java读取文件(更新jdk7及jdk8)
2024-08-29 16:39:16
以字节的方式读取:
InputStream inputStream = new FileInputStream(file);
int temp = -1;
StringBuilder sb = new StringBuilder();
while((temp = inputStream.read()) != -1){
sb.append((char)temp);
}
inputStream.close();
也可以多个字节一起读取:
InputStream inputStream = new FileInputStream(file);
byte[] bytes = new byte[10];
StringBuilder sb = new StringBuilder();
int length = -1;
while((length = inputStream.read(bytes))!= -1){
sb.append(new String(bytes,0,length,Charset.forName("utf-8")));
}
inputStream.close();
以字符的方式读取:
InputStream inputStream = new FileInputStream(file);
InputStreamReader isr = new InputStreamReader(inputStream,Charset.forName("utf-8"));
StringBuilder sb = new StringBuilder();
int temp = -1;
while((temp = (isr.read()))!= -1){
sb.append((char)temp);
}
inputStream.close();
isr.close();
或者用封装的BufferedReader按行读取,效率更高:
InputStream inputStream = new FileInputStream(file);
InputStreamReader isr = new InputStreamReader(inputStream,Charset.forName("utf-8"));
BufferedReader bufferedReader = new BufferedReader(isr);
StringBuilder sb = new StringBuilder();
String line = null;
while((line = bufferedReader.readLine())!=null){
sb.append(line + '\n');
}
inputStream.close();
isr.close();
bufferedReader.close();
-----------------------------------------------以上是jdk7之前一般使用的读取文件方法-------------------------------------------------------------------------------------------------------
jdk7引入了新的文件api: java.nio.file.Files。 Files.readAllBytes()方法将文件内容全部读入内存,并且确保读取完之后文件是关闭的,也就是说,不用手动调用close方法:
String path = "C:\\test.txt";
System.out.print(Files.readAllBytes(Paths.get(path)));
当文件过大时,不建议使用readAllBytes()方法将文件内容一次全部读入到内存里面。
java8中使用流的方式来读取更高效:
Files.lines(Paths.get(path),StandardCharsets.UTF_8).forEach(System.out::println);
最新文章
- C#获取屏幕鼠标所指点的颜色
- MySql 创建表 插入数据!
- UNIX网络编程-非阻塞connect和非阻塞accept
- Codeforce - Travelling Salesman
- OC语言-03-OC语言-三大特性
- Gym 100463A Crossings 逆序对
- python生态环境
- [RxJS] Drag and Drop example
- BZOJ 1069 最大土地面积
- MIUI是小米的核心竞争力
- wdcp升级php和mysql
- .net操作PDF的一些资源(downmoon收集)
- C#基于LibUsbDotNet实现USB通信(一)
- oracle之触发器
- RESTful API 设计思考
- 用U盘制作EXSI启动盘
- 移植Python3到TQ2440(二)
- opengl坐标系统
- Codeforces Round #504 D. Array Restoration
- bzoj2049: [Sdoi2008]Cave 洞穴勘测 lct裸题