Java动态代理的应用详解

复制代码代码如下:

package com.fans.common.proxy;

public interface BusinessProcessor {
public void processBusiness();
}

复制代码代码如下:

package com.fans.common.proxy;
/**
* 业务处理类
* @author fanshadoop
*
*/
public class BusinessProcessorImpl implements BusinessProcessor {

@Override
public void processBusiness() {
System.out.println("processing business.....");

}

}

复制代码代码如下:

package com.fans.common.proxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
/**
* 业务代理类
* @author fanshadoop
*
*/
public class BusinessProcessorHandler implements InvocationHandler {

private Object target = null;

BusinessProcessorHandler(Object target) {
this.target = target;
}

public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
System.out
.println("You can do something here before process your business");
Object result = method.invoke(target, args);
System.out
.println("You can do something here after process your business");
return result;
}

}

复制代码代码如下:

package com.fans.common.proxy;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;

public class Test {

/**
* @param args
*/
public static void main(String[] args) {
BusinessProcessorImpl bpimpl = new BusinessProcessorImpl();
BusinessProcessorHandler handler = new BusinessProcessorHandler(bpimpl);
BusinessProcessor bp = (BusinessProcessor) Proxy.newProxyInstance(
bpimpl.getClass().getClassLoader(), bpimpl.getClass()
.getInterfaces(), handler);
bp.processBusiness();

System.out.println(bp.getClass().getName());
printClassDefinition(bp.getClass());
}

public static String getModifier(int modifier) {
String result = "";
switch (modifier) {
case Modifier.PRIVATE:
result = "private";
case Modifier.PUBLIC:
result = "public";
case Modifier.PROTECTED:
result = "protected";
case Modifier.ABSTRACT:
result = "abstract";
case Modifier.FINAL:
result = "final";
case Modifier.NATIVE:
result = "native";
case Modifier.STATIC:
result = "static";
case Modifier.SYNCHRONIZED:
result = "synchronized";
case Modifier.STRICT:
result = "strict";
case Modifier.TRANSIENT:
result = "transient";
case Modifier.VOLATILE:
result = "volatile";
case Modifier.INTERFACE:
result = "interface";
}
return result;
}

public static void printClassDefinition(Class clz) {

String clzModifier = getModifier(clz.getModifiers());
if (clzModifier != null && !clzModifier.equals("")) {
clzModifier = clzModifier + " ";
}
String superClz = clz.getSuperclass().getName();
if (superClz != null && !superClz.equals("")) {
superClz = "extends " + superClz;
}
Class[] interfaces = clz.getInterfaces();
String inters = "";
for (int i = 0; i < interfaces.length; i++) {
if (i == 0) {
inters += "implements ";
}
inters += interfaces[i].getName();
}
System.out.println(clzModifier + clz.getName() + " " + superClz + " "
+ inters);
System.out.println("{");
Field[] fields = clz.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
String modifier = getModifier(fields[i].getModifiers());
if (modifier != null && !modifier.equals("")) {
modifier = modifier + " ";
}
String fieldName = fields[i].getName();
String fieldType = fields[i].getType().getName();
System.out.println(" " + modifier + fieldType + " " + fieldName
+ ";");
}

System.out.println();

Method[] methods = clz.getDeclaredMethods();
for (int i = 0; i < methods.length; i++) {
Method method = methods[i];

String modifier = getModifier(method.getModifiers());
if (modifier != null && !modifier.equals("")) {
modifier = modifier + " ";
}
String methodName = method.getName();
Class returnClz = method.getReturnType();
String retrunType = returnClz.getName();

Class[] clzs = method.getParameterTypes();
String paraList = "(";
for (int j = 0; j < clzs.length; j++) {
paraList += clzs[j].getName();
if (j != clzs.length - 1) {
paraList += ", ";
}
}
paraList += ")";
clzs = method.getExceptionTypes();
String exceptions = "";
for (int j = 0; j < clzs.length; j++) {
if (j == 0) {
exceptions += "throws ";
}
exceptions += clzs[j].getName();
if (j != clzs.length - 1) {
exceptions += ", ";
}
}
exceptions += ";";
String methodPrototype = modifier + retrunType + " " + methodName
+ paraList + exceptions;

System.out.println(" " + methodPrototype);
}
System.out.println("}");
}
}

复制代码代码如下:

You can do something here before process your business
processing business.....
You can do something here after process your business
$Proxy0
$Proxy0 extends java.lang.reflect.Proxy implements com.fans.common.proxy.BusinessProcessor
{
java.lang.reflect.Method m1;
java.lang.reflect.Method m3;
java.lang.reflect.Method m0;
java.lang.reflect.Method m2;

boolean equals(java.lang.Object);
java.lang.String toString();
int hashCode();
void processBusiness();
}