IOの利用字节流和字符流完成文件的复制demo

男娘i 2022-08-22 05:47 105阅读 0赞

package IO;
    
    import java.io.BufferedOutputStream;
    import java.io.BufferedReader;
    import java.io.BufferedWriter;
    import java.io.File;
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.FileReader;
    import java.io.FileWriter;
    import java.io.IOException;
    
    import org.junit.Test;
    
    //完成字符流和字节流的输入输出
    public class TestExer {
    
    	// 字符流利用程序复制
    	@Test
    	public void test4() {
    		BufferedReader bufferedReader = null;
    		BufferedWriter bufferedWriter = null;
    		try {
    			bufferedReader = new BufferedReader(new FileReader("test1.txt"));
    			bufferedWriter = new BufferedWriter(new FileWriter("hadi.txt"));
    			char[] c = new char[20];
    			int len;
    			while ((len = bufferedReader.read(c)) != -1) {
    				bufferedWriter.write(c, 0, len);
    			}
    			bufferedWriter.flush();
    
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		} finally {
    			if (bufferedWriter != null) {
    				try {
    					bufferedWriter.close();
    				} catch (IOException e) {
    					// TODO Auto-generated catch block
    					e.printStackTrace();
    				}
    			}
    			if (bufferedReader != null) {
    				try {
    					bufferedReader.close();
    				} catch (IOException e) {
    					// TODO Auto-generated catch block
    					e.printStackTrace();
    				}
    			}
    		}
    
    	}
    
    	// 使用字符流实现内容的读入
    	@Test
    	public void test3() {
    		BufferedReader bufferedReader = null;
    		try {
    			bufferedReader = new BufferedReader(new FileReader("test.txt"));
    			String string;
    			while ((string = bufferedReader.readLine()) != null) {
    				System.out.println(string);
    			}
    
    		} catch (IOException e) {
    			e.printStackTrace();
    		} finally {
    			if (bufferedReader != null) {
    				try {
    					bufferedReader.close();
    				} catch (IOException e) {
    					// TODO Auto-generated catch block
    					e.printStackTrace();
    				}
    			}
    
    		}
    
    	}
    
    	// 使用字符流实现内容输出
    	@Test
    	public void test2() {
    		BufferedWriter bufferedWriter = null;
    		try {
    			bufferedWriter = new BufferedWriter(new FileWriter(new File("test1.txt")));
    			// 可以直接写成这个：bufferedWriter = new BufferedWriter(new
    			// FileWriter("test1.txt"));
    			String string = "转换流：实现字节流与字符流之间的转换InputStreamReader输入时，\n" + "实现字节流到字符流的转换，提高操作的效率（前提是，数据是文本文件）\n"
    					+ "===>解码：从字节数组到字符串（相对于人能看懂了，所以叫解释了，解码）\n" + " ===>编码：从字符流到字节流（相对于人把文字变成了数字，看不懂了，叫编码）\n"
    					+ "OutputStreamWriter：输出时，实现字符流到字节流的转换。从看得懂到看不懂，\n"
    					+ "在底层用0101存储。 ===>编码：从字符流到字节流（相对于人把文字变成了数字，看不懂了，叫编码）\n"
    					+ "System.in:标准输入流：从键盘输入数据System.out:标准输出流：从显示器输出数据\n";
    
    			bufferedWriter.write(string);
    			bufferedWriter.flush();
    		} catch (IOException e) {
    			e.printStackTrace();
    		} finally {
    			if (bufferedWriter != null) {
    				try {
    					bufferedWriter.close();
    				} catch (IOException e) {
    					e.printStackTrace();
    				}
    			}
    		}
    
    	}
    
    	// 使用字节流实现内容的输出
    	@Test
    	public void test1() {
    
    		// 处理流缓冲流的创建
    		BufferedOutputStream bufferedOutputStream = null;
    		try {
    			bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(new File("test.txt")));
    
    			String string = "转换流：实现字节流与字符流之间的转换InputStreamReader输入时，\n" + "实现字节流到字符流的转换，提高操作的效率（前提是，数据是文本文件）\n"
    					+ "===>解码：从字节数组到字符串（相对于人能看懂了，所以叫解释了，解码）\n" + " ===>编码：从字符流到字节流（相对于人把文字变成了数字，看不懂了，叫编码）\n"
    					+ "OutputStreamWriter：输出时，实现字符流到字节流的转换。从看得懂到看不懂，\n"
    					+ "在底层用0101存储。 ===>编码：从字符流到字节流（相对于人把文字变成了数字，看不懂了，叫编码）\n"
    					+ "System.in:标准输入流：从键盘输入数据System.out:标准输出流：从显示器输出数据\n";
    
    			// 将一个字符串转化成字节数组，并写出到文件
    			bufferedOutputStream.write(string.getBytes());
    
    		} catch (IOException e1) {
    			e1.printStackTrace();
    		} finally {
    			if (bufferedOutputStream != null) {
    				// 关闭缓冲流，就会关闭相应的字节流
    				try {
    					bufferedOutputStream.close();
    				} catch (IOException e) {
    					e.printStackTrace();
    				}
    			}
    		}
    
    	}
    
    }