java代码动态生成java的.class文件

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1、目录使用例子： 29使用例子： 29雲亜旬-需要包：工具类 POBuildUtil 2工具类 BuildUtil 6工具类 Assistant 827RenderClass：使用例子： 29需要包：1. apache-commons-lang-*.jar2. asm-*.jar工具类 POBuildUtilimport java.io.File;import java.io.FileOutputStream;import java.util.Collection;import java.util.Iterator;import mons.lang.WordUtils;import org.ob

2、jectweb.asm.ClassWriter;import org.objectweb.asm.MethodVisitor;import org.objectweb.asm.Opcodes;public class POBuildUtil extends ClassLoader implements Opcodes public Class build(String clsname,String savepath,Collection properties)Class cls = null;tryString classname = BuildUtil.transferClassName(c

3、lsname); ClassWriter cw = new ClassWriter(false);cw.visit(V1_1, ACC_PUBLIC, classname, null, java/lang/Object, null);MethodVisitor mw = cw.visitMethod(ACC_PUBLIC, , ()V, null, null);mw.visitVarInsn(ALOAD, 0);mw.visitMethodInsn(INVOKESPECIAL, java/lang/Object, , ()V);mw.visitInsn(RETURN);mw.visitMaxs

4、(1, 1);mw.visitEnd();BuildProperty property = null;String propertytype = null;String propertyname = null;Iterator iterator = properties.iterator();while (iterator.hasNext()property = (BuildProperty)iterator.next();propertytypeBuildUtil.transferClassName(property.getType();propertyname = WordUtils.ca

5、pitalize(property.getName(); /System.out.println(propertyname);cw.visitField(ACC_PRIV ATE, property.getName(), L+propertytype+;, null, null).visitEnd();mw = cw.visitMethod(ACC_PUBLIC,get+propertyname, ()L+propertytype+;, null,null);mw.visitCode();mw.visitVarInsn(ALOAD, 0); mw.visitFieldInsn(GETFIELD

6、, classname, property.getName(),L+propertytype+;);mw.visitInsn(ARETURN);mw.visitMaxs(1, 1);mw.visitEnd();mw = cw.visitMethod(ACC_PUBLIC,set+propertyname, (L+propertytype+;)V,null, null);mw.visitCode();mw.visitVarInsn(ALOAD, 0);mw.visitVarInsn(ALOAD, 1);mw.visitFieldInsn(PUTFIELD,property.getName(),L

7、+propertytype+;); mw.visitMaxs(2, 2); mw.visitInsn(RETURN); mw.visitEnd();cw.visitEnd();byte code = cw.toByteArray();if (savepath!=null)Assistant.createNewFile(savepath);FileOutputStream fosFileOutputStream(savepath);fos.write(code);fos.close();classname,newcls = this.defineClass(clsname, code, 0, c

8、ode.length);return cis name.replace(/)；return cis name.replace(/)；catch (Throwable e)e.pri ntStackTrace();return cls; public class BuildUtil 工具类uildUtilpublic staticStri ng tran sferClassName(Class cls)String cls name = cls.getName();return cls name.replace( ., /);public static Stri ng tran sferClas

9、sName(Stri ngcls name)一. 工具类 BuildProperty public class BuildPropeiprivateStri ngn ame;privateStri ngtype ;publicBuildProperty()public BuildProperty(Stri ng n ame,Stri ng type)this . name = name;this . type = type;public String getName() returnn ame;public void setName(Stri ng n ame) this . name = n

10、ame;public String getType() return type ;public void setType(String type) this . type = type;工具类 Assistantimport java.io.BufferedReader;import java.io.BufferedWriter;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.InputStreamReader;import java.io.Out

11、putStreamWriter;import java.text.SimpleDateFormat;import java.util.Calendar;import javax.servlet.ServletContext;import javax.servlet.http.HttpServletRequest;import org.apache.log4j.Logger;public class Assistant private static final Logger log = Logger.getLogger(Assistant.class);public static String

12、convertRequestParameter(String parameter) throws Exceptionreturn convertRequestParameter(parameter,null);public static String convertRequestParameter(String parameter,String format) throws Exceptionif (parameter!=null)if (format=null) format=utf-8;parameter = .URLDecoder.decode(parameter,format); re

13、turn parameter;public static boolean notEmpty(HttpServletRequest request,String key)if (request.getParameter(key)!=null &request.getParameter(key).length()0)return true;elsereturn false;url,Stringpublic static void writeFileContent(String content ,ServletContext context) throws ExceptionwriteFileCon

14、tent( getFullPath(url,context),content);public static String HTMLEncode(String txt) if (txt!=null & txt.length()0)txt=txt.replaceAll(&,&); txt=txt.replaceAll(,>);txt=txt.replaceAll(,");txt=txt.replaceAll(,’);return txt;public static boolean existFile(String urlpath,ServletContext co

15、ntext)File file = new File(getFullPath(urlpath, context);if (file.exists()return true;elsereturn false;public static void writeFileContent(String path,String content) throwsExceptionFile file = new File(path);if (!file.exists()file.createNewFile();OutputStreamWriter write= new OutputStreamWriter(new

16、 FileOutputStream(file),GBK);BufferedWriter writer=new BufferedWriter(write); writer.write(content);writer.close();write.close();public static String getFileContent(String url,ServletContext context) throws ExceptionString filepath = getFullPath(url,context);return getFileContent(filepath);public st

17、atic String getFileContent(String path) throws ExceptionStringBuffer buf = new StringBuffer();File file = new File(path);if (file.exists()InputStreamReader read = new InputStreamReader(new FileInputStream(file),GBK);BufferedReader reader=new BufferedReader(read);tryString content = reader.readLine()

18、;while (content!=null)buf.append(content);content = reader.readLine();finallyif (reader!=null) reader.close();if (read!=null)read.close();return buf.toString();/? ? ?(? ? )public static java.util.Date addTimeByDay(java.util.Date date,int days)throws ExceptionCalendar calendar=Calendar.getInstance();

19、 calendar.setTime(date);calendar.set(Calendar.DATE,calendar.get(Calendar.DATE)+days); return calendar.getTime();public static java.util.Date addTimeByMinutes(java.util.Date date,int minutes) throws ExceptionCalendar calendar=Calendar.getInstance(); calendar.setTime(date);calendar.set(Calendar.MINUTE

20、,calendar.get(Calendar.MINUTE)+minute s);return calendar.getTime();public static java.util.Date addTimeBySeconds(java.util.Date date,int seconds) throws ExceptionCalendar calendar=Calendar.getInstance();calendar.setTime(date);calendar.set(Calendar.SECOND,calendar.get(Calendar.SECOND)+secon ds);retur

21、n calendar.getTime();public static java.util.Date nowTime() throws ExceptionSimpleDateFormat sdf = new SimpleDateFormat(yyyy-MM-dd);String datestr = sdf.format(java.util.Calendar.getInstance().getTime();return sdf.parse(datestr);public static java.util.Date nowFullTime() throws ExceptionSimpleDateFo

22、rmat sdf = new SimpleDateFormat(yyyy-MM-dd HH:mm:ss);String datestr = sdf.format(java.util.Calendar.getInstance().getTime();return sdf.parse(datestr);public static java.util.Date nowFullTime(String format) throws ExceptionSimpleDateFormat sdf = new SimpleDateFormat(format);String datestr = sdf.forma

23、t(java.util.Calendar.getInstance().getTime();return sdf.parse(datestr);public static String convertDateStrToString(String datestr,String format) throws ExceptionString result = null;SimpleDateFormat sdf = new SimpleDateFormat(format); tryresult = sdf.format(sdf.parse(datestr);catch (Exception ex)sdf

24、 = new SimpleDateFormat(yyyy-MM-dd);result = sdf.format(sdf.parse(datestr);return result;public static String convertDateToString(java.util.Date date,String format) throws ExceptionSimpleDateFormat sdf = new SimpleDateFormat(format); return sdf.format(date);public static java.util.Date formatDateStr

25、(String datestr) throws ExceptionSimpleDateFormat sdf = new SimpleDateFormat(yyyy-MM-dd);return sdf.parse(datestr);public static java.util.Date formatDateStr(String datestr,String format) throws Exceptionjava.util.Date result = null;SimpleDateFormat sdf = new SimpleDateFormat(format);tryresult = sdf

26、.parse(datestr);catch (Exception ex)sdf = new SimpleDateFormat(yyyy-MM-dd);result = sdf.parse(datestr);return result;public static java.util.Date formatFullDateStr(String datestr) throws Exceptionjava.util.Date result = null;SimpleDateFormat sdf = new SimpleDateFormat(yyyy-MM-dd HH:mm:ss);tryresult

27、= sdf.parse(datestr);catch (Exception ex)sdf = new SimpleDateFormat(yyyy-MM-dd);result = sdf.parse(datestr);return result;public static String getFileName(String filepath)filepath = filepath.replace(/, );String filename = filepath;if (filepath.lastIndexOf()0)filename = filepath.substring(filepath.la

28、stIndexOf()+1);return filename;public static void copy(ServletContext context,String form,String to ,boolean removeold) throws java.io.IOExceptioncopy(getFullPath(form,context),getFullPath(to,context),removeold);to,boolean/? ? ? ? ? ? ? ? removeold ? ? ? ? ? public static void copy( String from, Str

29、ing removeold )throws java.io.IOExceptionint BUFF_SIZE = 1024;byte buffer = new byte BUFF_SIZE ; java.io.InputStream in = null;java.io. OutputStream out = null;tryin = new FileInputStream( from );out = new FileOutputStream( to );while ( true )synchronized ( buffer )int amountRead = in.read( buffer )

30、;if ( amountRead = -1 )break;out.write( buffer, 0, amountRead );finallyif ( in != null )in.close();if ( out != null )out.close();System.out.println(Copy Finish);if (removeold)java.io.File file =new java.io.File(from);if (file.delete()System.out.println(delete file:+file.getPath();file.delete();publi

31、c static String getUploadPath(String path)if (path.indexOf(/)!=0)path = /+path;if (path.lastIndexOf(/)!=path.length()-1)path = path+/;return path;/? ? ? ?public static String getFullPath(String url,ServletContext context) url = url.replace(, /);String path = context.getRealPath(url);return path.repl

32、ace(/, );/? ?public static boolean deleteFile(String url,ServletContext context) throws Exception java.io.File file =new java.io.File(getFullPath(url.replace(/,),context);String filepath = file.getPath();String ext = filepath.substring(filepath.lastIndexOf(.)+1);String minifilepath =filepath.substri

33、ng(0,filepath.lastIndexOf(.)+_mini.+ext;java.io.File minifile = new java.io.File(minifilepath);if (minifile.exists()minifile.delete();if (file.exists()log.debug(delete file:+file.getPath(); return file.delete();return false;public static String createPathByDate(String url,ServletContext context)Stri

34、ng fullpath = getFullPath(url,context);if (fullpath.lastIndexOf()!=fullpath.length()-1) fullpath +=;Calendar nowtime = Calendar.getInstance();fullpath +=String.valueOf(nowtime.get(Calendar.YEAR)+; SimpleDateFormat sdf = new SimpleDateFormat(MMdd); fullpath+=sdf.format(nowtime.getTime()+;File file =

35、new File(fullpath);if (!file.exists() file.mkdirs();if (url.lastIndexOf()!=url.length()-1 & url.lastIndexOf(/)!=url.length()-1)url +=/;url += String.valueOf(nowtime.get(Calendar.YEAR)+/;url += sdf.format(nowtime.getTime()+/;return url;public static boolean createPath(String path,ServletContext conte

36、xt) throws ExceptionString fullpath = getFullPath(path,context);File file = new File(fullpath); boolean result= true;if (!file.exists()result =file.mkdirs();return result;II ?讹？?public static String getContextUrl(String url,HttpServletRequest request,ServletContext context)if(request.getContextPath(

37、)!=null&request.getContextPath().length()0)if (url.indexOf(/)!=0) url = /+url;url = request.getContextPath()+url; return url;？ ? ? request? ?貳？public static Object getValue(HttpServletRequest request,String key)if (notEmpty(request, key)return request.getParameter(key); elsereturn request.getAttribu

38、te(key);public static void createNewFile(String savepath) throws java.io.IOExceptionint pos = savepath.lastIndexOf();String dir = savepath.substri ng(0,pos);File directory 二new File(dir);if (!directory.exists()directory.mkdirs();File file = new File(savepath); if (file.exists()file.createNewFile();R

39、enderClass:package com.zte nc.proj.table.f un cti on;import java.util.List;/* ?*/publicclassRen derClass /* ?*/private StringclassName/* ?*/private StringclassPath/* ?*/private Listpropertiespublic Ren derClass() properties =n ull public String getClassName() retur nclassName ;public void setClassNa

40、me(Stri ng className) this . className = className;public Stri ng getTableName() return tableName ;public void setTableName(Stri ng tableName) this . tableName = tableName;publicLisgetProperties() return propertiespublic void setProperties(List properties) this . properties = properties;public void setClassPath(Stri ng classPath) this . classPath = classPath;public Stri ng getClassPath() return classPath使用例子:POBuildUtil utilnew POBuildUtil。;util.build(rc.getClassName(),rc.getClassPat,rc.getProph()+ +rc.getTableName()+ .class erties();/ 在这里成功生成。 class 文件注：以上代码均来自于网上资料。可直接复制即可使用