http断点续传简单实现（java)

/* +?_!8N8  
**SiteFileFetch.java H[=\_X1o(  
*/ `w@:h4f  
package NetFox; {9x_E {  
import java.io.*; /v{+V/'+  
import java.net.*; J@3,  
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public class SiteFileFetch extends Thread { eADCT  
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SiteInfoBean siteInfoBean = null; //文件信息Bean :#rP$LSYC  
long[] nStartPos; //开始位置 NoI|Dz  
long[] nEndPos; //结束位置 <FT7QO$I  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 f}:C~L!  
long nFileLength; //文件长度 j}+3+ 8D  
boolean bFirst = true; //是否第一次取文件 sZ `Tv[  
boolean bStop = false; //停止标志 U&^q#['  
File tmpFile; //文件下载的临时信息 ? x)^f+:9|  
DataOutputStream output; //输出到文件的输出流 VvhfD2*T  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） =2R4Z8
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public SiteFileFetch(SiteInfoBean bean) throws IOException iN;Pg_Kq  
{ y=3 dGOFB  
siteInfoBean = bean; w~3X m{  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); =ZgueUz,  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); !cW rB9  
if(tmpFile.exists ()) $WAwMS,  
{ A7p4M?09  
bFirst = false; -]N2V'QB  
read_nPos(); (J:+'u  
} AWO)]rM  
else i ;FKnK  
{ (.J/Ql0Y  
nStartPos = new long[bean.getNSplitter()]; T7[@ lMa?  
nEndPos = new long[bean.getNSplitter()]; :5YIoC  
} yV^Yp=f_  
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} ]c(FgYc  
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public void run() s:T%,xS  
{ $>rt0LOF  
//获得文件长度 )nN!% |J  
//分割文件 YvY|\2^K  
//实例FileSplitterFetch o}N@Q-i gq  
//启动FileSplitterFetch线程 DV5hTw0  
//等待子线程返回 EP>u%]#  
try{ 6H#:rM  
if(bFirst) FXCBX:LnvU  
{ w{ja*F6  
nFileLength = getFileSize(); O&Y;/$w  
if(nFileLength == -1) 6-U_TV  
{ }k-V(  
System.err.println("File Length is not known!"); /T _M't@j  
} 1?'4%>kp  
else if(nFileLength == -2) /~LE1^1&U  
{ x@#>l8k?  
System.err.println("File is not access!"); yR$_ZXsd  
} J=A)]YE  
else 0]d;)_`@  
{ *byUqY3(
 
for(int i=0;i<nStartPos.length;i++) U,rI/'  
{ \Ec<ch[)c  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); e@3SF  
} !j!w$  
for(int i=0;i<nEndPos.length-1;i++)
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{ [@i:qB>B  
nEndPos = nStartPos[i+1]; }*x1e_m}H  
} eMGJx"a  
nEndPos[nEndPos.length-1] = nFileLength; >}SEU-7&\  
} "L>'X22ed  
} Vgm*5a
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//启动子线程 =2!p>>t,d;  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; k*1Lr\1  
for(int i=0;i<nStartPos.length;i++) ,_V V;P  
{ |\(uO|)ju  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), QE]'Dc%  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), &bTCTDZh  
nStartPos,nEndPos,i); +\=g&G,  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); (T1< (YZ  
fileSplitterFetch.start(); a>j}@8[J  
} }geb959  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), hjL;B'IL  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); G)vNMl  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 'z} t= ?  
nEndPos = " + nFileLength); eo+<@83  
// fileSplitterFetch[nPos.length-1].start(); O:?3B!wF  
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//等待子线程结束  /
 
//int count = 0; 'lIs`Zc5N  
//是否结束while循环 xvl$,\iqE  
boolean breakWhile = false; MCN>
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while(!bStop) R+LKa Z  
{ |4\1V=(  
write_nPos(); #-yCR  
Utility.sleep(500); r;Sk[Y5#  
breakWhile = true; ]p!{   
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for(int i=0;i<nStartPos.length;i++) w)dnmrKDZg  
{
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if(!fileSplitterFetch.bDownOver) =
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{ iil<zEic  
breakWhile = false; 3aW<FSgP  
break; cC~
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} aAjl 58  
} }`qAb/Ov  
if(breakWhile) lu.]R>w  
break; ]dUG=dWO  
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//count++; 9KVJk</:n  
//if(count>4) atyvo0fNd  
// siteStop();
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} vPDw22L;
'  
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System.err.println("文件下载结束！"); ` -_!%m/  
} >9H^r\  
catch(Exception e){e.printStackTrace ();} x;~:p;]J2F  
} {SV/AN  
S=4o@3%$  
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//获得文件长度 ABCm2$<  
public long getFileSize() wv9HiHz8gD  
{ hTDK[4e  
int nFileLength = -1; /2p*uv}IP  
try{ /h>g-zb  
URL url = new URL(siteInfoBean.getSSiteURL()); uSfHlN4l
 
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); i.mv`u Dm  
httpConnection.setRequestProperty("User-Agent","NetFox"); v]k-xn|$j  
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b  
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int responseCode=httpConnection.getResponseCode(); R1zt6oY  
if(responseCode>=400) #*g=F4>t  
{ T]tP!a;K  
processErrorCode(responseCode); >ai
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return -2; //-2 represent access is error Go%Z^pF3CO  
} 6q^$}eOt  
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String sHeader; WZ'Z"'  
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for(int i=1;;i++) >eTbg"\  
{ iwF_'I$#N  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 2F2Hl  
//Utility.log(in.readLine()); 19$A!kH\  
sHeader=httpConnection.getHeaderFieldKey(i); 6l\5J6x  
if(sHeader!=null) \B#tB?rA  
{ bB$f=W!m%  
if(sHeader.equals("Content-Length")) J
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{ lsax.uG5x  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Jj=qC{]  
break; .`IhxE~mN  
}  I0mp[6  
} i)x0]XF  
else b<tV>d"Fv  
break; v6 5C j2ec  
} ~uhW~bT  
} w'TAM"D`  
catch(IOException e){e.printStackTrace ();} xeF>"6\  
catch(Exception e){e.printStackTrace ();} rD}g9?ut  
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Utility.log(nFileLength); =NY;#Jjn  
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return nFileLength; ?;l@yx  
} ZS.=GjK  
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dq
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//保存下载信息（文件指针位置） 5qM$ahN3wH  
private void write_nPos() %6q82}#`  
{ 5'set?  
try{ eay|>xa2  
output = new DataOutputStream(new FileOutputStream(tmpFile)); z\eQB%aM  
output.writeInt(nStartPos.length); N}5  
for(int i=0;i<nStartPos.length;i++) x+Yo#u22  
{ o<5`uV!f  
// output.writeLong(nPos); Q>$B.z  
output.writeLong(fileSplitterFetch.nStartPos); U$5x#{AFp  
output.writeLong(fileSplitterFetch.nEndPos); HVa D  
} syr0|K[  
output.close(); I7_8oq\3D  
} u4hn9**a1  
catch(IOException e){e.printStackTrace ();} WD%(RC"Q  
catch(Exception e){e.printStackTrace ();} ku,{NY f^Y  
} I3>8B  
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//读取保存的下载信息（文件指针位置） \~8W0q.4M  
private void read_nPos() eZ:iW#YF  
{ pJFn 8&!J  
try{ =bh: U90y  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Y%/RGYKh  
int nCount = input.readInt(); v(;yy{>8"  
nStartPos = new long[nCount]; z*T41;b  
nEndPos = new long[nCount]; f2c<-}wR  
for(int i=0;i<nStartPos.length;i++) q
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{ 4AL,=C3  
nStartPos = input.readLong(); P DY :?/  
nEndPos = input.readLong(); V(Pw|u" e  
} qcO~}MJr}^  
input.close(); v9H t~\>  
} "iEnsP@'Wg  
catch(IOException e){e.printStackTrace ();} <%.%q  
catch(Exception e){e.printStackTrace ();} jUE:QOfRib  
} d_(>:|oh  
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K  
private void processErrorCode(int nErrorCode) Vsi:O7|+ }  
{ u)h {"pP  
System.err.println("Error Code : " + nErrorCode); @MibKj>o  
} jS]Saqd  
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//停止文件下载 lrc%GU):  
public void siteStop() k% \;$u=%  
{ #CLjQJ  
bStop = true; :g$"Xc8Zn  
for(int i=0;i<nStartPos.length;i++) wxBHlgK4z  
fileSplitterFetch.splitterStop(); A'CD,R+gR  
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} |?jgjn&RQ  
} ~H#c-B  
//负责部分文件的抓取 Oa:C'M b  
**FileSplitterFetch.java #qVvh3#g  
*/ w&YUb,{Y  
package NetFox; &L0Ii)Ns  
$MvKwQ/  
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import java.io.*; Q^<amM!  
import java.net.*; N'{Yhx u  
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public class FileSplitterFetch extends Thread { &(<>} r  
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l'<&H#A;'  
String sURL; //File URL PO5,lcBD<  
long nStartPos; //File Snippet Start Position #O_%!7M{4  
long nEndPos; //File Snippet End Position M5RN Z%  
int nThreadID; //Thread's ID VS4Glx73  
boolean bDownOver = false; //Downing is over ;^s|n)F#c  
boolean bStop = false; //Stop identical i9 CQ~  
FileAccessI fileAccessI = null; //File Access interface 5vD\?,f E  
vy2<'V*y}  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException v2rzHzFU  
{ fp
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this.sURL = sURL; |5>A^a  
this.nStartPos = nStart; uUS~"\`fk  
this.nEndPos = nEnd; >l-u{([B  
nThreadID = id; 7Z+Fjy-B  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Otr=+i ZI  
} @Wd(>*"zw  
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public void run() ((AK7hb  
{ 5o{U$  
while(nStartPos < nEndPos && !bStop) 3qGz(6w6E  
{
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try{ x]Nx,tt  
URL url = new URL(sURL); [< 9%IGH  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); b!MN QGs  
httpConnection.setRequestProperty("User-Agent","NetFox"); KBi(Ns#+  
String sProperty = "bytes="+nStartPos+"-"; $EIKi'!8  
httpConnection.setRequestProperty("RANGE",sProperty); nT4Ryld  
Utility.log(sProperty); V@RdvQy  
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InputStream input = httpConnection.getInputStream(); /Xc9}~t6  
//logResponseHead(httpConnection); .|DrXJ\c  
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byte[] b = new byte[1024]; +p _?ekV\  
int nRead; (!m6>m2  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) r1.zURY  
{ _lT'nFe=Q  
nStartPos += fileAccessI.write(b,0,nRead); Y$,++wx  
//if(nThreadID == 1) %c$|.TkX  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); JSq3)o9?/  
} V_^pPBa  
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Utility.log("Thread " + nThreadID + " is over!"); >^W6'Q$P<  
bDownOver = true; zSMM?g^T  
//nPos = fileAccessI.write (b,0,nRead); WAuT`^"u  
} fhdqes])  
catch(Exception e){e.printStackTrace ();} MdEds|D  
} 'b[O-6v  
} x~m$(LT  
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//打印回应的头信息 4!3<[J;N;  
public void logResponseHead(HttpURLConnection con) 3ohHBo  
{ U![$7k>,pr  
for(int i=1;;i++) ^K8XY@{&  
{ ]m&Ss  
String header=con.getHeaderFieldKey(i); rHybP6C<  
if(header!=null) l  ~xXy<  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); TZn5s~t  
Utility.log(header+" : "+con.getHeaderField(header)); xIb{*)BUwc  
else p_zVrlVb  
break; J?E!\V&U  
} Zu~t )W  
} ~U]%>Zf  
c/F!cW{z^  
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public void splitterStop() %k"hzjXAw  
{ 9N2.:<so  
bStop = true; 0>;[EFL  
} )Fqtb;W=  
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} z0YL,  
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/* ,#^2t_c/  
**FileAccess.java 6%o@!|=I  
*//文件访问(定位，写) 3+C;zDKa  
package NetFox; n(n7"+B  
import java.io.*; {q&`B  
'Vhnio;qC  
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public class FileAccessI implements Serializable{ !0Ak)Q]e'  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 R$it`0D4o  
RandomAccessFile oSavedFile; xkkG#n)  
long nPos; R&'Mze fb  
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public FileAccessI() throws IOException K)\D,5X^  
{ ZxDh!_[s  
this("",0); (f*r  
} t?;=\%^<  
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public FileAccessI(String sName,long nPos) throws IOException V Kc`mE  
{ g,RhUt9  
oSavedFile = new RandomAccessFile(sName,"rw"); G+3uY25y  
this.nPos = nPos; COH.`Tv{*  
oSavedFile.seek(nPos); ~(cqFf  
} B\dhw@hM  
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public synchronized int write(byte[] b,int nStart,int nLen) @3I?T Q1  
{ m .En!~t  
int n = -1; (+
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try{ \qJ^n %  
oSavedFile.write(b,nStart,nLen); v1
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n = nLen; D]V&
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} PJh9
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catch(IOException e) L[:M[,?=`  
{ D6P/39}W  
e.printStackTrace (); s6oIj$  
} od3b,Q  
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return n; ><)fK5x  
}  8KzH -  
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} ve*6WDK,H  
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/* w< |Lx#L}  
**SiteInfoBean.java k%LsjN.S  
*/ J]&nZud`  
package NetFox; uq]E^#^  
y)`q% J&  
35SL*zS@-
 
public class SiteInfoBean { bB.Yq3KI  
[\"<=lb`  
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private String sSiteURL; //Site's URL 71HrpTl1fw  
private String sFilePath; //Saved File's Path oeG?2!Zh  
private String sFileName; //Saved File's Name ??Dv\yLZI  
private int nSplitter; //Count of Splited Downloading File ]Ai!G7s8P  
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public SiteInfoBean() 4"V6k4i5  
{//nSplitter的缺省值为5 2!Pwg0%2  
//default value of nSplitter is 5 ?)"v~vs  
this("","","",5); ; 5!8LmZ0#  
} Dl=vv9
 
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) .J9\Fr@  
{  ev(E  
sSiteURL= sURL; 9QN(Wq@  
sFilePath = sPath; VD2o#.7*eu  
sFileName = sName; X#u< 3<P  
this.nSplitter = nSpiltter; ltmD=-]G_  
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} X0%BE!  
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public String getSSiteURL() 8B7,qxZ  
{ LwEc*79  
return sSiteURL; x!9bvQT  
} coc:$Sr%  
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public void setSSiteURL(String value) uBBW2  
{ 5?gZw;yiv%  
sSiteURL = value; x9H qc9q  
} 4S,/Z{ J.  
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=zKbvwe%X  
public String getSFilePath() '3ZYoA%  
{ 3x~AaC.j  
return sFilePath; {]:B80I;2  
} Ty"=3AvRLV  
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,DWC=:@X  
public void setSFilePath(String value) N!=Q]\ZD  
{ 3 p9LVa  
sFilePath = value; WevXQ-eKm  
} qt#4i.Iu+  
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7)+%;|~  
public String getSFileName() 3`\)Qm  
{
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return sFileName; 
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} 9w,u4q  

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public void setSFileName(String value) ]%/a'[  
{ $;%dQ!7*  
sFileName = value; q5(Z   
} {V9}W<  
Oe%jV,S|V  
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public int getNSplitter() $5m_)]w4a  
{ " ^:$7~%bA  
return nSplitter; N?;5%pG <  
} wC[Bh^]  
#NLLlEE  
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public void setNSplitter(int nCount) *Ad7GG1/u  
{ p~THliwd  
nSplitter = nCount; 7Y(ySW  
} tpi>$:e  
} HR83{B21  
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/* \V,;F!*#G  
**Utility.java R9z^=QKcH  
*/ i\?P>:)  
package NetFox; <\cH9D`dE  
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public class Utility { b(~ gQM  
#TX=%x6  
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public Utility() !*gTC1bvB  
{ &`'gO 9  
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} k(;c<Z{?1  
zSiSZMP"  
//线程睡眠 QAy9RQ0  
public static void sleep(int nSecond) K>`7f]?H*e  
{ SAEr$F^  
try{ a,U =irBA  
Thread.sleep(nSecond); GBZx@B[TY  
} WqC6c&NM  
catch(Exception e) w^&TG3m1~  
{ z.[ Ok  
e.printStackTrace (); >, &6zj  
} ~qiSkG  
} 66%#$WH#  
{O,Cc$_  
//日志 %XqLyeOS  
public static void log(String sMsg) (r^IW{IndX  
{ WbS2w @8  
System.err.println(sMsg); K`@GNT&  
} F~ n}Ep~1  
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T]nZ3EZ  
public static void log(int sMsg) d%9r"=/  
{ )^^r\  
System.err.println(sMsg); 'C~NQ{1TV  
} ~}mX#,  
} 'PlKCn`(w  
>:s.`jV<  
9`)NFy?  
/* J680|\ER  
**TestMethod.java ?|:!PF*L~z  
*/ %f@VOSs  
package NetFox; )*
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public class TestMethod { oj<.axA,  
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public TestMethod() yi7-[W}  
{ ///xx/weblogic60b2_win.exe F5J=+Q%8[&  
try{ }_M.-Xm  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); >U9!KB  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); F#
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SiteFileFetch fileFetch = new SiteFileFetch(bean); HF5aU:M  
fileFetch.start(); 2u6N';jgZ  
} jo<[|ZD  
catch(Exception e){e.printStackTrace ();} C did*hxJ  
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bs]ret$?(q  
} U;6~]0^K  
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public static void main(String[] args) m{x!uq  
{ $Kb-mFR  
new TestMethod(); 4%p5X8|\ih  
} tB[(o%k  
} ~@bCSOIy  
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