Java动态生成类以及动态添加属性

有个技术实现需求：动态生成类，其中类中的属性来自参数对象中的全部属性以及来自参数对象properties文件。

那么技术实现支持：使用CGLib代理。

具体的实现步骤：

1.配置Maven文件：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion>

<groupId>com.journey</groupId>
<artifactId>journey</artifactId>
<version>1.0-SNAPSHOT</version>

<dependencies>
<dependency>
<groupId>cglib</groupId>
<artifactId>cglib</artifactId>
<version>2.2.2</version>
</dependency>
</dependencies>

</project>

2.封装的cglib类
package com.journey;

import net.sf.cglib.beans.BeanGenerator;
import net.sf.cglib.beans.BeanMap;

import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
* Created by little_eleventh_wolf on 2017/11/18.
*/
public class DynamicBean {
private Object object = null; //动态生成的类
private BeanMap beanMap = null; //存放属性名称以及属性的类型

public DynamicBean() {
super();
}

public DynamicBean(Map propertyMap) {
this.object = generateBean(propertyMap);
this.beanMap = BeanMap.create(this.object);
}

/**
* @param propertyMap
* @return
*/
private Object generateBean(Map propertyMap) {
BeanGenerator generator = new BeanGenerator();
Set keySet = propertyMap.keySet();
for(Iterator i = keySet.iterator(); i.hasNext(); ) {
String key = (String) i.next();
generator.addProperty(key, (Class) propertyMap.get(key));
}
return generator.create();
}

/**
* 给bean属性赋值
* @param property 属性名
* @param value 值
*/
public void setValue(Object property, Object value) {
beanMap.put(property, value);
}

/**
* 通过属性名得到属性值
* @param property 属性名
* @return 值
*/
public Object getValue(String property) {
return beanMap.get(property);
}

/**
* 得到该实体bean对象
* @return
*/
public Object getObject() {
return this.object;
}
}

3.需求的实现类：
package com.journey;

import java.beans.BeanInfo;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Properties;
import java.util.Set;

/**
* Created by little_eleventh_wolf on 2017/11/18.
*/
public class ClassUtil {
private String filePath = "/config/"; //配置文件路径

public String getFilePath() {
return filePath;
}

public void setFilePath(String filePath) {
this.filePath = filePath;
}

public Object dynamicClass(Object object) throws Exception {
HashMap returnMap = new HashMap();
HashMap typeMap = new HashMap();
//读取配置文件
Properties prop = new Properties();
String sourcepackage = object.getClass().getName();
String classname = sourcepackage.substring(sourcepackage.lastIndexOf(".") + 1);
InputStream in = ClassUtil.class.getResourceAsStream(filePath + classname + ".properties");
prop.load(in);

Set<String> keylist = prop.stringPropertyNames();

Class type = object.getClass();
BeanInfo beanInfo = Introspector.getBeanInfo(type);
PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
for(int i = 0; i < propertyDescriptors.length; i++) {
PropertyDescriptor descriptor = propertyDescriptors[i];
String propertyName = descriptor.getName();
if(!propertyName.equals("class")) {
Method readMethod = descriptor.getReadMethod();
Object result = readMethod.invoke(object, new Object[0]);
if(result != null) {
returnMap.put(propertyName, result);
} else {
returnMap.put(propertyName, "");
}
typeMap.put(propertyName, descriptor.getPropertyType());
}
}
//加载配置文件中的属性
Iterator<String> iterator = keylist.iterator();
while(iterator.hasNext()) {
String key = iterator.next();
returnMap.put(key, prop.getProperty(key));
typeMap.put(key, Class.forName("java.lang.String"));
}
//map转换成实体对象
DynamicBean bean = new DynamicBean(typeMap);
//赋值
Set keys = typeMap.keySet();
for(Iterator it = keys.iterator(); it.hasNext(); ) {
String key = (String) it.next();
bean.setValue(key, returnMap.get(key));
}
Object obj = bean.getObject();
return obj;
}

public static void main(String[] args) throws Exception {
new ClassUtil().dynamicClass(new LeapRole()/*LeapRole是个普通类，未贴源码*/);
}
}

4.技术实现目的：前台框架表格数据源实际上就是带有数据的实体，但是grid中数据的类型、以及是否可见、toolbar工具栏上的按钮、是否分页，是针对实体而言，所以目前把这些信息作为实体的配置文件。在展示页面之前，读取全部信息，转为参数对象的完整对象。