数据库读取和写入大文件
针对大文本：Clob：字符大对象：Character large object
// file.txt的文件保存到数据库中
@Test
public void test(){
Connction conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try{
conn = JdbcUtil.getConnection();
stmt = conn.prepareStatement("insert into count(id,content) values (?,?)");
stmt.setInt(1,1);
// 使用字符流的形式存储，提高效率
File file = new File("c:/file.txt");
Reader reader = new FileReader(file);
stmt.setCharacterStream(2,reader, (int)file.length());
stmt.executeUpdate();
}catch(Exception e){
throw new RuntimeException(e);
}finally{
JdbcUtil.release(rs, stmt, conn);
}
}
// 将id=1的记录content的内容写到磁盘上
@Test
public void test(){
Connction conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try{
conn = JdbcUtil.getConnection();
stmt = conn.prepareStatement("select * from count where id=1");
// 查询结果集
rs = stmt.executeQuery();
if(rs.next()){
// 得到结果字符流
Reader reader = rs.getCharacterStream("content");
// 得到一只笔，写入到文件中
Writer writer = new Writer("c:/deng.txt");
// 开始写入
char[] buf = new char[1024];
int len = -1;
while((len=reader.read(buf))!=-1){
writer.write(buf,0,len);
}
writer.close();
reader.close();
}
}catch(Exception e){
throw new RuntimeException(e);
}finally{
JdbcUtil.release(rs, stmt, conn);
}
}
// 大二进制数据：语音、视频、图片、压缩包.Blob:二进制大对象 Binary Large Object
// 将1.jpg保存到数据库中
@Test
public void test(){
Connction conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try{
conn = JdbcUtil.getConnection();
stmt = conn.prepareStatement("insert into t2(id, content) values (?,?)");
stmt.setInt(1,1);
// 使用字节流传输数据，提高工作效率
InputStream in = new FileInputStream("c:/1.jpg");
stmt.setBinaryStream(2,in, in.available());
stmt.executeUpdate();
}catch(Exception e){
throw new RuntimeException(e);
}finally{
JdbcUtil.release(rs, stmt, conn);
}
}
// 把content的内容写到磁盘上
@Test
public void test(){
Connction conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try{
conn = JdbcUtil.getConnection();
stmt = conn.prepareStatement("select * from count where id=1");
// 查询结果集
rs = stmt.executeQuery();
if(rs.next()){
// 得到结果输入字节流
InputStream in = rs.getBinaryStream("content");
// 字节输出流，将内容输出到对应的文件
OutputStream out = new FileOutputStream("c:/deng.txt");
// 开始写入
byte[] buf = new byte[1024];
int len = -1;
while((len=in.read(buf))!=-1){
out.write(buf,0,len);
}
out.close();
in.close();
}
}catch(Exception e){
throw new RuntimeException(e);
}finally{
JdbcUtil.release(rs, stmt, conn);
}
}
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