Gen中的switch分析及lookupswitch与tableswitch指令

int chooseNear(int i) {
	switch (i) {
	case 0:
		return 0;
	case 1:
		return 1;
	case 2:
		return 2;
	default:
		return -1;
	}
}

最终生成的class文件内容如下：

public class com.test19.Test07
  SourceFile: "Test07.java"
  minor version: 0
  major version: 51
  flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
   #1 = Methodref          #3.#18         //  java/lang/Object."<init>":()V
   #2 = Class              #19            //  com/test19/Test07
   #3 = Class              #20            //  java/lang/Object
   #4 = Utf8               <init>
   #5 = Utf8               ()V
   #6 = Utf8               Code
   #7 = Utf8               LineNumberTable
   #8 = Utf8               LocalVariableTable
   #9 = Utf8               this
  #10 = Utf8               Lcom/test19/Test07;
  #11 = Utf8               chooseNear
  #12 = Utf8               (I)I
  #13 = Utf8               i
  #14 = Utf8               I
  #15 = Utf8               StackMapTable
  #16 = Utf8               SourceFile
  #17 = Utf8               Test07.java
  #18 = NameAndType        #4:#5          //  "<init>":()V
  #19 = Utf8               com/test19/Test07
  #20 = Utf8               java/lang/Object
{
  public com.test19.Test07();
    flags: ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1                  // Method java/lang/Object."<init>":()V
         4: return
      LineNumberTable:
        line 34: 0
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
               0       5     0  this   Lcom/test19/Test07;

  int chooseNear(int);
    flags:
    Code:
      stack=1, locals=2, args_size=2
         0: iload_1
         1: tableswitch   { // 0 to 2
                       0: 28
                       1: 30
                       2: 32
                 default: 34
            }
        28: iconst_0
        29: ireturn
        30: iconst_1
        31: ireturn
        32: iconst_2
        33: ireturn
        34: iconst_m1
        35: ireturn
      LineNumberTable:
        line 50: 0
        line 52: 28
        line 54: 30
        line 56: 32
        line 58: 34
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
               0      36     0  this   Lcom/test19/Test07;
               0      36     1     i   I
      StackMapTable: number_of_entries = 4
           frame_type = 28 /* same */
           frame_type = 1 /* same */
           frame_type = 1 /* same */
           frame_type = 1 /* same */

}