nio实现文件读取写入数据库或文件

1.nio实现读取大文件，之后分批读取写入数据库

2.nio实现读取大文件，之后分批写入指定文件


[java] view plain copy
 print?
  1. package com.ally;  
  2.   
  3. import java.io.File;  
  4. import java.io.RandomAccessFile;  
  5. import java.nio.ByteBuffer;  
  6. import java.nio.channels.FileChannel;  
  7. import java.sql.*;  
  8.   
  9. /** 
  10.  * Created by admin on 2016/6/28. 
  11.  * 1.nio分批读取sql文件并执行插入数据库 
  12.  * 2.读取一个文件写入另外文件 
  13.  */  
  14. public class TestNio {  
  15.     public static void main(String args[]) throws Exception {  
  16.         System.err.println("begin");  
  17.         long start = System.currentTimeMillis();  
  18.         int _5M = 1024 * 1024 * 5;  
  19.         File fin = new File("D:\drug_general_info.sql");  
  20.         FileChannel fcin = new RandomAccessFile(fin, "r").getChannel();  
  21.         ByteBuffer rBuffer = ByteBuffer.allocate(_5M);  
  22.         //将文件读取执行到数据库  
  23.         readFileByLine(_5M, fcin, rBuffer);  
  24.   
  25.         //将文件读取并写入另外文件  
  26.         File fout = new File("D:\mm.sql");  
  27.         FileChannel fcout = new RandomAccessFile(fout, "rws").getChannel();  
  28.         ByteBuffer wBuffer = ByteBuffer.allocateDirect(_5M);  
  29.         saveOtherFile( _5M,  fcin, rBuffer,  fcout,  wBuffer);  
  30.         System.err.print((System.currentTimeMillis() - start) / 1000);  
  31.     }  
  32.   
  33.     /** 
  34.      * 将一个文件内容写入另外一个 
  35.      * @param bufSize 
  36.      * @param fcin 
  37.      * @param rBuffer 
  38.      * @param fcout 
  39.      * @param wBuffer 
  40.      */  
  41.     public static void saveOtherFile(int bufSize, FileChannel fcin,  
  42.                                      ByteBuffer rBuffer, FileChannel fcout, ByteBuffer wBuffer){  
  43.             Statement pst = null;  
  44.             String enterStr = " ";  
  45.             try {  
  46.                 byte[] bs = new byte[bufSize];  
  47.                 StringBuilder strBuf = new StringBuilder("");  
  48.                 String tempString = null;  
  49.                 while (fcin.read(rBuffer) != -1) {  
  50.                     int rSize = rBuffer.position();  
  51.                     rBuffer.rewind();  
  52.                     rBuffer.get(bs);  
  53.                     rBuffer.clear();  
  54.                     tempString = new String(bs, 0, rSize);  
  55.                     int fromIndex = 0;  
  56.                     int endIndex = 0;  
  57.                     int i = 0;  
  58.                     while ((endIndex = tempString.indexOf(enterStr, fromIndex)) != -1) {  
  59.                         String line = tempString.substring(fromIndex, endIndex);  
  60.                         line = strBuf.toString() + line;  
  61.                         writeFileByLine(fcout, wBuffer, line);  
  62.                         strBuf.delete(0, strBuf.length());  
  63.                         fromIndex = endIndex + 1;  
  64.   
  65.                     }  
  66.                 }  
  67.             } catch (Exception e) {  
  68.                 e.printStackTrace();  
  69.             }  
  70.   
  71.     }  
  72.   
  73.     /** 
  74.      * 读文件写入数据库 
  75.      * @param bufSize 
  76.      * @param fcin 
  77.      * @param rBuffer 
  78.      */  
  79.     public static void readFileByLine(int bufSize, FileChannel fcin,  
  80.                                       ByteBuffer rBuffer) {  
  81.         Connection conn = null;  
  82.         Statement pst = null;  
  83.         String enterStr = " ";  
  84.         try {  
  85.             byte[] bs = new byte[bufSize];  
  86.             StringBuilder strBuf = new StringBuilder("");  
  87.             String tempString = null;  
  88.             Class.forName("com.mysql.jdbc.Driver");  
  89.             conn = DriverManager.getConnection(  
  90.                     "jdbc:mysql://localhost:3306/doctor?useUnicode=true&characterEncoding=utf-8", "root", "root");  
  91.             pst = conn.createStatement();  
  92.             while (fcin.read(rBuffer) != -1) {  
  93.   
  94.                 int rSize = rBuffer.position();  
  95.                 rBuffer.rewind();  
  96.                 rBuffer.get(bs);  
  97.                 rBuffer.clear();  
  98.                 tempString = new String(bs, 0, rSize);  
  99.                 int fromIndex = 0;  
  100.                 int endIndex = 0;  
  101.                 int i = 0;  
  102.                 while ((endIndex = tempString.indexOf(enterStr, fromIndex)) != -1) {  
  103.                     String line = tempString.substring(fromIndex, endIndex);  
  104.                     line = strBuf.toString() + line;  
  105.                     strBuf.delete(0, strBuf.length());  
  106.                     fromIndex = endIndex + 1;  
  107.                     pst.addBatch(line);  
  108.                   /*  System.out.println("-----------------------"); 
  109.                     System.out.println(line); 
  110.                     System.out.println("-----------------------");*/  
  111.                     if (i % 100 == 0) {  
  112.                         System.out.println("执行了：" + i);  
  113.                         if (i == 2700) {  
  114.                             System.out.println("导了：" + i);  
  115.                         }  
  116.                         int[] flag = pst.executeBatch();  
  117.                         System.out.println("结果：" + flag[0]);  
  118.                     }  
  119.                     i += 1;  
  120.                 }  
  121.                 // 执行批量更新  
  122.                 pst.executeBatch();  
  123.   
  124.                 if (rSize > tempString.length()) {  
  125.                     strBuf.append(tempString.substring(fromIndex,  
  126.                             tempString.length()));  
  127.                 } else {  
  128.                     strBuf.append(tempString.substring(fromIndex, rSize));  
  129.                 }  
  130.                 //  System.out.println(strBuf.toString());  
  131.             }  
  132.   
  133.         } catch (Exception e) {  
  134.             e.printStackTrace();  
  135.         } finally {  
  136.             try {  
  137.                 if (pst != null) {  
  138.                     pst.close();  
  139.                 }  
  140.                 if (conn != null) {  
  141.                     conn.close();  
  142.                 }  
  143.             } catch (SQLException e) {  
  144.                 e.printStackTrace();  
  145.             }  
  146.         }  
  147.     }  
  148.   
  149.     public static void writeFileByLine(FileChannel fcout, ByteBuffer wBuffer,  
  150.                                        String line) {  
  151.         try {  
  152.             fcout.write(wBuffer.wrap(line.getBytes()), fcout.size());  
  153.         } catch (Exception e) {  
  154.             e.printStackTrace();  
  155.         }  
  156.     }  
  157. }  


【推广】 免费学中医，健康全家人
原文地址：https://www.cnblogs.com/jpfss/p/8085304.html