Blob

java.lang.Object
- ohos.data.orm.Blob

所有已实现的接口:

Blob
```
public class Blob
extends Object
implements Blob
```
Represents a Blob that stores Binary Large Objects (BLOBs) in the Object Relational Mapping (ORM) system.
This class is inherited from java.sql.Blob. The Blob is used to store binary data in and read binary data from the SQLite database.

从以下版本开始:

1

SystemCapability

SystemCapability.Data#DATA_APPDATAMGR

构造器概要

构造器
构造器	说明
`Blob()`	An no-argument constructor used to create a `Blob` object.
`Blob(byte[] blob)`	A constructor used to create a `Blob` object from data in an array of bytes.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`boolean`	`equals(Object object)`	Indicates whether some other object is "equal to" this one.
`void`	`free()`	This method frees the `Blob` object and releases the resources that it holds.
`InputStream`	`getBinaryStream()`	Retrieves the `BLOB` value designated by this `Blob` instance as a stream.
`InputStream`	`getBinaryStream(long pos, long length)`	Returns an `InputStream` object that contains a partial `Blob` value, starting with the byte specified by pos, which is length bytes in length.
`byte[]`	`getBytes(long pos, int length)`	Retrieves all or part of the `BLOB` value that this `Blob` object represents, as an array of bytes.
`int`	`hashCode()`	Returns a hash code value for the object.
`long`	`length()`	Returns the number of bytes in the `BLOB` value designated by this `Blob` object.
`long`	`position(byte[] pattern, long start)`	This method is not supported currently.
`long`	`position(Blob pattern, long start)`	This method is not supported currently.
`OutputStream`	`setBinaryStream(long indexToWriteAt)`	Retrieves a stream that can be used to write to the `BLOB` value that this `Blob` object represents.
`int`	`setBytes(long writeAt, byte[] bytes)`	Writes the given array of bytes to the `BLOB` value that this `Blob` object represents, starting at position `pos`, and returns the number of bytes written.
`int`	`setBytes(long writeAt, byte[] bytes, int offset, int length)`	Writes all or part of the given `byte` array to the `BLOB` value that this `Blob` object represents and returns the number of bytes written.
`void`	`truncate(long len)`	Truncates the `BLOB` value that this `Blob` object represents to be `len` bytes in length.

从类继承的方法 java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

- 构造器详细资料
  - Blob
```
public Blob()
```
    An no-argument constructor used to create a Blob object.
    You can call this method as needed.
    
    从以下版本开始:
    
    1
  - Blob
```
public Blob(byte[] blob)
```
    A constructor used to create a Blob object from data in an array of bytes.
    
    参数:
    
    blob - Indicates the data in the array of bytes.
    
    从以下版本开始:
    
    1
- 方法详细资料
  - length
```
public long length()
```
    从接口复制的说明: Blob
    
    Returns the number of bytes in the BLOB value designated by this Blob object.
    
    指定者:
    
    length 在接口中 Blob
    
    返回:
    
    length of the BLOB in bytes
  - getBytes
```
public byte[] getBytes(long pos,
                       int length)
```
    从接口复制的说明: Blob
    
    Retrieves all or part of the BLOB value that this Blob object represents, as an array of bytes. This byte array contains up to length consecutive bytes starting at position pos.
    
    指定者:
    
    getBytes 在接口中 Blob
    
    参数:
    
    pos - the ordinal position of the first byte in the BLOB value to be extracted; the first byte is at position 1
    
    length - the number of consecutive bytes to be copied; the value for length must be 0 or greater
    
    返回:
    
    a byte array containing up to length consecutive bytes from the BLOB value designated by this Blob object, starting with the byte at position pos
    
    另请参阅:
    
    Blob.setBytes(long, byte[])
  - getBinaryStream
```
public InputStream getBinaryStream()
```
    从接口复制的说明: Blob
    
    Retrieves the BLOB value designated by this Blob instance as a stream.
    
    指定者:
    
    getBinaryStream 在接口中 Blob
    
    返回:
    
    a stream containing the BLOB data
    
    另请参阅:
    
    Blob.setBinaryStream(long)
  - position
```
public long position(byte[] pattern,
                     long start)
```
    This method is not supported currently.
    
    指定者:
    
    position 在接口中 Blob
    
    参数:
    
    pattern - the byte array for which to search
    
    start - the position at which to begin searching; the first position is 1
    
    返回:
    
    the position at which the pattern appears, else -1
    
    抛出:
    
    UnsupportedOperationException - Throws this exception when this method is called.
    
    从以下版本开始:
    
    1
  - position
```
public long position(Blob pattern,
                     long start)
```
    This method is not supported currently.
    
    指定者:
    
    position 在接口中 Blob
    
    参数:
    
    pattern - the Blob object designating the BLOB value for which to search
    
    start - the position in the BLOB value at which to begin searching; the first position is 1
    
    返回:
    
    the position at which the pattern begins, else -1
    
    抛出:
    
    UnsupportedOperationException - Throws this exception when this method is called.
    
    从以下版本开始:
    
    1
  - setBytes
```
public int setBytes(long writeAt,
                    byte[] bytes)
```
    从接口复制的说明: Blob
    
    Writes the given array of bytes to the BLOB value that this Blob object represents, starting at position pos, and returns the number of bytes written. The array of bytes will overwrite the existing bytes in the Blob object starting at the position pos. If the end of the Blob value is reached while writing the array of bytes, then the length of the Blob value will be increased to accommodate the extra bytes.
    Note: If the value specified for pos is greater then the length+1 of the BLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.
    
    指定者:
    
    setBytes 在接口中 Blob
    
    参数:
    
    writeAt - the position in the BLOB object at which to start writing; the first position is 1
    
    bytes - the array of bytes to be written to the BLOB value that this Blob object represents
    
    返回:
    
    the number of bytes written
    
    另请参阅:
    
    Blob.getBytes(long, int)
  - setBytes
```
public int setBytes(long writeAt,
                    byte[] bytes,
                    int offset,
                    int length)
```
    从接口复制的说明: Blob
    
    Writes all or part of the given byte array to the BLOB value that this Blob object represents and returns the number of bytes written. Writing starts at position pos in the BLOB value; len bytes from the given byte array are written. The array of bytes will overwrite the existing bytes in the Blob object starting at the position pos. If the end of the Blob value is reached while writing the array of bytes, then the length of the Blob value will be increased to accommodate the extra bytes.
    Note: If the value specified for pos is greater then the length+1 of the BLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.
    
    指定者:
    
    setBytes 在接口中 Blob
    
    参数:
    
    writeAt - the position in the BLOB object at which to start writing; the first position is 1
    
    bytes - the array of bytes to be written to this BLOB object
    
    offset - the offset into the array bytes at which to start reading the bytes to be set
    
    length - the number of bytes to be written to the BLOB value from the array of bytes bytes
    
    返回:
    
    the number of bytes written
    
    另请参阅:
    
    Blob.getBytes(long, int)
  - setBinaryStream
```
public OutputStream setBinaryStream(long indexToWriteAt)
```
    Retrieves a stream that can be used to write to the BLOB value that this Blob object represents. The stream begins at position pos. The bytes written to the stream will overwrite the existing bytes in the Blob object starting at the position pos. If the end of the Blob value is reached while writing to the stream, then the length of the Blob value will be increased to accommodate the extra bytes.
    Note: If the value specified for pos is greater then the length+1 of the BLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.
    
    指定者:
    
    setBinaryStream 在接口中 Blob
    
    参数:
    
    indexToWriteAt - Indicates the start position. The value ranges from 1 to Integer.MAX_VALUE.
    
    返回:
    
    a java.io.OutputStream object to which data can be written
    
    抛出:
    
    IllegalArgumentException - Throws this exception if the length of the indexToWriteAt value is less than 1.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    Blob.getBinaryStream()
  - truncate
```
public void truncate(long len)
```
    Truncates the BLOB value that this Blob object represents to be len bytes in length.
    Note: If the value specified for pos is greater then the length+1 of the BLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.
    
    指定者:
    
    truncate 在接口中 Blob
    
    参数:
    
    len - Indicates the start position. The value ranges from 1 to binary data's length.
    
    抛出:
    
    IllegalArgumentException - Throws this exception if the length of the indexToWriteAt value is less than 1 or larger than binary data's length.
    
    从以下版本开始:
    
    1
  - free
```
public void free()
```
    从接口复制的说明: Blob
    
    This method frees the Blob object and releases the resources that it holds. The object is invalid once the free method is called.
    After free has been called, any attempt to invoke a method other than free will result in a SQLException being thrown. If free is called multiple times, the subsequent calls to free are treated as a no-op.
    
    指定者:
    
    free 在接口中 Blob
  - getBinaryStream
```
public InputStream getBinaryStream(long pos,
                                   long length)
```
    Returns an InputStream object that contains a partial Blob value, starting with the byte specified by pos, which is length bytes in length.
    
    指定者:
    
    getBinaryStream 在接口中 Blob
    
    参数:
    
    pos - Indicates the start position. The value ranges from 1 to binary data's length.
    
    length - the length in bytes of the partial value to be retrieved
    
    返回:
    
    InputStream through which the partial Blob value can be read.
    
    从以下版本开始:
    
    1
  - equals
```
public boolean equals(Object object)
```
    从类复制的说明: Object
    Indicates whether some other object is "equal to" this one.
    The equals method implements an equivalence relation on non-null object references:
    - It is reflexive: for any non-null reference value x, x.equals(x) should return true.
    - It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
    - It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
    - It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
    - For any non-null reference value x, x.equals(null) should return false.
    The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).
    Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.
    覆盖:
    
    equals 在类中 Object
    
    参数:
    
    object - the reference object with which to compare.
    
    返回:
    
    true if this object is the same as the obj argument; false otherwise.
    
    另请参阅:
    
    Object.hashCode(), HashMap
  - hashCode
```
public int hashCode()
```
    从类复制的说明: Object
    Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.
    The general contract of hashCode is:
    - Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
    - If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
    - It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
    As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java™ programming language.)
    覆盖:
    
    hashCode 在类中 Object
    
    返回:
    
    a hash code value for this object.
    
    另请参阅:
    
    Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

类 Blob

构造器概要

方法概要

从类继承的方法 java.lang.Object

构造器详细资料

Blob

Blob

方法详细资料

length

getBytes

getBinaryStream

position

position

setBytes

setBytes

setBinaryStream

truncate

free

getBinaryStream

equals

hashCode