Java中如何按行读取文件及一次性全部读取数据呢?

读取文件的实现思路

1.一行一行读取文件
   使用readLine()方法

2.一次读取全部文件
   使用read()方法

一行一行的读取文件

ClassPathResource classPathResource = new ClassPathResource("fileName.txt");
InputStream inputStream =classPathResource.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String txt = "";
while(reader.ready()) {
 
    txt += reader.readLine();
}
 
String s = new String(Base64.encodeBase64(txt.getBytes(UTF_8)), UTF_8);


一次性读取文件
private String getFile(String fileName) throws IOException {

	ClassPathResource classPathResource = new ClassPathResource(fileName);
	File file = classPathResource.getFile();
	FileInputStream in = new FileInputStream(file);
	byte[] fileContent = new byte[(int) file.length()];
	in.read(fileContent);
	String txt = new String(fileContent);

	String pileString = new String(Base64.encodeBase64(txt.getBytes(UTF_8)), UTF_8);
	return pileString;
}