JDBC处理大数据

Posted 2020-11-17 牛穿疯

1、处理大文本

 1 package com.demo;
 2 
 3 import java.io.File;
 4 import java.io.FileNotFoundException;
 5 import java.io.FileReader;
 6 import java.io.FileWriter;
 7 import java.io.IOException;
 8 import java.io.Reader;
 9 import java.sql.Connection;
10 import java.sql.PreparedStatement;
11 import java.sql.ResultSet;
12 import java.sql.SQLException;
13 
14 import org.junit.Test;
15 
16 import com.utils.DButils;
17 
18 //jdbc存大文本数据
19 
20 public class Demo1 {
21     @Test
22     public void insert() throws SQLException, FileNotFoundException{
23         Connection con = null;
24         PreparedStatement st = null;
25         ResultSet result = null;
26         try {
27             con = DButils.getConnection();
28             String sql = "insert into testclob(id,resume) values(?,?)";
29             st = con.prepareStatement(sql);
30             st.setString(1,"1");
31             
32             File file = new File("src/1.txt");
33             FileReader reader = new FileReader(file);
34             
35             //设置大文本的列
36             st.setCharacterStream(2, reader, file.length());
37             int num = st.executeUpdate();
38             if(num>0){
39                 System.out.println("插入成功");
40             }
41         }finally{
42             DButils.release(con, st, result);
43         }
44     }
45     
46     //读取大文本数据
47     @Test
48     public void read() throws SQLException, IOException{
49         Connection con = null;
50         PreparedStatement st = null;
51         ResultSet result = null;
52         
53         try {
54             con = DButils.getConnection();
55             String sql = "select id,resume from testclob where id=‘1‘";
56             st = con.prepareStatement(sql);
57             result = st.executeQuery();
58             if(result.next()){
59                 //String resume = result.getString("resume");不能用String保存，占用内存过大
60                 Reader reader = result.getCharacterStream("resume");
61                 FileWriter writer = new FileWriter("c:\1.text");
62                 try{
63                     int len = 0;
64                     char buffer[] = new char[1024];
65                     while((len=reader.read(buffer))>0){
66                         writer.write(buffer, 0, len);
67                     }
68                 }finally{
69                     if(reader!=null){
70                         reader.close();
71                     }
72                     writer.close();
73                 }
74             }
75         }finally{
76             DButils.release(con, st, result);
77         }
78     }
79     
80 }

 

2、处理二进制文件

 1 package com.demo;
 2 
 3 import java.io.File;
 4 import java.io.FileInputStream;
 5 import java.io.FileNotFoundException;
 6 import java.io.FileOutputStream;
 7 import java.io.IOException;
 8 import java.io.InputStream;
 9 import java.io.OutputStream;
10 import java.sql.Connection;
11 import java.sql.PreparedStatement;
12 import java.sql.ResultSet;
13 import java.sql.SQLException;
14 
15 import org.junit.Test;
16 
17 import com.utils.DButils;
18 
19 //jdbc存取二进制文件
20 public class Demo2 {
21     @Test
22     public void insert() throws SQLException, FileNotFoundException{
23         Connection con = null;
24         PreparedStatement st = null;
25         ResultSet result = null;
26         try{
27             con = DButils.getConnection();
28             String sql = "insert into testblob(id,image) values(?,?)";
29             st = con.prepareStatement(sql);
30             st.setString(1, "1");
31             File file = new File("src/1.jpg");
32             FileInputStream in = new FileInputStream(file);
33             st.setBinaryStream(2, in, file.length());
34             st.executeUpdate();
35         }finally{
36             DButils.release(con, st, result);
37         }
38     }
39     
40     @Test
41     public void read() throws SQLException, IOException{
42         Connection con = null;
43         PreparedStatement st = null;
44         ResultSet result = null;
45         try{
46             con = DButils.getConnection();
47             String sql = "select id,image from testblob where id=‘1‘";
48             st = con.prepareStatement(sql);
49             result = st.executeQuery();
50             if(result.next()){
51                 InputStream in = result.getBinaryStream("image");
52                 OutputStream out = new FileOutputStream("c:\1.jpg");
53                 try{
54                      int len = 0;
55                      byte[] buffer = new byte[1024];
56                      while((len=in.read(buffer))>0){
57                          out.write(buffer, 0, len);
58                      }
59                 }finally{
60                     if(in!=null){
61                         in.close();
62                     }
63                     if(out!=null){
64                         out.close();
65                     }
66                 }
67             }
68         }finally{
69             DButils.release(con, st, result);
70         }
71     }
72 }