1、手动创建handle接口
public interface InterfaceHandle {
public Object invoke(Method method, Object[] args);
}
2、实现handle接口
public class User_InvoctionHandle implements InterfaceHandle {
private Object target;
public User_InvoctionHandle(Object target) {
this.target = target;
}
public Object invoke(Method method, Object[] args) {
System.out.println("我是自定义invoke方法");
try {
return method.invoke(this.target, null);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
return null;
}
}
3、手写代理类（附带逻辑重写）
public class ProxyUtil {
public static Object getInstance(Class targetInfo, User_InvoctionHandle handle) {
Object proxy = null;
// Class targetInfo = target.getClass().getInterfaces()[0];
String tab = "\t";
String line = "\n";
String implName = targetInfo.getSimpleName();
//创建java内容
String javaContent = "";
//package
String packageContent = "package com.proxy;" + line;
//importClass
String impPackageContent = "import "+handle.getClass().getName()+";"+line+
"import java.lang.reflect.Method;"+line+
"import "+targetInfo.getName()+";"+line;
//创建类体
String classContent = "public class $Proxy implements " + implName + " {" + line;
//创建私有对象handle
String privateObject = tab + "private " + handle.getClass().getSimpleName() + " h;" + line;
//创建构造,将handle当做对象
String constructorContent = tab + "public $Proxy (" + handle.getClass().getSimpleName() + " h ){" + line;
constructorContent += tab + tab + "this.h = h;";
constructorContent += line + tab + "}" + line;
//创建方法
String methedContent = "";
Method[] methods = targetInfo.getDeclaredMethods();
for (Method method : methods) {
//获取方法的返回类型
String methodTypeName = method.getReturnType().getSimpleName();
//获取方法的名字
String methodName = method.getName();
methedContent += tab + "public " + methodTypeName + " " + methodName + " (";
//创建参数
Object[] args = method.getParameterTypes();
String argContent = "";
for (int i = 0; i < args.length - 1; i++) {
//获取参数的类型
String argsTypeName = args[i].getClass().getSimpleName();
//获取参数名称 i1 i2
argContent = argsTypeName + " i" + i;
if (i != args.length - 1) {
//多个参数的情况下需要使用','但是最后一个不需要
argContent += ",";
}
}
//组装方法内容，会自动将方法与目标方法一致
methedContent += argContent + "){"
+ line + tab + tab +"try{"
+ line + tab + tab + tab + "Method method = Class.forName(\""+targetInfo.getName()+"\").getDeclaredMethod(\""+method.getName()+"\");"+line + tab + tab + tab ;
if(!"void".equals(methodTypeName)){
methedContent+= "return ("+methodTypeName+")";
}
methedContent+= "h.invoke(method,null);" + line
+ tab + tab +"}catch(Exception e){"
+ line + tab + tab + tab + "e.printStackTrace();"
+ line + tab + tab +"}";
if(!"void".equals(methodTypeName)){
methedContent+= line + tab + tab +"return null;";
}
methedContent+= line + tab +"}"+line+line;
}
javaContent = packageContent + impPackageContent + classContent + privateObject +
constructorContent +
methedContent + line + "}";
//1、使用IO字符流将创建好String 放到D盘中，用于查看是否存在问题。
String filePath = "D:\\com\\proxy\\";
String classFileName = "com.proxy.$Proxy";
File fileDir = new File("D:\\com\\proxy\\");
try {
if (!fileDir.isDirectory()) {
fileDir.mkdirs();
}
File file = new File("D:\\com\\proxy\\$Proxy.java");
if (!file.exists()) {
file.createNewFile();
}
FileWriter fileWriter = new FileWriter(file);
fileWriter.write(javaContent);
fileWriter.flush();
fileWriter.close();
//创建java编译器
JavaCompiler javaCompiler = ToolProvider.getSystemJavaCompiler();
//第三方管理器
StandardJavaFileManager fileMgr = javaCompiler.getStandardFileManager(null, null, null);
//将java文件放到管理器中
Iterable units = fileMgr.getJavaFileObjects(file);
//创建编译任务
JavaCompiler.CompilationTask task = javaCompiler.getTask(null, fileMgr, null, null, null, units);
//开始启动任务
task.call();
fileMgr.close();
//使用反射获取编译后的$Proxy对象
URL [] urls = new URL[]{new URL("file:D:\\\\")};
URLClassLoader ucl = new URLClassLoader(urls);
Class clazz = ucl.loadClass(classFileName);
Constructor constructor = clazz.getConstructor(User_InvoctionHandle.class);
proxy = constructor.newInstance(handle);
System.out.println("成功！");
} catch (Exception e) {
System.out.println("失败！");
e.printStackTrace();
}
return proxy;
}
}
4、测试
public static void main(String args[]) {
//调用手动写的代理
ObjectDao objectDao = (ObjectDao) ProxyUtil.getInstance(ObjectDao.class, new User_InvoctionHandle(new User_Defined_Dao()));
System.out.println(objectDao.queryStr());
}
5、测试重生成的$Proxy代理类及class
自动生成代理类的编码
package com.dao;
import com.handle.User_InvoctionHandle;
import java.lang.reflect.Method;
import com.dao.ObjectDao;
public class $Proxy implements ObjectDao {
private User_InvoctionHandle h;
public $Proxy (User_InvoctionHandle h ){
this.h = h;
}
public void query (){
try{
Method method = Class.forName("com.dao.ObjectDao").getDeclaredMethod("query");
h.invoke(method,null);
}catch(Exception e){
e.printStackTrace();
}
}
public String queryStr (){
try{
Method method = Class.forName("com.dao.ObjectDao").getDeclaredMethod("queryStr");
return (String)h.invoke(method,null);
}catch(Exception e){
e.printStackTrace();
}
return null;
}
}
结果
