jdbc往mysql数据库读取图片

分手后的思念是犯贱 2022-07-12 01:25 172阅读 0赞

blob字段用于存储二进制数据，例如图像、声音、二进制文等。

package utils;
    
    import java.io.InputStream;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.Properties;
    
    public class JdbcUtil {
    	private static String password;
    	private static String username;
    	private static String url;
    	static {
    		try {
    			InputStream in = JdbcUtil.class.getClassLoader().getResourceAsStream("db.properties");
    			Properties pr = new Properties();
    			pr.load(in);
    			username=pr.getProperty("username");
    			url = pr.getProperty("url");
    			password = pr.getProperty("password");
    			String driver = pr.getProperty("driver");
    			Class.forName(driver);
    		} catch (Exception e) {
    			throw new RuntimeException(e);
    		}
    	}
    	
    	public static Connection getConnection() throws SQLException {
    		return DriverManager.getConnection(url, username, password);
    	}
    
    	public static void release(Connection conn, PreparedStatement st, ResultSet rs) {
    		if(rs!=null){
    			try{
    				rs.close();
    			}catch (Exception e){
    				throw new RuntimeException(e);
    			}
    			rs = null;
    		}
    		if(st != null){
    			try{
    				st.close();
    			}catch (Exception e){
    				throw new RuntimeException(e);
    			}
    			st = null;
    		}
    		if(conn != null){
    			try{
    				conn.close();
    			}catch (Exception e){
    				throw new RuntimeException(e);
    			}
    			conn = null;
    		}
    	}
    }

package jdbc;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.InputStream;
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    
    import org.junit.Test;
    
    import utils.JdbcUtil;
    
    public class TestBolb {
    	@Test
    	public void add() {
    		Connection conn = null;
    		PreparedStatement st = null;
    		ResultSet rs = null;
    		try {
    			conn = JdbcUtil.getConnection();
    			String sql = "insert into testblob(content) values(?)";
    			st = conn.prepareStatement(sql);
    
    //			String path = TestClob.class.getClassLoader().getResource("123.jpg").getPath();
    			String path = "d:\\123.jpg";
    			File file = new File(path);
    			st.setBinaryStream(1, new FileInputStream(file), file.length());
    			int num = st.executeUpdate();
    			if (num > 0) {
    				System.out.println("插入成功！！");
    			}
    		} catch (Exception e) {
    			throw new RuntimeException(e);
    		} finally {
    			JdbcUtil.release(conn, st, rs);
    		}
    	}
    
    	@Test
    	public void read(){
    		Connection conn = null;
    		PreparedStatement st = null;
    		ResultSet rs = null;
    		try{
    			conn = JdbcUtil.getConnection();
    			String sql = "select * from testblob where id = 1";
    			st = conn.prepareStatement(sql);
    			rs = st.executeQuery();
    
    			if (rs.next()) {
    				FileOutputStream out = new FileOutputStream("d:\\1.jpg");
    				InputStream reader = rs.getBinaryStream("content");
    				byte buffer[] = new byte[1024];
    				int len = 0;
    				while ((len = reader.read(buffer)) > 0) {
    					out.write(buffer, 0, len);
    				}
    				out.close();
    				reader.close();
    			}
    		}catch(Exception e){
    			throw new RuntimeException(e);
    		}finally{
    			JdbcUtil.release(conn, st, rs);
    		}
    	}
    	
    }