java中有關IO操作的API太多了,而且因爲歷史原因,有些api已經被廢棄,有時不免讓一些初學者比較迷糊,今天抽時間整理了我平時常用的流操作,分享出來,如果有寫錯的地方,還請大家指正,因爲大部分方法都寫了註釋,所以main中的測試代碼就不寫註釋了.
對於理論性的資料大家可參閱http://www.blogjava.net/spark/archive/2006/09/29/72733.html這位朋友總結的非常好,如果大家對理論已經有所認知,正需要動手操作的話下面的代碼正適合你.
2008.07.03進行了重新編輯，新增加了一些方法。
package com.syj.util;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Arrays;
/**
* <p>
* Title:IO工具類
* </p>
*
* <p>
* Description:常用的IO操作封裝
* </p>
*
* <p>
* Copyright: 轉載請註明出處http://blog.csdn.net/sunyujia/
* </p>
*
* @author 孫鈺佳
* @main [email protected]
* @date Jun 15, 2008 4:37:58 PM
*/
public class IOUtil {
/**
* 緩衝區大小 1MB
*/
private static final int BUFFER_SIZE = 1024 * 1024;
/**
*
* Description: 將輸入流輸出到輸出流
*
* @param in
* 輸入流
* @param out
* 輸出流
* @param bufferSize
* 緩衝區大小
* @throws IOException
* @mail [email protected]
* @since：Jun 15, 2008 5:57:24 PM
*/
public static void in2OutStream(InputStream in, OutputStream out,
int bufferSize) throws IOException {
byte[] buffer = new byte[bufferSize];// 緩衝區
for (int bytesRead = 0; (bytesRead = in.read(buffer)) != -1;) {
out.write(buffer, 0, bytesRead);
Arrays.fill(buffer, (byte) 0);
}
}
/**
*
* Description:將read中的內容寫入writer
*
* @param in
* @param out
* @param bufferSize
* @throws IOException
* @mail [email protected]
* @since：Jul 2, 2008 11:22:42 PM
*/
public static void read2Writer(Reader in, Writer out, int bufferSize)
throws IOException {
char[] buffer = new char[bufferSize];// 緩衝區
for (int bytesRead = 0; (bytesRead = in.read(buffer)) != -1;) {
out.write(buffer, 0, bytesRead);
buffer = new char[bufferSize];
}
}
/**
*
* Description:將read中的內容寫入writer(逐行)
*
* @param in
* @param out
* @param bufferSize
* @throws IOException
* @mail [email protected]
* @since：Jul 2, 2008 11:22:42 PM
*/
public static void read2Writer(BufferedReader in, PrintWriter out)
throws IOException {
for (String line; (line = in.readLine()) != null;) {
out.println(line);
}
}
/**
*
* Description: 讀取文件返回字節數組流
*
* @param file
* 文件
* @return 字節數組流
* @mail [email protected]
* @since：Jun 15, 2008 4:52:41 PM
*/
public static ByteArrayOutputStream readFileToByteStream(File file)
throws IOException {
FileInputStream fis = null;
ByteArrayOutputStream bos = null;
try {
fis = new FileInputStream(file);
bos = new ByteArrayOutputStream();
in2OutStream(fis, bos, BUFFER_SIZE);
} finally {
if (fis != null)
fis.close();
}
return bos;
}
/**
*
* Description:讀取文件返回字節數組
*
* @param file
* 文件
* @return 字節數組
* @throws IOException
* @mail [email protected]
* @since：Jun 15, 2008 5:38:50 PM
*/
public static byte[] readFileToByteArray(File file) throws IOException {
ByteArrayOutputStream bos = null;
try {
bos = readFileToByteStream(file);
} finally {
if (bos != null)
bos.close();
}
return bos.toByteArray();
}
/**
*
* Description:從Reader對象中讀取字符串
*
* @param reader
* @return
* @throws IOException
* @mail [email protected]
* @since：Jul 2, 2008 11:08:32 PM
*/
public static String readString(Reader reader) throws IOException {
PrintWriter sw = null;
BufferedReader in = null;
try {
in = new BufferedReader(reader);
StringWriter swr = new StringWriter();
sw = new PrintWriter(swr, true);
read2Writer(in, sw);
return swr.toString();
} finally {
try {
if (in != null)
in.close();
} finally {
if (sw != null)
sw.close();
}
}
}
/**
*
* Description:讀取文件內容
*
* @param file
* 文件
* @return String內容
* @throws IOException
* @mail [email protected]
* @since：Jun 15, 2008 5:46:32 PM
*/
public static String readFileToString(File file) throws IOException {
return readString(new FileReader(file));
}
/**
*
* Description:複製文件
*
* @param src
* 源文件
* @param dest
* 目標文件
* @param cover
* 是否覆蓋
* @throws IOException
* @mail [email protected]
* @since：Jun 15, 2008 6:08:28 PM
*/
public static void copyFile(File src, File dest, boolean cover)
throws IOException {
FileInputStream in = null;
FileOutputStream out = null;
try {
if (!dest.exists()) {
dest.createNewFile();
} else if (dest.exists() && cover) {
dest.delete();
dest.createNewFile();
} else {
return;
}
in = new FileInputStream(src);
out = new FileOutputStream(dest);
in2OutStream(in, out, BUFFER_SIZE);
} finally {
try {
if (in != null)
in.close();
} finally {
if (out != null)
out.close();
}
}
}
/**
*
* Description:寫文件
*
* @param file
* 文件
* @param str
* 內容
* @throws IOException
* @mail [email protected]
* @since：Jun 15, 2008 6:17:24 PM
*/
public static void writeFile(File file, String str) throws IOException {
PrintWriter out = null;
BufferedReader in = null;
try {
if (!file.exists())
file.createNewFile();
in = new BufferedReader(new StringReader(str));
out = new PrintWriter(new BufferedWriter(new FileWriter(file)));
read2Writer(in, out);
} finally {
try {
if (in != null)
in.close();
} finally {
if (out != null)
out.close();
}
}
}
/**
*
* Description:從控制檯讀取一串字符串
*
* @return 讀取的字符串
* @throws IOException
* @mail [email protected]
* @since：Jun 15, 2008 6:42:29 PM
*/
public static String readStringFromSystemIn() throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
try {
return br.readLine();
} finally {
if (br != null)
br.close();
}
}
/**
*
* Description:當ObjectInputStream對象調用
* readObject();時,會從ByteArrayInputStream流中反序列化出的對象
*
*
* @param bi
* @return
* @throws IOException
* @mail [email protected]
* @since：Jun 15, 2008 7:07:53 PM
*/
public static ObjectInputStream buildObjectInputStream(
ByteArrayInputStream bi) throws IOException {
return new ObjectInputStream(bi);
}
/**
*
* Description:當ObjectOutputStream對象調用
* writeObject(o);時,o對象會序列化到ByteArrayOutputStream流中去
*
* @param bos
* 字節數組流
* @return 對象輸出流
* @throws IOException
* @mail [email protected]
* @since：Jun 15, 2008 7:06:00 PM
*/
public static ObjectOutputStream buildObjectOutputStream(
ByteArrayOutputStream bos) throws IOException {
return new ObjectOutputStream(bos);
}
public static BufferedReader buildBufferedReader(String str) {
return new BufferedReader(new StringReader(str));
}
public static ByteArrayInputStream buildByteArrayInputStream(String str) {
return new ByteArrayInputStream(str.getBytes());
}
public static ByteArrayInputStream buildByteArrayInputStream(byte[] bt) {
return new ByteArrayInputStream(bt);
}
public static BufferedReader buildReader(InputStream is) {
return new BufferedReader(new InputStreamReader(is));
}
/**
*
* Description:測試代碼
*
* @param args
* @throws Exception
* @mail [email protected]
* @since：Jul 3, 2008 8:18:33 PM
*/
public static void main(String[] args) throws Exception {
byte[] bootFileBytes = IOUtil.readFileToByteArray(new File(
"C://boot.ini"));
System.out.println(new String(bootFileBytes));
String bootFileStr = readFileToString(new File("C://boot.ini"));
System.out.println(bootFileStr);
System.out.println(new String(bootFileBytes).equals(bootFileStr));
IOUtil.copyFile(new File("C://boot.ini"), new File("C://boot1.ini"),
true);
IOUtil.writeFile(new File("C://boot2.ini"), bootFileStr);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = IOUtil.buildObjectOutputStream(bos);
oos.writeObject(new String("abcd"));
ObjectInputStream ois = IOUtil.buildObjectInputStream(IOUtil
.buildByteArrayInputStream(bos.toByteArray()));
System.out.println(ois.readObject());
System.out.println(IOUtil.readString(new StringReader("測試")));
System.out.println(IOUtil.readStringFromSystemIn());
}
}