java io读取文件操作代码实例
这篇文章主要介绍了java io读取文件操作代码实例,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下
主要分为字节读取和字符读取,字节读取可以一个一个读取和字节数组读取,字符读取同样之,字符读取适合文本读取,字节读取皆可以
这里直接上代码,读取文件的9个小demo
package com.io; import org.junit.Test; import java.io.*; public class FileTest { //1、字节流字节一个一个读取 @Test public void test() throws IOException{ InputStream fis = new FileInputStream(new File("E:\project_test\src\com\io\readme.txt")); int len; //按字节一个一个读取 while ((len = fis.read())!=-1){ System.out.print((char)len+"t"); }; fis.close(); } //输出结果h e l l o w o r l d //2、字节流字节数组读取 @Test public void test1() throws IOException{ InputStream fis = new FileInputStream(new File("E:\project_test\src\com\io\readme.txt")); byte[] bytes = new byte[2]; int len ; //按字节数组读取 bytes存储的是读取的数据 while ((len = fis.read(bytes))!=-1){ System.out.print((new String(bytes))+"t"); }; fis.close(); } //输出结果 he ll ow or ld //3、缓冲字节流字节一个一个读取 @Test public void test2() throws IOException{ BufferedInputStream bis = new BufferedInputStream(new FileInputStream(new File("E:\project_test\src\com\io\readme.txt"))); int len ; while ((len = bis.read())!=-1){ System.out.print((char)len+"t"); }; bis.close(); } //输出结果h e l l o w o r l d //4、缓冲字节流字节数组读取 @Test public void test3() throws IOException{ BufferedInputStream bis = new BufferedInputStream(new FileInputStream(new File("E:\project_test\src\com\io\readme.txt"))); byte[] bytes = new byte[3]; int len ; //按字节数组读取 bytes存储的是读取的数据 while ((len = bis.read(bytes))!=-1){ System.out.print(new String(bytes)+"t"); }; bis.close(); } //输出结果hel low orl drl //5、字符流一个一个读取 @Test public void test4() throws IOException{ InputStreamReader isr = new InputStreamReader(new FileInputStream(new File("E:\project_test\src\com\io\readme.txt"))); int len ; //按字节数组读取 bytes存储的是读取的数据 while ((len = isr.read())!=-1){ System.out.print((char)len+"t"); }; isr.close(); } //6、字符流字符数组读取 @Test public void test5() throws IOException{ InputStreamReader isr = new InputStreamReader(new FileInputStream(new File("E:\project_test\src\com\io\readme.txt"))); char[] chars = new char[3]; int len ; //按字节数组读取 bytes存储的是读取的数据 while ((len = isr.read(chars))!=-1){ System.out.print(new String(chars)+"t"); }; isr.close(); } //7、缓冲字符流字符一个一个读取 @Test public void test6() throws IOException{ BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("E:\project_test\src\com\io\readme.txt")))); int len ; //按字节数组读取 bytes存储的是读取的数据 while ((len = br.read())!=-1){ System.out.print((char)len+"t"); }; br.close(); } //8、缓冲字符流字符数组读取 @Test public void test7() throws IOException{ BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("E:\project_test\src\com\io\readme.txt")))); char[] chars = new char[3]; int len ; //按字节数组读取 bytes存储的是读取的数据 while ((len = br.read(chars))!=-1){ System.out.print(new String(chars)+"t"); }; br.close(); } //9、缓冲字符流按行读取 @Test public void test8() throws IOException{ BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File("E:\project_test\src\com\io\readme.txt")))); //按字节数组读取 bytes存储的是读取的数据 String str; while ( (str = br.readLine())!=null){ System.out.print(str+"t"); }; br.close(); } }
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