowSet的execute功能,原因大家都知
道……PS:05年我用Hibernate还比较少,现在看来和Hierbante的ScrollableResults接口超级类似,颇感java技术
殊途同归|||)。
但在此类get数据时,由于我将所有ResultSet数据无差别以object方式存储,当object为二进制对象时,为实现blob和clob接口就需要进行数据转换,将二进制对象转为blob或clob实现,为此完成代码如下。
比较hibernate的blobimpl而言(hibernate的blobimpl只有getBinaryStream()实现,因为别的对它也没用……),实现了更多的函数以供调用。
BlobImpl.java
package org.loon.framework.dao.lob;
import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.SQLException;
import org.loon.framework.Loon;
import org.loon.framework.helper.FileHelper;
/** *//** * <p>
* Title: LoonFramework
* </p>
* <p>
* Description:二进制大对象Blob实现,用于转化二进制对象为blob实例,只提供get部分方法(虽然象征性的写了
* set实现,但没有对数据库进行操作,只是摆设……).
* </p>
* <p>
* Copyright: Copyright (c) 2007
* </p>
* <p>
* Company: LoonFramework
* </p>
* <p>
* License: [url]http://www.apache.org/licenses/LICENSE-2.0[/url] * </p>
*
* @author chenpeng
* @email:[email]ceponline@yahoo.com.cn[/email]
* @version 0.1
*/public class BlobImpl implements Blob ...{
private byte[] _bytes = new byte[0];
private int _length = 0;
/** *//** * 构造函数,以byte[]构建blob
*
* @param bytes
*/ public BlobImpl(byte[] bytes) ...{
init(bytes);
}
/** *//** * 构造函数,以InputStream构建blob
*
* @param bytes
*/ public BlobImpl(InputStream input) ...{
init(FileHelper.read(input));
}
/** *//** * 构造函数,以blob重新构建blob
*
* @param bytes
*/ public BlobImpl(Blob blob) ...{
init(blobToBytes(blob));
}
/** *//** * 初始化byte[]
*
* @param b
*/ private void init(byte[] bytes) ...{
_bytes = bytes;
_length = _bytes.length;
}
/** *//** * 将blob转为byte[]
*
* @param blob
* @return */ private byte[] blobToBytes(Blob blob) ...{
BufferedInputStream is = null;
try ...{
is = new BufferedInputStream(blob.getBinaryStream());
byte[] bytes = new byte[(int) blob.length()];
int len = bytes.length;
int offset = 0;
int read = 0;
while (offset < len
&& (read = is.read(bytes, offset, len - offset)) >= 0) ...{
offset += read;
} return bytes;
} catch (Exception e) ...{
return null;
} finally ...{
try ...{
is.close();
is = null;
} catch (IOException e) ...{
return null;
}
} }
/** *//** * 获得blob中数据实际长度
*
* @return * @throws SQLException
*/ public long length() throws SQLException ...{
return _bytes.length;
}
/** *//** * 返回指定长度的byte[]
*
* @param pos
* @param len
* @return * @throws SQLException
*/ public byte[] getBytes(long pos, int len) throws SQLException ...{
if (pos == 0 && len == length())
return _bytes;
try ...{
byte[] newbytes = new byte[len];
System.arraycopy(_bytes, (int) pos, newbytes, 0, len);
return newbytes;
} catch (Exception e) ...{
throw new SQLException("Inoperable scope of this array");
} }
/** *//** * 返回InputStream
*
* @return * @throws SQLException
*/ public InputStream getBinaryStream() throws SQLException ...{
return new ByteArrayInputStream(_bytes);
}
/** *//** * 获取此byte[]中start的字节位置
*
* @param pattern
* @param start
* @return * @throws SQLException
*/ public long position(byte[] pattern, long start) throws SQLException ...{
start--;
if (start < 0) ...{
throw new SQLException("start < 0");
} if (start >= _length) ...{
throw new SQLException("start >= max length");
} if (pattern == null) ...{
throw new SQLException("pattern == null");
} if (pattern.length == 0 || _length == 0 || pattern.length > _length) ...{
return -1;
} int limit = (int) _length - pattern.length;
for (int i = (int) start; i <= limit; i++) ...{
int p;
for (p = 0; p < pattern.length && _bytes[i + p] == pattern[p]; p++) ...{
if (p == pattern.length) ...{
return i + 1;
} } } return -1;
}
/** *//** * 获取指定的blob中start的字节位置
*
* @param pattern
* @param start
* @return * @throws SQLException
*/ public long position(Blob pattern, long start) throws SQLException ...{
return position(blobToBytes(pattern), start);
}
/** *//** * 不支持操作异常抛出
*
*/ void nonsupport() ...{
throw new UnsupportedOperationException("This method is not supported!");
}
/** *//** * 释放Blob对象资源
*
* @throws SQLException
*/ public void free() throws SQLException ...{
_bytes = new byte[0];
_length = 0;
}
/** *//** * 返回指定长度部分的InputStream,并返回InputStream
*
* @param pos
* @param len
* @return * @throws SQLException
*/ public InputStream getBinaryStream(long pos, long len) throws SQLException ...{
return new ByteArrayInputStream(getBytes(pos, (int) len));
}
/** *//** * 以指定指定长度将二进制流写入OutputStream,并返回OutputStream
*
* @param pos
* @return * @throws SQLException
*/ public OutputStream setBinaryStream(long pos) throws SQLException ...{
// 暂不支持 nonsupport();
pos--;
if (pos < 0) ...{
throw new SQLException("pos < 0");
} if (pos > _length) ...{
throw new SQLException("pos > length");
} // 将byte[]转为ByteArrayInputStream ByteArrayInputStream inputStream = new ByteArrayInputStream(_bytes);
ByteArrayOutputStream os = new ByteArrayOutputStream();
byte[] bytes = new byte[(int) pos];
try ...{
bytes = new byte[inputStream.available()];
int read;
while ((read = inputStream.read(bytes)) >= 0) ...{
os.write(bytes, 0, read);
}
} catch (IOException e) ...{
e.getStackTrace();
}
// 返回OutputStream return (OutputStream) os;
}
/** *//** * 设定byte[]
*
* @param pos
* @param bytes
* @param offset
* @param size
* @param copy
* @return * @throws SQLException
*/ private int setBytes(long pos, byte[] bytes, int offset, int size,
boolean copy) throws SQLException ...{
// 暂不支持 nonsupport();
pos--;
if (pos < 0) ...{
throw new SQLException("pos < 0");
} if (pos > _length) ...{
throw new SQLException("pos > max length");
} if (bytes == null) ...{
throw new SQLException("bytes == null");
} if (offset < 0 || offset > bytes.length) ...{
throw new SQLException("offset < 0 || offset > bytes.length");
} if (size < 0 || pos + size > (long) Integer.MAX_VALUE
|| offset + size > bytes.length) ...{
throw new SQLException();
} // 当copy数据时 if (copy) ...{
_bytes = new byte[size];
System.arraycopy(bytes, offset, _bytes, 0, size);
} else ...{ // 否则直接替换对象 _bytes = bytes;
} return _bytes.length;
}
/** *//** * 设定指定开始位置byte[]
*
* @param pos
* @param bytes
* @return * @throws SQLException
*/ public int setBytes(long pos, byte[] bytes) throws SQLException ...{
// 暂不支持 nonsupport();
return setBytes(pos, bytes, 0, bytes.length, true);
}
/** *//** * 设定byte[]
*
* @param pos
* @param bytes
* @param offset
* @param len
* @return * @throws SQLException
*/ public int setBytes(long pos, byte[] bytes, int offset, int len)
throws SQLException ...{
// 暂不支持 nonsupport();
return setBytes(pos, bytes, offset, len, true);
}
/** *//** * 截取相应部分数据
*
* @param len
* @throws SQLException
*/ public void truncate(long len) throws SQLException ...{
if (len < 0) ...{
throw new SQLException("len < 0");
} if (len > _length) ...{
throw new SQLException("len > max length");
} _length = (int) len;
}
public static void main(String[] args) ...{
//获得一个指定文件的blob
//PS:天地良心啊,没抄袭hibernate写法,无奈的写一样了,不过比他多实现了点方法……(还特意把函数改名,不然更像|||)…… Blob blob = Loon.makeBlob("D:\test.txt");
// 以byte[]获得blob实例
//Blob blob = new BlobImpl(bytes); try ...{
// getBytes测试
// 取出0到blob结束范围的byte[] byte[] buffer = blob.getBytes(0, (int) blob.length());
// 以gb2312编码将byte[]转为string显示 System.out.println(new String(buffer, "gb2312"));
// getBinaryStream测试 BufferedInputStream is = new BufferedInputStream(blob
.getBinaryStream());
buffer = new byte[(int) blob.length()];
int len = buffer.length;
int offset = 0;
int read = 0;
while (offset < len
&& (read = is.read(buffer, offset, len - offset)) >= 0) ...{
offset += read;
} System.out.println(new String(buffer, "gb2312"));
// getBinaryStream范围取值测试,取0to4的byte[] is = new BufferedInputStream(blob.getBinaryStream(0, 4));
//将is转为byte[]后转为String显示 System.out.println(FileHelper.readToString(is, "gb2312"));
} catch (Exception e) ...{
e.printStackTrace();
}
}
}