总结整理一下Java文件操作的几种方式。无论哪种编程语言，文件读写操作时避免不了的一件事情，Java也不例外。Java读写文件一般是通过字节、字符和行三种方式来进行文件的操作。
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
public class FileUtil {
/**
* 按行读取文件
*/
public static void ReadFileByLine(String filename) {
File file = new File(filename);
InputStream is = null;
Reader reader = null;
BufferedReader bufferedReader = null;
try {
is = new FileInputStream(file);
reader = new InputStreamReader(is);
bufferedReader = new BufferedReader(reader);
String line = null;
while ((line = bufferedReader.readLine()) != null) {
System.out.println(line);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (null != bufferedReader)
bufferedReader.close();
if (null != reader)
reader.close();
if (null != is)
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 按字节读取文件
*
* @param filename
*/
public static void ReadFileByBytes(String filename) {
File file = new File(filename);
InputStream is = null;
try {
is = new FileInputStream(file);
int index = 0;
while (-1 != (index = is.read())) {
System.out.write(index);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
if (null != is)
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
System.out.println("-----------------------------------");
try {
is = new FileInputStream(file);
byte[] tempbyte = new byte[1000];
int index = 0;
while (-1 != (index = is.read(tempbyte))) {
System.out.write(tempbyte, 0, index);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
if (null != is)
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 按字符读取文件
*
* @param filename
*/
public static void ReadFileByChar(String filename) {
File file = new File(filename);
InputStream is = null;
Reader isr = null;
try {
is = new FileInputStream(file);
isr = new InputStreamReader(is);
int index = 0;
while (-1 != (index = isr.read())) {
System.out.print((char) index);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (null != is)
is.close();
if (null != isr)
isr.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 通过OutputStreamWriter写文件
*
* @param filename
*/
public static void Write2FileByOutputStream(String filename) {
File file = new File(filename);
FileOutputStream fos = null;
// BufferedOutputStream bos = null;
OutputStreamWriter osw = null;
try {
if (!file.exists()) {
file.createNewFile();
}
fos = new FileOutputStream(file);
osw = new OutputStreamWriter(fos);
osw.write("Write2FileByOutputStream");
// bos = new BufferedOutputStream(fos);
// bos.write("Write2FileByOutputStream".getBytes());
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (null != osw) {
try {
osw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (null != fos) {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
/**
* 通过BufferedWriter写文件
*
* @param filename
*/
public static void Write2FileByBuffered(String filename) {
File file = new File(filename);
FileOutputStream fos = null;
OutputStreamWriter osw = null;
BufferedWriter bw = null;
try {
if (!file.exists()) {
file.createNewFile();
}
fos = new FileOutputStream(file);
osw = new OutputStreamWriter(fos);
bw = new BufferedWriter(osw);
bw.write("Write2FileByBuffered");
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (null != bw) {
try {
bw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (null != osw) {
try {
osw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (null != fos) {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
/**
* 通过FileWriter写文件
*
* @param filename
*/
public static void Write2FileByFileWriter(String filename) {
File file = new File(filename);
FileWriter fw = null;
try {
if (!file.exists()) {
file.createNewFile();
}
fw = new FileWriter(file);
fw.write("Write2FileByFileWriter");
} catch (IOException e) {
e.printStackTrace();
} finally {
if (null != fw) {
try {
fw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public static void main(String[] args) {
String filename = "D:/testfile.txt";
// ReadFileByLine(filename);
// ReadFileByBytes(filename);
// ReadFileByChar(filename);
String writeFile = "javawrite2file.txt";
// Write2FileByOutputStream(writeFile);
// Write2FileByBuffered(writeFile);
Write2FileByFileWriter(writeFile);
}
}
Java读写文件的大体情况应该就上面的几种方式，然而从效率的角度来讲。InputStream、OutputStream的效率比BufferedInputStream、BufferedOutputStream的效率要差，至于Reader、Writer没做进一步的比较。网上看到一些资料说Java.nio的效率最高，没有进一步做比较，不得而知了，等有时间再做进一步测试吧。
本文转载 https://www.cnblogs.com/rwxwsblog/p/4798855.html
原文链接：https://www.qiquanji.com/post/8366.html
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