Java反射初级学习

 

package main.java.reflection.model;

import java.util.ArrayList;
import java.util.List;


public class Demo {
	private String id;
	private String name;
	private int age;
	private List<String> list = new ArrayList<String>();
	
	public Demo(){}
	
	public Demo(String id, String name, int age, List<String> list) {
		super();
		this.id = id;
		this.name = name;
		this.age = age;
		this.list = list;
	}

	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	
	public List<String> getList() {
		return list;
	}

	public void setList(List<String> list) {
		this.list = list;
	}

	@Override
	public String toString() {
		return "[id="+id+";name="+name+";age="+age+"]";
	}
}

 

package main.java.reflection;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.List;
import main.java.reflection.model.Demo;

public class TestDemo {
	public static void main(String[] args) throws Exception {
		TestDemo td = new TestDemo();
		td.test();
		td.testField();
		td.testMethodSet();
		td.testMethodGet();
		td.test2();
		td.test4();
	}


	/**
	 * Title:test
	 * Description:范型基础
	 */
	public void test() {
		Demo d= new Demo();
		System.out.println(d.getClass().getName());
		System.out.println("count of Demo's constructor:"+d.getClass().getConstructors().length);
		for (Constructor<?> c : d.getClass().getDeclaredConstructors()) {
			System.out.println(c);
		}
		
		System.out.println("所以方法：");
		for (Method m: d.getClass().getMethods()) {			//所以的方法（包括继承过来的）
			System.out.println(m.getName());
		}
		System.out.println("自定义的方法:");
		for (Method m: d.getClass().getDeclaredMethods()) {	//自定义的方法
			System.out.println(m.getName());
		}
		System.out.println("属性:");
		for (Field f : d.getClass().getDeclaredFields()) {
			if(f.getType().toString().endsWith("java.lang.String")){
				System.out.println("..."+f.getType()+":"+Modifier.toString(f.getModifiers()));
			};
			System.out.println(f.getName()+":"+f.getType().getSimpleName()+"("+f.getType()+")");
		}
	}

	/**
	 * Title:testField
	 * Description:属性赋值
	 */
	public void testField() throws Exception {
		Class<?> demo = Class.forName("main.java.reflection.model.Demo");
		Object obj = demo.newInstance();
		Field field = demo.getDeclaredField("name");
        field.setAccessible(true);
        field.set(obj, "xiao");
        System.out.println(field.get(obj));
	}
	
	/**
	 * Title:testMethodSet
	 * Description:利用反射执行对象的set方法
	 */
	public void testMethodSet() throws Exception {
		Class<?> demo = Class.forName("main.java.reflection.model.Demo");
		Demo obj = (Demo) demo.newInstance();
		Method m = demo.getMethod("setId",String.class);
		m.invoke(obj, "11");
		System.out.println(obj.getId());
	}
	
	/**
	 * Title:testMethodGet
	 * Description:利用反射执行对象的get方法
	 */
	public void testMethodGet() throws Exception {
		Class<?> demo = Class.forName("main.java.reflection.model.Demo");
		Demo obj = (Demo) demo.newInstance();
		Method m = demo.getMethod("getId");
		if(m.invoke(obj)== null);
			System.out.println("....");
	}
	
	
	/**
	 * Title:test2
	 * Description:将对象中为String类型的属性对应的数据全部去掉首尾空格
	 */
	public void test2() throws Exception{
		List<Demo> dList = new ArrayList<Demo>();
		List<String> strList = new ArrayList<String>();
		dList.add(new Demo(" 1 "," Java ",11,strList));
		dList.add(new Demo("2   ","   Ruby",22,strList));
		dList.add(new Demo("   3","Ada   ",33,strList));
		for (Demo demo : dList) {
			System.out.println(demo.toString());
		}
		for (Demo demo : dList) {
			Method m = null;
			String tmp = "";
			for (Field f : demo.getClass().getDeclaredFields()) {
				if(f.getType().toString().endsWith("java.lang.String")){
					m = demo.getClass().getMethod("get"+f.getName().substring(0,1).toUpperCase()+f.getName().substring(1));
					if(m.invoke(demo) != null)
						tmp = m.invoke(demo).toString();
					else
						tmp = "";
					m = demo.getClass().getMethod("set"+f.getName().substring(0,1).toUpperCase()+f.getName().substring(1),String.class);
					m.invoke(demo, tmp.trim());
				};
			}
		}
		for (Demo demo : dList) {
			System.out.println(demo.toString());
		}
	}
	
	/**
	 * Title:test4
	 * Description:使用范型将对象中为String类型的属性对应的数据全部去掉首尾空格
	 */
	public void test4() throws Exception{
		CommonBean<Demo> cb = new CommonBean<Demo>();
		List<CommonBean<Demo>> dList = new ArrayList<CommonBean<Demo>>();
		List<String> strList = new ArrayList<String>();
		dList.add(new CommonBean<Demo>(new Demo(" 1 "," Java ",11,strList)));
		dList.add(new CommonBean<Demo>(new Demo("2   ",null,22,strList)));
		dList.add(new CommonBean<Demo>(new Demo("   3","Ada   ",33,strList)));
		dList = cb.getListOfStringTrim(dList);
		for (CommonBean<Demo> cm : dList) {
			System.out.println(cm.getObj().toString());
		}
	}
}

 

package main.java.reflection;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.List;


public class CommonBean<T> {
	T obj;
	
	public CommonBean(){
		
	}
	public CommonBean(T obj) {
		this.obj = obj;
	}

	public T getObj() {
		return obj;
	}

	public void setObj(T obj) {
		this.obj = obj;
	}
	
	public List<CommonBean<T>> getListOfStringTrim(List<CommonBean<T>> list) throws Exception{
		T obj = null;
		for (CommonBean<T> cm : list) {
			obj = cm.getObj();
			Method m = null;
			String tmp = "";
			for (Field f : obj.getClass().getDeclaredFields()) {
				if(f.getType().toString().endsWith("java.lang.String")){
					m = obj.getClass().getMethod("get"+f.getName().substring(0,1).toUpperCase()+f.getName().substring(1));
					if(m.invoke(obj) != null)
						tmp = m.invoke(obj).toString();
					else
						tmp = "";
					m = obj.getClass().getMethod("set"+f.getName().substring(0,1).toUpperCase()+f.getName().substring(1),String.class);
					m.invoke(obj, tmp.trim());
				};
			}
		}
		return list;
	}
}