JDBC访问二进制数据（BLOB）

2018-09-09
loubth
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import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
 
public class Test {
 
    /**
     * @param args
     * @throws IOException
     * @throws SQLException
     */
    public static void main(String[] args) throws SQLException, IOException {
        // create();
        read();
    }
 
    static void read() throws SQLException, IOException {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        try {
            // 2.建立连接
            conn = JdbcUtils.getConnection();
            // 3.创建语句
            st = conn.createStatement();
            // 4.执行语句
            rs = st.executeQuery("select big_bit  from blob_test");
            // 5.处理结果
            while (rs.next()) {
                // Blob blob = rs.getBlob(1);
                // InputStream in = blob.getBinaryStream();
                InputStream in = rs.getBinaryStream("big_bit");
                File file = new File("IMG_0002_bak.jpg");
                OutputStream out = new BufferedOutputStream(new FileOutputStream(file));
                byte[] buff = new byte[1024];
                for (int i = 0; (i = in.read(buff)) > 0; ) {
                    out.write(buff, 0, i);
                }
                out.close();
                in.close();
            }
        } finally {
            JdbcUtils.free(rs, st, conn);
        }
    }
 
    static void create() throws SQLException, IOException {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            // 2.建立连接
            conn = JdbcUtils.getConnection();
            // 3.创建语句
            String sql = "insert into blob_test(big_bit) values (?) ";
            ps = conn.prepareStatement(sql);
            File file = new File("IMG_0002.jpg");
            InputStream in = new BufferedInputStream(new FileInputStream(file));
            ps.setBinaryStream(1, in, (int) file.length());
            // 4.执行语句
            int i = ps.executeUpdate();
            in.close();
            System.out.println("i=" + i);
        } finally {
            JdbcUtils.free(rs, ps, conn);
        }
    }
}