TableGenerator (Java EE 5 SDK)

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Java EE 5 SDK

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摘要: REQUIRED | OPTIONAL

详细信息: ELEMENT

javax.persistence Annotation Type TableGenerator

@Target(value={TYPE,METHOD,FIELD}) @Retention(value=RUNTIME) public @interface TableGenerator

This annotation defines a primary key generator that may be referenced by name when a generator element is specified for the GeneratedValue annotation. A table generator may be specified on the entity class or on the primary key field or property. The scope of the generator name is global to the persistence unit (across all generator types).

    Example 1:
    
    @Entity public class Employee {
        ...
        @TableGenerator(
            name="empGen", 
            table="ID_GEN", 
            pkColumnName="GEN_KEY", 
            valueColumnName="GEN_VALUE", 
            pkColumnValue="EMP_ID", 
            allocationSize=1)
        @Id
        @GeneratedValue(strategy=TABLE, generator="empGen")
        public int id;
        ...
    }
    
    Example 2:
    
    @Entity public class Address {
        ...
        @TableGenerator(
            name="addressGen", 
            table="ID_GEN", 
            pkColumnName="GEN_KEY", 
            valueColumnName="GEN_VALUE", 
            pkColumnValue="ADDR_ID")
        @Id
        @GeneratedValue(strategy=TABLE, generator="addressGen")
        public int id;
        ...
    }

从以下版本开始:: Java Persistence 1.0

Required Element Summary
`String`	`name` (Required) A unique generator name that can be referenced by one or more classes to be the generator for id values.

Optional Element Summary
`int`	`allocationSize` (Optional) The amount to increment by when allocating id numbers from the generator.
`String`	`catalog` (Optional) The catalog of the table.
`int`	`initialValue` (Optional) The initial value to be used when allocating id numbers from the generator.
`String`	`pkColumnName` (Optional) Name of the primary key column in the table.
`String`	`pkColumnValue` (Optional) The primary key value in the generator table that distinguishes this set of generated values from others that may be stored in the table.
`String`	`schema` (Optional) The schema of the table.
`String`	`table` (Optional) Name of table that stores the generated id values.
`UniqueConstraint[]`	`uniqueConstraints` (Optional) Unique constraints that are to be placed on the table.
`String`	`valueColumnName` (Optional) Name of the column that stores the last value generated.

元素详细信息

name

public abstract String name

(Required) A unique generator name that can be referenced by one or more classes to be the generator for id values.

table

public abstract String table

(Optional) Name of table that stores the generated id values.

Defaults to a name chosen by persistence provider.

默认值:: ""

catalog

public abstract String catalog

(Optional) The catalog of the table.

Defaults to the default catalog.

默认值:: ""

schema

public abstract String schema

(Optional) The schema of the table.

Defaults to the default schema for user.

默认值:: ""

pkColumnName

public abstract String pkColumnName

(Optional) Name of the primary key column in the table.

Defaults to a provider-chosen name.

默认值:: ""

valueColumnName

public abstract String valueColumnName

(Optional) Name of the column that stores the last value generated.

Defaults to a provider-chosen name.

默认值:: ""

pkColumnValue

public abstract String pkColumnValue

(Optional) The primary key value in the generator table that distinguishes this set of generated values from others that may be stored in the table.

Defaults to a provider-chosen value to store in the primary key column of the generator table

默认值:: ""

initialValue

public abstract int initialValue

(Optional) The initial value to be used when allocating id numbers from the generator.

默认值:: 0

allocationSize

public abstract int allocationSize

(Optional) The amount to increment by when allocating id numbers from the generator.

默认值:: 50

uniqueConstraints

public abstract UniqueConstraint[] uniqueConstraints

(Optional) Unique constraints that are to be placed on the table. These are only used if table generation is in effect. These constraints apply in addition to primary key constraints.

Defaults to no additional constraints.

默认值:: {}

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