Java –将文件转换为字符串

红太狼 2023-02-15 05:08 1阅读 0赞

在Java中，我们有很多方法可以将File转换为String。

文本文件，供以后测试。

c:\\\\projects\\\\app.log

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## 1. Java 11 – Files.readString ##

在`java.nio.file.Files`添加了一个新方法`Files.readString` ，它使从File中读取字符串变得更加容易。

FileToString1.java

package com.mkyong;
    
    import java.io.IOException;
    import java.nio.file.Files;
    import java.nio.file.Paths;
    
    public class FileToString1 {
    
        public static void main(String[] args) {
    
            String path = "c:\\projects\\app.log";
    
            try {
    
                // default StandardCharsets.UTF_8
                String content = Files.readString(Paths.get(path));
                System.out.println(content);
    
            } catch (IOException e) {
                e.printStackTrace();
            }
    
        }
    
    }

Terminal

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    E

## 2. Java 8 – Files.lines ##

将文件转换为`Stream`并加入。

FileToString2.java

package com.mkyong;
    
    import java.io.IOException;
    import java.nio.file.Files;
    import java.nio.file.Paths;
    import java.util.stream.Collectors;
    import java.util.stream.Stream;
    
    public class FileToString2 {
    
        public static void main(String[] args) {
    
            String path = "c:\\projects\\app.log";
    
            try (Stream<String> lines = Files.lines(Paths.get(path))) {
    
                // Formatting like \r\n will be lost
                // String content = lines.collect(Collectors.joining());
    
                // UNIX \n, WIndows \r\n
                String content = lines.collect(Collectors.joining(System.lineSeparator()));
                System.out.println(content);
    
    			// File to List
                //List<String> list = lines.collect(Collectors.toList());
    
            } catch (IOException e) {
                e.printStackTrace();
            }
    
        }
    
    }

Terminal

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## 3. Java 7 – Files.readAllLines ##

将文件转换为`List`

FileExample3.java

package com.mkyong;
    
    import java.io.IOException;
    import java.nio.charset.StandardCharsets;
    import java.nio.file.Files;
    import java.nio.file.Paths;
    import java.util.List;
    
    public class FileToString3 {
    
        public static void main(String[] args) {
    
            String path = "c:\\projects\\app.log";
    
            try {
    
                // default StandardCharsets.UTF_8
                // Java 8
                // List<String> content = Files.readAllLines(Paths.get(path));
    
    			// Java 7
                List<String> content = Files.readAllLines(Paths.get(path), StandardCharsets.UTF_8);
    
                System.out.println(content);
    
            } catch (IOException e) {
                e.printStackTrace();
            }
    
        }
    
    }

输出量

Terminal

[A, B, C, D, E]

## 4. Apache Commons IO ##

pom.xml

<dependency>
    		<groupId>commons-io</groupId>
    		<artifactId>commons-io</artifactId>
    		<version>2.6</version>
    	</dependency>

FileToString4.java

package com.mkyong;
    
    import org.apache.commons.io.FileUtils;
    
    import java.io.File;
    import java.io.IOException;
    import java.nio.charset.StandardCharsets;
    
    public class FileToString4 {
    
        public static void main(String[] args) {
    
            String path = "c:\\projects\\app.log";
    
            try {
                String content = FileUtils.readFileToString(new File(path), StandardCharsets.UTF_8);
                System.out.println(content);
            } catch (IOException e) {
                e.printStackTrace();
            }
    
        }
    
    }

输出量

Terminal

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## 参考文献 ##

*  [文件JavaDocs][JavaDocs]
 *  [BufferedReader JavaDocs][]
 *  [如何用Java读取文件– BufferedReader][Java_ BufferedReader]
 *  [Java 8 Stream –逐行读取文件][Java 8 Stream]

标记： [Java 11][] [Java 7][] [Java 8][] [java.io][] [java.nio][]

> 翻译自: [https://mkyong.com/java/java-convert-file-to-string/][https_mkyong.com_java_java-convert-file-to-string]

[JavaDocs]: https://docs.oracle.com/javase/8/docs/api/java/nio/file/Files.html
[BufferedReader JavaDocs]: https://docs.oracle.com/javase/8/docs/api/java/io/BufferedReader.html
[Java_ BufferedReader]: https://www.mkyong.com/java/how-to-read-file-from-java-bufferedreader-example/
[Java 8 Stream]: https://www.mkyong.com/java8/java-8-stream-read-a-file-line-by-line/
[Java 11]: https://mkyong.com/tag/java-11/
[Java 7]: https://mkyong.com/tag/java-7/
[Java 8]: https://mkyong.com/tag/java-8/
[java.io]: https://mkyong.com/tag/java-io/
[java.nio]: https://mkyong.com/tag/java-nio/
[https_mkyong.com_java_java-convert-file-to-string]: https://mkyong.com/java/java-convert-file-to-string/