下面是15个非常有用的java程序片段，希望能对你有用。1.字符串有整型的相互转换
Stringa=String.valueOf(2);//integertonumericstring
inti=Integer.parseInt(a);//numericstringtoanint
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2.向文件末尾添加内容
BufferedWriterout=null;
try{
out=newBufferedWriter(newFileWriter(”filename”,true));
out.write(”aString”);
}catch(IOExceptione){
//errorprocessingcode
}finally{
if(out!=null){
out.close();
}
}
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3.得到当前方法的名字
StringmethodName=Thread.currentThread().getStackTrace()[1].getMethodName();
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4.转字符串到日期
strongjava.util.Date=java.text.DateFormat.getDateInstance().parse(dateString);/strong
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或者是：
SimpleDateFormatformat=newSimpleDateFormat(dd.MM.yyyy);
Datedate=format.parse(myString);
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5.使用JDBC链接Oracle
publicclassOracleJdbcTest
{
StringdriverClass=oracle.jdbc.driver.OracleDriver;
Connectioncon;
publicvoidinit(FileInputStreamfs)throwsClassNotFoundException,SQLException,FileNotFoundException,IOException
{
Propertiesprops=newProperties();
props.load(fs);
Stringurl=props.getProperty(db.url);
StringuserName=props.getProperty(db.user);
Stringpassword=props.getProperty(db.password);
Class.forName(driverClass);
con=DriverManager.getConnection(url,userName,password);
}
publicvoidfetch()throwsSQLException,IOException
{
PreparedStatementps=con.prepareStatement(selectSYSDATEfromdual);
ResultSetrs=ps.executeQuery();
while(rs.next())
{
//dothethingyoudo
}
rs.close();
ps.close();
}
publicstaticvoidmain(String[]args)
{
OracleJdbcTesttest=newOracleJdbcTest();
test.init();
test.fetch();
}
}
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你也可以看看：Java建立和Mysql、sqlserver和Oracle数据库的连接6.把Javautil.Date转成sql.Date
java.util.DateutilDate=newjava.util.Date();
java.sql.DatesqlDate=newjava.sql.Date(utilDate.getTime());
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7.使用NIO进行快速的文件拷贝
publicstaticvoidfileCopy(Filein,Fileout)
throwsIOException
{
FileChannelinChannel=newFileInputStream(in).getChannel();
FileChanneloutChannel=newFileOutputStream(out).getChannel();
try
{
//inChannel.transferTo(0,inChannel.size(),outChannel);//original--apparentlyhastroublecopyinglargefilesonWindows
//magicnumberforWindows,64Mb-32Kb)
intmaxCount=(64**)-(32*);
longsize=inChannel.size();
longposition=0;
while(positionsize)
{
position+=inChannel.transferTo(position,maxCount,outChannel);
}
}
finally
{
if(inChannel!=null)
{
inChannel.close();
}
if(outChannel!=null)
{
outChannel.close();
}
}
}
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8.创建图片的缩略图
privatevoidcreateThumbnail(Stringfilename,intthumbWidth,intthumbHeight,intquality,StringoutFilename)
throwsInterruptedException,FileNotFoundException,IOException
{
//loadimagefromfilename
Imageimage=Toolkit.getDefaultToolkit().getImage(filename);
MediaTrackermediaTracker=newMediaTracker(newContainer());
mediaTracker.addImage(image,0);
mediaTracker.waitForID(0);
//usethistotestforerrorsatthispoint:System.out.println(mediaTracker.isErrorAny());
//determinethumbnailsizefromWIDTHandHEIGHT
doublethumbRatio=(double)thumbWidth/(double)thumbHeight;
intimageWidth=image.getWidth(null);
intimageHeight=image.getHeight(null);
doubleimageRatio=(double)imageWidth/(double)imageHeight;
if(thumbRatioimageRatio){
thumbHeight=(int)(thumbWidth/imageRatio);
}else{
thumbWidth=(int)(thumbHeight*imageRatio);
}
//draworiginalimagetothumbnailimageobjectand
//scaleittothenewsizeon-the-fly
BufferedImagethumbImage=newBufferedImage(thumbWidth,thumbHeight,BufferedImage.TYPE_INT_RGB);
Graphics2Dgraphics2D=thumbImage.createGraphics();
graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);
graphics2D.drawImage(image,0,0,thumbWidth,thumbHeight,null);
//savethumbnailimagetooutFilename
BufferedOutputStreamout=newBufferedOutputStream(newFileOutputStream(outFilename));
JPEGImageEncoderencoder=JPEGCodec.createJPEGEncoder(out);
JPEGEncodeParamparam=encoder.getDefaultJPEGEncodeParam(thumbImage);
quality=Math.max(0,Math.min(quality,));
param.setQuality((float)quality/.0f,false);
encoder.setJPEGEncodeParam(param);
encoder.encode(thumbImage);
out.close();
}
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9.创建JSON格式的数据
请先阅读这篇文章了解一些细节，并下面这个JAR文件：json-rpc-1.0.jar(75kb)
importorg.json.JSONObject;
...
...
JSONObjectjson=newJSONObject();
json.put(city,Mumbai);
json.put(country,India);
...
Stringoutput=json.toString();
...
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10.使用iTextJAR生成PDF
阅读这篇文章了解更多细节
fontcolor=rgb(51,51,51)fontstyle=background-color:rgb(,,)fontface=宋体importjava.io.File;
importjava.io.FileOutputStream;
importjava.io.OutputStream;
importjava.util.Date;
import白癜风的症状图片初期北京治疗白癜风技术