java 动态编译及执行实现Web式java开发

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废话不说，让大家等了这么久，先看看截图 ：

编译失败图：

编译成功，执行图：

编译完成，执行时出现异常图：

呵呵，这里当然只能执行一些简单的java编程文件，如果要做更强大的功能还需要大家的努力，下面就揭开内幕：

1.文件保存

package com.servlets;

import java.io.File;
import java.io.FileWriter;

public class FileTool {
  public static void saveStringToFile(final String content, final String fileName) throws Exception {
    final File file = new File(fileName);
    if(file.isDirectory()){
      throw new Exception("dir is not allowed!");
    }
    if(file.exists()){
      file.delete();
      file.createNewFile();
    }
    FileWriter fileWriter=new FileWriter(file);
    fileWriter.write(content);
    fileWriter.flush();
    fileWriter.close();
  }

  public static void makeDir(String baseDir) {
    File file = new File(baseDir);
    file.mkdirs();
  }
}

2.Servlet

package com.servlets;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONObject;

import com.dynamic.DynamicCompile;

/**
 * Servlet implementation class JavaProcess
 */
@WebServlet("/JavaProcess.sock")
public class JavaProcess extends HttpServlet {
  private static final long serialVersionUID = 1L;
  private final static String ABSLUTE_PATH = "E:/Compile";

  /**
   * @see HttpServlet#HttpServlet()
   */
  public JavaProcess() {
    super();

  }

  /**
   * @see Servlet#init(ServletConfig)
   */
  public void init(ServletConfig config) throws ServletException {
    // TODO Auto-generated method stub
  }

  /**
   * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String action = request.getParameter("action");
    System.out.println(action);
    if ("compile".equals(action)) {
      compileFile(request, response);
    }
    else if ("run".equals(action)) {
      run(request, response);
    }
    else {

    }
  }

  private void run(HttpServletRequest request, HttpServletResponse response) {
    String className = request.getParameter("name");
    className = className.replace('.', '/');
    final String baseDir = ABSLUTE_PATH + "/" + request.getSession().getId() + "/";
    ByteArrayOutputStream out=new ByteArrayOutputStream();
    DynamicCompile.run(className,baseDir, out);
    String result = new String(out.toByteArray());
    Result result2=new Result(true, result);
    JSONObject ob = JSONObject.fromObject(result2);
    ServletOutputStream outputStream;
    try {
      outputStream = response.getOutputStream();
      PrintWriter o = new PrintWriter(outputStream);
      o.print(ob);
      o.flush();
      o.close();
    }
    catch (IOException e) {
    }
  
  }

  private void compileFile(HttpServletRequest request, HttpServletResponse response) {
    String className = request.getParameter("name");
    String content = request.getParameter("file");
    className=className.substring(className.lastIndexOf('.')+1);
    final String baseDir = ABSLUTE_PATH + "/" + request.getSession().getId() + "/";
    final String dir = baseDir + className.trim() + ".java";
    try {
      createDir(baseDir);
      savefileToDir(dir, content);
      ByteArrayOutputStream out = new ByteArrayOutputStream();
      PrintWriter writer = new PrintWriter(out);
      compileFile(dir, baseDir, writer);
      String result = new String(out.toByteArray());
      JSONObject ob;
      Result result2;
      if (result.isEmpty()) {
        result2 = new Result(true, result);
      }
      else {
        result2 = new Result(false, result);
      }
      ob = JSONObject.fromObject(result2);
      ServletOutputStream outputStream = response.getOutputStream();
      PrintWriter o = new PrintWriter(outputStream);
      o.print(ob);
      o.flush();
      o.close();
    }
    catch (Exception e) {
      e.printStackTrace();
    }
  }

  private void createDir(String baseDir) {
    FileTool.makeDir(baseDir);
  }

  private void compileFile(String dir, String baseDir, PrintWriter writer) {
    DynamicCompile.compile(dir, baseDir, writer);
  }

  private void savefileToDir(String dir, String content) throws Exception {
    FileTool.saveStringToFile(content, dir);

  }

  /**
   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

  }


}

3.执行编译

package com.dynamic;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import com.sun.tools.javac.Main;

public class DynamicCompile {
    public static void compile(String dir, String baseDir,PrintWriter writer){
      String[] agrs=new String[]{"-d",baseDir,dir};
      Main.compile(agrs,writer);
    }
    
    public static boolean run(String className,final String baseDir, ByteArrayOutputStream out){
      PrintStream out1=new PrintStream(out);
      PrintStream err = System.err;
      PrintStream out2 = System.out;
      System.setErr(out1);
      System.setOut(out1);
      XClassLoader load=null;
      load=new XClassLoader(baseDir);
      try {
        Class<?> loadClass = load.loadClass(className);
        final Method method = loadClass.getMethod("main",  new Class[] { String[].class });
        method.invoke(null,new Object[]{new String[]{"21","df","dd"}});
        
      }
      catch (ClassNotFoundException e) {
        e.printStackTrace();
      }
      catch (SecurityException e) {
        e.printStackTrace();
      }
      catch (NoSuchMethodException e) {
        e.printStackTrace();
      }
      catch (IllegalArgumentException e) {
        e.printStackTrace();
      }
      catch (IllegalAccessException e) {
        e.printStackTrace();
      }
      catch (InvocationTargetException e) {
        e.printStackTrace();
      }
      
      System.setErr(err);
      System.setOut(out2);
      return false;
      
    }
}

4.类加载

package com.dynamic;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

public class XClassLoader extends ClassLoader {
  private final String classPath;
  
  public XClassLoader(String classPath) {
    super();
    this.classPath = classPath;
  }

  @Override
  protected Class<?> findClass(String name) throws ClassNotFoundException {
    FileInputStream fs;
    try {
      final String path = classPath+ name +".class";
      fs = new FileInputStream(path);
      int s=fs.available();
      byte[] bs=new byte[ s];
      fs.read(bs, 0, s); 
      final String className = name.replace('/','.');
      return this.defineClass(className, bs, 0, s);
    }
    catch (FileNotFoundException e) {
      throw new ClassNotFoundException("Not Found");
    }
    catch (IOException e) {
      throw new ClassNotFoundException("Not Found");
    }
    }

}

5.返回数据对象类

package com.servlets;

public class Result {
   private boolean success;
   private String msg;

   public Result(boolean success, String msg) {
     super();
     this.success = success;
     this.msg = msg;
   }

  public boolean isSuccess() {
    return success;
  }

  public void setSuccess(boolean success) {
    this.success = success;
  }

  public String getMsg() {
    return msg;
  }

  public void setMsg(String msg) {
    this.msg = msg;
  }

 }

6.前台界面

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link rel="stylesheet" type="text/css"
	href="./extjs3/resources/css/ext-all.css" />
<script type="text/javascript" src="./extjs3/adapter/ext/ext-base.js"></script>
<script type="text/javascript" src="./extjs3/ext-all.js"></script>
<style type="text/css">
html,body {
	font: normal 12px verdana;
	margin: 0;
	padding: 0;
	border: 0 none;
	overflow: hidden;
	height: 100%;
}
</style>

<title>Java Compile</title>
<script type="text/javascript">
	Ext.onReady(function() {
		Ext.BLANK_IMAGE_URL = './extjs3/resources/images/default/s.gif';
		var text = new Ext.form.TextArea({
			region : 'center'
		});
		var textName = new Ext.form.TextField({
			fieldLabel : 'Class Name',
			allowBlank:false,
			width : '98%'
			
		});
		var namePanel = new Ext.Panel({
			region : 'north',
			height : '30px',
			items : [ {
				xtype : 'form',
				layout : 'form',
				labelWidth :70,
				layoutConfig : {
					labelSeparator : ':'
				},
				labelAlign : 'left',
				frame : false,
				padding : '8px',
				items : [ textName ]
			} ]
		});
		var compileBtn = new Ext.Button({
			text : 'Compile'
		});
		var runBtn = new Ext.Button({
			text : 'Run'
		});
		var panel_text = new Ext.Panel({
			region : 'center',
			title : 'Java Compile',
			layout : 'border',
			items : [ namePanel, text ],
			buttons : [ compileBtn, runBtn ]
		});
		var console_text = new Ext.form.TextArea({
			width : '100%',
			readOnly : true,
			height : 200
		});
		var panel_console = new Ext.Panel({
			region : 'south',
			title : 'Console',
			collapsible : true,
			height : 200,
			items : [ console_text ]

		});
		var viewport = new Ext.Viewport({
			layout : 'border',
			items : [ panel_console, panel_text ]
		});

		var comileSuccess = function(response,ops) {
			var rs=Ext.util.JSON.decode(response.responseText);
			console_text.setValue(rs.msg);
		}
		var faild = function(e) {
		}
		var compile = function(e) {
			if (e == 'ok') {
				var javaCode = text.getValue();
				var clsName = textName.getValue();
				Ext.Ajax.request({
					url : 'JavaProcess.sock',
					method :'GET',
					success : comileSuccess,
					failure : faild,
					params : {
						action:'compile',
						file : javaCode,
						name : clsName

					}
				});
			}
		}
		compileBtn.on('click', function() {
			Ext.Msg.show({
				title : 'Notice',
				msg : 'Are you sure to compile the code?',
				buttons : Ext.Msg.OKCANCEL,
				fn : compile,
				icon : Ext.MessageBox.QUESTION
			});
		});
		runBtn.on('click',function(){
			var clsName = textName.getValue();
			Ext.Ajax.request({
				url : 'JavaProcess.sock',
				method :'GET',
				success : comileSuccess,
				failure : faild,
				params : {
					action:'run',
					name : clsName

				}
			});
		});

	});
</script>
</head>
</body>
</html>

小结：在此例子中使用了java反射技术，java动态编译，加载类技术和Jave EE技术，达到了在网页里面编写简单java程序的功能，抛砖引玉，希望大家看了之后能够想到更多，实现更强大的功能。譬如说把编译后的class存在数据库里面，实现一些匪夷所思的功能：）