翻译：JVM虚拟机规范1.7中的运行时常量池部分（二）

本篇为JVM虚拟机规范1.7中的运行时常量池部分系列的第二篇。

4.4.4. The `CONSTANT_Integer_info` and `CONSTANT_Float_info` Structures

The CONSTANT_Integer_info and CONSTANT_Float_info structures represent 4-byte numeric (int and float) constants:

代表4字节的数字常量，如int和float：

The items of these structures are as follows:

tag

The tag item of the CONSTANT_Integer_info structure has the value CONSTANT_Integer (3).

The tag item of the CONSTANT_Float_info structure has the value CONSTANT_Float (4).

类型分别必须为CONSTANT_Integer和CONSTANT_Float

bytes

The bytes item of the CONSTANT_Integer_info structure represents the value of the int constant. The bytes of the value are stored in big-endian (high byte first) order.

The bytes item of the CONSTANT_Float_info structure represents the value of the float constant in IEEE 754 floating-point single format (§2.3.2). The bytes of the single format representation are stored in big-endian (high byte first) order.

The value represented by the CONSTANT_Float_info structure is determined as follows. The bytes of the value are first converted into an int constant bits. Then:

If bits is 0x7f800000, the float value will be positive infinity.
If bits is 0xff800000, the float value will be negative infinity.
If bits is in the range 0x7f800001 through 0x7fffffff or in the range 0xff800001 through 0xffffffff, the float value will be NaN.

　　　　　　In all other cases, let s, e, and m be three values that might be computed from bits:

　　 bytes在CONSTANT_Integer_info 中代表int常量的值。大端序（高字节在前）存储

　　 bytes在CONSTANT_Float_info 中代表以IEEE 754 浮点数格式存储的float常量。大端序存储。

CONSTANT_Float_info结构体的内容按照如下规则。bytes的值首先被转换为int常量比特，然后：

　　　　如果bits是0x7f800000，那么浮点值为正无穷。

　　　　如果bits是0xff800000，那么浮点值为负无穷。

　　　如果bits是在0x7f800001 到0x7fffffff或者0xff800001到0xffffffff，值为NaN。

　　　　其他情况，参考上图算出s，e，m，则值为 s · m · 2^e-150.

4.4.5. The CONSTANT_Long_info and CONSTANT_Double_info Structures

看看它的存储结构体：

其余和int和float差不多，只是变成了两个4字节来存储。

4.4.6. The `CONSTANT_NameAndType_info` Structure

The CONSTANT_NameAndType_info structure is used to represent a field or method, without indicating which class or interface type it belongs to:

　　代表一个字段或者方法，没标识属于哪个类或者接口：

The items of the CONSTANT_NameAndType_info structure are as follows:

条目如下：

tag

The tag item of the CONSTANT_NameAndType_info structure has the value CONSTANT_NameAndType (12).

tag值为CONSTANT_NameAndType

name_index

The value of the name_index item must be a valid index into the constant_pool table. The constant_pool entry at that index must be a CONSTANT_Utf8_info structure (§4.4.7) representing either the special method name <init> (§2.9) or a valid unqualified name denoting a field or method (§4.2.2).

name_index项必须为有效索引项。必须指向CONSTANT_Utf8_info 结构体，代表特殊方法名，如<init>或者一个有效的相对名标识字段或方法。

descriptor_index

The value of the descriptor_index item must be a valid index into the constant_pool table. The constant_pool entry at that index must be a CONSTANT_Utf8_info structure (§4.4.7) representing a valid field descriptor or method descriptor (§4.3.2, §4.3.3).

　　　值必须为有效索引。必须指向CONSTANT_Utf8_info ，代表有效的字段描述符或者方法描述符。（应该是一个域前面的那些：private，static，final之类的修饰符吧）