JDBC学习笔记：用JDBC处理大段数据

1 create table  clob_test
2 (
3 id integer not null auto_increment primary key,
4 big_text text not null
5 );

 1     @Test
 2     public void create() throws SQLException, IOException {
 3         Connection conn = null;
 4         PreparedStatement ps = null;
 5         ResultSet rs = null;
 6         try {
 7             // 建立连接
 8             conn = JdbcUtils.getConnection();
 9             String sql = "insert into clob_test(big_text) values(?)";
10             ps = conn.prepareStatement(sql);
11             File file = new File("src/cn/itcast/jdbc/JdbcUtils.java");
12             Reader reader = new BufferedReader(new FileReader(file));
13             ps.setCharacterStream(1, reader, (int)file.length());
14             
15             int i = ps.executeUpdate();
16             reader.close();
17             System.out.println("i = " + i);
18         } finally {
19             JdbcUtils.free(rs, ps, conn);
20         }
21     }

 1     @Test
 2     public void read() throws SQLException, IOException {
 3         Connection conn = null;
 4         Statement st = null;
 5         ResultSet rs = null; 
 6         try {
 7             conn = JdbcUtils.getConnection();
 8             st = conn.createStatement();
 9             rs = st.executeQuery("select big_text from clob_test");
10             
11             while (rs.next()) {
12                 Clob clob = rs.getClob(1);
13                 Reader reader = clob.getCharacterStream();
14                 // reader = rs.getCharacterStream(1)
15                 
16                 //将从数据库中读取的大段文本数据写入到JdbcUtils_bak.java文件中
17                 File file = new File("JdbcUtils_bak.java");
18                 Writer writer = new BufferedWriter(new FileWriter(file));
19                 char[] buff = new char[1024];
20                 
21                 for (int i = 0; (i=reader.read(buff)) > 0;) {
22                     writer.write(buff, 0, i);
23                 }
24                 writer.close();
25                 reader.close();
26             }
27         } finally {
28             JdbcUtils.free(rs, st, conn);
29         }
30     }

 1     @Test
 2     public void create() throws SQLException, IOException {
 3         Connection conn = null;
 4         PreparedStatement ps = null;
 5         ResultSet rs = null;
 6         try {
 7             conn = JdbcUtils.getConnection();
 8             String sql = "insert into blob_test(big_bit) values(?)";
 9             ps = conn.prepareStatement(sql);
10             File file = new File("14.jpg");// 文件放在根目录下,大小不能超过64k
11             InputStream in = new BufferedInputStream(new FileInputStream(file));
12             
13             ps.setBinaryStream(1, in, (int)file.length());
14             
15             int i = ps.executeUpdate();
16             in.close();
17             System.out.println("i = " + i);
18         } finally {
19             JdbcUtils.free(rs, ps, conn);
20         }
21     }

 1     @Test
 2     public void read() throws SQLException, IOException {
 3         Connection conn = null;
 4         Statement st = null;
 5         ResultSet rs = null;
 6         try {
 7             conn = JdbcUtils.getConnection();
 8             st = conn.createStatement();
 9             rs = st.executeQuery("select big_bit from blob_test");
10             
11             while(rs.next()) {
12                 InputStream in = rs.getBinaryStream(1);
13                 
14                 File file = new File("14_bak.jpg");
15                 OutputStream out = new BufferedOutputStream(new FileOutputStream(file));
16                 byte[] buff = new byte[1024];
17                 for (int i = 0; (i = in.read(buff)) > 0;) {
18                     out.write(buff, 0, i);
19                 }
20                 out.close();
21                 in.close();
22             }
23         } finally {
24             JdbcUtils.free(rs, st, conn);
25         }
26     }