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JAVA进阶-IO流(2)
<2>以下介绍一些7.0中比较高级的io流.
5.DirectoryStream根据给定路径列举当前文件
1)Files.newDirectoryStream(path,".*");第2个参数指定搜索的文件格式
/**
* 列举目录/文件
*
* @author Lean @date:2014-9-22
*/
public class DirListing {
public static void main(String[] args) {
listDir("E:\\zftphoneTv");
}
public static void listDir(String fileDir){
Path path=Paths.get(fileDir);
DirectoryStream<Path> dirctoryStream=null;
try {
dirctoryStream=Files.newDirectoryStream(path,".*");
for (Path p : dirctoryStream) {
System.out.println(p.getParent()+"\\"+p.getFileName());
}
} catch (IOException e) {
e.printStackTrace();
}finally{
if (dirctoryStream!=null) {
try {
dirctoryStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
6.合并文件
1)通过BufferedWriter循环写入
/**
* 级联合并文件
*
* @author Lean @date:2014-9-22
*/
public class LeveFileSample {
public static void main(String[] args) {
String infilePath1 = "C:/Users/Administrator/Desktop/aa.txt";
String inFilePath2 = "C:/Users/Administrator/Desktop/bb.txt";
String outFilePath = "C:/Users/Administrator/Desktop/cc.txt";
concenateFile(outFilePath, infilePath1,inFilePath2);
}
public static void concenateFile(String outFilePath,String... filePaths){
BufferedWriter bufferedWriter=null;
try {
bufferedWriter=new BufferedWriter(new FileWriter(new File(outFilePath)));
for (String filePath : filePaths) {
FileReader reader=null;
try {
reader=new FileReader(new File(filePath));
int readNum=0;
char[] buff=new char[128];
while ((readNum=reader.read(buff))!=-1) {
bufferedWriter.write(buff,0,readNum);
}
bufferedWriter.newLine();
buff=new char[128];
} catch (IOException e) {
}finally{
if (reader!=null) {
reader.close();
}
}
}
} catch (IOException e) {
e.printStackTrace();
}finally{
try {
if (bufferedWriter!=null) {
bufferedWriter.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
2)SequenceInputStream,通过枚举循环并入流中.如下:将合并的流写入新文件
/**
* 合并流
*
* @author Lean @date:2014-9-23
*/
public class FileMerge {
public Vector<String> fileNames=new Vector<String>();
public Vector<InputStream> fileStreams=new Vector<InputStream>();
public static void main(String[] args) {
FileMerge fileMerge=new FileMerge();
fileMerge.getFileNames();
try {
if (fileMerge.getFileStream()) {
fileMerge.mergeFiles();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
private void mergeFiles() {
String outFilePath="C:/Users/Administrator/Desktop/kk.txt";
OutputStream outputStream=null;
byte[] buff=new byte[512];
int readNum=0;
try {
outputStream=new FileOutputStream(outFilePath);
SequenceInputStream sequenceInputStream=new SequenceInputStream(fileStreams.elements());
while ((readNum=(sequenceInputStream.read(buff)))!=-1) {
outputStream.write(buff,0,readNum);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally{
if (outputStream!=null) {
try {
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
private boolean getFileStream() throws FileNotFoundException {
if (fileNames.size()<1)
return false;
for (String fileName : fileNames) {
fileStreams.add(new FileInputStream(fileName));
}
return true;
}
public void getFileNames(){
String aFile="C:/Users/Administrator/Desktop/a.txt";
String bFile="C:/Users/Administrator/Desktop/b.txt";
String cFile="C:/Users/Administrator/Desktop/c.txt";
fileNames.add(aFile);
fileNames.add(bFile);
fileNames.add(cFile);
}
}
7.ByteArrayOutputStream/DataOutputStream与ByteArrayInputStream/DataInputStream相互对应,data为byte的装饰器.一般应用在对象转换成字节数组传输的情况下,被传输的对象不需要继承任何接口.
/**
* 字节流/数组 应用
*
* @author Lean @date:2014-9-23
*/
public class LiveData {
private ByteArrayOutputStream outputStream;
public static void main(String[] args) {
LiveData data=http://www.mamicode.com/new LiveData();>
8.有的时候,我们需要计算文档的字数,或对文档的控制转换成对文档内容的控制(控制/查询文字/数字).JAVA为我们提供了StreamTokenizer.该类可以将文件流转换成一个个的指令,相当于指针控制内存.
/**
* 文字/数字 解析
*
* @author Lean @date:2014-9-23
*/
public class WordAndNumberParser {
public static void main(String[] args) {
WordAndNumberParser parser=new WordAndNumberParser();
parser.parseFile("C:/Users/Administrator/Desktop/kk.txt");
}
public void parseFile(String fileName){
int wordCount=0;
int numberCount=0;
try (FileReader reader=new FileReader(fileName);){
StreamTokenizer tokenizer=new StreamTokenizer(reader);
tokenizer.slashSlashComments(true);
tokenizer.slashStarComments(true);
while (tokenizer.nextToken()!=StreamTokenizer.TT_EOF) {
if (tokenizer.ttype==StreamTokenizer.TT_WORD) {
wordCount++;
}else if (tokenizer.ttype==StreamTokenizer.TT_NUMBER) {
numberCount++;
}
if (tokenizer.sval!=null&&tokenizer.sval.equals("a")) {
System.out.println(tokenizer.toString());
}
}
System.out.println("wordCount:"+wordCount +" numberCount:"+numberCount);
} catch (Exception e) {
System.out.println("error parser");
}
}
}
9.RandomAccessFile同样也是对文件的操作,只不过它是对字节的操作.seek()方法跳过非法的内容.其一般应用在多线程下载/断点下载.以下为断点下载的例子:
/**
*
*
* @author Lean @date:2014-9-23
*/
public class RecordFile {
public static int fileLength(String urlPath){
HttpURLConnection connection=null;
int length=0;
try {
URL url=new URL(urlPath);
connection=(HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(5000);
if (connection.getResponseCode()==200) {
length=connection.getContentLength();
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return length;
}
public static long downFileLength(String downPath){
File file=new File(downPath);
return file.length();
}
}
/**
*
*
* @author Lean @date:2014-9-23
*/
public class BreakPointDownLoad extends Thread{
private String downLoadPath;
private String urlPath;
public BreakPointDownLoad(String downLoadPath,String urlPath) {
this.downLoadPath=downLoadPath;
this.urlPath=urlPath;
}
@Override
public void run() {
RandomAccessFile raf=null;
InputStream fis=null;
HttpURLConnection conn=null;
try {
int allFileLength=RecordFile.fileLength(urlPath);
long currDownLength=RecordFile.downFileLength(downLoadPath);
long startIndex=currDownLength!=0?currDownLength+1:currDownLength;
System.out.println(allFileLength+" "+currDownLength);
conn=(HttpURLConnection) new URL(urlPath).openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
//request header note!
conn.setRequestProperty("Range", "bytes="+startIndex+"-"+allFileLength);
if (conn.getResponseCode()==206) {
raf=new RandomAccessFile(downLoadPath,"rwd");
raf.seek(startIndex);
fis=conn.getInputStream();
byte[] buff=new byte[512];
int readNum=0;
while ((readNum=(fis.read(buff)))!=-1) {
raf.write(buff,0,readNum);
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally{
try {
if (raf!=null) {
raf.close();
}
if (fis!=null) {
fis.close();
}
conn.disconnect();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
(高级部分还有如PrintStream,LineNumberInputStream,PushbackInputStream等,只不过比较少用)JAVA进阶-IO流(2)
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