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 startlabel = new Label();
visitLabel(startlabel);
visitLineNumber(13, startlabel);
visitMethodInsn(Opcodes.INVOKESTATIC, "java/lang/System", "currentTimeMillis", "()J", false);
visitVarInsn(Opcodes.LSTORE, 2);
Label ctmlabel = new Label();
visitLabel(ctmlabel);
visitLineNumber(14, ctmlabel);
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 sdlabel = new Label();
visitLabel(sdlabel);
visitLineNumber(16, sdlabel);
Label endlabel = new Label();
visitLabel(endlabel);
visitLocalVariable("this", "Lcom/shihuan/field/AccountField;", null, startlabel, endlabel, 0);
visitLocalVariable("starttime", "J", null, ctmlabel, endlabel, 2);
visitLocalVariable("startdate", "Ljava/util/Date;", null, sdlabel, endlabel, 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();
}
}
【注】：本例中涉及到org.objectweb.asm.Label类和visitTypeInsn、visitInsn、visitVarInsn、visitLocalVariable等函数的参数意义问题，如果有想深入学习Asm5.0.2的朋友，请联系笔者，笔者学习Asm5.0.2的Java代码在[email protected]的网盘的原创作品里。
----------------------------------------------------------------------------------
下面是笔者改Oracle的代码例子:
package oracle.jdbc.driver;
public class OracleMyEnd {
public static void getMySqlInfo(OraclePreparedStatement opsObj, java.util.Date startdate){
System.out.println(startdate);
System.out.println("ShiHuan Is Inner --->> " + opsObj.sqlObject.originalSql);
}
}
package oracle.jdbc.driver;
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 OracleGeneratorAsm {
public static void main(String[] args) throws IOException {
ClassReader cr = new ClassReader("oracle.jdbc.driver.OraclePreparedStatement");
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 startlabel = new Label();
visitLabel(startlabel);
visitLineNumber(3362, startlabel);
visitMethodInsn(Opcodes.INVOKESTATIC, "java/lang/System", "currentTimeMillis", "()J", false);
visitVarInsn(Opcodes.LSTORE, 5);
Label ctmlabel = new Label();
visitLabel(ctmlabel);
visitLineNumber(3363, ctmlabel);
visitTypeInsn(Opcodes.NEW, "java/util/Date");
visitInsn(Opcodes.DUP);
visitVarInsn(Opcodes.LLOAD, 5);
visitMethodInsn(Opcodes.INVOKESPECIAL, "java/util/Date", "<init>", "(J)V", false);
visitVarInsn(Opcodes.ASTORE, 7);
Label sdlabel = new Label();
visitLabel(sdlabel);
visitLineNumber(3364, sdlabel);
Label endlabel = new Label();
visitLabel(endlabel);
visitLocalVariable("this", "Loracle/jdbc/driver/OraclePreparedStatement;", null, startlabel, endlabel, 0);
visitLocalVariable("starttime", "J", null, ctmlabel, endlabel, 5);
visitLocalVariable("startdate", "Ljava/util/Date;", null, sdlabel, endlabel, 7);
super.visitCode();
}
public void visitInsn(int opcode) {
if ((opcode >= Opcodes.IRETURN && opcode <= Opcodes.RETURN) || opcode == Opcodes.ATHROW) {
visitVarInsn(Opcodes.ALOAD, 0);
visitVarInsn(Opcodes.ALOAD, 7);
visitMethodInsn(
Opcodes.INVOKESTATIC,
"oracle/jdbc/driver/OracleMyEnd",
"getMySqlInfo",
"(Loracle/jdbc/driver/OraclePreparedStatement;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:/ojdbc6_b/oracle/jdbc/driver/OraclePreparedStatement.class");
fos.write(code);
fos.close();
}
}