java常用代码有哪些
发布时间：2024-01-29 点击：95
java常用代码有：1、 字符串有整型的相互转换；2、向文件末尾添加内容；3、得到当前方法的名字 ；4、转字符串到日期；5、使用jdbc链接oracle；6、使用nio进行快速的文件拷贝。
java常用代码有：
1. 字符串有整型的相互转换
string a = string.valueof(2); //integer to numeric string int i = integer.parseint(a); //numeric string to an int相关学习推荐：java基础教程
2. 向文件末尾添加内容
bufferedwriter out = null; try { out = new bufferedwriter(new filewriter(”filename”, true)); out.write(”astring”); } catch (ioexception e) { // error processing code } finally { if (out != null) { out.close(); } }3. 得到当前方法的名字
string methodname = thread.currentthread().getstacktrace()[1].getmethodname();4. 转字符串到日期
java.util.date = java.text.dateformat.getdateinstance().parse(date string);//或者是：simpledateformat format = new simpledateformat( "dd.mm.yyyy" ); date date = format.parse( mystring );5. 使用jdbc链接oracle
public class oraclejdbctest { string driverclass = "oracle.jdbc.driver.oracledriver"; connection con; public void init(fileinputstream fs) throws classnotfoundexception, sqlexception, filenotfoundexception, ioexception { properties props = new properties(); props.load(fs); string url = props.getproperty("db.url"); string username = props.getproperty("db.user"); string password = props.getproperty("db.password"); class.forname(driverclass); con=drivermanager.getconnection(url, username, password); } public void fetch() throws sqlexception, ioexception { preparedstatement ps = con.preparestatement("select sysdate from dual"); resultset rs = ps.executequery(); while (rs.next()) { // do the thing you do } rs.close(); ps.close(); } public static void main(string[] args) { oraclejdbctest test = new oraclejdbctest(); test.init(); test.fetch(); } }6. 把 java util.date 转成 sql.date
java.util.date utildate = new java.util.date(); java.sql.date sqldate = new java.sql.date(utildate.gettime());7. 使用nio进行快速的文件拷贝
public static void filecopy( file in, file out ) throws ioexception { filechannel inchannel = new fileinputstream( in ).getchannel(); filechannel outchannel = new fileoutputstream( out ).getchannel(); try { // inchannel.transferto(0, inchannel.size(), outchannel); // original -- apparently has trouble copying large files on windows // magic number for windows, 64mb - 32kb) int maxcount = (64 * 1024 * 1024) - (32 * 1024); long size = inchannel.size(); long position = 0; while ( position < size ) { position = inchannel.transferto( position, maxcount, outchannel ); } } finally { if ( inchannel != null ) { inchannel.close(); } if ( outchannel != null ) { outchannel.close(); } } }8. 创建图片的缩略图
private void createthumbnail(string filename, int thumbwidth, int thumbheight, int quality, string outfilename) throws interruptedexception, filenotfoundexception, ioexception { // load image from filename image image = toolkit.getdefaulttoolkit().getimage(filename); mediatracker mediatracker = new mediatracker(new container()); mediatracker.addimage(image, 0); mediatracker.waitforid(0); // use this to test for errors at this point: system.out.println(mediatracker.iserrorany()); // determine thumbnail size from width and height double thumbratio = (double)thumbwidth / (double)thumbheight; int imagewidth = image.getwidth(null); int imageheight = image.getheight(null); double imageratio = (double)imagewidth / (double)imageheight; if (thumbratio < imageratio) { thumbheight = (int)(thumbwidth / imageratio); } else { thumbwidth = (int)(thumbheight * imageratio); } // draw original image to thumbnail image object and // scale it to the new size on-the-fly bufferedimage thumbimage = new bufferedimage(thumbwidth, thumbheight, bufferedimag
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java常用代码有：
1. 字符串有整型的相互转换
string a = string.valueof(2); //integer to numeric string int i = integer.parseint(a); //numeric string to an int相关学习推荐：java基础教程
2. 向文件末尾添加内容
bufferedwriter out = null; try { out = new bufferedwriter(new filewriter(”filename”, true)); out.write(”astring”); } catch (ioexception e) { // error processing code } finally { if (out != null) { out.close(); } }3. 得到当前方法的名字
string methodname = thread.currentthread().getstacktrace()[1].getmethodname();4. 转字符串到日期
java.util.date = java.text.dateformat.getdateinstance().parse(date string);//或者是：simpledateformat format = new simpledateformat( "dd.mm.yyyy" ); date date = format.parse( mystring );5. 使用jdbc链接oracle
public class oraclejdbctest { string driverclass = "oracle.jdbc.driver.oracledriver"; connection con; public void init(fileinputstream fs) throws classnotfoundexception, sqlexception, filenotfoundexception, ioexception { properties props = new properties(); props.load(fs); string url = props.getproperty("db.url"); string username = props.getproperty("db.user"); string password = props.getproperty("db.password"); class.forname(driverclass); con=drivermanager.getconnection(url, username, password); } public void fetch() throws sqlexception, ioexception { preparedstatement ps = con.preparestatement("select sysdate from dual"); resultset rs = ps.executequery(); while (rs.next()) { // do the thing you do } rs.close(); ps.close(); } public static void main(string[] args) { oraclejdbctest test = new oraclejdbctest(); test.init(); test.fetch(); } }6. 把 java util.date 转成 sql.date
java.util.date utildate = new java.util.date(); java.sql.date sqldate = new java.sql.date(utildate.gettime());7. 使用nio进行快速的文件拷贝
public static void filecopy( file in, file out ) throws ioexception { filechannel inchannel = new fileinputstream( in ).getchannel(); filechannel outchannel = new fileoutputstream( out ).getchannel(); try { // inchannel.transferto(0, inchannel.size(), outchannel); // original -- apparently has trouble copying large files on windows // magic number for windows, 64mb - 32kb) int maxcount = (64 * 1024 * 1024) - (32 * 1024); long size = inchannel.size(); long position = 0; while ( position < size ) { position = inchannel.transferto( position, maxcount, outchannel ); } } finally { if ( inchannel != null ) { inchannel.close(); } if ( outchannel != null ) { outchannel.close(); } } }8. 创建图片的缩略图
private void createthumbnail(string filename, int thumbwidth, int thumbheight, int quality, string outfilename) throws interruptedexception, filenotfoundexception, ioexception { // load image from filename image image = toolkit.getdefaulttoolkit().getimage(filename); mediatracker mediatracker = new mediatracker(new container()); mediatracker.addimage(image, 0); mediatracker.waitforid(0); // use this to test for errors at this point: system.out.println(mediatracker.iserrorany()); // determine thumbnail size from width and height double thumbratio = (double)thumbwidth / (double)thumbheight; int imagewidth = image.getwidth(null); int imageheight = image.getheight(null); double imageratio = (double)imagewidth / (double)imageheight; if (thumbratio < imageratio) { thumbheight = (int)(thumbwidth / imageratio); } else { thumbwidth = (int)(thumbheight * imageratio); } // draw original image to thumbnail image object and // scale it to the new size on-the-fly bufferedimage thumbimage = new bufferedimage(thumbwidth, thumbheight, bufferedimag
选购云主机服务器价格实惠
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ofo小黄车是如何打造情感化设计的？来看总监的自述！
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3月阿里云开年采购云服务器秒杀