android 将图片保存到数据库

最新推荐文章于 2023-02-03 10:29:31 发布

wayne512

最新推荐文章于 2023-02-03 10:29:31 发布

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CC 4.0 BY-SA版权

文章标签： android exception null string sql byte

本文链接：https://blog.youkuaiyun.com/wayne512/article/details/6731686

本文介绍如何利用JDBC技术与数据库进行交互，实现文件的上传和下载操作，包括连接数据库、执行SQL语句、使用PreparedStatement进行参数化查询、设置二进制流以处理文件数据，并在最后展示如何通过ResultSet获取并保存文件到本地。

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public class ExamJdbc11 { 
public static  void method1() { 
Connection conn = null;	
PreparedStatement stmt = null; 
try { 
conn = SQLHelper.getConnection(); 
String sql = "insert into tb_file values(?,?)"; 
stmt = conn.prepareStatement(sql); 
stmt.setString(1, "c:/1.jpg"); 

InputStream in = new FileInputStream("c:/1.jpg"); 
stmt.setBinaryStream(2, in, in.available());//存入图片的大小，这样才可以取得 
stmt.executeUpdate(); 
} catch (Exception e) { 
e.printStackTrace(); 
} finally { 
SQLHelper.close(null, stmt, conn); 
} 
} 
//取出来 
public static  void method2() { 
Connection conn = null; 
PreparedStatement stmt = null; 
ResultSet rs = null; 
try { 

conn = SQLHelper.getConnection(); 
String sql = "select * from tb_file where filename = ?"; 
stmt = conn.prepareStatement(sql); 
stmt.setString(1, "c:/1.jpg"); 
rs = stmt.executeQuery(); 
rs.next(); 

InputStream in = rs.getBinaryStream("filecontent"); 
FileOutputStream fout = new FileOutputStream("d:/2.jpg"); 
byte[] buff = new byte[1024]; 
int length = 0; 
while ((length = in.read(buff)) != -1) { 
fout.write(buff, 0, length); 
fout.flush(); 
} 
fout.close(); 
in.close(); 

} catch (Exception e) { 
e.printStackTrace(); 
} finally { 
SQLHelper.close(rs, stmt, conn); 
} 

} 

public static void main(String[] args){ 
method2(); 

} 
}