By using the io and scanner classes provided by java, and the api provided by apache to process large file data performance analysis and comparison, the code is as follows:
- package test;
- import java.io.BufferedOutputStream;
- import java.io.BufferedReader;
- import java.io.BufferedWriter;
- import java.io.File;
- import java.io.FileInputStream;
- import java.io.FileOutputStream;
- import java.io.FileReader;
- import java.io.IOException;
- import java.io.InputStream;
- import java.io.OutputStream;
- import java.io.OutputStreamWriter;
- import java.io.Reader;
- import java.util.Random;
- import java.util.Scanner;
- import org.apache.commons.io.FileUtils;
- import org.apache.commons.io.LineIterator;
- import org.junit.Test;
- public class TestFile {
- //@Test
- //Create data and test the performance of the following methods to read data
- public void makeFile() throws IOException
- {
- File file = new File("D:\\phone.txt");
- OutputStream os = new BufferedOutputStream(new FileOutputStream(file));
- BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(os));
- //2 million
- for(int i=0; i < 2000000; i++)
- {
- bw.write(bulidPhone());
- bw.newLine();
- }
- bw.close();
- os.close();
- }
- //generate string
- private String bulidPhone()
- {
- Long lo = new Random().nextLong();
- return String.valueOf(lo);
- }
- /**
- * @Title: readTxt1
- * @Description: Use regular jdk io to parse output file data
- * @throws IOException
- */
- @Test
- public void readTxt1() throws IOException
- {
- long start = System.currentTimeMillis();
- File file = new File("D:\\phone.txt");
- Reader in = new FileReader(file);
- BufferedReader br = new BufferedReader(in);
- while(br.ready())
- {
- //System.out.println(br.readLine());
- br.readLine();
- }
- in.close();
- br.close();
- long end = System.currentTimeMillis();
- System.out.println("readTxt1方法,使用内存="+(Runtime.getRuntime().totalMemory()-Runtime.getRuntime().freeMemory())+",使用时间毫秒="+(end-start));
- }
- /**
- * @Title: readTxt2
- * @Description: 使用Scanner扫面文件解析文件数据
- * @throws IOException
- */
- @Test
- public void readTxt2() throws IOException
- {
- long start = System.currentTimeMillis();
- File file = new File("D:\\phone.txt");
- InputStream is = new FileInputStream(file);
- Scanner scan = new Scanner(is,"UTF-8");
- while(scan.hasNextLine())
- {
- //System.out.println(scan.nextLine());
- scan.nextLine();
- //scan.next();
- }
- is.close();
- scan.close();
- long end = System.currentTimeMillis();
- System.out.println("readTxt2方法,使用内存="+(Runtime.getRuntime().totalMemory()-Runtime.getRuntime().freeMemory())+",使用时间毫秒="+(end-start));
- }
- /**
- * @Title: readTxt3
- * @Description: 使用org.apache.commons.io.FileUtils,apache工具类解析文件
- * @throws IOException
- */
- @Test
- public void readTxt3() throws IOException
- {
- long start = System.currentTimeMillis();
- File file = new File("D:\\phone.txt");
- LineIterator it = FileUtils.lineIterator(file, "UTF-8");
- while(it.hasNext())
- {
- it.next();
- }
- it.close();
- long end = System.currentTimeMillis();
- System.out.println("readTxt3方法,使用内存="+(Runtime.getRuntime().totalMemory()-Runtime.getRuntime().freeMemory())+",使用时间毫秒="+(end-start));
- }
- }
运行结果如下:
通过分析比较:
1.apache的api处理时间最短,但是消耗的内存比jdk的io多。
2.scanner类表现的最差,销售内存高,时间久。
3.传统的jdk的io处理时间稍长,内存消耗低。