java反射技术与类使用示例
作者：
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"));
}
}