http断点续传简单实现（java)

/* V*H7m'za  
**SiteFileFetch.java #y*p7~|@  
*/ Yk=2ld;;  
package NetFox; O[15xH,  
import java.io.*; LjPpnjU  
import java.net.*; WuMr";2*E  
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public class SiteFileFetch extends Thread { k]~|!`  
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SiteInfoBean siteInfoBean = null; //文件信息Bean =PIarUJ  
long[] nStartPos; //开始位置 }$@EpM  
long[] nEndPos; //结束位置 A}G>JL  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 >N-l2?rE  
long nFileLength; //文件长度 ".sRi  
boolean bFirst = true; //是否第一次取文件 kS
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boolean bStop = false; //停止标志 nJcY>Rp?  
File tmpFile; //文件下载的临时信息 `Tc"a_p9t  
DataOutputStream output; //输出到文件的输出流 Y%Tm `$^V  
-~ H?R  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） {C5-M!D{<  
public SiteFileFetch(SiteInfoBean bean) throws IOException y)mtSA8  
{ 9F2MCqvcm  
siteInfoBean = bean; 1-}M5]Y  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); T~)R,OA7m  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); `@^s}rt+  
if(tmpFile.exists ()) k FCdGl  
{ yQE9S+%M  
bFirst = false; YSux#*#H  
read_nPos(); !XQ
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} *&tv(+P  
else Mu/hTTiNx  
{ ]. 0;;v6)  
nStartPos = new long[bean.getNSplitter()]; hFMT@Gy  
nEndPos = new long[bean.getNSplitter()]; J Mm'JK?  
} Ah_0o_Di  
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} Ti&v9re%wO  
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public void run() WP >VQZ&  
{ t(Gg 1  
//获得文件长度 vQmqYyOc2  
//分割文件 $Go)Zs-bL?  
//实例FileSplitterFetch Ti$_V_  
//启动FileSplitterFetch线程 XvIY=~  
//等待子线程返回 Zb$P`~(%  
try{ `!y/$7p  
if(bFirst) 4q*mEV  
{ 5U6b\jxX  
nFileLength = getFileSize(); {QVs[ J1  
if(nFileLength == -1)  >f*Zf(F  
{ ASUleOI79(  
System.err.println("File Length is not known!"); EM!9_8 f  
} ZiC~8p
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else if(nFileLength == -2) 2<tU  
{ cBQ+`DXn5c  
System.err.println("File is not access!"); !YIW8SP)  
} H0-v^H>^  
else $fG~;`T  
{ 4ZtsLMwLD  
for(int i=0;i<nStartPos.length;i++) I8VCR
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{ (w-@b70E  
nStartPos = (long)(i*(nFileLength/nStartPos.length));
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} ?wREX[Tqs  
for(int i=0;i<nEndPos.length-1;i++) o ^""=Z  
{ s^HI%mdf  
nEndPos = nStartPos[i+1]; ]K|td)1X  
} qqSFy>`P  
nEndPos[nEndPos.length-1] = nFileLength; OPC8fX5.  
} KN".0WU  
} 9{8xMM-  
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//启动子线程 BVu{To:g  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; w]O,xO  
for(int i=0;i<nStartPos.length;i++) ?[2>x{5Z  
{ }s:~E2?In  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), eDY)i9"W  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), PLRMW2  
nStartPos,nEndPos,i); fT.MglJcb  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ="de+S8W  
fileSplitterFetch.start(); >*WT[UU  
} S#nW )=   
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), B!((N{4H+  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); "mc ]^O  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", o8fY!C)  
nEndPos = " + nFileLength); }A&
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// fileSplitterFetch[nPos.length-1].start(); q,>4#J[2;s  
@bZ,)R  
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//等待子线程结束 YRu#JYti  
//int count = 0; ,$Xhwr  
//是否结束while循环 Lm*PHG  
boolean breakWhile = false; \e~5Dx1  
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while(!bStop) <aQ5chf7  
{ tv%B=E!r  
write_nPos(); #3_ @aq*  
Utility.sleep(500); .p(%gmOp#  
breakWhile = true; ~8U0(n:^  
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>tE6^7B*  
for(int i=0;i<nStartPos.length;i++) :ka^ztXG  
{ =Y5_@}\0  
if(!fileSplitterFetch.bDownOver) ^u> fW["[  
{ qK]Om6 a~  
breakWhile = false; AA0\C_W0p  
break; z@v2t>@3k  
} X<&Y5\%F  
} 3,1HD_  
if(breakWhile) r0q?e`nsA  
break; JC iB;!y  
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//count++; Y|ErVf4  
//if(count>4) QypUBf  
// siteStop(); #'BPW<Ob  
} %Ot*k%F  
}J $\<ZT  
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System.err.println("文件下载结束！"); ]Rj?OSok  
} .yB{+  
catch(Exception e){e.printStackTrace ();} RcOfesW o  
} C(kL
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//获得文件长度 [F 24xC+  
public long getFileSize() g0#w 4rGF)  
{ Q^):tO]!Ma  
int nFileLength = -1; MH|R@g  
try{ WWT1_&0  
URL url = new URL(siteInfoBean.getSSiteURL()); R#ZO<g%'  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); +*wr=9>  
httpConnection.setRequestProperty("User-Agent","NetFox"); .mplML0oW  
"-S@R=bi  
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int responseCode=httpConnection.getResponseCode(); ^O,r8K{1n  
if(responseCode>=400) 9# #(B  
{ YT6dI"48  
processErrorCode(responseCode); ZqXp f  
return -2; //-2 represent access is error u}89v1._Jn  
} b-RuUfUn0  
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String sHeader; }6gum  
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for(int i=1;;i++) 0cq<!{d  
{ &r2\P6J  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ZE9
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//Utility.log(in.readLine()); "O~kIT?/v  
sHeader=httpConnection.getHeaderFieldKey(i); -t: U4r(  
if(sHeader!=null) "[0.a\ d<  
{ q@1xYz:J  
if(sHeader.equals("Content-Length")) <GLn!~Px@5  
{ KxDp+]N]  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); AWd,qldv  
break; Cv[1HO<  
} nPk&/H%5hn  
} w-3Lw<  
else I3u)y|Y=  
break; ZS[Ut  
} 4hzdc] a  
} @@cc
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catch(IOException e){e.printStackTrace ();} bnJ4Ed
y  
catch(Exception e){e.printStackTrace ();} 7&u$^c S(  
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Utility.log(nFileLength); l#Vg=zrT  
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return nFileLength; {nw.bKq7  
} rU6A^p\,  
{C0Y8:"`  
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//保存下载信息（文件指针位置） UG[r /w5(F  
private void write_nPos()
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{ GJF &id  
try{ MjWxfW/  
output = new DataOutputStream(new FileOutputStream(tmpFile)); J|vg<
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output.writeInt(nStartPos.length); kK/XYC 0D  
for(int i=0;i<nStartPos.length;i++) $9@AwS@Uu  
{ ;]@Pm<f  
// output.writeLong(nPos); :(@P *"j  
output.writeLong(fileSplitterFetch.nStartPos); )_Z^oH ]<  
output.writeLong(fileSplitterFetch.nEndPos); ,T$ GOjt  
} o#=C[d5BV  
output.close(); g>l+oH[Tv|  
} P#D|CP/Cu  
catch(IOException e){e.printStackTrace ();} a ,"   
catch(Exception e){e.printStackTrace ();} G#M0 C>n  
} `3`.usw  
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//读取保存的下载信息（文件指针位置） F)v  
private void read_nPos() 0Ua=&;/2  
{ *F!1xyg  
try{ nxNHf3   
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 1}Y3|QxF  
int nCount = input.readInt(); %0 i)l|  
nStartPos = new long[nCount]; ci/qm\JI<<  
nEndPos = new long[nCount]; D$@2H>.-  
for(int i=0;i<nStartPos.length;i++) D c;k)z=  
{ \0vs93>?  
nStartPos = input.readLong(); jAU&h@  
nEndPos = input.readLong(); N9*:]a  
} uP(t+}dQ+3  
input.close(); \>G}DGz  
} t#3_M=L  
catch(IOException e){e.printStackTrace ();} `5!AHQ/  
catch(Exception e){e.printStackTrace ();} fI1 9p Q  
} $/|vbe,  
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private void processErrorCode(int nErrorCode) Y B,c=Wx  
{ FBbaLqgVF{  
System.err.println("Error Code : " + nErrorCode); ~Z!YB,)bp  
} n$v4$_qS  
noM=8C&U  
1vxQ`)a  
//停止文件下载 [YZgQ  
public void siteStop() !0vLSF=  
{ b`@C#qB  
bStop = true; :HwdXhA6  
for(int i=0;i<nStartPos.length;i++)
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fileSplitterFetch.splitterStop(); P$Oj3HD LM  
}2iR=$2  
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} e<*qaUI  
} F-oe49p5e  
//负责部分文件的抓取 >\w]i*%  
**FileSplitterFetch.java vB}c6A4'U  
*/ EW1,&H  
package NetFox; GdY@$&z{i  
Q J-|zS.W  
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import java.io.*; *8po0s  
import java.net.*; >]_^iD]*t  
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public class FileSplitterFetch extends Thread { CWocb=E  
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String sURL; //File URL
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long nStartPos; //File Snippet Start Position iy_Y!wZ{  
long nEndPos; //File Snippet End Position Pq8oK'z-  
int nThreadID; //Thread's ID z;F HZb9t,  
boolean bDownOver = false; //Downing is over ,B_c  
boolean bStop = false; //Stop identical N-_APWA  
FileAccessI fileAccessI = null; //File Access interface n:2._s T  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException P/.<sr=2  
{ 5bAdF'~  
this.sURL = sURL; %y
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this.nStartPos = nStart; <U1T_fiBoc  
this.nEndPos = nEnd; N5,LHO  
nThreadID = id; mC$y*G  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 d9BFeq8  
} '^>} =f  
8Znr1=1   
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public void run() &(A#F[ =0  
{ dH PvVe/  
while(nStartPos < nEndPos && !bStop) Bv!{V)$  
{ Wbei{3~$Y"  
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try{ [P =P8-5  
URL url = new URL(sURL); )#cZ& O  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); IZ7o6Etti  
httpConnection.setRequestProperty("User-Agent","NetFox"); _+NjfF|  
String sProperty = "bytes="+nStartPos+"-"; 2#sFY/@  
httpConnection.setRequestProperty("RANGE",sProperty); ybw\^t  
Utility.log(sProperty); pGjwI3_K  
Yj/o17  
6]~/`6Dub  
InputStream input = httpConnection.getInputStream(); \Ta5c31S+  
//logResponseHead(httpConnection); PJ0~ymE1~G  
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byte[] b = new byte[1024]; KFwuz()7  
int nRead; yxHo0U  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ,?erAI  
{ ?]$<Ufr  
nStartPos += fileAccessI.write(b,0,nRead); `Wg"m~l$N  
//if(nThreadID == 1) _,)_(R ,h  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); #}+H  
} ]xHiy+  
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Utility.log("Thread " + nThreadID + " is over!"); 4 ZnQpKg  
bDownOver = true; |1(x2x%}D^  
//nPos = fileAccessI.write (b,0,nRead); |+W{c`KL  
} UMe?nAC  
catch(Exception e){e.printStackTrace ();} sTl^j gV7j  
} t;6<k7h  
} S.~L[iLc  
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//打印回应的头信息 O- QT+]  
public void logResponseHead(HttpURLConnection con) ^tGAJ_b79  
{ o>C,Db~L/  
for(int i=1;;i++) 2HmK['(  
{ m~AAO{\:b  
String header=con.getHeaderFieldKey(i); V [g^R*b  
if(header!=null) j8p<HE51  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); k>mXh{(  
Utility.log(header+" : "+con.getHeaderField(header)); =VzJ>!0  
else j \jMN*dmV  
break; hmGlGc,lf  
} r9WR1&T)  
} Dg.~"h5mT  
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,"is%O.  
public void splitterStop() k
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{ ?
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bStop = true; :rQDA=Ps  
} eN.6l2-  
oSD=3DQ;  
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} 1>rQ).eT  
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v#&;z_I+  
/* Y4 z  
**FileAccess.java j0}wv
~\  
*//文件访问(定位，写) qsW&kW~  
package NetFox;  ~deS*  
import java.io.*; syW[uXNLZ  
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n
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public class FileAccessI implements Serializable{ "h_f-vP  
,$:u^;V(  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 9e K~g0m  
RandomAccessFile oSavedFile; aOGoJCt C  
long nPos; p-{ 4 $W  
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public FileAccessI() throws IOException H 4ELIF#@  
{ jyW={%&  
this("",0); pJ}U'*Z2  
} l+F29_o#  
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public FileAccessI(String sName,long nPos) throws IOException aC2Vz9e  
{ jFdgFKc)  
oSavedFile = new RandomAccessFile(sName,"rw"); OP=brLGu0  
this.nPos = nPos; en'[_43  
oSavedFile.seek(nPos); HJN GO[*g  
} 1?H; c5?d&  
NzyEsZ]$  
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public synchronized int write(byte[] b,int nStart,int nLen) |
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{ Y+Z+Y)K
  
int n = -1; aSIb0`(3  
try{ `oikSx$vB.  
oSavedFile.write(b,nStart,nLen); }||p#R@?  
n = nLen; 1/?Wa  
} vc|tp_M67  
catch(IOException e) #oTVfY#  
{ g]L8Jli  
e.printStackTrace (); }C_g;7*  
} 1q!k#Cliu  
1
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return n; ^2$b8]q  
} YU-wE';H6  
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} oCOv 6(  
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/* 6O{QmB0KK  
**SiteInfoBean.java >oJabR  
*/ cQ-#]  
package NetFox; D? %*L  
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public class SiteInfoBean { jRC{8^
98  
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private String sSiteURL; //Site's URL RyX11XU  
private String sFilePath; //Saved File's Path *(yw6(9%  
private String sFileName; //Saved File's Name 
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private int nSplitter; //Count of Splited Downloading File ?3fnt"  
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public SiteInfoBean() >x6\A7  
{//nSplitter的缺省值为5 t=Rl`1=(K  
//default value of nSplitter is 5 3Y)z{o>P  
this("","","",5); hk5!
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} >ph=?MKD  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 
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{ n-M6~   
sSiteURL= sURL; F-:AT$Ok  
sFilePath = sPath; `$1A;wg<  
sFileName = sName; TxQsi"0c  
this.nSplitter = nSpiltter; { /!ryOA65  
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} a] c03$fK  
,/p+#|>C=  
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public String getSSiteURL() $> QJ%v9+  
{ Hfj.8$   
return sSiteURL; nt>3i! l  
} /!Ag/SmS!9  
y{(Dv} 
 
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public void setSSiteURL(String value) Cd^1E]O0{  
{ q/*veL  
sSiteURL = value; 3:WHC3}W  
} C3=0st$  
<Sd
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public String getSFilePath() 3;z1Hp2X  
{ uYlyU~M:D  
return sFilePath; m=h/A xW  
} !sI^Lh,Y  
jt6_1^   
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public void setSFilePath(String value) ?Mo)&,__  
{ F#9^RA)9  
sFilePath = value; Es}`SIe/  
} H'$H@Kn]-  
:##
$-K*W"  
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public String getSFileName() vD#kH1  
{ voRb>xF  
return sFileName; =YO<.(Lu  
} NoF|j57?u'  
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%8DI)n#H  
public void setSFileName(String value) "+O/OKfR0  
{ _Ad63.Uq))  
sFileName = value; t; #@t/`  
} -8"
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N@X6Z!EO  
*=O3kUoL  
public int getNSplitter() UnVa`@P^:G  
{ ib> ~3s;  
return nSplitter; 4yTgH0(T  
} R9-mq;u+  
p {.6  
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public void setNSplitter(int nCount) N8x&<H  
{ .P5
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nSplitter = nCount; MR4k#{:w  
} Y>c+j  
} <M5fk?n,|  
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/* 4k{xo~+%,  
**Utility.java Xep2)3k>  
*/ 2Gj)fMK38  
package NetFox; 4,YL15.  
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public class Utility { ^XYK }J  
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public Utility() pIpd
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{ M|@@ LJ'  
m%;LJ~R  
-~J5aG[@~>  
} )B+zv,#q  
* _usVg  
//线程睡眠 8qfXc ^6  
public static void sleep(int nSecond) @Wm:Rz  
{ NTK9`#SA  
try{ |G/)<1P  
Thread.sleep(nSecond); mss.\  
} S&l [z,  
catch(Exception e) ;2?fz@KZ  
{ XCyb[(4  
e.printStackTrace (); m#_M"B.cm  
} L"c.15\  
} e^;:iJS  
b ettOg  
//日志 &N/dxKZcc  
public static void log(String sMsg) ]sP  
{ 3;uLBuZOCN  
System.err.println(sMsg); ]i1OssV~>  
} S5H}   
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I;?PDhDb  
public static void log(int sMsg) Ms3GvPsgv  
{ s6}SdmE  
System.err.println(sMsg); Fwvc+ a  
} Tk 'Pv  
} ;>5]KNj  
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m9c`"!  
/* $Dv5TUKw  
**TestMethod.java 9`H4"H>yG  
*/ OYmutq  
package NetFox; ]70ZerQ~L  
&VCg`r-{~  
ESFJN}Q%0.  
public class TestMethod { v/vPU  
F]<2nb7  
96; gzG@1!  
public TestMethod() Ut/%+r"s  
{ ///xx/weblogic60b2_win.exe r1=j$G  
try{ b8%TwYp  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {od@Sl  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); QWt3KW8)  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Azr|cKu]  
fileFetch.start(); d}|z+D  
} rAqS;@]0  
catch(Exception e){e.printStackTrace ();} QaA?UzB  
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} +RiI5.$=Z  
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public static void main(String[] args) 7dE.\#6r  
{ u35"oLV6}#  
new TestMethod(); DV>;sCMJ %  
} LU@1Gol  
} f+)LVT8p  
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