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Added in API level 1

Blob

public interface Blob

java.sql.Blob

在SQL的Java ^TM编程语言的表示（映射） BLOB值。 SQL BLOB是一种内置类型，它将二进制大对象作为列值存储在数据库表的一行中。默认情况下，驱动程序使用SQL locator(BLOB)实现Blob ，这意味着Blob对象包含一个指向SQL BLOB数据的逻辑指针，而不是数据本身。一个Blob对象在创建事务期间有效。

方法在接口ResultSet ， CallableStatement ，并PreparedStatement ，如getBlob和setBlob允许编程人员访问SQL BLOB值。 Blob接口提供了获取SQL BLOB （二进制大对象）值的长度的方法，用于在客户机上实现BLOB值，并确定BLOB值内字节模式的位置。此外，该接口还具有更新BLOB值的方法。

如果JDBC驱动程序支持数据类型，则必须完全实现 Blob接口上的所有方法。

Summary

Public methods
`abstract void`	`free()` 此方法释放 `Blob`对象并释放它拥有的资源。
`abstract InputStream`	`getBinaryStream(long pos, long length)` 返回一个 `InputStream`对象，其中包含部分 `Blob`值，从pos指定的字节开始，长度为字节长度。
`abstract InputStream`	`getBinaryStream()` 以流的 `BLOB`检索此 `Blob`实例指定的 `BLOB`值。
`abstract byte[]`	`getBytes(long pos, int length)` 检索的所有或部分 `BLOB`值，这 `Blob`对象表示，如字节数组。
`abstract long`	`length()` 返回此 `Blob`对象指定的 `BLOB`值中的字节数。
`abstract long`	`position(Blob pattern, long start)` 检索 `pattern`开始的 `Blob`对象指定的 `BLOB`值中的字节位置。
`abstract long`	`position(byte[] pattern, long start)` 检索指定的字节数组 `pattern`在 `Blob`对象表示的 `BLOB`值内开始的字节位置。
`abstract OutputStream`	`setBinaryStream(long pos)` 检索可用于写入 `Blob`对象所表示的 `BLOB`值的流。
`abstract int`	`setBytes(long pos, byte[] bytes, int offset, int len)` 将给定的 `byte`数组的全部或部分写入 `Blob`对象表示的 `BLOB`值，并返回写入的字节数。
`abstract int`	`setBytes(long pos, byte[] bytes)` 将给定的字节数组写入 `Blob`对象表示的 `BLOB`值，从位置 `pos`开始，并返回写入的字节数。
`abstract void`	`truncate(long len)` 截断 `Blob`对象表示的 `BLOB`值的长度为 `len`个字节。

Public methods

free

Added in API level 9

void free ()

此方法释放Blob对象并释放它拥有的资源。一旦调用free方法，该对象就无效。

在free之后，任何尝试调用除free之外的方法free将导致SQLException被抛出。如果free被多次调用，在后续调用free被视为无操作。

Throws
`SQLException`	if an error occurs releasing the Blob's resources
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

getBinaryStream

Added in API level 9

InputStream getBinaryStream (long pos, 
                long length)

返回包含部分 Blob值的 InputStream对象，从pos指定的字节开始，长度为字节长度。

Parameters
`pos`	`long`: the offset to the first byte of the partial value to be retrieved. The first byte in the `Blob` is at position 1
`length`	`long`: the length in bytes of the partial value to be retrieved

Returns
`InputStream`	`InputStream` through which the partial `Blob` value can be read.

Throws
`SQLException`	if pos is less than 1 or if pos is greater than the number of bytes in the `Blob` or if pos + length is greater than the number of bytes in the `Blob`
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

getBinaryStream

Added in API level 1

InputStream getBinaryStream ()

以流的 BLOB检索此 Blob实例指定的 BLOB值。

Returns
`InputStream`	a stream containing the `BLOB` data

Throws
`SQLException`	if there is an error accessing the `BLOB` value
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

也可以看看：

setBinaryStream(long)

getBytes

Added in API level 1

byte[] getBytes (long pos, 
                int length)

检索的所有或部分BLOB值，这Blob对象表示，如字节数组。此byte阵列包含从位置pos开始的最多length个连续字节。

Parameters
`pos`	`long`: the ordinal position of the first byte in the `BLOB` value to be extracted; the first byte is at position 1
`length`	`int`: the number of consecutive bytes to be copied; the value for length must be 0 or greater

Returns
`byte[]`	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`

Throws
`SQLException`	if there is an error accessing the `BLOB` value; if pos is less than 1 or length is less than 0
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

也可以看看：

setBytes(long, byte[])

length

Added in API level 1

long length ()

返回此 Blob对象指定的 BLOB值中的字节数。

Returns
`long`	length of the `BLOB` in bytes

Throws
`SQLException`	if there is an error accessing the length of the `BLOB`
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

position

Added in API level 1

long position (Blob pattern, 
                long start)

检索pattern开始的Blob对象指定的BLOB值中的字节位置。搜索从位置start开始。

Parameters
`pattern`	`Blob`: the `Blob` object designating the `BLOB` value for which to search
`start`	`long`: the position in the `BLOB` value at which to begin searching; the first position is 1

Returns
`long`	the position at which the pattern begins, else -1

Throws
`SQLException`	if there is an error accessing the `BLOB` value or if start is less than 1
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

position

Added in API level 1

long position (byte[] pattern, 
                long start)

检索指定的字节数组pattern在Blob对象表示的BLOB值内开始的字节位置。搜索pattern开始于位置start 。

Parameters
`pattern`	`byte`: the byte array for which to search
`start`	`long`: the position at which to begin searching; the first position is 1

Returns
`long`	the position at which the pattern appears, else -1

Throws
`SQLException`	if there is an error accessing the `BLOB` or if start is less than 1
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

setBinaryStream

Added in API level 1

OutputStream setBinaryStream (long pos)

获取可用于写入的一个流BLOB ，该值Blob对象表示。流开始于位置pos 。写入流的字节将覆盖在现有的字节Blob在位置对象起始pos 。如果年底Blob同时写入流达到的值，那么长度Blob值将增加以容纳额外的字节。

注意：如果为pos指定的值大于BLOB值的长度+ 1，则行为未定义。某些JDBC驱动程序可能会抛出SQLException而其他驱动程序可能会支持此操作。

Parameters
`pos`	`long`: the position in the `BLOB` value at which to start writing; the first position is 1

Returns
`OutputStream`	a `java.io.OutputStream` object to which data can be written

Throws
`SQLException`	if there is an error accessing the `BLOB` value or if pos is less than 1
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

也可以看看：

getBinaryStream()

setBytes

Added in API level 1

int setBytes (long pos, 
                byte[] bytes, 
                int offset, 
                int len)

将给定的byte数组的全部或部分写入Blob对象表示的BLOB值，并返回写入的字节数。写作部分起始于pos在BLOB值; 来自给定字节数组的len字节被写入。字节阵列将覆盖在现有的字节Blob对象开始在位置pos 。如果在写入字节数组的过程中达到Blob值的末尾，则会增加Blob值的长度以容纳额外的字节。

注意：如果为pos指定的值大于BLOB值的长度+ 1，则行为未定义。某些JDBC驱动程序可能会抛出SQLException而其他驱动程序可能会支持此操作。

Parameters
`pos`	`long`: the position in the `BLOB` object at which to start writing; the first position is 1
`bytes`	`byte`: the array of bytes to be written to this `BLOB` object
`offset`	`int`: the offset into the array `bytes` at which to start reading the bytes to be set
`len`	`int`: the number of bytes to be written to the `BLOB` value from the array of bytes `bytes`

Returns
`int`	the number of bytes written

Throws
`SQLException`	if there is an error accessing the `BLOB` value or if pos is less than 1
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

也可以看看：

getBytes(long, int)

setBytes

Added in API level 1

int setBytes (long pos, 
                byte[] bytes)

将给定的字节数组写入Blob对象表示的BLOB值，从位置pos开始，并返回写入的字节数。字节阵列将覆盖在现有的字节Blob对象开始在位置pos 。如果的端Blob而写入的字节的阵列达到值，则长度Blob值将增加以容纳额外的字节。

注意：如果为pos指定的值大于BLOB值的长度+ 1，则行为未定义。某些JDBC驱动程序可能会抛出SQLException而其他驱动程序可能会支持此操作。

Parameters
`pos`	`long`: the position in the `BLOB` object at which to start writing; the first position is 1
`bytes`	`byte`: the array of bytes to be written to the `BLOB` value that this `Blob` object represents

Returns
`int`	the number of bytes written

Throws
`SQLException`	if there is an error accessing the `BLOB` value or if pos is less than 1
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

也可以看看：

getBytes(long, int)

truncate

Added in API level 1

void truncate (long len)

截断此 Blob对象表示的长度为 len字节的 BLOB值。

注意：如果为pos指定的值大于BLOB值的长度+ 1，则行为未定义。某些JDBC驱动程序可能会抛出SQLException而其他驱动程序可能会支持此操作。

Parameters
`len`	`long`: the length, in bytes, to which the `BLOB` value that this `Blob` object represents should be truncated

Throws
`SQLException`	if there is an error accessing the `BLOB` value or if len is less than 0
`SQLFeatureNotSupportedException`	if the JDBC driver does not support this method

Interfaces

Classes

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Exceptions

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Blob

Summary

Public methods

Public methods

free

getBinaryStream

getBinaryStream

getBytes

length

position

position

setBinaryStream

setBytes

setBytes

truncate