java ASM动态生成类

BeanTest2.java

import java.io.FileOutputStream;

import org.objectweb.asm.AnnotationVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.FieldVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

public class BeanTest2 extends ClassLoader implements Opcodes{

    public static void main(String []args) throws Exception
    {
        ClassWriter cw = new ClassWriter(0);
        //类名
        cw.visit(V1_7, ACC_PUBLIC, "com/xxx/model/_766ComLeakInfo", null, "com/xxx/model/LeakInfo", null);
        //注释
        AnnotationVisitor  av = cw.visitAnnotation("Lorg/springframework/data/mongodb/core/mapping/Document;", true);
        //注释参数
        av.visit("collection", "uc_members");
        av.visitEnd();
        //构造函数
        MethodVisitor mw = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null,null);
        mw.visitVarInsn(ALOAD, 0);
        mw.visitMethodInsn(INVOKESPECIAL, "com/xxx/model/LeakInfo", "<init>", "()V");
        mw.visitInsn(RETURN);
        mw.visitMaxs(1, 1);
        mw.visitEnd();

        //字段
        FieldVisitor  fv = cw.visitField(ACC_PUBLIC, "description", "Ljava/lang/String;", null, null);
        fv.visitEnd();

        byte[] code = cw.toByteArray();

         //将二进制流写到本地磁盘上
       FileOutputStream fos = new FileOutputStream("E:/asm/bin/com/xxx/model/_766ComLeakInfo.class");
       fos.write(code);
       fos.close();

       BeanTest2 loader = new BeanTest2();
        Class<?> clazz = loader.defineClass(null, code, 0, code.length);
        Object beanObj = clazz.getConstructor().newInstance();

        clazz.getField("description").set(beanObj, "Adobe客户信息泄露!");

        String nameString = (String) clazz.getField("description").get(beanObj);
        System.out.println("filed value : " + nameString);
    }
}

LeakInfo.java

import java.io.Serializable;

import org.springframework.data.mongodb.core.mapping.Document;

@SuppressWarnings("serial")
@Document
public class LeakInfo implements Serializable{

    //@Id
    long id;
    String type;
    String username;
    String email;
    String password;
    String source;
    String description;

    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }

    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getSource() {
        return source;
    }
    public void setSource(String source) {
        this.source = source;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }

}

生成类

import org.springframework.data.mongodb.core.mapping.*;

@Document(collection = "uc_members")
public class _766ComLeakInfo extends LeakInfo
{
    public String description;
}