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hutool actual combat (take you to master various tools inside) directory

Purpose: IO tool class (common operation of stream)

Usage scenario

The IO tool class is only used to read and write auxiliary streams and is not responsible for closing streams. The reason is that the stream may be read and written many times, which is easy to cause problems after reading and writing is closed.
Including but not limited to: flush,close, compare the contents of two streams, calculate the check code of the stream and return the line traverser, etc.

Project reference

The basis of this blog post: hutool-5.6.5 version source code

        <dependency>
			<groupId>cn.hutool</groupId>
			<artifactId>hutool-core</artifactId>
			<version>5.6.5</version>
		</dependency>

Method summary

 LineIterator it = null; try { 	it = IoUtil.lineIter(reader); 	while (it.hasNext()) { 		String line = it.nextLine(); 		// do something with line 	} } finally { 		it.close(); } 

 LineIterator it = null; try { 	it = IoUtil.lineIter(in, CharsetUtil.CHARSET_UTF_8); 	while (it.hasNext()) { 		String line = it.nextLine(); 		// do something with line 	} } finally { 		it.close(); } 

Method details

Method name: CN hutool. core. io. IoUtil. flush(java.io.Flushable)

Method description

Flush data from cache

Supported version and above

4.2.2

Parameter Description:

Return value:

Reference case:

//Traditional writing
		File dest = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/flushTest.txt") ;
		FileOutputStream outputStream = null;
		OutputStreamWriter outputStreamWriter = null;
		try {
			//Create stream
			outputStream = new FileOutputStream(dest);
			//For the new OutputStreamWriter object, remember to turn off recycling
			outputStreamWriter = IoUtil.getUtf8Writer(outputStream);
			String content = "1hello Xiaoxuzhu\n2hello Xiaoxuzhu";
			int c;
			for (int i = 0; i < content.length(); i++) {
				c = content.charAt(i);
				outputStreamWriter.write((char) c);

			}
			outputStreamWriter.flush();
		} catch (IOException e) {
			//Throw a runtime exception (stop the program directly)
			throw new RuntimeException("Runtime exception",e);
		} finally {
			try {
				//If it is empty, it means that the creation of the stream fails and does not need to be closed
				if (outputStream != null) {
					outputStream.close();
				}
			} catch (Exception e) {
				//Failed to close the resource. Stop the program
				throw new RuntimeException("Failed to close resource");
			}finally {
				try {
					if (outputStreamWriter != null) {
						outputStreamWriter.close();
					}
				} catch (Exception e) {
					throw new RuntimeException("Failed to close resource");
				}
			}
		}
		
		//Use ioutil How to write flush
				File dest = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/flushTest.txt") ;
		FileOutputStream outputStream = null;
		OutputStreamWriter outputStreamWriter = null;
		try {
			//Create stream
			outputStream = new FileOutputStream(dest);
			//For the new OutputStreamWriter object, remember to turn off recycling
			outputStreamWriter = IoUtil.getUtf8Writer(outputStream);
			String content = "1hello Xiaoxuzhu\n2hello Xiaoxuzhu";
			int c;
			for (int i = 0; i < content.length(); i++) {
				c = content.charAt(i);
				outputStreamWriter.write((char) c);

			}
			IoUtil.flush(outputStreamWriter);
		} catch (IOException e) {
			//Throw a runtime exception (stop the program directly)
			throw new RuntimeException("Runtime exception",e);
		} finally {
			IoUtil.close(outputStream);
			IoUtil.close(outputStreamWriter);
		}

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. close(java.io.Closeable)

Method description

close

If the shutdown fails, no exception will be thrown

Supported version and above

Parameter Description:

Return value:

Reference case:

//Traditional writing
		File dest = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/flushTest.txt") ;
		FileOutputStream outputStream = null;
		OutputStreamWriter outputStreamWriter = null;
		try {
			//Create stream
			outputStream = new FileOutputStream(dest);
			//For the new OutputStreamWriter object, remember to turn off recycling
			outputStreamWriter = IoUtil.getUtf8Writer(outputStream);
			String content = "1hello Xiaoxuzhu\n2hello Xiaoxuzhu";
			int c;
			for (int i = 0; i < content.length(); i++) {
				c = content.charAt(i);
				outputStreamWriter.write((char) c);

			}
			outputStreamWriter.flush();
		} catch (IOException e) {
			//Throw a runtime exception (stop the program directly)
			throw new RuntimeException("Runtime exception",e);
		} finally {
			try {
				//If it is empty, it means that the creation of the stream fails and does not need to be closed
				if (outputStream != null) {
					outputStream.close();
				}
			} catch (Exception e) {
				//Failed to close the resource. Stop the program
				throw new RuntimeException("Failed to close resource");
			}finally {
				try {
					if (outputStreamWriter != null) {
						outputStreamWriter.close();
					}
				} catch (Exception e) {
					throw new RuntimeException("Failed to close resource");
				}
			}
		}
		
		//Use ioutil How to write close
				File dest = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/flushTest.txt") ;
		FileOutputStream outputStream = null;
		OutputStreamWriter outputStreamWriter = null;
		try {
			//Create stream
			outputStream = new FileOutputStream(dest);
			//For the new OutputStreamWriter object, remember to turn off recycling
			outputStreamWriter = IoUtil.getUtf8Writer(outputStream);
			String content = "1hello Xiaoxuzhu\n2hello Xiaoxuzhu";
			int c;
			for (int i = 0; i < content.length(); i++) {
				c = content.charAt(i);
				outputStreamWriter.write((char) c);

			}
			IoUtil.flush(outputStreamWriter);
		} catch (IOException e) {
			//Throw a runtime exception (stop the program directly)
			throw new RuntimeException("Runtime exception",e);
		} finally {
			IoUtil.close(outputStream);
			IoUtil.close(outputStreamWriter);
		}

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. closeIfPosible(java.lang.Object)

Method description

Try to close the specified object < br >
If the judgment object implements {@ link autoclosable}, call it

Supported version and above

4.3.2

Parameter Description:

Return value:

Reference case:

		public class AutoCloseableObject implements AutoCloseable{
	@Override
	public void close() throws Exception {
		System.out.println("--close AutoCloseableObject--");
	}

	public void demo(){
		System.out.println("This is AutoCloseableObject In the object demo method");
		//After 1.7, as long as the autocolosable interface is implemented
		try (FileInputStream fileInputStream = new FileInputStream("C:\\Users\\Administrator\\Desktop\\xuzhu/flushTest.txt")) {
			System.out.println("--fileInputStream--");
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}


	}
}
		//----------------------------------
		//First understand the working principle of autoclosable
		//1,AutoCloseable jdk1.7 + is supported
		//2. try method can manage multiple resources and use; Number separation
		//3. The managed resources must implement the autoclosable interface
		try(AutoCloseableObject object = new AutoCloseableObject())  {
			System.out.println("--implement closeIfPosibleTest method--");
			System.out.println("--demo--");
			object.demo();
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}

Reference case 2:

	try (FileInputStream fileInputStream = new FileInputStream("C:\\Users\\Administrator\\Desktop\\xuzhu/flushTest.txt")) {
			System.out.println("--fileInputStream--");
			IoUtil.closeIfPosible(fileInputStream);
			System.out.println(fileInputStream);
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. contentEquals(java.io.InputStream, java.io.InputStream)

Method description

Compare whether the contents of two streams are the same < br >
The internal stream will be converted to {@ link BufferedInputStream}

Supported version and above

4.0.6

Parameter Description:

Return value:

If the contents of the two streams are consistent, return true, otherwise false

Reference case 1:

		File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/copyTest1.txt") ;
		File dest = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/toCopyTest1.txt") ;
		try (FileInputStream srcFileInputStream = new FileInputStream(src);
			 FileInputStream destFileInputStream = new FileInputStream(dest)) {
			Assert.assertEquals(Boolean.TRUE, IoUtil.contentEquals(srcFileInputStream,destFileInputStream));
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}	

Reference case 2:

				File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/copyTest1.txt") ;
		File flushFile = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/flushTest.txt") ;
		try (FileInputStream srcFileInputStream = new FileInputStream(src);
			 FileInputStream flushFileInputStream = new FileInputStream(flushFile)) {
			Assert.assertEquals(Boolean.FALSE, IoUtil.contentEquals(srcFileInputStream,flushFileInputStream));
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. contentEquals(java.io.Reader, java.io.Reader)

Method description

Compare whether the contents of two readers are consistent < br >
The internal stream will be converted to {@ link BufferedInputStream}

Supported version and above

4.0.6

Parameter Description:

Return value:

If the contents of the two streams are consistent, return true, otherwise false

Reference case 1:

	File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/copyTest1.txt") ;
		File dest = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/toCopyTest1.txt") ;
		try (FileReader srcFileFileReader = new FileReader(src);
			 FileReader destFileFileReader = new FileReader(dest)) {
			Assert.assertEquals(Boolean.TRUE, IoUtil.contentEquals(srcFileFileReader,destFileFileReader));
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}	

Reference case 2:

	File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/copyTest1.txt") ;
		File flushFile = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/flushTest.txt") ;
		try (FileReader srcFileFileReader = new FileReader(src);
			 FileReader flushFileFileReader = new FileReader(flushFile)) {
			Assert.assertEquals(Boolean.FALSE, IoUtil.contentEquals(srcFileFileReader,flushFileFileReader));
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}

​

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. contentEqualsIgnoreEOL(java.io.Reader, java.io.Reader)

Method description

Compare whether the contents of the two streams are the same, and ignore the EOL character < br >
The internal stream will be converted to {@ link BufferedInputStream}

Supported version and above

4.0.6

Parameter Description:

Return value:

If the contents of the two streams are consistent, return true, otherwise false

Reference case 1:

		//Compare whether the contents of the two streams are the same. Ignore the EOL character. For example, \ R is the EOL character
		File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/contentEqualsIgnoreEOLTest1.txt") ;
		File dest = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/toContentEqualsIgnoreEOLTest1.txt") ;
		try (FileReader srcFileFileReader = new FileReader(src);
			 FileReader destFileFileReader = new FileReader(dest)) {
			Assert.assertEquals(Boolean.TRUE, IoUtil.contentEqualsIgnoreEOL(srcFileFileReader,destFileFileReader));
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}

Reference case 2:

		//Compare whether the contents of the two streams are the same. Ignore the EOL character. For example, \ R is the EOL character
		File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/contentEqualsIgnoreEOLTest1.txt") ;
		File flushFile = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/contentEqualsIgnoreEOLTest2.txt") ;
		try (FileReader srcFileFileReader = new FileReader(src);
			 FileReader flushFileFileReader = new FileReader(flushFile)) {
			Assert.assertEquals(Boolean.TRUE, IoUtil.contentEqualsIgnoreEOL(srcFileFileReader,flushFileFileReader));
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. checksumCRC32(java.io.InputStream)

Method description

Calculate the CRC32 check code of the stream, and close the stream after calculation

(what is CRC32: CRC is a value that is used to verify the correctness of data. Similar checks include MD5 check code)

Supported version and above

4.0.6

Parameter Description:

Return value:

CRC32 value

Reference case:

		File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/contentEqualsIgnoreEOLTest1.txt") ;
		try {
			FileInputStream srcFileInputStream = new FileInputStream(src);
			//Calculate the check code of the flow, and close the flow after calculation
			System.out.println( IoUtil.checksumCRC32(srcFileInputStream));
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. checksum(java.io.InputStream, java.util.zip.Checksum)

Method description

Calculate the check code of the flow and close the flow after calculation

Supported version and above

4.0.10

Parameter Description:

Return value:

Checksum

Reference case:

		File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/contentEqualsIgnoreEOLTest1.txt") ;
		try {
			FileInputStream srcFileInputStream = new FileInputStream(src);
			//Calculate the check code of the flow, close the flow after calculation, and support the optional check code to realize Checksum
			System.out.println( IoUtil.checksum(srcFileInputStream,new CRC32()).getValue());
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. checksumValue(java.io.InputStream, java.util.zip.Checksum)

Method description

Calculate the check code of the flow and close the flow after calculation

Supported version and above

5.4.0

Parameter Description:

Return value:

Checksum

Reference case:

		File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/contentEqualsIgnoreEOLTest1.txt") ;
		try {
			FileInputStream srcFileInputStream = new FileInputStream(src);
			//Calculate the check code of the flow, close the flow after calculation, and support the optional check code to realize Checksum
			System.out.println( IoUtil.checksumValue(srcFileInputStream,new CRC32()));
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
		}

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. lineIter(java.io.Reader)

Method description

Return line iterator

 LineIterator it = null;
 try {
 	it = IoUtil.lineIter(reader);
 	while (it.hasNext()) {
 		String line = it.nextLine();
 		// do something with line
 	}
 } finally {
 		it.close();
 }
 

Supported version and above

5.6.1

Parameter Description:

Return value:

{@link LineIter}

Reference case:

		File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/contentEqualsIgnoreEOLTest1.txt") ;
		LineIter it = null;
		try (FileReader srcFileFileReader = new FileReader(src)) {
			//Return line iterator
			it = IoUtil.lineIter(srcFileFileReader);
			while (it.hasNext()) {
	 		String line = it.nextLine();
				System.out.println("Row traverser row data:"+line);
	  	}
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
			it.close();
		}

Source code analysis:

Link: to be added

Method details

Method name: CN hutool. core. io. IoUtil. lineIter(java.io.InputStream, java.nio.charset.Charset)

Method description

Return line iterator

 LineIterator it = null;
 try {
 	it = IoUtil.lineIter(in, CharsetUtil.CHARSET_UTF_8);
 	while (it.hasNext()) {
 		String line = it.nextLine();
 		// do something with line
 	}
 } finally {
 		it.close();
 }
 

Supported version and above

5.6.1

Parameter Description:

Return value:

{@link LineIter}

Reference case:

		File src = new File("C:\\Users\\Administrator\\Desktop\\xuzhu/contentEqualsIgnoreEOLTest1.txt") ;
		LineIter it = null;
		try (FileInputStream srcFileInputStream = new FileInputStream(src);) {
			//Return line iterator
			it = IoUtil.lineIter(srcFileInputStream,CharsetUtil.CHARSET_UTF_8);
			while (it.hasNext()) {
				String line = it.nextLine();
				System.out.println("Row traverser row data:"+line);
			}
		}catch (Exception e){
			System.out.println("--exception--");
		}finally {
			System.out.println("--finally--");
			it.close();
		}

Source code analysis:

Link: to be added