Question

JDBC 从数据库中读取一张图片，怎么读出来的大小不一样

public class Readbigpic {
public static void main(String[] args) throws Exception, SQLException, IOException {
test();
}

public static void test() throws ClassNotFoundException, SQLException, IOException{
Class.forName("com.mysql.jdbc.Driver");
Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/jdbc","root","1234");
String sql="select bigpic from big_pic";
PreparedStatement ps=conn.prepareStatement(sql);
ResultSet rs=ps.executeQuery();
while(rs.next()){
//以blob对象获取数据集中指定列的值
Blob b=rs.getBlob(1);
InputStream is=b.getBinaryStream();
File file=new File("20141314.jpg");
BufferedReader bfr=new BufferedReader(new InputStreamReader(is));
BufferedWriter bfw=new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file)));
String line=null;
while((line=bfr.readLine())!=null){
bfw.write(line);
}
bfw.close();
bfr.close();
}
rs.close();
ps.close();
conn.close();
}
}

Answer 1

你忽略了一个很重要的问题，当数据库字段类型为blob时，一定要使用ParedStatement中的

setBinaryStream(int,InputStream,int)方法。

给你一个例子:

存储:

读取：