大家好怎样读取blob类型的数据 MYSQL 中
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发布时间：2022-05-01 21:24
共2个回答
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时间：2022-05-02 01:45
然后是数据库连接的工具类：
package blobtest;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class JDBCUtil {
/*使用静态代码块完成驱动的加载*/
static {
try {
String driverName = "com.mysql.jdbc.Driver";
Class.forName(driverName);
} catch (Exception e) {
e.printStackTrace();
}
}
/*提供连接的方法*/
public static Connection getConnection() {
Connection con = null;
try {
//连接指定的MMySQL数据库，三个参数分别是：数据库地址、账号、密码
con = DriverManager.getConnection("jdbc:mysql://127.0.0.1/test?useUnicode=true&characterEncoding=utf8", "root", "w513723");
} catch (Exception e) {
e.printStackTrace();
}
return con;
}
/*关闭连接的方法*/
public static void close(ResultSet rs, Statement stmt, Connection con) {
try {
if (rs != null)
rs.close();
} catch (Exception ex) {
ex.printStackTrace();
}
try {
if (stmt != null)
stmt.close();
} catch (Exception ex) {
ex.printStackTrace();
}
try {
if (con != null)
con.close();
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
接下来是真正的插入数据库的java代码：
package blobtest;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class ReadWriteBlobwithMysql
{
private Connection con;
private Statement stmt;
public Statement getStmt()
{
return stmt;
}
public void setStmt(Statement stmt)
{
this.stmt = stmt;
}
public ResultSet getRs()
{
return rs;
}
public void setRs(ResultSet rs)
{
this.rs = rs;
}
ResultSet rs;
public Connection getCon()
{
return con;
}
public void setCon(Connection con)
{
this.con = con;
}
public void insert(Connection con) throws SQLException
{
String fileName = "E:\JavaProject\HelloWorld\src\blobtest\test.html";
File file = new File(fileName);
try
{
FileInputStream fis = new FileInputStream(file);
String sql = "insert into blobtest values(‘12‘,‘0000‘,‘平安银行‘,?)";
PreparedStatement prest = con.prepareStatement(sql);
prest.setBlob(1, fis,file.length());
prest.execute();
} catch (FileNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public ReadWriteBlobwithMysql(Connection con)
{
this.setCon(con);
try
{
stmt = con.createStatement();
} catch (SQLException e)
{
e.printStackTrace();
}
}
public static void main(String[] args)
{
Connection con = JDBCUtil.getConnection();
ReadWriteBlobwithMysql dao = new ReadWriteBlobwithMysql(con);
try
{
// dao.createTable();
dao.insert(con);
} catch (SQLException e)
{
e.printStackTrace();
} finally
{
JDBCUtil.close(dao.getRs(), dao.getStmt(), dao.getCon());
}
}
}
使用select语句查看一下执行结果，第二条是使用程序插入的，其他的是使用sql语句直接插入的：
下面是增加了从数据库读取blob数据的java代码，增加了queryBlob(。。。)函数：
package blobtest;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class ReadWriteBlobwithMysql
{
private Connection con;
private Statement stmt;
public Statement getStmt()
{
return stmt;
}
public void setStmt(Statement stmt)
{
this.stmt = stmt;
}
public ResultSet getRs()
{
return rs;
}
public void setRs(ResultSet rs)
{
this.rs = rs;
}
ResultSet rs;
public Connection getCon()
{
return con;
}
public void setCon(Connection con)
{
this.con = con;
}
public void insert(Connection con) throws SQLException
{
String fileName = "E:\JavaProject\HelloWorld\src\blobtest\test.html";
File file = new File(fileName);
try
{
FileInputStream fis = new FileInputStream(file);
String sql = "insert into blobtest values(‘12‘,‘0000‘,‘平安银行‘,?)";
PreparedStatement prest = con.prepareStatement(sql);
prest.setBlob(1, fis, file.length());
prest.execute();
} catch (FileNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void queryBlob(String id, Connection con) throws IOException
{
String fileName = "E:\JavaProject\HelloWorld\src\blobtest\test1.html";
String sql = "select * from blobtest where primary_id= ?";
try
{
PreparedStatement prest = con.prepareStatement(sql);
prest.setString(1, id);
ResultSet rs = prest.executeQuery();
while (rs.next())
{
Blob bl = rs.getBlob("blob_data");// 数据保存在表的blob_data字段中，这里取出这里保存的数据。
InputStream is = bl.getBinaryStream(); // 查看blob,可以通过流的形式取出来。 注意一定要是用流的方式读取出来
BufferedInputStream buffis = new BufferedInputStream(is);
// 保存到buffout
BufferedOutputStream buffout = new BufferedOutputStream(new FileOutputStream(fileName));
byte[] buf = new byte[1024];
int len = buffis.read(buf, 0, 1024);
while (len > 0)
{
buffout.write(buf);
len = buffis.read(buf, 0, 1024);
}
buffout.flush();
buffout.close();
buffis.close();
}
} catch (SQLException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public ReadWriteBlobwithMysql(Connection con)
{
this.setCon(con);
try
{
stmt = con.createStatement();
} catch (SQLException e)
{
e.printStackTrace();
}
}
public static void main(String[] args)
{
Connection con = JDBCUtil.getConnection();
ReadWriteBlobwithMysql dao = new ReadWriteBlobwithMysql(con);
try
{
// dao.createTable();
// dao.insert(con);
dao.queryBlob("12",con);
} catch (IOException e)
{
e.printStackTrace();
} finally
{
JDBCUtil.close(dao.getRs(), dao.getStmt(), dao.getCon());
}
}
}
mysql存取blob类型数据
标签：ext this sql数据库 comment idt lex 存在 manage create
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时间：2022-05-01 22:53
LPVOIDlpvImageMem= NULL;
long lImageSize = rs->GetFields()->GetItem("图片")->ActualSize;
if(lImageSize > 0)
{
