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java动态字符画代码 java动态创建字符串数组

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java用字符串动态创建对象/**
* 根据传入的类名和值 ， 动态构造该类的实例
*
* @param _sClassName
*要构造的类名 如：java.lang.String
* @param _sRealValue
*要创建的对象的值，比如“wuguowei”
* @return 返回String对象，即值为“wuguowei”的字符串
* @throws Exception
*/
private Object getAttributeObject(String _sClassName, String _sRealValue)
throws Exception {
//1.加载类对象
Class attrObjClass = Class.forName(_sClassName);
//2.如果是Long类
if (attrObjClass.isInstance(new Long(0))) {
return new Long(_sRealValue);
}
//3.如果是Integer类
if (attrObjClass.isInstance(new Integer(0))) {
return new Integer(_sRealValue);
}
//4.其他类型……
//5.返回当前类的实例对象
return attrObjClass;
}
java怎么把一段字符串当做代码来执行在javascript中eval()可以实现字符串转代码，java中需要使用动态编译 。
把获得的字符串写入一个临时文件中，然后编译它，在调用其中的函数 。
我们把要转换的字符串构造一个完整的类:如果方法是有返回值的.则:
public object eval(string str){
//生成java文件
string s = "class temp{";
s += "object rt(){"
s += "myclass mc = new myclass();"
s += " return mc."+str+"();";
s += "}"
s +="}";
file f = new file("temp.java");
printwriter pw = new printwriter(new filewriter(f));
pw.println(s);
pw.close();
//动态编译
com.sun.tools.javac.main javac = new com.sun.tools.javac.main();
string[] cpargs = new string[] {"-d", "所在目录","temp.java"};
int status = javac.compile(cpargs);
if(status!=0){
system.out.println("没有成功编译源文件!");
return null;
}
//调用temp的rt方法返回结果:
myclassloader mc = new myclassloader();
class clasz = mc.loadclass("test.class",true);
method rt = clasz.getmethod("rt", new class[]{ string[].class });
return rt.invoke(null, new object[] { new string[0] });
//如果方法没有返回就直接调用
}
我们可以先写好多个重载的eval,有返回值和没有返回值的.以及可以传递参数的.
这样我们就可以用字符串转换为java的语句来执行.
求java做动画代码import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class TestImage extends Frame
{
private static final long serialVersionUID = 1L;
private static boolean PRESSED = false;
private static int pointX = 0;
private static int pointy = 200;
private static int RIGHT_GO = 0;
private static int LEFT_GO = 0;
private static int DIR = 0;
private static int ANGLE = 0;
private static int W = 50;
private static int H = 60;
private _Canvas canvas = null;
public TestImage ()
{
add (canvas = new _Canvas ());
setIgnoreRepaint (true);
requestFocus ();
}
public class _Canvas extends Canvas implements Runnable
{
private static final long serialVersionUID = 1L;
private BufferedImage bi = null;
private Image bufferedImage = null;
private Thread thread = null;
private long sleepTime = 10;
public _Canvas ()

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