Java IO總結
阿新 • • 發佈：2019-02-04
IO流
| 抽象基類 | 節點流 | 緩衝流 | 轉換流 |
|---|---|---|---|
| Inputstream | FileInputStream | bufferinputstream | 無 |
| outputstream | fileoutputstream | bufferoutputstream (flush()) | 無 |
| reader | filereader | bufferreader | inputstreamreader(將位元組流轉化為字元流) |
| writer | filerwriter | bufferwriter (flush()) | outputstramwriter(將位元組流轉化為字元流) |
節點流
位元組流
- OutputStream(向檔案中寫資料)
@Test
public void write() {
File file = new File("E:\\log\\log.log");
try {
FileOutputStream fileOutputStream = new FileOutputStream(file);
fileOutputStream.write(new String("我叫龍海成").getBytes());
fileOutputStream.close();
} catch - InputStream(活得指定檔案中的內容)
@Test
public void getcontent - 檔案的複製和黏貼實現
@Test
public void copy() {
FileInputStream input = null;
FileOutputStream outputStream = null;
try {
input = new FileInputStream("E:\\log\\1.txt");
outputStream = new FileOutputStream("E:\\log\\2.txt",true);
byte[] b = new byte[1024];
int num;
while ((num = input.read(b)) != -1) {
outputStream.write(new String(b, 0, num).getBytes());
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
outputStream.close();
input.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}字元流
1.filereader:讀入檔案
@Test
public void getread() {
File file = new File("E:\\log\\2.txt");
FileReader fileReader = null;
try {
fileReader = new FileReader(file);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
char[] c = new char[1024];
int a;
try {
while ((a = fileReader.read(c)) != -1) {
String s = new String(c, 0, a);
System.out.println(s);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
fileReader.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}2.檔案的黏貼複製
@Test
public void copy() {
File file1 = new File("E:\\log\\log.log");
File file2 = new File("E:\\log\\1.txt");
FileReader reader = null;
FileWriter writer = null;
try {
reader = new FileReader(file2);
writer = new FileWriter(file1,true);
char[] ch = new char[1024];
int a;
while((a = reader.read(ch)) != -1) {
writer.write(new String (ch,0,a));
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
writer.close();
reader.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}緩衝流（速度比節點流更快BUff）
- 讀取檔案
@Test
public void readfile() {
BufferedInputStream bufferedInputStream = null;
try {
bufferedInputStream = new BufferedInputStream(new FileInputStream(new File("E:\\log\\1.txt")));
byte[] b = new byte[1024];
int a;
while ((a = bufferedInputStream.read(b)) != -1) {
String af = new String(b, 0, a);
System.out.println(af);
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
bufferedInputStream.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}2.檔案的複製與黏貼
@Test
public void readfile() {
BufferedInputStream bufferedInputStream = null;
BufferedOutputStream bufferedOutputStream = null;
try {
bufferedInputStream = new BufferedInputStream(new FileInputStream(new File("E:\\log\\1.txt")));
bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(new File("E:\\log\\hhk.txt")));
byte[] b = new byte[1024];
int a;
while ((a = bufferedInputStream.read(b)) != -1) {
bufferedOutputStream.write(new String(b, 0, a).getBytes());
bufferedOutputStream.flush();
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
bufferedOutputStream.close();
bufferedInputStream.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}3.bufferreader讀取檔案中的資料
@Test
public void bufferreader() {
File file = new File("E:\\log\\1.txt");
FileReader reader = null;
try {
reader = new FileReader(file);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
BufferedReader readers = new BufferedReader(reader);
String str;
try {
while ((str = readers.readLine()) != null) {
System.out.println(str);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}轉換流(inputstreamreader和outputstreamwrite)
@Test
public void getreader() {
FileInputStream fis = null;
FileOutputStream fos = null;
InputStreamReader isr = null;
OutputStreamWriter osw = null;
BufferedReader bufferreader = null;
BufferedWriter bw = null;
try {
fis = new FileInputStream(new File("E:\\log\\1.txt"));
isr = new InputStreamReader(fis, "utf8");
bufferreader = new BufferedReader(isr);
fos = new FileOutputStream(new File("E:\\log\\2.txt"));
osw = new OutputStreamWriter(fos, "utf8");
bw = new BufferedWriter(osw);
String str;
while ((str = bufferreader.readLine()) != null) {
bw.write(str);
bw.newLine();
bw.flush();
}
System.out.println("結束");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
bufferreader.close();
isr.close();
fis.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}標準輸入輸出流
- System.in
- System.out
從鍵盤讀取輸入，並在控制檯輸出
@Test
public void getstream() {
BufferedReader bufferedReader = null;
bufferedReader = new BufferedReader(new InputStreamReader(System.in));
String str = null;
while (true) {
System.out.println("請輸入字串：");
try {
str = bufferedReader.readLine();
if (str.equalsIgnoreCase("e") || str.equalsIgnoreCase("exit")) {
System.out.println("程式結束");
break;
}
String s = str.toUpperCase();
System.out.println(s);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}隨機檔案的讀取
RandomAccessFile類
@Test
public void accessfile() {
RandomAccessFile r1 = null;
RandomAccessFile r2 = null;
try {
r1 = new RandomAccessFile(new File("E:\\log\\log.log"), "r");
r2 = new RandomAccessFile(new File("E:\\log\\2.txt"), "rw");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
byte[] b = new byte[1024];
int num;
try {
while ((num = r1.read(b)) != -1) {
r2.write(b, 0, num);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (r2 != null) {
try {
r2.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (r1 != null) {
try {
r1.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}在某個點之後插入字元
@Test
public void insertchar() {
RandomAccessFile radomaccessfile = null;
try {
radomaccessfile = new RandomAccessFile(new File("E:\\log\\2.txt"), "rw");
try {
radomaccessfile.seek(3);
radomaccessfile.write("軟體".getBytes());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (radomaccessfile != null) {
try {
radomaccessfile.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}