java夯实基础-输入输出流

Myth丶恋晨 2022-06-07 03:48 217阅读 0赞

**本文测试java中的字节流、字符流、缓冲流、随机流、文件锁。**

**一、字符流：Reader和Writer**

package com.wllfengshu.test; import java.io.File; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import org.junit.Test; /** * 字符流：Reader和Writer */ public class Test1字符流 { //文件读取字符流 @Test public void test1(){ File file=new File("E:","bbb.txt"); System.out.println(file.canRead()); FileReader reader=null; try { reader=new FileReader(file); char[] a=new char[256]; while(reader.read(a)!=-1){ String str=new String(a); System.out.println(str); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally{ try { reader.close(); } catch (IOException e) { e.printStackTrace(); } } } //文件写入字符流 @Test public void test2(){ File file=new File("E:","bbb.txt"); System.out.println(file.canWrite()); FileWriter writer=null; try { writer=new FileWriter(file,true); char[] a=new char[256]; a="我是中午，我在输出".toCharArray(); writer.write(a); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally{ try { writer.close(); } catch (IOException e) { e.printStackTrace(); } } } }

**二、字节流：InputStream和OutputStream**

package com.wllfengshu.test; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import org.junit.Test; /** * 字节流：InputStream和OutputStream * 字符流：Reader和Writer */ public class Test2字节流 { //测试文件输入字节流 @Test public void test1(){ File file=new File("E:","bbb.txt"); System.out.println(file.canRead()); System.out.println(file.getAbsolutePath()); if (file.exists()) { System.out.println("存在"); } FileInputStream inputStream = null; try { inputStream = new FileInputStream(file); byte[] a=new byte[1024]; while(inputStream.read(a)!=-1){ String str=new String(new String(a,"gbk").getBytes(),"utf-8"); System.out.println(str); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally{ try { inputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } //测试文件输出字节流 @Test public void test2(){ File file=new File("E:","bbb.txt" ); System.out.println(file.canWrite()); FileOutputStream outputStream=null; try { outputStream=new FileOutputStream(file,true);//第二个参数为true，表示在文件末尾添加 byte[] a=new byte[1024]; String b="kkkkfff我是中文的"; a=b.getBytes(); outputStream.write(a); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally{ try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } }

**三、缓冲流：BufferedReader和BufferedWriter**

package com.wllfengshu.test; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.File; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import org.junit.Test; /** * 测试缓冲流：BufferedReader和BufferedWriter */ public class Test3缓冲流 { //缓冲输入流 @Test public void test1(){ File file=new File("E:","bbb.txt"); FileReader reader=null; BufferedReader bufferedReader=null; String str=null; try { reader=new FileReader(file); bufferedReader=new BufferedReader(reader); while((str=bufferedReader.readLine())!=null){ System.out.println(str); } }catch (IOException e) { e.printStackTrace(); }finally{ try { bufferedReader.close(); reader.close(); } catch (IOException e) { e.printStackTrace(); } } } //缓冲输出流 @Test public void test2(){ File file=new File("E:","bbb.txt"); String[] content={"商品","物品","名称"}; FileWriter writer=null; BufferedWriter bufferedWriter=null; try { writer=new FileWriter(file); bufferedWriter=new BufferedWriter(writer); for (String str : content) { bufferedWriter.write(str); bufferedWriter.newLine(); } }catch (IOException e) { e.printStackTrace(); }finally{ try { bufferedWriter.close(); writer.close(); } catch (IOException e) { e.printStackTrace(); } } } }

**四、随机流：RandomAccessFile**

package com.wllfengshu.test; import java.io.File; import java.io.FileNotFoundException; import java.io.IOException; import java.io.RandomAccessFile; import org.junit.Test; /** * 随机流：RandomAccessFile */ public class Test4随机流 { @Test public void test1(){ RandomAccessFile randomAccessFile=null; try { File file=new File("E:","bbb.txt"); randomAccessFile=new RandomAccessFile(file, "rw"); String str=new String("aaa"); System.out.println(str); randomAccessFile.writeChars(str);//写 String readLine = randomAccessFile.readLine();//读 System.out.println(readLine); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }finally{ try { randomAccessFile.close(); } catch (IOException e1) { e1.printStackTrace(); } } } }

**五、文件锁：FileLock和FileChannel**

package com.wllfengshu.test; import java.io.File; import java.io.RandomAccessFile; import java.nio.channels.FileChannel; import java.nio.channels.FileLock; import org.junit.Test; /** * 文件锁：FileLock和FileChannel */ public class Test5文件锁 { @Test public void test1(){ RandomAccessFile randomAccessFile=null; try { File file=new File("E:","bbb.txt"); randomAccessFile=new RandomAccessFile(file, "rw"); FileChannel channel=randomAccessFile.getChannel();//通道 FileLock lock=channel.tryLock();//加锁 Thread.sleep(2000); lock.release();//解锁 randomAccessFile.writeChars("2222"); randomAccessFile.close(); } catch (Exception e) { } } }