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  • 在 Java 中如何读取文件并将文件转换为字符串？ （5种不同的方式）

在 Java 中如何读取文件并将文件转换为字符串？ （5种不同的方式）

已发表: 2021-11-21
在 Java 中如何读取文件并将文件转换为字符串？ （5种不同的方式）

将文件读入字符串的最简单方法是什么？ 你想用 Java 读取纯文本文件吗？ 您想如何将 File 对象转换为 String 对象？ 我们可以通过多种方式读取文件并将其转换为字符串。

有 5 种方法可以将整个文本文件转换为 Java 中的字符串。

  1. 文件.readString()
  2. Files.readAllLines(Paths.get(path), StandardCharsets.UTF_8);
  3. FileUtils.readFileToString(new File(path), StandardCharsets.UTF_8); – Apache Commons IO 依赖
  4. 文件.lines()
  5. Files.newBufferedReader()

让我们开始吧：

  • 确保在下面添加 Apache Commons IO 依赖项。
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       < dependency >
             < groupId > commons - io < / groupId >
             < artifactId > commons - io < / artifactId >
             < version > 2.11.0 < / version >
         < / dependency >
  • 创建类 CrunchifyConvertFileToString.java。
  • 将以下代码复制并粘贴到其中。

CrunchifyConvertFileToString.java

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package crunchify . com . java . tutorials ;
 
import org . apache . commons . io . FileUtils ;
 
import java . io . File ;
import java . io . IOException ;
import java . nio . charset . StandardCharsets ;
import java . nio . file . Files ;
import java . nio . file . Paths ;
import java . util . List ;
 
/**
* @author Crunchify.com
* Program: In Java How to Read a File and Convert File to String? (5 different ways)
*/
 
public class CrunchifyConvertFileToString {
     public static void main ( String [ ] args ) {
 
         // Files.readString()
         crunchifyFilesReadString ( ) ;
 
         // Files.readAllLines(Paths.get();
         crunchifyFilesReadAllLines ( ) ;
 
         // FileUtils.readFileToString(new File();
         // Apache Commons IO method
         crunchifyFileUtilsReadFileToString ( ) ;
 
         // Files.lines()
         // Please visit: https://crunchify.me/3CDrP7N
         crunchifyFilesLines ( ) ;
 
         // Files.newBufferedReader()
         // Please visit: https://crunchify.me/3CDrP7N
         crunchifyFilesNewBufferedReader ( ) ;
 
     }
 
 
     /*
    Method-1: Files.readString()
     */
     private static void crunchifyFilesReadString ( ) {
         String crunchifyFilePath = "/Users/app/Downloads/crunchify-file-to-string.txt" ;
 
         try {
             crunchifyLog ( "\n================= Files.readString() =================" ) ;
 
             // Files: This class consists exclusively of static methods that operate on files, directories, or other types of files.
             // Paths: This class consists exclusively of static methods that return a Path by converting a path string or URI.
             // get(): Converts a path string, or a sequence of strings that when joined form a path string, to a Path.
 
             String crunchifyFileData = Files . readString ( Paths . get ( crunchifyFilePath ) ) ;
 
             crunchifyLog ( crunchifyFileData ) ;
 
         } catch ( IOException exception ) {
             exception . printStackTrace ( ) ;
         }
     }
 
     /*
    Simple Logging Utility
     */
     private static void crunchifyLog ( Object crunchifyFileData ) {
 
         System . out . println ( crunchifyFileData ) ;
     }
 
     /*
    Method-2: Files.readAllLines(Paths.get();
     */
     private static void crunchifyFilesReadAllLines ( ) {
 
         crunchifyLog ( "================= Files.readAllLines() =================" ) ;
 
         String crunchifyFilePath = "/Users/app/Downloads/crunchify-file-to-string.txt" ;
 
         try {
 
             // readAllLines(): Read all lines from a file. This method ensures that the file is closed when
             // all bytes have been read or an I/O error, or other runtime exception, is thrown.
             // Bytes from the file are decoded into characters using the specified charset.
 
             // This method recognizes the following as line terminators:
 
             /*  \u000D followed by \u000A, CARRIAGE RETURN followed by LINE FEED
                \u000A, LINE FEED
                \u000D, CARRIAGE RETURN
            */
 
             List < String > crunchifyFileData = Files . readAllLines ( Paths . get ( crunchifyFilePath ) , StandardCharsets . UTF_8 ) ;
 
             crunchifyLog ( crunchifyFileData ) ;
 
         } catch ( IOException exception ) {
             exception . printStackTrace ( ) ;
         }
 
     }
 
     /*
    Method-3: FileUtils.readFileToString(new File();
    Apache Commons IO:  <dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.6</version></dependency>
     */
     private static void crunchifyFileUtilsReadFileToString ( ) {
 
         crunchifyLog ( "\n================= FileUtils.readFileToString() =================" ) ;
 
         String crunchifyFilePath = "/Users/app/Downloads/crunchify-file-to-string.txt" ;
 
         try {
 
             // readFileToString: Reads the contents of a file into a String. The file is always closed.
             String crunchifyFileData = FileUtils . readFileToString ( new File ( crunchifyFilePath ) , StandardCharsets . UTF_8 ) ;
             // UTF_8: Eight-bit UCS Transformation Format.
 
             crunchifyLog ( crunchifyFileData ) ;
         } catch ( IOException exception ) {
             exception . printStackTrace ( ) ;
         }
 
     }
 
     /*
    Method-4: Files.lines()
    */
     private static void crunchifyFilesLines ( ) {
 
         // Please visit: https://crunchify.me/3CDrP7N
     }
 
     /*
    Method-5: Files.newBufferedReader()
    */
     private static void crunchifyFilesNewBufferedReader ( ) {
 
         // Please visit: https://crunchify.me/3CDrP7N
     }
 
}
 

IntelliJ IDEA 控制台结果：

只需将上述程序作为 Java 应用程序运行，您将看到如下结果。

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================= Files . readString ( ) =================
Five Ways to Read File and Convert it to String : )
 
Files . readString ( )
Files . readAllLines ( Paths . get ( path ) , StandardCharsets . UTF_8 ) ;
FileUtils . readFileToString ( new File ( path ) , StandardCharsets . UTF_8 ) ;
Files . lines ( )
Files . newBufferedReader ( )
 
================= Files . readAllLines ( ) =================
[ Five Ways to Read File and Convert it to String : ) , , Files . readString ( ) , Files . readAllLines ( Paths . get ( path ) , StandardCharsets . UTF_8 ) ; , FileUtils . readFileToString ( new File ( path ) , StandardCharsets . UTF_8 ) ; , Files . lines ( ) , Files . newBufferedReader ( ) ]
 
================= FileUtils . readFileToString ( ) =================
Five Ways to Read File and Convert it to String : )
 
Files . readString ( )
Files . readAllLines ( Paths . get ( path ) , StandardCharsets . UTF_8 ) ;
FileUtils . readFileToString ( new File ( path ) , StandardCharsets . UTF_8 ) ;
Files . lines ( )
Files . newBufferedReader ( )
 
 
Process finished with exit code 0

如果您在运行以上代码时遇到任何问题，请告诉我。

这里有一个解释方法 4 和方法 5 的教程：

如何使用 Java 8 Stream 逐行读取文件 – Files.lines() 和 Files.newBufferedReader() 实用程序 API