java常见的输入和输出流案例研究（一个）

FileInputStream(Filefile)

FileInputStream

File

file

FileInputStream(FileDescriptorfdObj)

fdObj

FileInputStream

FileInputStream(Stringname)

FileInputStream

name

available()

close()

finalize()

close

getChannel()

FileChannel

getFD()

FileDescriptor

FileInputStream

read()

read(byte[]b)

b.length

read(byte[]b,intoff,intlen)

len

skip(longn)

n

read(byte[]b,intoff,intlen)

len

importjava.io.FileInputStream;
importjava.io.FileNotFoundException;
importjava.io.IOException;

publicclassTest{

/**
*@paramargs
*/
publicstaticvoidmain(String[]args){
//TODOAuto-generatedmethodstub
try{
intb;
//创建输入流
FileInputStreamreadfile=newFileInputStream("E:\\test.txt");
bytebuffer[]=newbyte[2500];//创建字节数组
//从输入流中读取字节并存入buffer数组中，最长读取2500个字节。返回值b为实际读取的长度
b=readfile.read(buffer,1,2000);//1为buffer数组中的起始偏移量
Stringstr=newString(buffer,0,b,"Default");
System.out.println(str);
System.out.println(b);
readfile.close();
}catch(FileNotFoundExceptione){
//TODOAuto-generatedcatchblock
e.printStackTrace();
}catch(IOExceptione){
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
}
}

FileOutputStream(Filefile)

File

FileOutputStream(Filefile,booleanappend)

File

FileOutputStream(FileDescriptorfdObj)

FileOutputStream(Stringname)

FileOutputStream(Stringname,booleanappend)

name

close()

finalize()

close

getChannel()

FileChannel

getFD()

write(byte[]b)

b.length

write(byte[]b,intoff,intlen)

off

len

write(intb)

importjava.io.File;
importjava.io.FileInputStream;
importjava.io.FileOutputStream;

publicclassTest{
publicstaticvoidmain(String[]args){
try{
intb;
Filefile=newFile("E:\\test.txt");
//创建输入流
FileInputStreamreadfile=newFileInputStream(file);
bytebuffer[]=newbyte[2500];//创建字节数组
//从输入流中读取字节并存入buffer数组中，最长读取2500个字节，返回值b为实际读取的长度
b=readfile.read(buffer,1,2000);//1为buffer数组中的起始偏移量
Stringstr=newString(buffer,0,b,"Default");
System.out.println(str);
readfile.close();//关闭流
//创建一个输出流，true表示保留文件原有数据，新数据追加到结尾处
FileOutputStreamwritefile=newFileOutputStream(file,true);
writefile.write(buffer,0,b);
writefile.close();
}catch(Exceptione){
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
}
}

importjava.io.FileReader;
importjava.io.FileWriter;

publicclassTest{
publicstaticvoidmain(String[]args){
try{
//字符输入流，读取文件信息
FileReaderfileread=newFileReader("F:\\test.txt");
char[]cbuf=newchar[500];
intb=fileread.read(cbuf,0,500);
System.out.println(String.valueOf(cbuf));
fileread.close();
//字符输出流。想输出流中写入信息,而且保留原有数据，追加数据值末尾处
FileWriterfilewriter=newFileWriter("F:\\test.txt",true);
filewriter.write(cbuf);
filewriter.close();
}catch(Exceptione){
//TODOAuto-generatedcatchblock
e.printStackTrace();
}
}
}

File(Fileparent,Stringchild)

File

File(Stringpathname)

File

File(Stringparent,Stringchild)

File

File(URIuri)

pathSeparator

pathSeparatorChar

separator

separatorChar

canExecute()

canRead()

canWrite()

compareTo(Filepathname)

createNewFile()

createTempFile(Stringprefix,Stringsuffix)

createTempFile(Stringprefix,Stringsuffix,
Filedirectory)

delete()

deleteOnExit()

equals(Objectobj)

exists()

getAbsoluteFile()

getAbsolutePath()

getCanonicalFile()

getCanonicalPath()

getFreeSpace()

getName()

getParent()

null

getParentFile()

null

getPath()

getTotalSpace()

getUsableSpace()

hashCode()

isAbsolute()

isDirectory()

isFile()

isHidden()

lastModified()

length()

list()

list(FilenameFilterfilter)

listFiles()

listFiles(FileFilterfilter)

listFiles(FilenameFilterfilter)

listRoots()

mkdir()

mkdirs()

renameTo(Filedest)

setExecutable(booleanexecutable)

setExecutable(booleanexecutable,booleanownerOnly)

setLastModified(longtime)

setReadable(booleanreadable)

setReadable(booleanreadable,booleanownerOnly)

setReadOnly()

setWritable(booleanwritable)

setWritable(booleanwritable,booleanownerOnly)

toString()

toURI()

importjava.io.File;
importjava.io.IOException;

publicclassTest{
publicstaticvoidmain(String[]args)throwsIOException{
//实例化一个File对象，注意这个文件夹是不存在的，我们又一次创建
Filemydir=newFile("F:\\mydir");
if(!mydir.exists()){
mydir.mkdir();//创建这个文件夹
}//那么我们訪问下面文件夹名试试
System.out.println(mydir.getName());
System.out.println(mydir.getAbsolutePath());
System.out.println(mydir.separator);
//我们给这个文件夹下创建一个文件吧
Filemyfile=newFile("F:\\mydir\\file.txt");
if(!myfile.exists()){
myfile.createNewFile();
}
//我们通过文件夹来訪问文件夹下的这个文件
Filefiles[]=mydir.listFiles();
for(inti=0;i<files.length;i++){
System.out.println(files[i].getName());
System.out.println(files[i].lastModified());
}
}
}

RandomAccessFile(Filefile,
Stringmode)

File

RandomAccessFile(Stringname,
Stringmode)

longgetFilePointer()

longlength()

read()

read(byte[]b)

b.length

read(byte[]b,intoff,intlen)

len

readChar()

seek(longpos)

skipBytes(intn)

n

write(byte[]b)

b.length

write(byte[]b,intoff,intlen)

len

off

writeBoolean(booleanv)

boolean

importjava.io.IOException;
importjava.io.RandomAccessFile;

publicclassTest{
publicstaticvoidmain(String[]args)throwsIOException{
//创建一个RAF流，mode类型为“rw”，可写入可读取
RandomAccessFileraf=newRandomAccessFile("F:\\test.txt","rw");
intnum[]={1,2,3,4,5};
for(inti=0;i<num.length;i++){
raf.writeInt(num[i]);//写入int类型数据
}
raf.seek(0L);//又一次定位流所指向的文件指针位置
for(inti=0;raf.getFilePointer()<raf.length();i++){
raf.seek(i*4);//这里的int占四个字节，定位值依照字节定位的
System.out.println(raf.readInt());
}
raf.close();
}
}