InputStreamReader read = new InputStreamReader(new FileInputStream(file), encoding);
时间: 2023-12-04 08:22:41 浏览: 32
This line of code creates a new InputStreamReader object that takes in a FileInputStream object and an encoding parameter. The FileInputStream object represents a file input stream that reads bytes from the specified file. The InputStreamReader object then converts those bytes into characters using the specified encoding.
The resulting InputStreamReader object can be used to read the contents of the file as characters, rather than bytes. This is useful when working with text files, as it allows you to read and manipulate the contents of the file as strings.
相关问题
InputStreamReader
The InputStreamReader class is a subclass of the Reader class in Java. It reads bytes from an InputStream and decodes them into characters using a specified character encoding. The decoded characters are then made available to the programmer as a stream of characters.
The InputStreamReader class is used when we want to read data from an InputStream and process it as text. It provides a convenient way to convert binary data into text data.
Here is an example of using an InputStreamReader to read data from an InputStream:
```java
InputStream inputStream = new FileInputStream("data.txt");
InputStreamReader reader = new InputStreamReader(inputStream, "UTF-8");
int data = reader.read();
while (data != -1) {
char ch = (char) data;
System.out.print(ch);
data = reader.read();
}
reader.close();
inputStream.close();
```
In this example, we create an InputStream from a file called "data.txt". We then create an InputStreamReader using the UTF-8 character encoding. We read data from the InputStreamReader one character at a time using the read() method. The read() method returns -1 when the end of the stream is reached. Finally, we close the InputStreamReader and the InputStream.
java判断编码格式
Java可以通过以下方式判断一个文件的编码格式:
1. 使用 `InputStreamReader` 类读取文件,并指定字符集编码,如果能够正常读取文件,则表示该文件的编码格式与指定的字符集编码相同。
```java
File file = new File("文件路径");
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));
InputStreamReader isr = new InputStreamReader(bis, "utf-8");
char[] buffer = new char[1024];
int length = 0;
StringBuilder sb = new StringBuilder();
while ((length = isr.read(buffer)) != -1) {
sb.append(buffer, 0, length);
}
isr.close();
bis.close();
String content = sb.toString();
```
2. 使用 `UniversalDetector` 类判断文件的编码格式。
```java
File file = new File("文件路径");
byte[] buffer = new byte[4096];
UniversalDetector detector = new UniversalDetector(null);
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));
int nread;
while ((nread = bis.read(buffer)) > 0 && !detector.isDone()) {
detector.handleData(buffer, 0, nread);
}
detector.dataEnd();
String encoding = detector.getDetectedCharset();
detector.reset();
bis.close();
```
需要注意的是,这种方式需要依赖 `juniversalchardet` 库,可以通过 Maven 或 Gradle 等构建工具引入该库。
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