标签:desktop while 缓冲流 基本 缓冲 ace public tab tput
流的关系体系和字符流
package stream; import java.io.File; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import org.junit.jupiter.api.Test; /* * 流的体系结构: 抽象基类 节点流(或文件流) 缓冲流(处理流的一种) * 字节输入流 InputStream FileInputStream BufferedInputStream * 字节输出流 OutputStream FileOutputStream BufferedOutputStream * 字符输入流 Reader FileReader BufferedReader * 字符输出流 Writer FileWriter BufferedWriter * * 字符流只能处理字符,字节流能处理图片,二进制文件 * */ public class FileReaderWriterTest { /* * 通过File类对象new FileReader类对象,并通过read方法读取字符 * */ @Test public void test() throws IOException { //1.实例化File类的对象 //2.提供具体的流 FileReader fr = null; try { File file = new File("hello.txt"); System.out.println(file.getAbsolutePath()); File file1 = new File("C:\\Users\\ASUS\\Desktop\\JAVAEE\\practice\\IO_FIle\\hello.txt"); System.out.println(file1.getAbsolutePath()); fr = new FileReader(file); //3.数据的读入: //read()方法:return一个读入的字符,如果读到结尾则输出-1 int data; while((data = fr.read())!=-1) System.out.println((char)data); } catch (Exception e) { System.out.println(e.getMessage()); } finally { //4.流的关闭操作 try { if(fr != null) fr.close(); } catch (Exception e) { e.printStackTrace(); } } } //对read()操作升级:使用read的重载方法read(buf),每次尽可能把buf读满,返回读取字符的个数 @Test public void testFileReader1() { //2.FileReader流的实例化 FileReader fr = null; try { //1.File File file = new File("hello.txt"); fr = new FileReader(file); //3.读入的操作 //read(buf):返回每次读入buf的字符的个数,如果达到文件尾,返回-1 char [] buf = new char[5]; int len; while((len = fr.read(buf)) != -1) { String s = new String(buf,0,len); System.out.println(s); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { try { //4.资源的关闭 if(fr!=null) fr.close(); } catch (IOException e) { e.printStackTrace(); } } } /* * 输出操作:对应的File可以不存在的 * 如果不存在,在输出的过程中会自动创建此文件 * 如果存在,则会覆盖此文件 * 但是可以增加第二个参数 true 进行追加 */ @Test public void testFileWriter() { FileWriter fw = null; try { //1.提出File类的对象,指明写出到的文件 File file = new File("hello1.txt"); //2.提供FileWriter的对象,用于数据的写出 fw = new FileWriter(file); //3.写出的操作 fw.write("i have a dream.\n"); fw.write("you have a dream too"); } catch (Exception e) { e.printStackTrace(); } finally { //4.关闭流 try { if(fw != null) fw.close(); } catch (IOException e) { e.printStackTrace(); } } } /* * 进行文件复制 * FileWriter 的重载write(buf,buf的start,len) * */ @Test public void testFileReaderFileWriter() { FileReader fr = null; FileWriter fw = null; try { File sfile = new File("hello.txt"); File ttfile = new File("hello2.txt"); fr = new FileReader(sfile); fw = new FileWriter(ttfile); char [] buf = new char[5]; int len; while((len = fr.read(buf))!=-1) { fw.write(buf,0,len); } } catch (Exception e) { e.printStackTrace(); } finally { //4.关闭资源 try { fw.close(); } catch (IOException e) { e.printStackTrace(); } try { fr.close(); } catch (IOException e) { e.printStackTrace(); } } } }
字节流
package stream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import org.junit.jupiter.api.Test; /* * 文本文件(txt,java,cpp,c)使用字符流读写 * 非文本文件 使用字节流读写 * */ public class FileInputOutputStreamTest { @Test public void testFileInputStream() { //2.进流 FileInputStream fis = null; try { //1.造文件 File file = new File("hello.txt"); fis = new FileInputStream(file); //3.读数据 byte[] buffer = new byte[5]; int len; //每次读取的字节的个数 while((len = fis.read(buffer)) != -1) { String s = new String(buffer,0,len); System.out.println(s); } } catch (Exception e) { e.printStackTrace(); } finally { try { if(fis!=null) fis.close(); } catch (Exception e) { e.printStackTrace(); } } } /* * 实现对图片的复制 * */ @Test public void testFileInputOutputStream() { FileInputStream fis = null; FileOutputStream fos = null; try { File sfile = new File("zsben.jpg"); File tfile = new File("zsbenn.jpg"); fis = new FileInputStream(sfile); fos = new FileOutputStream(tfile); byte [] buffer = new byte[20]; int len; while((len = fis.read(buffer)) != -1) { fos.write(buffer,0,len); } } catch (Exception e) { e.printStackTrace(); } finally { try { fis.close(); } catch (Exception e) { e.printStackTrace(); } try { fos.close(); } catch (Exception e) { e.printStackTrace(); } } } }
标签:desktop while 缓冲流 基本 缓冲 ace public tab tput
原文地址:https://www.cnblogs.com/zsben991126/p/12160811.html