http断点续传简单实现（java)

/* EmODBTu+  
**SiteFileFetch.java {_S}H1,  
*/ yto,>Utzg  
package NetFox; Xlb0/T<g!  
import java.io.*; <^z
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import java.net.*; du)~kU>l  
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public class SiteFileFetch extends Thread { 'bo~%WA]n  
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SiteInfoBean siteInfoBean = null; //文件信息Bean sFQ^2PwbS  
long[] nStartPos; //开始位置 Gi "941zVl  
long[] nEndPos; //结束位置 )hk   
FileSplitterFetch[] fileSplitterFetch; //子线程对象 B<~ NS)w  
long nFileLength; //文件长度 Q8D
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boolean bFirst = true; //是否第一次取文件 rFC" Jx  
boolean bStop = false; //停止标志 -u?S=h}  
File tmpFile; //文件下载的临时信息 9nH?l{As  
DataOutputStream output; //输出到文件的输出流 `;)\u  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） tkXEHsRT  
public SiteFileFetch(SiteInfoBean bean) throws IOException u%/goxA  
{ fH)YFn/  
siteInfoBean = bean; 'k4E4OB  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); RB+N IoQQ|  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Sr%;fq  
if(tmpFile.exists ()) t`+'r}=d  
{ dw TMq*e  
bFirst = false; Q",0F{'  
read_nPos(); 7^Ns&Q  
} jK' N((Hz  
else C&6IU8l\  
{ "m^' &L  
nStartPos = new long[bean.getNSplitter()]; ^b7GH9<&  
nEndPos = new long[bean.getNSplitter()]; qA!]E^0*Ke  
} VMCLHpSfW  
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} Vo7dAHHL  
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public void run() >5j<4ShW  
{ &[At`Nw71  
//获得文件长度 (XXheC  
//分割文件 MdXchO-Lyc  
//实例FileSplitterFetch v$=QA:!U  
//启动FileSplitterFetch线程 XEdzpkB  
//等待子线程返回 ixV0|P8,c  
try{ )x]3Zq  
if(bFirst) qY>{cjo  
{ cetvQAGXY  
nFileLength = getFileSize(); **+e7k  
if(nFileLength == -1) P)uDLFp]  
{ QMsHC%l3b  
System.err.println("File Length is not known!"); TuW/N L|  
} CEC nq3  
else if(nFileLength == -2) YG8>czC  
{ W$'R}L  
System.err.println("File is not access!"); B}eA\O4}I  
} /'hCi]b@v  
else +z9gbcx  
{ & u!\<\  
for(int i=0;i<nStartPos.length;i++) j+^
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{ r@{~ 5&L  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ^::E
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} W;1|+6x  
for(int i=0;i<nEndPos.length-1;i++) >OP+^^oZ<  
{ o=RM-tR`v  
nEndPos = nStartPos[i+1]; ^{\<N()R  
} .)+hH y  
nEndPos[nEndPos.length-1] = nFileLength; DaH?@Q
 
} 4:7V./" 9  
} Lgz$]Jbl8  
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//启动子线程 TyKWy0x-3  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; :d8W+|1u  
for(int i=0;i<nStartPos.length;i++) zvvP81$W  
{ <jS~ WI@  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), E0/mSm"(T  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), U#n#7G6fRp  
nStartPos,nEndPos,i); `y+
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); O8]'o*<]  
fileSplitterFetch.start(); x'zBK0i  
} hb/]8mR  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), [I:KpAd/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); g}f9dB,F  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", HK)cKzG[s!  
nEndPos = " + nFileLength); "Pl9nE  
// fileSplitterFetch[nPos.length-1].start(); yIb,,!y9{  
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//等待子线程结束 -B$~`2-  
//int count = 0; XM<KF&pVB  
//是否结束while循环 i-U4RZE  
boolean breakWhile = false; <}jPXEB"  
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while(!bStop) $^ 'aCU0C  
{ Ro=AADv@  
write_nPos(); $hR)i  
Utility.sleep(500); ^+SkCO  
breakWhile = true; 7B3w\
 
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for(int i=0;i<nStartPos.length;i++) XI Jlc~2  
{ L5IbExjV  
if(!fileSplitterFetch.bDownOver) %g]vxm5?  
{ a4gi,pz$
]  
breakWhile = false; >\<*4J$PZ  
break; P%Ay3cR+E  
} U"f??y%)  
} ~Cc.cce5  
if(breakWhile) !}M,  
break; #(LfYw.P1V  
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//count++; _U|7'^|  
//if(count>4) _kFYB
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// siteStop(); 02AI%OOH  
} iO1nwl !#  
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System.err.println("文件下载结束！"); =wi*Nd7L  
} n uQM^2  
catch(Exception e){e.printStackTrace ();} Z<b"`ty.  
} {}>n{_  
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/DS?}I.*]  
//获得文件长度 w-N1.^  
public long getFileSize() sTHq&(hLUG  
{ >n.z)ZJ  
int nFileLength = -1; Bz
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try{ fvo<(c#Y#  
URL url = new URL(siteInfoBean.getSSiteURL()); +UWU|:  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); IF k  
httpConnection.setRequestProperty("User-Agent","NetFox"); 1D([@)^  
|I[7,`C~  
}ublR&zlp
 
int responseCode=httpConnection.getResponseCode(); @=]8^?$t 0  
if(responseCode>=400) |E/L.gdP7  
{ -[#n+`M  
processErrorCode(responseCode); q$ghLGz  
return -2; //-2 represent access is error SjcL#S($&Y  
} GtI6[ :1t  
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String sHeader; DhKr;e  
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for(int i=1;;i++) X.|Ygx  
{ >X Qv?5  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); hY\{|  
//Utility.log(in.readLine()); ?H;{~n?  
sHeader=httpConnection.getHeaderFieldKey(i); CVKnTEs  
if(sHeader!=null) ( 76{2  
{ j=sBq.S  
if(sHeader.equals("Content-Length")) |DG@ht  
{ &,W$-[  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); /r$&]C:Fi  
break; m^Lj+=Z"  
} }#N]0I)JI  
} $@[)nvV\  
else I^0t2[M  
break; Xza
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} 0-e  
} c]m! G'L_/  
catch(IOException e){e.printStackTrace ();} iK}v`xq  
catch(Exception e){e.printStackTrace ();} Gi$gtLtNh  
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Utility.log(nFileLength); {/UhUG  
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return nFileLength; ,nE&Me&#J  
} _`aR_%Gx  
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//保存下载信息（文件指针位置） .ewZV9P)t  
private void write_nPos() (Pz8iz  
{ lBiovT  
try{ XJFnih  
output = new DataOutputStream(new FileOutputStream(tmpFile)); q+/l"&j.  
output.writeInt(nStartPos.length); F.KrZ3%4iB  
for(int i=0;i<nStartPos.length;i++) Dc:DY:L^  
{ r@$B'CsLj  
// output.writeLong(nPos); z>:U{!5k  
output.writeLong(fileSplitterFetch.nStartPos); *)%dXVf  
output.writeLong(fileSplitterFetch.nEndPos); FGVb@=TO>  
} IQ{?_'  
output.close(); F$ {4X /9n  
} ,P{HE8.  
catch(IOException e){e.printStackTrace ();} A+2oh3  
catch(Exception e){e.printStackTrace ();} FW^.m?}|  
} + U5U.f%  
%c0z)R~  
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//读取保存的下载信息（文件指针位置） .;Z.F7{q  
private void read_nPos() !rHx}n{rw  
{ [tN` :}?  
try{ .\4l'THn,0  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); yM17H\=  
int nCount = input.readInt();
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nStartPos = new long[nCount]; 4 m$sJ  
nEndPos = new long[nCount]; 5ZUy:  
for(int i=0;i<nStartPos.length;i++) `t9.xB#Z  
{ {c?ymkK  
nStartPos = input.readLong(); q(1r<2  
nEndPos = input.readLong(); 7<4xtK`+b  
} u2,H ]-  
input.close(); MBv/  
} K Dz]wNf  
catch(IOException e){e.printStackTrace ();} .' IeHh  
catch(Exception e){e.printStackTrace ();} i"fCpkAP  
} Wa}"SqYr h  
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private void processErrorCode(int nErrorCode) ,N;v~D$Y  
{ wJ(8}eI  
System.err.println("Error Code : " + nErrorCode); .hgH9$\  
} jRwa0Px(  
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r?]
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//停止文件下载 BWohMT  
public void siteStop() cyHhy_~R  
{ #\0TxG5'QA  
bStop = true; .CvFE~  
for(int i=0;i<nStartPos.length;i++) Bj+wayMi  
fileSplitterFetch.splitterStop(); y* rY~U#3  
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} {[N?+ZJD*L  
} uh1S 7!^  
//负责部分文件的抓取 8eN%sm  
**FileSplitterFetch.java c0SX]4} G  
*/ {Bc#?n  
package NetFox; m.Twgin  
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import java.io.*; ,Z?m`cx  
import java.net.*; V3 qT<}y|  
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public class FileSplitterFetch extends Thread { c'xUJhEL  
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String sURL; //File URL va@XbUC  
long nStartPos; //File Snippet Start Position ]|t9B/()i  
long nEndPos; //File Snippet End Position \
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int nThreadID; //Thread's ID rAL1TU(vm  
boolean bDownOver = false; //Downing is over J&'>IA  
boolean bStop = false; //Stop identical iY}QgB< M  
FileAccessI fileAccessI = null; //File Access interface h<Gypl
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException l'W3=,G[?  
{ &^AzIfX}Gw  
this.sURL = sURL; )Kxs@F  
this.nStartPos = nStart; 6|%^pjX5  
this.nEndPos = nEnd; @Ap@m6K?q  
nThreadID = id; JN-D/s  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 |}:e+?{o  
} >
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public void run() ]aREQ?ma&z  
{ <.;@ksCPW{  
while(nStartPos < nEndPos && !bStop) @wg&6uQ  
{ GOUY_&}tL  
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try{ |:~("rA+v  
URL url = new URL(sURL); qxRT1B]{Wx  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); D%6ir*%T  
httpConnection.setRequestProperty("User-Agent","NetFox"); I|GV :D  
String sProperty = "bytes="+nStartPos+"-"; ]kyle3#-~  
httpConnection.setRequestProperty("RANGE",sProperty); `'dX/d  
Utility.log(sProperty); =c :lS&B  
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InputStream input = httpConnection.getInputStream(); 
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//logResponseHead(httpConnection); \Sz4Gr0g3Z  
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byte[] b = new byte[1024]; .%-6&%1  
int nRead; ,{#RrF e  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ;}UIj{sj*  
{ v'mJ~tz  
nStartPos += fileAccessI.write(b,0,nRead); f'7d4  
//if(nThreadID == 1) }dV9%0s!  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ; |
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} p{\qSPK  
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Utility.log("Thread " + nThreadID + " is over!"); dVY(V&p  
bDownOver = true; ^sr:N5~z`  
//nPos = fileAccessI.write (b,0,nRead); RPa?Nv?e  
} %fexuy4  
catch(Exception e){e.printStackTrace ();} eSQzjR*  
} >"PqQO  
} D}k-2RM2k  
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h^.tomg8  
//打印回应的头信息 >*<6 zQf  
public void logResponseHead(HttpURLConnection con) f4A4  
{ KoxGxHz^Y3  
for(int i=1;;i++) UH1S_:6  
{ q9g[+*9]$  
String header=con.getHeaderFieldKey(i); 2Be?5
+  
if(header!=null) Sm*Jysy`  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); GDNh?R  
Utility.log(header+" : "+con.getHeaderField(header)); Bsih<`KF^  
else T9U2j-lA?  
break; X+'^Sp  
} %O4}i@Fe  
} ^R8U-V8:  
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public void splitterStop() 9FIe W[  
{ XeIUdg4>R  
bStop = true; 67KRM(S  
} J6^Ct  
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} a|6x!p2X  
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/* $<>EwW  
**FileAccess.java y}:)cA~o(y  
*//文件访问(定位，写) bCaPJ!ZO  
package NetFox; LGo@F;!n  
import java.io.*; 5shu76  
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public class FileAccessI implements Serializable{ kT }'"  
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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 l3Bxi1k[C  
RandomAccessFile oSavedFile; \w0b"p  
long nPos; h,WY2Hr  
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public FileAccessI() throws IOException ~=AKX(Q  
{ ("JV:u.L+  
this("",0); w#G=Z_Tt  
} g0:4zeL  
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public FileAccessI(String sName,long nPos) throws IOException ?lwQne8/  
{ -C'X4C+  
oSavedFile = new RandomAccessFile(sName,"rw"); ~ Dp:j*H  
this.nPos = nPos; _l{5'm  
oSavedFile.seek(nPos); L]}RSE2  
} @<TfA>*VJ  
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public synchronized int write(byte[] b,int nStart,int nLen) `7qp\vYL  
{ n40MP5RxY  
int n = -1; AIxBZt7{b  
try{ %M,d
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oSavedFile.write(b,nStart,nLen); On.x~t  
n = nLen; $-9@/%Y  
} jme5'FR
 
catch(IOException e) }B '*8^S  
{ %1?V6&  
e.printStackTrace (); dbUZGn~  
} !>2\OSp!  
.SV3<)  
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return n; qD%&\ZT  
} q>:&xR"ra  
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} '/Cz{<,  
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/* Q.2nUT`  
**SiteInfoBean.java OUk5c$M(  
*/ 4x{ti5Y0  
package NetFox; o4
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I;Fy k70w;  
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public class SiteInfoBean { Qp{-!*  
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private String sSiteURL; //Site's URL 8Gg/M%wq9U  
private String sFilePath; //Saved File's Path 34^Cfh  
private String sFileName; //Saved File's Name Ru')X{]25  
private int nSplitter; //Count of Splited Downloading File bl>b/u7/6  
"sx&8H"  
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public SiteInfoBean() @OY-(cW  
{//nSplitter的缺省值为5 Ahbu
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//default value of nSplitter is 5 qq_,"~  
this("","","",5); yj+b/9My   
} ;GT)sI  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) `DllW{l  
{ N~J Eia%  
sSiteURL= sURL; _O,ZeES  
sFilePath = sPath; +vSE}   
sFileName = sName; GFa/9Bi  
this.nSplitter = nSpiltter; @CI6$  
xLK0~|_#!  
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} 6MNA.{Jdd  
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public String getSSiteURL() hBE>ea  
{ y]4`d  
return sSiteURL; Hll}8d6[  
} ^tcBxDC"]  
~RAH -]  
H^:|`T|,  
public void setSSiteURL(String value) ucPMT0k  
{ %<|KJb4?  
sSiteURL = value; )_K@?rWS  
} FNEmGz/4  
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ah9',((!  
public String getSFilePath() J4#]8!A  
{ i4rF~'h@  
return sFilePath; 4yv31QG$  
} dKpa5f7  
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public void setSFilePath(String value) r!,V_a4n  
{ h18y?e7MU  
sFilePath = value; T["(YFCByg  
} 2<@!m@  
@0'|Uygn  
kk+8NwM1  
public String getSFileName() p;=(-4\V}  
{ y<d#sv(s  
return sFileName; ~'=4K/39  
} Vnb#N4vR  
In M'zAhb  
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public void setSFileName(String value) 7'uc;5:  
{ 0|;=mYa4M  
sFileName = value; _/
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} $u"$mg7x  
@ RBwT  

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public int getNSplitter() Mwc3@  
{ e|yuPd  
return nSplitter; g>zL{[e!  
} y8z%s/gRh  
]#n4A|&H  
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public void setNSplitter(int nCount) |Wk G='02  
{ pj]<i.p  
nSplitter = nCount; vrbh+  
} 1PSb72h<  
} pASVnXJZ  
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/* I r~X#$Upc  
**Utility.java d*L'`BBsp  
*/ ]EQ/*ct  
package NetFox; aa/9o]  
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public class Utility { VIzZmd  
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public Utility() vNGvEJ`qn  
{ DAW%?
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} h6/Z_
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kZQ;\QL1}  
//线程睡眠 S}
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public static void sleep(int nSecond) BL67sva;  
{ tO7{g  
try{ #G
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Thread.sleep(nSecond);
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} whCv9)x  
catch(Exception e) ~\P.gSiz  
{ UlrY  
e.printStackTrace (); ] ?(=rm9u  
} 2lRZ/xaF%P  
} . {I7sUQ  
CR<l"~X  
//日志 #x21e }Li  
public static void log(String sMsg) )Pq.kn{Sp  
{ AI2CfH#:C  
System.err.println(sMsg); \X!!(Z;6A  
} _qV_(TpS+  
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kel48B  
public static void log(int sMsg) 3$Je,|bs  
{ ,P^"X5$  
System.err.println(sMsg); UWI5/R  
} A@UnrbX:  
} I$$!YMm.N  
DcS
~@ ;  
-IE;5f#e  
/* ^s5)FdF8  
**TestMethod.java 8Ex0[e  
*/ ":OXs9Yg  
package NetFox; vJ!t.Vou  
xQQ6D  
R##O9BSI8Z  
public class TestMethod { ;I>`!|mT  
;\h'A(  
4"{q|~&=:$  
public TestMethod() eX\t]{\oC  
{ ///xx/weblogic60b2_win.exe @ o]F~x  
try{ FE`J.aw^X  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ; ?!sU  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ||qW'kNWM  
SiteFileFetch fileFetch = new SiteFileFetch(bean); d<]/,BY'  
fileFetch.start(); ,Fb#%r%  
} @B+];lr/-  
catch(Exception e){e.printStackTrace ();} <iMLM<J<w  
sB $!X@  
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} t;'__">:q  
il:""x7^y  
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public static void main(String[] args) %lujme  
{ -Jb I7Le  
new TestMethod(); bcQ$S;U)  
} H=0Y4 T@)T  
} Rcu/ @j{O  
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