http断点续传简单实现（java)

/* `L 1+j  
**SiteFileFetch.java Wu<;QY($5  
*/ &*'^
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package NetFox; P7zUf  
import java.io.*; 6M`gy|"(~  
import java.net.*; Dq<DW2It>  
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public class SiteFileFetch extends Thread { E
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SiteInfoBean siteInfoBean = null; //文件信息Bean ?<^8,H  
long[] nStartPos; //开始位置 i/n ee_  
long[] nEndPos; //结束位置 *k_<|{>j(  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ZO/Jf Jn~  
long nFileLength; //文件长度 ,SNrcwv  
boolean bFirst = true; //是否第一次取文件 Ipq0 1 +  
boolean bStop = false; //停止标志
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File tmpFile; //文件下载的临时信息 XEbVsw  
DataOutputStream output; //输出到文件的输出流 0,)2\`99#k  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） mjg@c|rTG  
public SiteFileFetch(SiteInfoBean bean) throws IOException ]UEA"^  
{ 9XtO#!+48  
siteInfoBean = bean; 62,dFM7  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); *xpn-hCp<  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); P*?|E@;s`  
if(tmpFile.exists ()) WA1d8nl  
{ =No#/_  
bFirst = false; ~GX ]K H  
read_nPos(); <QFayZ$  
} +>1?ck  
else t3
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{ T%&vq6  
nStartPos = new long[bean.getNSplitter()]; zj] g
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nEndPos = new long[bean.getNSplitter()]; f OR9N/  
} (B$>o.
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} m:`M&Xs&  
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public void run() "P@ SR`v#  
{ YaSBIq{z  
//获得文件长度 bo90;7EK8  
//分割文件 #_S]\=N(  
//实例FileSplitterFetch 2[3t7C  
//启动FileSplitterFetch线程
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//等待子线程返回 9O-~Ws ;  
try{ `?R{sNr.  
if(bFirst) 'R'hRMD9o  
{ ,
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nFileLength = getFileSize(); 0fBw
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if(nFileLength == -1)
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{ 5yK#;!:h  
System.err.println("File Length is not known!"); d9U)O6=  
} kZF<~U  
else if(nFileLength == -2) c%hXj#;  
{ L[9Kh&c  
System.err.println("File is not access!"); R31Z(vY  
} L5zCL0j`  
else 0AffD:  
{ a?nK|Q=e  
for(int i=0;i<nStartPos.length;i++) YJHb\Cf.  
{ `Rfe*oAf  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ,D 
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} k)Lhzr[  
for(int i=0;i<nEndPos.length-1;i++) 1;c>#20  
{ \xggIW.^0  
nEndPos = nStartPos[i+1]; |;~2y>E  
} LXxQI(RO  
nEndPos[nEndPos.length-1] = nFileLength; U`EOun,  
} dL+yd0b*  
} '{.4~:  
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//启动子线程 #"!ga)a%L  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; x+za6e_k"  
for(int i=0;i<nStartPos.length;i++) -hm/lxyU  
{ y7!&  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), oVZzvK(zR  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), Kn1;=k  
nStartPos,nEndPos,i); L)\<7  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 'Z.C&6_  
fileSplitterFetch.start(); Zqe$S +u  
} ?yjg\S?L  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), !LpjTMYs  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); F."ZCEb  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", vxk0@k_  
nEndPos = " + nFileLength); U _A'/p^D  
// fileSplitterFetch[nPos.length-1].start(); vdgK3I  
>0ZG&W9  
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//等待子线程结束 *tRsm
"}  
//int count = 0; b+ycEs=_  
//是否结束while循环 UcB&pt&  
boolean breakWhile = false; "\}h  
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while(!bStop) #prYZcHv:_  
{ |XG&[TI- "  
write_nPos(); -V~Fj~b#  
Utility.sleep(500); Ut'T!RD  
breakWhile = true; ,:J[|9  
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for(int i=0;i<nStartPos.length;i++) @XtrC|dkkE  
{ DBaZcO(U  
if(!fileSplitterFetch.bDownOver) y>E:]#F  
{ )7+z/y+[n  
breakWhile = false; hO3 q|SL  
break; $)KODI>|  
} aN*{nW  
} iZ}c[hC'3`  
if(breakWhile) 0L3
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break; #T>?g5I  
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//count++; iJoY
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//if(count>4) `<v$+mG  
// siteStop(); Z}vDP^rf  
} &{<h
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: KFK2yD  
System.err.println("文件下载结束！"); L?|
}!  
} `w>D6K+  
catch(Exception e){e.printStackTrace ();} v,QvCozOz  
} l/nBin&YGv  
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//获得文件长度 RR+kjK?  
public long getFileSize() -u"|{5? '  
{ w{L9-o3A  
int nFileLength = -1; Btzes.  
try{ 8pr toCB  
URL url = new URL(siteInfoBean.getSSiteURL()); ^;s/4  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); $n!5JS@40  
httpConnection.setRequestProperty("User-Agent","NetFox"); z>,tP  
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int responseCode=httpConnection.getResponseCode(); Hq<4G:#  
if(responseCode>=400) iQ2}*:Jc$  
{ Vfk"}k/do  
processErrorCode(responseCode); J[Mj8ee#  
return -2; //-2 represent access is error Ev3'EA~`  
} {t! &x:  
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String sHeader; I;wxgWOP  
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for(int i=1;;i++) 8Ara^Xh}q  
{ p8-$MF]]6  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); K$}K2w  
//Utility.log(in.readLine()); eE .wnn  
sHeader=httpConnection.getHeaderFieldKey(i); <=6F=u3PtU  
if(sHeader!=null) 1oiS
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{ I Ij:3HP  
if(sHeader.equals("Content-Length")) :XAyMK7  
{ yN`&oya  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); w<h8`K`3  
break; LfW:G5@-  
} 8|\ -(:v  
} b~*iL!<  
else $`\qY ^.(  
break; ^["D>@yIR  
} s.;'-oA  
} kxEq_FX  
catch(IOException e){e.printStackTrace ();} N>a~k}pPH  
catch(Exception e){e.printStackTrace ();} ^q& Rl\  
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Utility.log(nFileLength); F,VWi$Po\N  
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return nFileLength; Fz<1xyc(  
} .9z}S=ZK  
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//保存下载信息（文件指针位置） GoX<d{  
private void write_nPos() <1lB[:@%U  
{ 37?X@@Z=  
try{ ac@\\2srV  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Hl(W'>*oL  
output.writeInt(nStartPos.length); rc>}3?o  
for(int i=0;i<nStartPos.length;i++) Tyaqa0  
{ r
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// output.writeLong(nPos); hMS:t(N{  
output.writeLong(fileSplitterFetch.nStartPos); <liprUFsn  
output.writeLong(fileSplitterFetch.nEndPos); A@d 2Ukv  
} 'ta&qp
 
output.close(); bW/T}FND  
} jp~Tlomp  
catch(IOException e){e.printStackTrace ();} S
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catch(Exception e){e.printStackTrace ();} |=VWE>g  
} {hf_Xro&  
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//读取保存的下载信息（文件指针位置） J
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private void read_nPos() jJvd!,=)  
{ D_ej%QtB@  
try{ !U2<\!_  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); HL$7Ou  
int nCount = input.readInt(); `\ IaeMvo  
nStartPos = new long[nCount]; 9)=bBQyr:  
nEndPos = new long[nCount]; Vx5fQ mx  
for(int i=0;i<nStartPos.length;i++) dikX_ Q>D  
{ %$)Sz[=  
nStartPos = input.readLong(); LB$0'dZU  
nEndPos = input.readLong(); yD!GgnW  
} qJl DQc-  
input.close(); J%q)6&  
} In:V.'D/>t  
catch(IOException e){e.printStackTrace ();} 0%HAa|L,,  
catch(Exception e){e.printStackTrace ();} L:@COy  
} f0%'4t  
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private void processErrorCode(int nErrorCode) @_c&lToj_  
{ g.;2N9  
System.err.println("Error Code : " + nErrorCode); &F[N$6:v  
} #ifjQ7(:  
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//停止文件下载 ]JmE(Y1(1  
public void siteStop() n^qwE
 
{ `)w=@9B)"  
bStop = true; G'wW-|  
for(int i=0;i<nStartPos.length;i++) b rDyjh  
fileSplitterFetch.splitterStop(); ^aJ]|*m  
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}
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} e_rEu'[av  
//负责部分文件的抓取 /yUKUXi  
**FileSplitterFetch.java $6r> Tc](  
*/ &:g1*+  
package NetFox; e&[~}f?  
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import java.io.*; ]*)l_mut7  
import java.net.*; CSWA/#&8>  
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public class FileSplitterFetch extends Thread { #X{lV]Z  
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String sURL; //File URL {VM^K1  
long nStartPos; //File Snippet Start Position HuSE6an  
long nEndPos; //File Snippet End Position ao(Lv+   
int nThreadID; //Thread's ID Gw6!cp|/  
boolean bDownOver = false; //Downing is over _]3#C[1L  
boolean bStop = false; //Stop identical 1guiuR4  
FileAccessI fileAccessI = null; //File Access interface s{Y-Vdx  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException |x _jpR  
{ dIQ3snG  
this.sURL = sURL; bG.`>   
this.nStartPos = nStart; K^b'<} $|p  
this.nEndPos = nEnd; 4Uwcc):f  
nThreadID = id; v`7~#Avhz  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 :8+x&zn  
} A&-2f]L tl  
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public void run() 4VsttT  
{ fP
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while(nStartPos < nEndPos && !bStop) =gd~rk9  
{ k%N$eO$  
*
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try{ 1^WkW\9kO  
URL url = new URL(sURL); LiGECqWBa'  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 0NvicZ7VR  
httpConnection.setRequestProperty("User-Agent","NetFox"); YXU2UIY<~  
String sProperty = "bytes="+nStartPos+"-"; ]yFO~4Nu  
httpConnection.setRequestProperty("RANGE",sProperty); }^odUIj  
Utility.log(sProperty); ^Vc(oa&;  
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InputStream input = httpConnection.getInputStream(); A*]sN8  
//logResponseHead(httpConnection); JRtDjZ4>  
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byte[] b = new byte[1024]; \x8'K  
int nRead; }tH_Y
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) HMKogGTTo  
{ x IL]Y7HWM  
nStartPos += fileAccessI.write(b,0,nRead); uF D  
//if(nThreadID == 1) >ca`0gu  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); w,!N{hv(  
} _.W;hf`  
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Utility.log("Thread " + nThreadID + " is over!"); {k'$uW`  
bDownOver = true;
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//nPos = fileAccessI.write (b,0,nRead); ,v9*|>4  
} TD!c+${w  
catch(Exception e){e.printStackTrace ();} G/1V4-@  
} ySlGqR1H  
} 6\QsK96_  
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//打印回应的头信息 h4~VzCR4x\  
public void logResponseHead(HttpURLConnection con) 5
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{ I]91{dq  
for(int i=1;;i++) a3 t||@v!  
{ O&dh<  
String header=con.getHeaderFieldKey(i); W#x~x|(c  
if(header!=null) HJe6h. P  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); `cRRdD:dA  
Utility.log(header+" : "+con.getHeaderField(header)); v/Xz.?a\jF  
else }ol<DV  
break; G98fBw  
} IfCa6g<&(  
} 0A75)T=lQ  
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public void splitterStop() 5J6~]J  
{ '@5"p.  
bStop = true; {'+.?g  
} M(Yt9}Z%Y  
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} j>hBNz  
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/* @@6c{r^P  
**FileAccess.java gI+dyoh  
*//文件访问(定位，写) !qs3fe<uh"  
package NetFox; 1#vi]CX  
import java.io.*; !~}@Eoii4  
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public class FileAccessI implements Serializable{ 7{OD/*|  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 )=#zMdK&  
RandomAccessFile oSavedFile; RJD(c#r$  
long nPos; ooN?x31  
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public FileAccessI() throws IOException Okd7ua-f  
{ *
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this("",0); p2wDk^$  
} )JR&  
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public FileAccessI(String sName,long nPos) throws IOException Cuom_+wV&  
{ $69d9g8-(!  
oSavedFile = new RandomAccessFile(sName,"rw"); p!`S]\XEB  
this.nPos = nPos; D+4$l+\u  
oSavedFile.seek(nPos); G,@Jo[e  
} /+
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public synchronized int write(byte[] b,int nStart,int nLen) Rw`64L_
  
{ wG&rkg";#  
int n = -1; %/%TR@/  
try{ `_pVwa<@w  
oSavedFile.write(b,nStart,nLen); ]/?$DNjCc  
n = nLen; xL!@$;J  
} 7$JE+gL/7  
catch(IOException e) {$_Gjv  
{ .oe\wJS6  
e.printStackTrace (); i[n3ILn  
} }^*m0`H  
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return n; G~zP&9N|  
} slG%o5|m  
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} fa
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/* i [2bz+Z?  
**SiteInfoBean.java :eR\0cn  
*/ dPF*G$  
package NetFox; .2*h!d)E  
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public class SiteInfoBean { '6f)^DYA'?  
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private String sSiteURL; //Site's URL cbv%1DT3  
private String sFilePath; //Saved File's Path }?,Eb~q  
private String sFileName; //Saved File's Name XGDJCN  
private int nSplitter; //Count of Splited Downloading File v2f|%i;tq  
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public SiteInfoBean() @8|i@S@4  
{//nSplitter的缺省值为5 9&OhCrxW-  
//default value of nSplitter is 5 Y]+KsiOL  
this("","","",5); 0 TOw4pC  
} \|C~VU@  
vH>s2\V"  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) C9nCSbGMY{  
{ y:R+;91  
sSiteURL= sURL; Y?JB%%WWI  
sFilePath = sPath;
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sFileName = sName; ?2Sm f  
this.nSplitter = nSpiltter; W$Z8AZ{E  
.-.b:gdO(  
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} 8>!-|VSn  
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public String getSSiteURL() L?b;TjLe  
{ .N Z  
return sSiteURL; GBGna3  
} kwrM3nq  
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public void setSSiteURL(String value) >$;,1N $bd  
{ PS`F  
sSiteURL = value; 3Hhu]5  
} #++D|oE  
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public String getSFilePath() c=4z+_K  
{ B8?j"AF  
return sFilePath; Vu Ey`c  
} F&D,y-CQ  
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public void setSFilePath(String value) ]nm(V  
{ lrK?&a9AB  
sFilePath = value; (xMq(g  
} !.w|+-JKO  
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public String getSFileName() t9&=; s  
{ m%)S<L7 l  
return sFileName; |pR'#M4j4A  
} (%*~5%l\  
8,]wOxwqi  
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public void setSFileName(String value) nSq$,tk(  
{ Bh()?{q  
sFileName = value; !r9~K^EI
 
} 3tCT"UvTD  
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public int getNSplitter() +D M,+{}  
{ %=i/MFGX  
return nSplitter; P&AaD!Qn  
} j`_tb
 
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public void setNSplitter(int nCount) +Q+!#  
{ c"NGE  
nSplitter = nCount; :-cqC|Y  
} \1#~]1~ s  
} 0MN)Z(Sa  
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/* &IkHP/  
**Utility.java .Iv`B:4  
*/ s,7OoLE  
package NetFox; )?k~E=&o  
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public class Utility { Y$
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public Utility() +@anYtv%7  
{ 0|]qWcD  
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} Q-||A  
|O[ I=!  
//线程睡眠 0t)5KO  
public static void sleep(int nSecond) $2$jV1s  
{ 3OJGBiDAr  
try{ 1b8}TG2  
Thread.sleep(nSecond); }XRRM:B|)(  
} B'D~Q  
catch(Exception e) QMwV6cA  
{ |S3w
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e.printStackTrace (); CA,2&v"  
} P8GGN  
} vJuL+'[i  
(_eM:H=e>  
//日志 %wIb@km  
public static void log(String sMsg) c5t7X-LB  
{ RHuc#b0  
System.err.println(sMsg); <Mf(2`T  
} ^PowL:  
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g
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public static void log(int sMsg) i[Pk
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{ 1"U.-I@  
System.err.println(sMsg); nT@FSt  
} I
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} EK
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/* Z xR  
**TestMethod.java Qz([\Xx:  
*/ 8%^W<.Y  
package NetFox; r&nEM6  
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public class TestMethod { Nzb
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public TestMethod() mlbSs_LT^  
{ ///xx/weblogic60b2_win.exe d&%}u1 .  
try{ G_6!w//  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); #=I5_
u  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); u7bji>j  
SiteFileFetch fileFetch = new SiteFileFetch(bean); &(~"OD  
fileFetch.start(); 3 /LW6W|  
} 6?= ^8  
catch(Exception e){e.printStackTrace ();} Tyw
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} _&PF(/w  
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public static void main(String[] args) {EVHkQ+o  
{ CMHg]la  
new TestMethod(); p\r V6+  
} W";Po)YC  
} Z^GXKOeq  
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