java反射技术与类使用示例

代码如下:

package com.java.db;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import com.java.entity.BookShelf;
import com.java.util.GetMetaDataCloumName;
public class GetNewInstances<T> {
Class[] cl = {};
Object[] ob = {};
/**
* 每次用完之后设为空不然会累加
*/
public void setNullToArrays(){
  this.cl = new Class[]{};
  this.ob = new Object[]{};
}
/**
* copy Object数组
*
* @param obj
*            构造方法里需要的实际值
* @return
*/
public Object[] getObjectArrays(Object obj) {
   ob = Arrays.copyOf(ob,ob.length + 1);
   ob[ob.length - 1] = obj;
   return ob;
}

/**
* copy Class 数组
*
* @param cla
*            要添加的class
*
* @return
*/
@SuppressWarnings("unchecked")
public Class[] getClassArrays(Class<?> cla) {
  if (cla != null) {
   cl = Arrays.copyOf(cl,cl.length + 1);
   cl[cl.length - 1] = cla;
   return cl;
  }else{
   return cl;
  }
}

/**
* 得到类的实例
*
* @param clazz
*            要实例化的类
* @return 实例化之后的类
* @throws InstantiationException
* @throws IllegalAccessException
* @throws IllegalArgumentException
* @throws SecurityException
* @throws InvocationTargetException
* @throws NoSuchMethodException
*/
@SuppressWarnings("unchecked")
public Object getClassNewInstance(Class<?> clazz)
   throws InstantiationException, IllegalAccessException,
   IllegalArgumentException, SecurityException,
   InvocationTargetException, NoSuchMethodException {
  Object oj = null;
  Constructor[] cons = clazz.getDeclaredConstructors();// 得到构造函数
  Class[] cla = cons[1].getParameterTypes();
     System.out.println("提示用户是否需要添加字段   构造函数参数的大小:"+cla.length);
  for (int i = 0; i < cla.length; i++) {
   String classStr = cla[i].toString();
   // System.out.println("参数的类型："+classStr);
   if (classStr.equals("class java.lang.String")) {
    getClassArrays(String.class);
   } else if (classStr.equals("int")) {
    getClassArrays(int.class);
   } else if (classStr.equals("double")) {
    getClassArrays(double.class);
   } else if (classStr.equals("boolean")) {
    getClassArrays(boolean.class);
   } else if (classStr.equals("float")) {
    getClassArrays(float.class);
   } else if (classStr.equals("class java.lang.Integer")) {
    getClassArrays(Integer.class);
   }else if(classStr.equals("class java.lang.Float")){
    getClassArrays(Float.class);
   }
  }
  oj = clazz.newInstance();//返回当前对象具体的实例化构造在BDOperater
  return oj;
}
/**
* 通过构造函数得到具体的实例类
* @param clazz
* @return
* @throws IllegalArgumentException
* @throws SecurityException
* @throws InstantiationException
* @throws IllegalAccessException
* @throws InvocationTargetException
* @throws NoSuchMethodException
*/
public Object getObjCon(Class<?> clazz) throws IllegalArgumentException, SecurityException, InstantiationException, IllegalAccessException, InvocationTargetException, NoSuchMethodException{
  Object obj=null;
   obj = this.getClassNewInstance(clazz);
  return obj;
}
/**
* 得到对象的实例
* @param clazz
* @return
* @throws InstantiationException
* @throws IllegalAccessException
*/
public Object getNewinstance(Class clazz) throws InstantiationException, IllegalAccessException{
  Object obj = null;
  obj = clazz.newInstance();
  return obj;
}
/**
* 根据反射得到类中的所有属性
* @param clazz 需要被获取属性的类
* @return 属性集合
* @throws SecurityException
* @throws IllegalArgumentException
* @throws InstantiationException
* @throws IllegalAccessException
* @throws InvocationTargetException
* @throws NoSuchMethodException
*/
public Field[] getFielsdArray(Class<Object> clazz) throws SecurityException, IllegalArgumentException, InstantiationException, IllegalAccessException, InvocationTargetException, NoSuchMethodException{
  Field[] fields = null;
  fields = clazz.getDeclaredFields();
  return fields;
}
    /**
     * 根据字符串得到setter格式的属性
     * @param str 需要格式化的属性
     * @return
     */
public String getSetterStr(String str){
  String info = null;
  String strValue = str.substring(0,1).toUpperCase();
  info = "set"+strValue+str.substring(1,str.length());
  return info;
}
/**
* 把setXX还原为XX
* @param str
* @return
*/
public String setSetStr(String str){
  String info = null;
  String strValue = str.substring(3,str.length());
  String lower = strValue.substring(0).toLowerCase().substring(0,1);
  info = lower+str.substring(4,str.length());
  return info;
}
/**
* 得到类中的方法
* @param clazz 需要的得到方法的类
* @return
*/
public Method[] getMethodsArray(Class clazz){
  Method[] methods = clazz.getMethods();
  return methods;
}
/**
* 根据list<map>实例化构造函数
* @param listMap
* @param clazz
* @param tableName 数据库名称
* @return
* @throws NoSuchMethodException
* @throws InvocationTargetException
* @throws SecurityException
* @throws IllegalArgumentException
* @throws IllegalAccessException
* @throws InstantiationException
*/
@SuppressWarnings({ "unchecked" })
public List<Object> getListByMap(List<Map<String,Object>> listMap,Class clazz,String tableName) throws InstantiationException, IllegalAccessException, IllegalArgumentException, SecurityException, InvocationTargetException, NoSuchMethodException{
  List<Object> listLast = new ArrayList<Object>();
  List<String> metaList = GetMetaDataCloumName.getCloumNameList(tableName);
  Iterator<Map<String,Object>> it = listMap.iterator();
  while(it.hasNext()){
           Map<String,Object> map = it.next();
           Iterator<String> iitt = metaList.iterator();
           while(iitt.hasNext()){
             String info = iitt.next();
             this.getObjectArrays(map.get(info));
           }
            System.out.println("调用反射："+this.cl.length+"    "+this.ob.length);
           Object Tobj = this.getClassNewInstance(clazz).getClass().getConstructor(this.cl).newInstance(this.ob);
           listLast.add(Tobj);
           this.setNullToArrays();
  }
  return listLast;
}
public static void main(String[] args) {
  GetNewInstances ge = new GetNewInstances();
  System.out.println(ge.getSetterStr("nameSpace")=="setNameSpace");
  System.out.println("1a"=="1a");
  System.out.println(ge.setSetStr("setNameSpace"));
}
}