http断点续传简单实现（java)

/* Yq/.-4y  
**SiteFileFetch.java 8Dvazg}4  
*/ IJ/sX_k  
package NetFox; 5Vi>%5A>l  
import java.io.*; ncx(pp  
import java.net.*; _!|/ ;Nk  
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public class SiteFileFetch extends Thread { 3"{.37Q  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 8#Q$zLK42N  
long[] nStartPos; //开始位置 x
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long[] nEndPos; //结束位置 SRSvot};C  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 [b$4Shx  
long nFileLength; //文件长度 Reu*Pe  
boolean bFirst = true; //是否第一次取文件 kHqztg  
boolean bStop = false; //停止标志 2./3 \n2  
File tmpFile; //文件下载的临时信息 D_8x6`z  
DataOutputStream output; //输出到文件的输出流 %E_b'[8  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） mLL340c#\  
public SiteFileFetch(SiteInfoBean bean) throws IOException Dwl3Cj  
{ K).n.:vYZ  
siteInfoBean = bean; ;m2<eS`o'  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ?h1H.s2X
 
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); _A0w[n  
if(tmpFile.exists ()) )>c>oMgl  
{  kQ  
bFirst = false; 6eokCc"o  
read_nPos(); }=!,o  
} #h@J=Ki  
else
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{ r `eU~7  
nStartPos = new long[bean.getNSplitter()]; 72veLB  
nEndPos = new long[bean.getNSplitter()]; )P|[r  
} vpU#xm.K  
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} ,[A'tUl _  
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public void run() lb:/EUd5  
{ :EHJ\+kejX  
//获得文件长度 $\k0Nup}  
//分割文件 nQGQWg`  
//实例FileSplitterFetch (mlzg=szW  
//启动FileSplitterFetch线程 4l&g6YneX  
//等待子线程返回 ^3hn0DVQ  
try{ 4hw@yTUo  
if(bFirst) 07Edfe  
{ V _c@b%  
nFileLength = getFileSize(); nbG/c80  
if(nFileLength == -1) !a~`Bs$'jr  
{ P+)DsZ0ig  
System.err.println("File Length is not known!"); xTGxvGv8  
} rS1fK1dys  
else if(nFileLength == -2) B:Z_9,gj-N  
{ [p=*u,-  
System.err.println("File is not access!"); YSaJeU>@  
} !p1qJ
[  
else @zgdq  
{ R=Tqj,6  
for(int i=0;i<nStartPos.length;i++) [ 4;Ii  
{ H}LS??P  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); !d&C>7nb  
} .Q)|vq^  
for(int i=0;i<nEndPos.length-1;i++) l$hJE;n  
{ @x/T&67k  
nEndPos = nStartPos[i+1]; Pf F=m'  
} ,TRTRb;  
nEndPos[nEndPos.length-1] = nFileLength; RaTH\>n  
} Jxqh)l  
} c/5W4_J  
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oDcKtB+2  
//启动子线程 ` gW<M  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; eyp,y2Tz  
for(int i=0;i<nStartPos.length;i++) Zatf9yGD  
{ +ht|N[P  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), R<x'l=,D(  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), .ZMW>U>  
nStartPos,nEndPos,i); G Xt4j  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); L>Mpi$L  
fileSplitterFetch.start(); '$ef+@y  
} Bb{!Yh].:A  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), FWC5&
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1);  9dzdrT  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", OMk5{-8B  
nEndPos = " + nFileLength); M.td^l0  
// fileSplitterFetch[nPos.length-1].start(); y&_m4Zw"  
4Z*U}w)  
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//等待子线程结束 *;|`E(  
//int count = 0; $0^P0RAH  
//是否结束while循环 I\|N  
boolean breakWhile = false; >5G>D~b  
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while(!bStop) 1|8<H~&  
{ vEQ<A<[Z  
write_nPos(); E|:!Q8"%w  
Utility.sleep(500); U1_&gy @y  
breakWhile = true; 0Aa`p3.)  
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for(int i=0;i<nStartPos.length;i++) O--7<Q\  
{ ]S 7^ITn  
if(!fileSplitterFetch.bDownOver) oVCmI"'  
{ X bkb5EkA  
breakWhile = false; ):EBgg4-N  
break; {0!#>["<  
} zdSh:  
} *5,c Rz  
if(breakWhile) @/%{15s.  
break; ~:_0CKa!  
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//count++; @U -$dw'4  
//if(count>4) TFDm5XJ  
// siteStop(); TOLl@p]lU  
} Eaad,VBtU  
#
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System.err.println("文件下载结束！"); ;1DdjETr  
} )R{UXk3q}  
catch(Exception e){e.printStackTrace ();} GJ'spgz  
} u1K\@jlw  
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5+X_4lEJK(  
//获得文件长度 oN(-rWdhZ  
public long getFileSize() wHsB,2H  
{ wb"RB A9  
int nFileLength = -1; L4f7s7rJ  
try{ j?n+>/sG,  
URL url = new URL(siteInfoBean.getSSiteURL()); N<z`yV  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ?TEK=mD#u  
httpConnection.setRequestProperty("User-Agent","NetFox"); !d9AG|  
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+
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int responseCode=httpConnection.getResponseCode(); TA}UY7v  
if(responseCode>=400) rVAL|0;3  
{ :XT?jdg  
processErrorCode(responseCode); POU}/e!Ua  
return -2; //-2 represent access is error nq`q[KV:  
} INMP"1  
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String sHeader; -.vDF?@G  
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for(int i=1;;i++) Fm j=  
{ 't>r sp+#  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); w!q&  
//Utility.log(in.readLine()); 2f:Mm'XdB  
sHeader=httpConnection.getHeaderFieldKey(i); @Hr+/52B  
if(sHeader!=null) 
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{ 2DMrMmLI  
if(sHeader.equals("Content-Length")) Sw! j=`O  
{ )@:l^$x  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); (N U0Tw  
break; Ex($  
} I 8Y*@$h  
} ]O!s'lC  
else oP$kRfXS!<  
break; Z6=~1'<X  
} L]zNf71RD  
} +*EKR  
catch(IOException e){e.printStackTrace ();} v}il(w;O  
catch(Exception e){e.printStackTrace ();} Sr y,@p)  
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Utility.log(nFileLength); {Jx7_T&  

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return nFileLength; <NQyP{p  
} 5t'Fv<g  
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//保存下载信息（文件指针位置） Y-&|VE2  
private void write_nPos() 41;)-(1  
{ 9A;6x$s  
try{ o8D{dS>,PL  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ( Yi=v'd  
output.writeInt(nStartPos.length); <:cpz* G4  
for(int i=0;i<nStartPos.length;i++) Oc-u=K,B  
{ ]%XK)[:5_=  
// output.writeLong(nPos); UA0tFeH  
output.writeLong(fileSplitterFetch.nStartPos); :J%'=_I&H  
output.writeLong(fileSplitterFetch.nEndPos); U?6yke  
} z_(eQP])  
output.close(); ?Y!^I2Y6  
} |4xo4%BQ>  
catch(IOException e){e.printStackTrace ();} h3t$>vs2F"  
catch(Exception e){e.printStackTrace ();} $n*%v85  
} T:#S86m  
X<K9L7/*  
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//读取保存的下载信息（文件指针位置） 5byeWH0n3  
private void read_nPos() xK!DtR
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{ {*__B} ,N  
try{ fv5C!> t  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); .WO/=#O  
int nCount = input.readInt(); GXEcpc08  
nStartPos = new long[nCount]; z"av|(?d  
nEndPos = new long[nCount]; Xv*}1PZH  
for(int i=0;i<nStartPos.length;i++) /yt7#!tm+  
{ x,-S1[#X;  
nStartPos = input.readLong(); ^cb)f_90  
nEndPos = input.readLong(); 4[_L=zD  
} 2|s<[V3rP-  
input.close(); Dpj-{q7C  
} |=,83,a  
catch(IOException e){e.printStackTrace ();} Uir*%*4:  
catch(Exception e){e.printStackTrace ();} Lv3XYZ
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} <4sj@C  
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private void processErrorCode(int nErrorCode) xi.IRAZX  
{ cLHF9B5  
System.err.println("Error Code : " + nErrorCode); A8mlw#`E8b  
} @bY?$fj_u  
*78)2)=~  
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//停止文件下载 m
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public void siteStop() zw< 4G[u  
{ G#'Q~N  
bStop = true; \P5>{2i  
for(int i=0;i<nStartPos.length;i++) 44Q9*."  
fileSplitterFetch.splitterStop(); v*vn<nPAQ>  
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} ;raz6DRO  
} {&0mK"z_  
//负责部分文件的抓取 7}A5u,.,ht  
**FileSplitterFetch.java AzxL%,_  
*/ b h*^
{  
package NetFox; CJm.K  
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import java.io.*; _HLC>pH~#  
import java.net.*; _/ct=  
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public class FileSplitterFetch extends Thread { di--:h/  
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String sURL; //File URL m$,cH>E  
long nStartPos; //File Snippet Start Position @81-kdTx  
long nEndPos; //File Snippet End Position is9}ePC7Xu  
int nThreadID; //Thread's ID :fRmUAK%  
boolean bDownOver = false; //Downing is over Z(KmS(  
boolean bStop = false; //Stop identical ^Wif!u/HM  
FileAccessI fileAccessI = null; //File Access interface sw[oQ!f  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException <{E;s)hD?  
{ sZ]'DH&_(  
this.sURL = sURL; g})6V  
this.nStartPos = nStart; MF&3e#mdB  
this.nEndPos = nEnd; B*y;>q "{U  
nThreadID = id; ] xb]8]  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 %)8d{1at  
} -xw98  
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public void run() ^eT@!N  
{ >vHH  
while(nStartPos < nEndPos && !bStop) "EN98^ Sl  
{ aF,jJ}On  
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try{ wTHK=n\i  
URL url = new URL(sURL); SrdE>fNbs  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); *C5:#A0  
httpConnection.setRequestProperty("User-Agent","NetFox"); ylkpYd  
String sProperty = "bytes="+nStartPos+"-"; ^uC"
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httpConnection.setRequestProperty("RANGE",sProperty); 'uPxEu4 >4  
Utility.log(sProperty); P\,F1N_?r  
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InputStream input = httpConnection.getInputStream(); !O~},pp  
//logResponseHead(httpConnection); |)28=Z|Z  
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byte[] b = new byte[1024]; jAA'hA  
int nRead; n"XdHW0  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 01&*`0?  
{ 5OPS&:  
nStartPos += fileAccessI.write(b,0,nRead); |}M~kJ)  
//if(nThreadID == 1) 7J0 ^
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); M7`UoTc+>d  
} CbnR<W-j  
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Utility.log("Thread " + nThreadID + " is over!"); ;~}-AI-  
bDownOver = true; CHQ{+?#  
//nPos = fileAccessI.write (b,0,nRead); +<'uw  
} C*"Rd   
catch(Exception e){e.printStackTrace ();} gUksO!7^1  
} M
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} *raIV]W3  
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O{;M6U8C\  
//打印回应的头信息 o@qN#Mg?>}  
public void logResponseHead(HttpURLConnection con) :GN)7|:  
{ R=2 gtW"r  
for(int i=1;;i++) Gh>
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{ Wwn5LlJ^  
String header=con.getHeaderFieldKey(i); ~*66 3pA  
if(header!=null) @/_
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); d/0/$Bz}P  
Utility.log(header+" : "+con.getHeaderField(header)); ^U0apI  
else E&
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break; >GdLEE'w  
} N&R '$w  
} :d!i[W*  
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public void splitterStop() <[ g$N4  
{ f)&`mqeE  
bStop = true; Mft0Dj/  
} [15hci+-  
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} a}^!TC>%1i  
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/* 3L 1lq .  
**FileAccess.java 73! x@Duh  
*//文件访问(定位，写) 18[?dV  
package NetFox; 4wM$5  
import java.io.*;  6Dr$
*9  
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public class FileAccessI implements Serializable{ T }8r;<P6  
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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 ,M+h9_&0?  
RandomAccessFile oSavedFile; (rY1O:*S  
long nPos; `9G$p|6  
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*;\ K5  
public FileAccessI() throws IOException l*m]2"n]  
{ %(O^as  
this("",0); q)zu}m  
} ^<5^9]x  
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public FileAccessI(String sName,long nPos) throws IOException v J,xz*rc`  
{ *}Ae9  
oSavedFile = new RandomAccessFile(sName,"rw"); a#^4xy:  
this.nPos = nPos; 6|(7G64{
 
oSavedFile.seek(nPos); `6l24_eKf  
} @Tj  6!v  
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9g^./k\8%  
public synchronized int write(byte[] b,int nStart,int nLen) 5]2!Bb6>  
{ ,2:L{8_L  
int n = -1; ht[TMdV  
try{ [/2@=Uh-  
oSavedFile.write(b,nStart,nLen); hTNYjXj  
n = nLen; 2Dwt4V  
} HDfQ9__  
catch(IOException e) COl%P  
{ \)6?u_(u  
e.printStackTrace (); *b7 ^s,?  
} ^_#
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return n; "N[gMp6U  
} a1Y_0  
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} HpgN$$\@  
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/* Z#E#P<&d  
**SiteInfoBean.java ysP/@;jC  
*/ 3By>t!~Q  
package NetFox; :WKyEt!3  
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public class SiteInfoBean { zw;(:fgY#  

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private String sSiteURL; //Site's URL {&AT}7  
private String sFilePath; //Saved File's Path @eD~FNf-]  
private String sFileName; //Saved File's Name C@:N5},]  
private int nSplitter; //Count of Splited Downloading File IU"!oM^  
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LAjw!QB  
public SiteInfoBean() 
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{//nSplitter的缺省值为5 B 0fo[Ev  
//default value of nSplitter is 5 Y&Nv>o_}5  
this("","","",5); hFF&(t2{^  
} dodz|5o%  
kJ:5msKwC  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ,}xC) >  
{ !ilDR<  
sSiteURL= sURL; ZkG##Jp\>  
sFilePath = sPath; wB0WR  
sFileName = sName; Wh&Z *J  
this.nSplitter = nSpiltter; "+OMo-<K7  
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} H "/e%  
{ l~T~3/i  
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public String getSSiteURL() 2yg'?tpj  
{ )FiU1E  
return sSiteURL; Ki6BPi^  
} +.Ukzu~s  
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public void setSSiteURL(String value) Xrs~ove1V  
{ #rL@  
sSiteURL = value; yD'h5)yu  
} }C1}T}U  
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public String getSFilePath() %Y[/Ucdm  
{ Rf$6}F  
return sFilePath; /60=N`i  
} w9}IM149  
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biuo.OG]  
public void setSFilePath(String value) (3S/"
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{ ;^SgV   
sFilePath = value; y(g Otg  
} u+I3VK_)  
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public String getSFileName() P?-44m#  
{ jYx(  
return sFileName; alD|-{Bf  
} *m/u3.\  
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p 8rAtz>=J  
public void setSFileName(String value) UYLI>XSd  
{ 
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sFileName = value; vIv3rN=5vB  
} l$@lk?dc  
IKj1{nZvDc  
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public int getNSplitter() W u{nC  
{ a_j#l(] 9  
return nSplitter; [^P2Kn  
} msJn;(Pn  
bm|8Jbsb&  
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public void setNSplitter(int nCount) <\NXCUqDpo  
{ |]^! 4[!U  
nSplitter = nCount; :RG6gvz  
} 3mpjSL  
} VUhu"h@w%  
fQ) ;+  
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/* .v!e=i}.  
**Utility.java epe}^Pl  
*/ pm|]GkM  
package NetFox; e70*y'1fu  
/pEkig7M  
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public class Utility { w Nnb@  
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public Utility() b9jm=U  
{ 21Opx~T3  
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} |&.)_+w  
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//线程睡眠 6=D;K.!  
public static void sleep(int nSecond) (
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{ L"0L_G  
try{ 2sH5<5G'  
Thread.sleep(nSecond); jHzb,&
  
} "a7d`l:  
catch(Exception e) o
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{ mB`r6'#=  
e.printStackTrace (); 4)z](e$  
} lw{|~m5`  
} bzS [X  
=T`-h"E~@  
//日志 g*uO IF  
public static void log(String sMsg) a;sZNUSn  
{ h9mR+ng*oD  
System.err.println(sMsg); 6fiJ' j@  
} [z9i v~  
_!ed.h.r:  
/r6DPR0\  
public static void log(int sMsg) O1"!'Gk[!L  
{ @2<J_Ja  
System.err.println(sMsg); zc#`qa:0  
} Et(prmH  
} A [JV*Dt  
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/* ,&$Y2+  
**TestMethod.java *SZ<ori  
*/ ,>Q,0bVhH0  
package NetFox; s]qfLC  

nHX@  
>8##~ZuF+
 
public class TestMethod { G(- `FH  
jB;+tDC!Co  
u|C9[(  
public TestMethod() F&Gb[Q&a8  
{ ///xx/weblogic60b2_win.exe *,(`%b[  
try{ #{(rOb6H)  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ]5/C"  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); `'/8ifKz  
SiteFileFetch fileFetch = new SiteFileFetch(bean); :MpCj<<[  
fileFetch.start(); F{[Q  
} "](~VF[J8  
catch(Exception e){e.printStackTrace ();} 8447hb?W$  
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#S"=)BZ8L  
} Je/R'QP^8  
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public static void main(String[] args) xc!"?&\*  
{ Bn.8wMB  
new TestMethod(); ojaZC,}  
} 8ViDh  
} @M1U)JoQ  
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