大文本的存取

 1 package cn.itcast.jdbc.lob;
 2 
 3 import java.io.File;
 4 import java.io.FileReader;
 5 import java.io.FileWriter;
 6 import java.io.Reader;
 7 import java.io.Writer;
 8 import java.sql.Connection;
 9 import java.sql.PreparedStatement;
10 import java.sql.ResultSet;
11 
12 import org.junit.Test;
13 
14 import cn.itcast.util.JdbcUtil;
15 //大文本的存取
16 /*
17 use day15;
18 create table t1(
19     id int primary key,
20     content longtext
21 );
22  */
23 public class ClobDemo {
24     @Test
25     public void testAdd(){
26         Connection conn = null;
27         PreparedStatement stmt = null;
28         try{
29             conn = JdbcUtil.getConnection();
30             stmt = conn.prepareStatement("insert into t1 (id,content) values (?,?)");
31             stmt.setInt(1, 1);
32             //大数据要使用流的形式
33             File file = new File("c:/jpm.txt");
34             Reader reader = new FileReader(file);
35             stmt.setCharacterStream(2, reader, (int)file.length());//不能使用long的参数，因为mysql根本支持不到那么大的数据，就没有实现
36             
37             int i = stmt.executeUpdate();
38             if(i>0)
39                 System.out.println("插入成功");
40             
41         }catch(Exception e){
42             e.printStackTrace();
43         }finally{
44             JdbcUtil.release(null, stmt, conn);
45         }
46     }
47     @Test
48     public void testRead(){
49         Connection conn = null;
50         PreparedStatement stmt = null;
51         ResultSet rs = null;
52         try{
53             conn = JdbcUtil.getConnection();
54             stmt = conn.prepareStatement("select * from t1 where id=?");
55             stmt.setInt(1, 1);
56             //大数据要使用流的形式
57             //保存到E盘上
58             rs = stmt.executeQuery();
59             if(rs.next()){
60                 Reader reader = rs.getCharacterStream("content");
61                 Writer writer = new FileWriter("E:/jpm.txt");
62                 char c[] = new char[1024];
63                 int len = -1;
64                 while((len=reader.read(c))!=-1){
65                     writer.write(c, 0, len);
66                 }
67                 reader.close();
68                 writer.close();
69             }
70             
71         }catch(Exception e){
72             e.printStackTrace();
73         }finally{
74             JdbcUtil.release(null, stmt, conn);
75         }
76     }
77 }