java常用功能例子总结.docx

1 JAVA1.1 JDK环境变量配置安装完JDK后,需要配置环境变量。配置环境变量目的有三个：第一，让操作系统自动查找编译器、解释器所在的路径；第二，设置程序编译和执行时需要的类路径；第三，Tomcat服务器安装时需要知道虚拟机所在的路径。（1）设置好path变量，使得我们能够在系统中的任何地方运行java应用程序，比如javac、java、javah等等,这就要找到我们安装JDK的目录，比如我们的JDK安装在C:jdk1.6.0目录下，那么在C:jdk1.6.0bin目录下就是我们常用的java应用程序，我们就需要把C:jdk1.6.0bin这个目录加到path环境变量里面。在系统变量里找到path变量，选择-编辑；(里面已经有很多的变量值,是在变量值的最前面加上C:jdk1.6.0bin;)变量名：path变量值：C:jdk1.6.0bin;（2）classpath环境变量，是当我们在开发java程序时需要引用别人写好的类时，要让java解释器知道到哪里去找这个类。通常，sun为我们提供了一些额外的丰富的类包，一个是dt.jar，一个是tools.jar，这两个jar包都位于C:jdk1.6.0lib目录下，所以通常我们都会把这两个jar包加到我们的classpath环境变量中set classpath=.;C:jdk1.6.0libtools.jar;C:jdk1.6.0libdt.jar; C:jdk1.6.0lib在系统环境变量那一栏中点-新建classpath变量名：classpath变量值：.;%JAVA_HOME%libtools.jar;%JAVA_HOME%libdt.jar;（注意，CLASSPATH最前面是有个“.”的，表示当前目录，这样当我们运行java AClass的时候，系统就会先在当前目录寻找AClass文件了。）；（3）设置JAVA_HOME：一是为了方便引用，比如，JDK安装在C:jdk1.6.0目录里，则设置JAVA_HOME为该目录路径, 那么以后要使用这个路径的时候，只需输入%JAVA_HOME%即可，避免每次引用都输入很长的路径串;二则是归一原则，当JDK路径改变的时候，仅需更改JAVA_HOME的变量值即可，否则，就要更改任何用绝对路径引用JDK目录的文档，要是万一没有改全，某个程序找不到JDK，后果是可想而知的系统崩溃!三则是第三方软件会引用约定好的JAVA_HOME变量，不然，你不能正常使用该软件。在系统环境变量那一栏中点-新建JAVA_HOME （JAVA_HOME指向的是JDK的安装路径） 变量名：JAVA_HOME 变量值：C:jdk1.6.0(4)测试是否配置成功配置完成下面写一个简单的java程式来测试J2SDK是否已安装成功：publicclassHelloWorld publicstaticvoidmain(Stringargs) ystem.out.println(Helloworld!); 将程式保存为文档名为HelloWorld.java的文档。打开命令提示符窗口，进入到HelloWorld.java所在目录，键入下面的命令javacHelloWorld.java javaHelloWorld此时若打印出来HelloWorld则安装成功，若没有打印出这句话，仔细检查以上配置是否正确。1.2 Action1.2.1 Action传参数1import javax.servlet.http.HttpServletRequest;HttpServletRequest request = ServletActionContext.getRequest();request.setAttribute(validity, 1);JSP中对应取参数：String validity=(String)request.getAttribute(validity);1.2.2 Action传参数2import java.io.IOException;import java.io.PrintWriter; import javax.servlet.http.HttpServletResponse;HttpServletResponse response=ServletActionContext.getResponse();response.setCharacterEncoding(utf-8);try System.out.println(name is # + name);PrintWriter pw = response.getWriter();pw.print(result:名称重复，请重新输入);pw.close(); catch (IOException e) e.printStackTrace();1.2.3 Action传参数3Struts配置： Action：private String message;public String getMessage() return message;public void setMessage(String message) this.message = message;this.message=名称重复，请重新输入;System.out.println(result is +this.message);return message;1.3 数据库1.3.1 数据库链接package com.edatongtu.utils;import java.sql.*; public class JdbcConnection public static String url =jdbc:oracle:thin::1521:ORCL; public static String username =lijuan; public static String password =123456; static try Class.forName(oracle.jdbc.driver.OracleDriver); catch (ClassNotFoundException e) throw new ExceptionInInitializerError(e); public static Connection getConnection() throws SQLException return DriverManager.getConnection(url, username, password); Connection con=JdbcConnection.getConnection();con.setAutoCommit(true); 自动提交 Statement myStatement=con.createStatement();注：需导入 com.edatongtu.utils.JdbcConnection1.3.2 Sql语句1.数据选择语句String sql=select * from tablestore where id=+lmid+; ResultSet rs=myStatement.executeQuery(sql);if(rs.next() element=rs.getString(element); 2.数据插入语句：String sql=”insert into refermodeltable (lmid,id,lmuniquename) values(”+lmid+”,”+id+”,”+uniquename+”)”;3.更新数据：update tablestore set default_style=“+id+” where id=”+lmid+”4.删除语句：delete from refermodeltable where id=”+lmid+”5.删除表：drop table+表名6条件查询：select classification_id,classification_name,classification_explain,(case if_default_classification when 0 then 否 when 1 then 是 end) if_default_classification from sys_ib_classification_system7.新建表: create table lijuantest2(id varchar(300) primary key,name varchar(300) not null)create table QT_4 (QUESTION_ID VARCHaR(50) primary key ,itembank_id varchar(50),question_type varchar(50),difficulty float(1),defaultpoint number(38),time_use number(38),knowledge_point_id varchar(50),editor_id varchar(50),update_time Date,explain varchar(50) default(无) ,statue number(38) default(1)8.更改表名：ALTER TABLE table111 RENAME TO table2229. or 和and 混合查询SELECT * FROM Persons WHERELastName=Svendson AND (FirstName=Tove OR FirstName=Ola)10 case select 选择查询select rownum rn,cu.question_id,cu.defaultpoint,cu.time_use,cu.knowledge_point_id,cu.editor_id,cu.UPDATE_TIME,cu.TIME,cu.EXPLAIN,(case when difficulty0 then 简单 when difficulty0.3 then 中等 when difficulty0.7 then 困难 end) DIFFICULTY, (case QUESTION_TYPE when xuanze then 选择题 when panduan then 判断题 when tiankong then 填空题 when jianda then 简答题 end) QUESTION_TYPE from QT_BASICFIELD_lijuantest1 cu11 表格数据复制（普通数据和BLOB数据均可以复制）insert into QT_BLOBFIELD_LIJUANTEST2 SELECT * FROM QT_BLOBFIELD_LIJUANTEST1 WHERE QUESTION_ID=5e2393ca-b754-42e0-bd78-26088d069ed51.4 字符串处理1.4.1 list转jsonJSONArray zNodes = JSONArray.fromObject( list );1.4.2 转jsonJSONObject zNodes = JSONObject.fromObject( list );1.4.3 判断字符串中是否有某个字段String ascs=ascs;if(ascs.indexOf(asc)!=-1)System.out.println(%);1.4.4 字符串转换，去空格大写defaultsort.trim().toUpperCase().equals(YES)1.4.5 字符串转date型di.executeQuery(insert into QT_BASICFIELD_ + target_itembank+ fields(question_id,EDITOR_ID,TIME,QUESTION_TYPE) values(+questionid+, + cell24+ , + to_date(+cell12+,yyyy-MM-dd) + , + questiontype + );1.4.6 哈希表package com.edatongtu.utils;import java.util.HashMap;import java.util.Iterator;import java.util.Map;public class MapUtils public static Map getParameterMap(Map properties) / 返回值MapMap returnMap = new HashMap();Iterator entries = properties.entrySet().iterator();Map.Entry entry;String name = ;Object value = ;while (entries.hasNext() entry = (Map.Entry) entries.next();name = (String) entry.getKey();Object valueObj = entry.getValue();if(null = valueObj)value = ;else if(valueObj instanceof String)String values = (String)valueObj;for(int i=0;ivalues.length;i+)value = valuesi + ,;value = String.valueOf(value).substring(0, String.valueOf(value).length()-1);elsevalue = valueObj;returnMap.put(name, value);return returnMap;Map params=MapUtils.getParameterMap(request.getParameterMap();Iterator it = params.entrySet().iterator();while (it.hasNext() Map.Entry entry = (Map.Entry) it.next(); String paramName=(String)entry.getKey(); if(paramName.startsWith(main_) elementName=paramName.substring(main_.length(); style_element+=+elementName+:+elementName+,+elementTitle+:+params.get(fld_+elementName+_title)+,+isdisplay+:+params.get(fld_+elementName+_display)+,+isanchor+:+params.get(fld_+elementName+_anchor)+,; style_element=style_element.substring(0,style_element.length()-1);style_element=+style_element+;1.4.7 时间正则表达式 String eL = 0-94-0-92-0-92;Pattern p = Ppile(eL);Matcher m = p.matcher(bbb);boolean dateFlag = m.matches();if (!dateFlag) System.out.println(格式错误);System.out.println(格式正确);1.4.8 ajax前台向后台传数据乱码问题后台处理String str=new String(SortName.getBytes(iso-8859-1),utf-8);前台处理：URL后跟参数是get方式，Data后aa：aapost方式应采用post方式。1.5 IO1.5.1 将文件以blob写入数据库先插入再更新di.execute(insert into QT_BLOBFIELD_ + target_itembank+ values(+blob_Id+,empty_blob(),empty_blob();/插入空数据String TableName=QT_BLOBFIELD_ + target_itembank+ ;String IdField=question_id;String FieldName=questioncontent;File file3 = new File(d:+docname+.doc); InputStream in = null;/获取试题文件流try in = new FileInputStream(file3); catch (FileNotFoundException e) e.printStackTrace(); service.exercuteInsertWithBlob(TableName, IdField,blob_Id, FieldName, in);public String exercuteInsertWithBlob(String TableName, String IdField,String Id, String FieldName, InputStream InStream) Connection connection = null;Statement statement = null;OutputStream outStream =null;Stringresult=true;StringSql=select +FieldName+ from +TableName+ where +IdField+=+Id+ for update;try connection = ConnPool.getConnection();statement = connection.createStatement();ResultSet rs = statement.executeQuery(Sql);if (rs.next() logger.debug(come in);/ 得到java.sql.Blob对象，然后Cast为oracle.sql.BLOBoracle.sql.BLOB blob = (oracle.sql.BLOB) rs.getBlob(1);/ 到数据库的输出流outStream = blob.getBinaryOutputStream();/ 将输入流写到输出流byte b = new byteblob.getBufferSize();int len = 0;while (len = InStream.read(b) != -1) outStream.write(b, 0, len);elselogger.debug(dont come in);result=nodata;if(null!=InStream)InStream.close(); if(null!=outStream)outStream.flush(); outStream.close(); if(null!=connection)mit(); ConnPool.freeResource(rs, statement, connection); catch (Exception e) e.printStackTrace();result=error;return result;1.5.2 获取inputstream流File file3 = new File(d:+docname+.doc); InputStream in = null;/获取试题文件流try in = new FileInputStream(file3); catch (FileNotFoundException e) e.printStackTrace();1.5.3 InputStream Convert to fileFile file4 = new File(D:11111.doc);InputStream in = null;/ 获取试题文件流try in = new FileInputStream(file4); catch (FileNotFoundException e) e.printStackTrace(); try File f=new File(D:lijuan111.doc); OutputStream out=new FileOutputStream(f); byte buf=new byte1024; int len; while(len=in.read(buf)0) out.write(buf,0,len); logger.debug(&*&); out.close(); in.close();/BufferedWriter bw = new BufferedWriter(new FileWriter(D:data.doc); /bw.write(in); catch (IOException e) / TODO Auto-generated catch blocke.printStackTrace(); 1.6 文件操作1.6.1 Java删除文件String filePath = d:+newdocname+.doc;File file = new File(filePath);file.delete(); 1.6.2 Fileupload文件上传 if (ServletFileUpload.isMultipartContent(request) DiskFileItemFactory dff = new DiskFileItemFactory(); dff.setRepository(tmpDir); dff.setSizeThreshold(1024000); ServletFileUpload upload = new ServletFileUpload(dff); upload.setFileSizeMax(5000000); upload.setSizeMax(10000000); List items = upload.parseRequest(request); Iterator iter = items.iterator(); while (iter.hasNext() FileItem fis = (FileItem) iter.next(); if (!fis.isFormField() & fis.getName().length() 0) String fileName = fis.getName(); realname=fis.getName().substring(0,fis.getName().lastIndexOf(.); suffix= fis.getName().substring( fis.getName().lastIndexOf(.); UniqueName=EDTTUUID.getUUID(); BufferedInputStream in = new BufferedInputStream(fis.getInputStream(); BufferedOutputStream out1 = new BufferedOutputStream( new FileOutputStream(new File(saveDir + + UniqueName+suffix); Streams.copy(in, out1, true); 1.7 Session1.7.1 Session 保存传递的数据if(request.getParameter(id)!=null)lmid=request.getParameter(id);session.setAttribute(LMID, lmid);elselmid=(String)session.getAttribute(LMID);1.8 常用1.8.1 自动生成idSys_guid();1.8.2 UUID使用package com.edatongtu.utils;import com.eaio.uuid.UUID;public class EDTTUUID public static String getUUID()returnnew UUID().toString();id=EDTTUUID.getUUID();注：需导入 com.edatongtu.utils.EDTTUUID1.8.3 路劲存储String savePath=/viewmodel;String dsavePath=request.getRealPath(savePath);1.8.4 批量删除ResultSet rs=myStatement.executeQuery(select id from refermodeltable);String checkedIds=;while(rs.next()String chkItemValue=request.getParameter(chk+rs.getString(id);if(chkItemValue=null) else if(chkItemValue.equals(on) if(!checkedIds.equals() checkedIds+=,; checkedIds+=+rs.getString(id)+; if(!checkedIds.equals() String sql=delete from refermodeltable where id in (+checkedIds+); myStatement.execute(sql); rs.close(); myStatement.close(); con.close();1.9 接口和类1.9.1 接口定义：public interface SortService public String addSort(String message,String name,String identifier,String discription,String defaultsort) ;1.9.2 具体实现：public class SortServiceImpl implements SortServicepublic String addSort(String message,String name,String identifier,String discription,String defaultsort) 1.9.3 调用类:方式一:SortService SortAddAction=new SortServiceImpl();SortAddAction.addSort(message,name,identifier,discription,defaultsort);方式二:运用Spring依赖注入1）SortService SortAddAction=(SortService)BeanLoader.getBean(SortServiceImpl);SortAddAction.addSort(message,name,identifier,discription,defaultsort);Spring配置：2）private SortServiceImpl SortAddAction ;public SortServiceImpl getSortAddAction() return SortAddAction;public void setSortAddAction(SortServiceImpl sortAddAction) SortAddAction = sortAddAction;SortAddAction.addSort(message,name,identifier,discription,defaultsort);Spring配置：1.10 Jacob word操作参考资料中jacob函数JacobWordBeanServiceImpl wordBean = new JacobWordBeanServiceImpl();/ 检查试题基本信息表格UUID newdocuuid = UUID.randomUUID(); String newdocname=newdocuuid.toString();wordBean.CreateDoc(newdocname);/ 创建一个新文件wordBean.OpenFile(d:+newdocname+.doc);wordBean.SetVisible(true); / 是否前台打开word 程序，或者后台运行wordBean.copyTableFromAnotherDoc(d:xiaokai.doc, 1);UUID savedocuuid = UUID.randomUUID(); String savedocname=newdocuuid.toString();wordBean.saveFileAs(d:+savedocname+.doc);/ 保存第一个表格，必须另存，不然会在前台是否保存word，则无法执行删除工作/ 检查表格行数列数是否正确int rowCount = wordBean.gettableRow();/ 表格行数int colCount = wordBean.gettableColumn();/ 表格列数int cols1 = wordBean.getCols(1);/ 第一行列数int cols2 = wordBean.getCols(2);/ 第二行列数 /* * * 名称：gettableColumn * 说明：获取表格列数 * 参数：param anotherDocPath * 参数：param tableIndex 设定文件 * 返回值：void 返回类型 * param anotherDocPath * param tableIndex * author:lijuan */ public int gettableColumn() Dispatch tables = Dispatch.get(document, Tables).toDispatch(); int tableCount = Dispatch.get(tables, Count).getInt(); / document中的表格数量 Dispatch table = Dispatch.call(tables, Item, new Variant(tableCount) .toDispatch();/ 文档中最后一个table Dispatch cols = Dispatch.get(table, Columns).toDispatch(); int colCount = Dispatch.get(cols, Count).getInt(); return colCount; /* * * 名称：gettableRow * 说明：TODO(这里用一句话描述这个方法的作用) * 参数：return 设定文件 * 返回值：int 返回类型 * return * author:lijuan */ public int gettableRow() Dispatch tables = Dispatch.get(document, Tables).toDispatch(); int tableCount = Dispatch.get(tables, Count).getInt(); / document中的表格数量 Dispatch table = Dispatch.call(tables, Item, new Variant(tableCount) .toDispatch();/ 文档中最后一个table Dispatch rows = Dispatch.get(table, Rows).toDispatch(); / 此表的所有行， int rowCount = Dispatch.get(rows, Count).getInt(); return rowCount; /* * * 名称：getCols * 说明：获取某一行的列数 * 参数：return 设定文件 * 返回值：int 返回类型 * return * author:lijuan */ public int getCols(int a) Dispatch tables = Dispatch.get(document, Tables).toDispatch(); int tableCount = Dispatch.get(tables, Count).getInt(); / document中的表格数量 Dispatch table = Dispatch.call(tables, Item, new Variant(tableCo