Java字节码实现Aop(续二)_JAVA_编程开发_程序员俱乐部

class="java" name="code">
package com.shihuan.field;

public class AccountField {

	String sql = "select * from tables";
	
	public void operation() {
        System.out.println("shihuan operation...");
    }
	
	int executeInternal() {
		
		System.out.println("shihuan executeInternal...");
		return 1;
	}
	
}

package com.shihuan.field;

public class TestAccountField {

	public static void main(String[] args) {
		AccountField t = new AccountField();
		t.operation();
		t.executeInternal();
	}

}

package com.shihuan.field;

public class SecurityCheckerField {
	
	public static void checkCode(AccountField afObj, java.util.Date startdate) {
		System.out.println("shihuan starttime --->> " + startdate);
		
		long endtime = System.currentTimeMillis();
		java.util.Date enddate = new java.util.Date(endtime);
		System.out.println("shihuan endtime --->> " + enddate);
		System.out.println(afObj.sql);
	}
	
}

package com.shihuan.field;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

public class GeneratorAsmField {

	public static void main(String[] args) throws IOException {
		ClassReader cr = new ClassReader("com.shihuan.field.AccountField");
		ClassWriter cw = new ClassWriter(cr, ClassWriter.COMPUTE_MAXS);
		ClassVisitor cv = new ClassVisitor(Opcodes.ASM5, cw) {
			
			public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
				MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions); // 先得到原始的方法
				MethodVisitor newMethod = mv;

				if (mv != null) {
					if ("executeInternal".equals(name)) { // 此处的executeInternal即为需要修改的方法，修改方法內容
						// 访问需要修改的方法
						newMethod = new MethodVisitor(Opcodes.ASM5, mv) {

							public void visitCode() {
								
								Label l0 = new Label();
								mv.visitLabel(l0);
								mv.visitLineNumber(12, l0);
								visitMethodInsn(Opcodes.INVOKESTATIC, "java/lang/System", "currentTimeMillis", "()J", false);
								visitVarInsn(Opcodes.LSTORE, 2);
								
								Label l1 = new Label();
								mv.visitLabel(l1);
								mv.visitLineNumber(13, l1);
								visitTypeInsn(Opcodes.NEW, "java/util/Date");
								visitInsn(Opcodes.DUP);
								visitVarInsn(Opcodes.LLOAD, 2);
								visitMethodInsn(Opcodes.INVOKESPECIAL, "java/util/Date", "<init>", "(J)V", false);
								visitVarInsn(Opcodes.ASTORE, 4);
								
								Label l2 = new Label();
								mv.visitLabel(l2);
								
								visitLocalVariable("starttime", "J", null, l0, l2, 2);
								visitLocalVariable("startdate", "Ljava/util/Date;", null, l1, l2, 4);
								
								super.visitCode();
							}
							
							public void visitInsn(int opcode) {
								if ((opcode >= Opcodes.IRETURN && opcode <= Opcodes.RETURN) || opcode == Opcodes.ATHROW) {
									visitVarInsn(Opcodes.ALOAD, 0);
									visitVarInsn(Opcodes.ALOAD, 4);
									visitMethodInsn(
											Opcodes.INVOKESTATIC,
											"com/shihuan/field/SecurityCheckerField",
											"checkCode",
											"(Lcom/shihuan/field/AccountField;Ljava/util/Date;)V",
											false);
								}
								super.visitInsn(opcode);
							}
							
						};

					}
				}
				return newMethod;
			}

		};
		cr.accept(cv, ClassReader.SKIP_DEBUG);

		byte[] code = cw.toByteArray();
		OutputStream fos = new FileOutputStream("D:/myworkspace/JavaAsm/bin/com/shihuan/field/AccountField.class");
		fos.write(code);
		fos.close();
	}

}