Java : Buffer 示例

Java 中的 Buffer (Java SE 22 & JDK 22) 及其示例。
您将找到大多数 Buffer 方法的代码示例。

注解 :

本文可能使用了翻译软件以方便阅读。另请查看英文原文。

简介

特定原始类型数据的容器。 (机器翻译)

Class diagram

final var buffer = IntBuffer.allocate(5);

System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.capacity()); // 5
System.out.println(buffer.limit()); // 5
System.out.println(buffer.position()); // 0

buffer.put(10);
System.out.println(buffer.position()); // 1

buffer.put(20);
System.out.println(buffer.position()); // 2

buffer.put(30);
System.out.println(buffer.position()); // 3

if (buffer.hasArray()) {
    final var ret = buffer.array();
    System.out.println(Arrays.toString(ret)); // [10, 20, 30, 0, 0]
}

final byte[] array = {10, 20, 30};
final var buffer = ByteBuffer.wrap(array);

System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.capacity()); // 3
System.out.println(buffer.limit()); // 3
System.out.println(buffer.position()); // 0

System.out.println(buffer.get()); // 10
System.out.println(buffer.position()); // 1

System.out.println(buffer.get()); // 20
System.out.println(buffer.position()); // 2

System.out.println(buffer.get()); // 30
System.out.println(buffer.position()); // 3

Methods

abstract Object array ()

返回支持此缓冲区的数组（可选操作）。 (机器翻译)

final Buffer buffer = IntBuffer.allocate(5)
        .put(10)
        .put(20)
        .put(30);

if (buffer.hasArray()) {
    if (buffer.array() instanceof int[] array) {
        System.out.println(Arrays.toString(array)); // [10, 20, 30, 0, 0]
    }
}

abstract int arrayOffset ()

返回此缓冲区的支持数组中缓冲区第一个元素的偏移量（可选操作）。 (机器翻译)

final byte[] bytes = {10, 20, 30, 40, 50};

final var buffer = ByteBuffer.wrap(bytes);
System.out.println(buffer instanceof Buffer); // true

final var sliced = buffer.slice(2, 3);
System.out.println(sliced instanceof Buffer); // true

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=0 lim=5 cap=5]
if (buffer.hasArray()) {
    System.out.println(buffer.arrayOffset()); // 0
    System.out.println(buffer.get()); // 10
    System.out.println(buffer.get()); // 20
    System.out.println(buffer.get()); // 30
    System.out.println(buffer.get()); // 40
    System.out.println(buffer.get()); // 50
}

System.out.println(sliced); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=3]
if (sliced.hasArray()) {
    System.out.println(sliced.arrayOffset()); // 2
    System.out.println(sliced.get()); // 30
    System.out.println(sliced.get()); // 40
    System.out.println(sliced.get()); // 50
}

final int capacity ()

返回此缓冲区的容量。 (机器翻译)

final Buffer buffer = ByteBuffer.allocate(100);
System.out.println(buffer.capacity()); // 100

final byte[] bytes = {10, 20, 30, 40, 50};
final Buffer buffer = ByteBuffer.wrap(bytes);

System.out.println(buffer.capacity()); // 5

Buffer clear ()

清除此缓冲区。 (机器翻译)

Please see also : rewind()

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

buffer.position(2);
buffer.limit(4);

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=2 lim=4 cap=5]

System.out.println(buffer.get()); // 30
System.out.println(buffer.get()); // 40
System.out.println(buffer.hasRemaining()); // false

System.out.println(buffer.clear()); // java.nio.HeapByteBuffer[pos=0 lim=5 cap=5]

System.out.println(buffer.get()); // 10
System.out.println(buffer.get()); // 20
System.out.println(buffer.get()); // 30
System.out.println(buffer.get()); // 40
System.out.println(buffer.get()); // 50
System.out.println(buffer.hasRemaining()); // false

abstract Buffer duplicate ()

创建一个共享此缓冲区内容的新缓冲区。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

buffer.position(1);
buffer.limit(4);

final var duplicated = buffer.duplicate();
System.out.println(duplicated instanceof Buffer); // true

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=1 lim=4 cap=5]
System.out.println(duplicated); // java.nio.HeapByteBuffer[pos=1 lim=4 cap=5]

System.out.println(buffer.get()); // 20
System.out.println(buffer.get()); // 30
System.out.println(buffer.get()); // 40

System.out.println(duplicated.get()); // 20
System.out.println(duplicated.get()); // 30
System.out.println(duplicated.get()); // 40

Buffer flip ()

翻转此缓冲区。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.get()); // 10
System.out.println(buffer.get()); // 20
System.out.println(buffer.get()); // 30

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=3 lim=5 cap=5]
System.out.println(buffer.flip()); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=5]

System.out.println(buffer.get()); // 10
System.out.println(buffer.get()); // 20
System.out.println(buffer.get()); // 30

abstract boolean hasArray ()

告知此缓冲区是否由可访问数组支持。 (机器翻译)

final var buffer = IntBuffer.allocate(5)
        .put(10)
        .put(20)
        .put(30);
System.out.println(buffer instanceof Buffer); // true

final var ret = buffer.hasArray();
System.out.println(ret); // true

if (ret) {
    final var array = buffer.array();
    System.out.println(Arrays.toString(array)); // [10, 20, 30, 0, 0]
}

final var buffer = ByteBuffer.allocateDirect(5);
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.hasArray()); // false
try {
    var _ = buffer.array();
} catch (UnsupportedOperationException e) {
    System.out.println("UnsupportedOperationException!");
}

// Result
// ↓
//UnsupportedOperationException!

final boolean hasRemaining ()

判断当前位置和限制之间是否存在任何元素。 (机器翻译)

final byte[] array = {10, 20, 30, 40};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

buffer.limit(3);

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=4]
System.out.println(buffer.hasRemaining()); // true
System.out.println(buffer.remaining()); // 3

System.out.println(buffer.get()); // 10

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=1 lim=3 cap=4]
System.out.println(buffer.hasRemaining()); // true
System.out.println(buffer.remaining()); // 2

System.out.println(buffer.get()); // 20

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=2 lim=3 cap=4]
System.out.println(buffer.hasRemaining()); // true
System.out.println(buffer.remaining()); // 1

System.out.println(buffer.get()); // 30

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=3 lim=3 cap=4]
System.out.println(buffer.hasRemaining()); // false
System.out.println(buffer.remaining()); // 0

abstract boolean isDirect ()

告知该缓冲区是否是直接的。 (机器翻译)

final Buffer buffer = ByteBuffer.allocate(5);
System.out.println(buffer.isDirect()); // false

final Buffer buffer = ByteBuffer.allocateDirect(5);
System.out.println(buffer.isDirect()); // true

abstract boolean isReadOnly ()

告知该缓冲区是否是只读的。 (机器翻译)

final var buffer = IntBuffer.allocate(5);
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.isReadOnly()); // false

buffer.put(10);
buffer.put(20);
buffer.put(30);

System.out.println(buffer); // java.nio.HeapIntBuffer[pos=3 lim=5 cap=5]

final var buffer = IntBuffer.allocate(5).asReadOnlyBuffer();
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.isReadOnly()); // true

try {
    buffer.put(10);
} catch (ReadOnlyBufferException e) {
    System.out.println("ReadOnlyBufferException!");
}

// Result
// ↓
//ReadOnlyBufferException!

final int limit ()

返回此缓冲区的限制。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final Buffer buffer = ByteBuffer.wrap(array);

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.limit()); // 5

System.out.println(buffer.limit(3)); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=5]
System.out.println(buffer.limit()); // 3

System.out.println(buffer.clear()); // java.nio.HeapByteBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.limit()); // 5

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.limit(3)); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=5]

System.out.println(buffer.get()); // 10
System.out.println(buffer.get()); // 20
System.out.println(buffer.get()); // 30

try {
    var _ = buffer.get();
} catch (BufferUnderflowException e) {
    System.out.println("BufferUnderflowException!");
}

// Result
// ↓
//BufferUnderflowException!

Buffer limit (int newLimit)

设置此缓冲区的限制。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final Buffer buffer = ByteBuffer.wrap(array);

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.limit()); // 5

System.out.println(buffer.limit(3)); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=5]
System.out.println(buffer.limit()); // 3

System.out.println(buffer.clear()); // java.nio.HeapByteBuffer[pos=0 lim=5 cap=5]
System.out.println(buffer.limit()); // 5

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.limit(3)); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=5]

System.out.println(buffer.get()); // 10
System.out.println(buffer.get()); // 20
System.out.println(buffer.get()); // 30

try {
    var _ = buffer.get();
} catch (BufferUnderflowException e) {
    System.out.println("BufferUnderflowException!");
}

// Result
// ↓
//BufferUnderflowException!

Buffer mark ()

在此缓冲区的位置设置其标记。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.get()); // 10
System.out.println(buffer.get()); // 20

System.out.println(buffer.position()); // 2
System.out.println(buffer.mark()); // java.nio.HeapByteBuffer[pos=2 lim=5 cap=5]

System.out.println(buffer.get()); // 30
System.out.println(buffer.get()); // 40
System.out.println(buffer.get()); // 50

System.out.println(buffer.position()); // 5
System.out.println(buffer.reset()); // java.nio.HeapByteBuffer[pos=2 lim=5 cap=5]

System.out.println(buffer.get()); // 30
System.out.println(buffer.get()); // 40
System.out.println(buffer.get()); // 50

final int position ()

返回此缓冲区的位置。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.position()); // 0

System.out.println(buffer.get()); // 10
System.out.println(buffer.position()); // 1

System.out.println(buffer.get()); // 20
System.out.println(buffer.position()); // 2

System.out.println(buffer.get()); // 30
System.out.println(buffer.position()); // 3

System.out.println(buffer.get()); // 40
System.out.println(buffer.position()); // 4

System.out.println(buffer.get()); // 50
System.out.println(buffer.position()); // 5

System.out.println(buffer.position(3)); // java.nio.HeapByteBuffer[pos=3 lim=5 cap=5]

System.out.println(buffer.get()); // 40
System.out.println(buffer.position()); // 4

System.out.println(buffer.get()); // 50
System.out.println(buffer.position()); // 5

Buffer position (int newPosition)

设置此缓冲区的位置。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.position()); // 0

System.out.println(buffer.get()); // 10
System.out.println(buffer.position()); // 1

System.out.println(buffer.get()); // 20
System.out.println(buffer.position()); // 2

System.out.println(buffer.get()); // 30
System.out.println(buffer.position()); // 3

System.out.println(buffer.get()); // 40
System.out.println(buffer.position()); // 4

System.out.println(buffer.get()); // 50
System.out.println(buffer.position()); // 5

System.out.println(buffer.position(3)); // java.nio.HeapByteBuffer[pos=3 lim=5 cap=5]

System.out.println(buffer.get()); // 40
System.out.println(buffer.position()); // 4

System.out.println(buffer.get()); // 50
System.out.println(buffer.position()); // 5

final int remaining ()

返回当前位置和限制之间的元素数。 (机器翻译)

final byte[] array = {10, 20, 30, 40};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

buffer.limit(3);

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=4]
System.out.println(buffer.hasRemaining()); // true
System.out.println(buffer.remaining()); // 3

System.out.println(buffer.get()); // 10

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=1 lim=3 cap=4]
System.out.println(buffer.hasRemaining()); // true
System.out.println(buffer.remaining()); // 2

System.out.println(buffer.get()); // 20

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=2 lim=3 cap=4]
System.out.println(buffer.hasRemaining()); // true
System.out.println(buffer.remaining()); // 1

System.out.println(buffer.get()); // 30

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=3 lim=3 cap=4]
System.out.println(buffer.hasRemaining()); // false
System.out.println(buffer.remaining()); // 0

Buffer reset ()

将此缓冲区的位置重置为先前标记的位置。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

System.out.println(buffer.get()); // 10
System.out.println(buffer.get()); // 20

System.out.println(buffer.position()); // 2
System.out.println(buffer.mark()); // java.nio.HeapByteBuffer[pos=2 lim=5 cap=5]

System.out.println(buffer.get()); // 30
System.out.println(buffer.get()); // 40
System.out.println(buffer.get()); // 50

System.out.println(buffer.position()); // 5
System.out.println(buffer.reset()); // java.nio.HeapByteBuffer[pos=2 lim=5 cap=5]

System.out.println(buffer.get()); // 30
System.out.println(buffer.get()); // 40
System.out.println(buffer.get()); // 50

Buffer rewind ()

倒回此缓冲区。 (机器翻译)

Please see also : clear()

final int[] array = {10, 20, 30, 40, 50};
final Buffer buffer = IntBuffer.wrap(array);

buffer.position(2);
buffer.limit(4);

System.out.println(buffer.position()); // 2
System.out.println(buffer.limit()); // 4

System.out.println(buffer.rewind()); // java.nio.HeapIntBuffer[pos=0 lim=4 cap=5]

System.out.println(buffer.position()); // 0
System.out.println(buffer.limit()); // 4

abstract Buffer slice ()

创建一个新的缓冲区，其内容是此缓冲区内容的共享子序列。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

buffer.position(1);
buffer.limit(4);

final var sliced = buffer.slice();
System.out.println(sliced instanceof Buffer); // true

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=1 lim=4 cap=5]
System.out.println(sliced); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=3]

System.out.println(buffer.get()); // 20
System.out.println(buffer.get()); // 30
System.out.println(buffer.get()); // 40
System.out.println(buffer.hasRemaining()); // false

System.out.println(sliced.get()); // 20
System.out.println(sliced.get()); // 30
System.out.println(sliced.get()); // 40
System.out.println(sliced.hasRemaining()); // false

abstract Buffer slice (int index, int length)

创建一个新的缓冲区，其内容是此缓冲区内容的共享子序列。 (机器翻译)

final byte[] array = {10, 20, 30, 40, 50};
final var buffer = ByteBuffer.wrap(array);
System.out.println(buffer instanceof Buffer); // true

final var sliced = buffer.slice(2, 3);
System.out.println(sliced instanceof Buffer); // true

System.out.println(buffer); // java.nio.HeapByteBuffer[pos=0 lim=5 cap=5]
System.out.println(sliced); // java.nio.HeapByteBuffer[pos=0 lim=3 cap=3]

System.out.println(buffer.get()); // 10
System.out.println(buffer.get()); // 20
System.out.println(buffer.get()); // 30
System.out.println(buffer.get()); // 40
System.out.println(buffer.get()); // 50
System.out.println(buffer.hasRemaining()); // false

System.out.println(sliced.get()); // 30
System.out.println(sliced.get()); // 40
System.out.println(sliced.get()); // 50
System.out.println(sliced.hasRemaining()); // false

API 示例
- Buffer

Java : Buffer 示例

简介

Methods

abstract Object array ()

abstract int arrayOffset ()

final int capacity ()

Buffer clear ()

abstract Buffer duplicate ()

Buffer flip ()

abstract boolean hasArray ()

final boolean hasRemaining ()

abstract boolean isDirect ()

abstract boolean isReadOnly ()

final int limit ()

Buffer limit (int newLimit)

Buffer mark ()

final int position ()

Buffer position (int newPosition)

final int remaining ()

Buffer reset ()

Buffer rewind ()

abstract Buffer slice ()

abstract Buffer slice (int index, int length)

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