http断点续传简单实现（java)

/* 8
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**SiteFileFetch.java Kud'pZ{P  
*/ ZkB3[$4C=5  
package NetFox; VF0dE  
import java.io.*; 6gOe!mm  
import java.net.*; NBl __q  
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public class SiteFileFetch extends Thread { [RU NuO   
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SiteInfoBean siteInfoBean = null; //文件信息Bean Y@F  
long[] nStartPos; //开始位置 pw'wWZE'  
long[] nEndPos; //结束位置 h7qBp300  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 MEwdw3  
long nFileLength; //文件长度 |)_-Bi;MW`  
boolean bFirst = true; //是否第一次取文件 &S74mV  
boolean bStop = false; //停止标志 ZI ?W5ISdg  
File tmpFile; //文件下载的临时信息 6ew "fCrH!  
DataOutputStream output; //输出到文件的输出流 2H?d+6Pt3  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） wX1ig  
public SiteFileFetch(SiteInfoBean bean) throws IOException fMK#x\.4  
{ Hlj6$%.  
siteInfoBean = bean; FquFRx  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Tvf~P w  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); L*?!Z^k  
if(tmpFile.exists ()) EY>8O+  
{ lj&>cScC  
bFirst = false; Zzd/K^gg  
read_nPos(); +lO'wa7|3  
} igDyp0t  
else nbdGt  
{ EH`0  
nStartPos = new long[bean.getNSplitter()]; %hT4qzJj  
nEndPos = new long[bean.getNSplitter()]; aW5~Be$ _  
} qJ[@:&:  
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} BH:  
:_d3//|  
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public void run() I6OSC&A`  
{ <6N_at3  
//获得文件长度 JE%A|R<Jl  
//分割文件 q"aPJ0ni'  
//实例FileSplitterFetch QV,E#(\5  
//启动FileSplitterFetch线程 nx4P^PC  
//等待子线程返回 >mIg@knE  
try{ DacJ,in_I{  
if(bFirst) fB#XhO  
{ &y:CW>T$/X  
nFileLength = getFileSize(); J^H=i)A  
if(nFileLength == -1) IKf`[_,t]  
{ |PM m?2^R  
System.err.println("File Length is not known!"); A1JzW)B  
} LR$z0rDEM  
else if(nFileLength == -2) q9}2  
{ shi Hy*(v  
System.err.println("File is not access!"); x%XT2+  
} ;A^K_w'  
else l`rC0kJ]  
{ By)3*<5a_  
for(int i=0;i<nStartPos.length;i++) ]O@"\_}  
{ Xm[Czd]%  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); zv%J=N$G
 
} {$TZ}z"DA  
for(int i=0;i<nEndPos.length-1;i++) E#h~V5Tf  
{ .Dv=pB,u  
nEndPos = nStartPos[i+1]; 3&J&^O  
} VJ1*|r,  
nEndPos[nEndPos.length-1] = nFileLength; q`loOm=y  
} :Ee?K  
} ],?pe  
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//启动子线程 q,,j',8kq/  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; (UW6F4:$  
for(int i=0;i<nStartPos.length;i++) ( Yi=v'd  
{ ^]rxhpS  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), u_'nOle K  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), G\mKCaI8  
nStartPos,nEndPos,i);  <qn,  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); L[]^{ O
 
fileSplitterFetch.start(); a@SUi~+3  
} 2NR7V*A  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), =K6c;  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); LkaG[^tfN  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", <
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nEndPos = " + nFileLength); U(3(ZqP  
// fileSplitterFetch[nPos.length-1].start(); 9A*rE.B+W  
?cBO6^  
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//等待子线程结束 97x%2.\:  
//int count = 0; j#o3  
//是否结束while循环 %AgA -pBp  
boolean breakWhile = false; t,?,F4j
 
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while(!bStop) Hd*Fc=>"Y  
{ QE6E
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write_nPos(); |B|@GF?:  
Utility.sleep(500); yam}x*O\xn  
breakWhile = true; BA`:miH<  
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for(int i=0;i<nStartPos.length;i++) ,9UCb$mh  
{ "8_,tYAH  
if(!fileSplitterFetch.bDownOver) .P%ym~S  
{ zW)gC9_|m-  
breakWhile = false; E.#6;HHzN  
break; KZ4zF  
} 1*#bfeoM  
} 5h(jeT8"  
if(breakWhile) u7(];  
break; =f4<({9  
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,7I},sZj  
//count++; ioWJj.%  
//if(count>4) NE[y|/  
// siteStop(); aL 8Gnqf2  
} ;&7,73!  
.S6ji~;r  
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System.err.println("文件下载结束！"); 9RB`$5F;  
} '2wCP EC  
catch(Exception e){e.printStackTrace ();} kXCY))vnn  
} )DRkS,I  
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//获得文件长度 v<+4BjV!J}  
public long getFileSize() _2; ^v`[  
{ a G@nErdW  
int nFileLength = -1; +0U#.|?  
try{ z[Z2H5[  
URL url = new URL(siteInfoBean.getSSiteURL()); hafECs  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); tU(y~)]  
httpConnection.setRequestProperty("User-Agent","NetFox"); Y@ObwKcG  
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int responseCode=httpConnection.getResponseCode(); n/?eZx1  
if(responseCode>=400) BMY>a  
{ u'=(&><  
processErrorCode(responseCode); TIETj~+  
return -2; //-2 represent access is error 0 S2v"(_T  
} pIvfmIm  
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k  
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String sHeader; #_{0Ndp2  
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for(int i=1;;i++) ,y{0bq9*2  
{ _2#zeT5  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); CQ$::;  
//Utility.log(in.readLine()); 6SV7\,2M  
sHeader=httpConnection.getHeaderFieldKey(i); k*O
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if(sHeader!=null) %`
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{ F G3Sk!O6  
if(sHeader.equals("Content-Length")) ,zD_% ox  
{ xl3zy~;M  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); D{Oq\*  
break; &0JK38(  
} Y+5"uq<'  
} .<HC[ls  
else /%5_~Jkr,  
break; ;m''9z)2  
} E*OG-r   
} YsZ{1W  
catch(IOException e){e.printStackTrace ();} z'_&|-m  
catch(Exception e){e.printStackTrace ();} .#sz|0  
|7]?>-  
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Utility.log(nFileLength);
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return nFileLength; %v_IX2'  
} @81-kdTx  
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//保存下载信息（文件指针位置） (*MNox?w  
private void write_nPos() B
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{ ix^gA
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try{ O@nqHZ  
output = new DataOutputStream(new FileOutputStream(tmpFile)); QH4k!^  
output.writeInt(nStartPos.length); AfUZO^<  
for(int i=0;i<nStartPos.length;i++) qQL.c+%L  
{ 5dqQws-,?1  
// output.writeLong(nPos); 8^8>qSD1  
output.writeLong(fileSplitterFetch.nStartPos); qw|JJ  
output.writeLong(fileSplitterFetch.nEndPos); o>@=N2n  
} -MDOZz\  
output.close(); )@!~8<_"  
} HOq4i!  
catch(IOException e){e.printStackTrace ();} 5/t
j  
catch(Exception e){e.printStackTrace ();} 7AI3|Ts]p  
} J`YnT  
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4 #aqz9k  
//读取保存的下载信息（文件指针位置） %)8d{1at  
private void read_nPos() Ica3  
{ 4sb )^3T  
try{
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); =Na/3\^WP  
int nCount = input.readInt(); qx Wgt(Os  
nStartPos = new long[nCount]; IY V-*/ |  
nEndPos = new long[nCount]; 3\7'm]  
for(int i=0;i<nStartPos.length;i++) Vu_&~z7h  
{
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nStartPos = input.readLong(); 4pLQ"&>}80  
nEndPos = input.readLong(); xy$vYDAFw  
} ]}p2Tp;1  
input.close(); RV( w%g  
}
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catch(IOException e){e.printStackTrace ();} 1po"gVot  
catch(Exception e){e.printStackTrace ();} ,c@r` x  
} cT_uJbP+  
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private void processErrorCode(int nErrorCode) #!w:_T%  
{ {An8/"bv}  
System.err.println("Error Code : " + nErrorCode); lr`?yn1D(  
} ~^^!"-  
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+xn&K"]:3  
//停止文件下载 4\&H?:c.  
public void siteStop() ?UxG/]",  
{ >BJ2v=RA  
bStop = true; cC b>zI  
for(int i=0;i<nStartPos.length;i++) ;>inT7?3|  
fileSplitterFetch.splitterStop(); w/qQ(]n8  
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} hm*Th  
} 2~#ZO?jE6  
//负责部分文件的抓取 J f\Qf  
**FileSplitterFetch.java ?nB helW^  
*/ (hpTJsZ  
package NetFox; :[A?A4l  
,@}W@GGP)  
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import java.io.*; PXOrOK  
import java.net.*; T^KCB\\<  
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public class FileSplitterFetch extends Thread { 5JQd)[Im  
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String sURL; //File URL /Lq;w'|I  
long nStartPos; //File Snippet Start Position Sja"(sJ  
long nEndPos; //File Snippet End Position U,oD44  
int nThreadID; //Thread's ID bk/.<Rt  
boolean bDownOver = false; //Downing is over +<'uw  
boolean bStop = false; //Stop identical NFdJb\  
FileAccessI fileAccessI = null; //File Access interface &z./4X  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 1i5 vW-'4  
{ &Tf=~6  
this.sURL = sURL; tfi2y]{A  
this.nStartPos = nStart; fGu5%T,  
this.nEndPos = nEnd; 6&i[g  
nThreadID = id; K~7'@\2 ?  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Q.j-C}a  
} 3m-edpH  
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public void run() h-z%C6  
{ Zr
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while(nStartPos < nEndPos && !bStop) {%]NpFg#b  
{ Ln"+nKr  
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try{ |usnY  
URL url = new URL(sURL); XS}Zq4H  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); (Q}PeKM?jq  
httpConnection.setRequestProperty("User-Agent","NetFox"); H=J
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String sProperty = "bytes="+nStartPos+"-"; ^%~Et>C  
httpConnection.setRequestProperty("RANGE",sProperty); Da9*/  
Utility.log(sProperty); <wIp$F.  

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InputStream input = httpConnection.getInputStream(); 2jI4V;H8g  
//logResponseHead(httpConnection); !1ie:z>s  
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byte[] b = new byte[1024]; UMHuIA:%U  
int nRead; m _t(rn~f6  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) |_Naun=+~  
{ o'x_g^ Y  
nStartPos += fileAccessI.write(b,0,nRead); nr'YWW  
//if(nThreadID == 1) `~w%Jf  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); +^^S'mP8  
} &*V0(  
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Utility.log("Thread " + nThreadID + " is over!"); `^s]?  
bDownOver = true; LM'*OtpDG  
//nPos = fileAccessI.write (b,0,nRead); $5q{vy  
} ?X8K$g  
catch(Exception e){e.printStackTrace ();} lB5[#z  
} %xH
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} ,iA2si  
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//打印回应的头信息 44/0}v]  
public void logResponseHead(HttpURLConnection con) @&am!+z  
{ aT`02X  
for(int i=1;;i++) |Oj,S|Z:  
{ t<KEx^gb  
String header=con.getHeaderFieldKey(i); EkfGw/WDw  
if(header!=null) ^c;skV&S  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); (HTk;vbZm  
Utility.log(header+" : "+con.getHeaderField(header)); h0y\,iWXb  
else PBPJ/puW  
break; #b]}cwd!  
} ;6\Ski0=l  
} e>)}_b  
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public void splitterStop() z
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{ g,z&{pZch  
bStop = true; gZ79u  
} ~gzpX,{n  
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#!<+:y'S?  
} %r}KvJgd  
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/* %n V@'3EI  
**FileAccess.java r*
 
*//文件访问(定位，写) sDh6 Uk  
package NetFox; v J,xz*rc`  
import java.io.*; hQW#a]]V:  
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iz,q8}/(  
public class FileAccessI implements Serializable{ `OF;>u*:  
BZ'y}Zu*  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 #L+s%OJ`  
RandomAccessFile oSavedFile; !O%f)v?  
long nPos; P[J qJi/H  
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public FileAccessI() throws IOException PauFuzPP  
{ #L1yL<'  
this("",0); .q;RNCUt  
} XN0RT>@  
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public FileAccessI(String sName,long nPos) throws IOException H 29 _ /  
{ ?M1 Q
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oSavedFile = new RandomAccessFile(sName,"rw"); YM,D`c[pX  
this.nPos = nPos; !Z9ikn4A  
oSavedFile.seek(nPos); fxf GJNR  
} HWao3Lz  
">4[+'  
kH
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public synchronized int write(byte[] b,int nStart,int nLen) 94>7-d  
{ ^Qb!k/$3y  
int n = -1; e\bF_ N2VA  
try{ qz_TcU'  
oSavedFile.write(b,nStart,nLen); Y;F,GxR}  
n = nLen; 56~da ){gd  
} CBgFB-!qpe  
catch(IOException e) khO<Z^wi[  
{ "N[gMp6U  
e.printStackTrace (); xBx?>nN  
} FL_ arhrqD  
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return n; >Gu>T\jpe.  
} A<G ;  
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} eVbh$cIrZ  
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/* EPUJa~4  
**SiteInfoBean.java [7t0[U~3?  
*/ <a/ZOuBzZ  
package NetFox; ;{)@ghD  
l#(g&x6J  
~'YSVx& )  
public class SiteInfoBean { I7-PF?  
w `9GygS  
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private String sSiteURL; //Site's URL
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private String sFilePath; //Saved File's Path :ftyNaq'  
private String sFileName; //Saved File's Name L[9+xK^g  
private int nSplitter; //Count of Splited Downloading File f>JzG
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public SiteInfoBean()
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{//nSplitter的缺省值为5 [}g5Z=l  
//default value of nSplitter is 5 .dq.F#2B;  
this("","","",5); 5<'Jd3N{&  
} "i5AAP?_]{  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) FU3IK3}  
{ #cg@Z  
sSiteURL= sURL; 7!d<>_oH  
sFilePath = sPath; U";Rp&\3;  
sFileName = sName; }lbx  
this.nSplitter = nSpiltter; o~z.7q  
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} G}O
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6/
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public String getSSiteURL() 'k) P(H  
{ 6Yi,%#  
return sSiteURL; l~>rpG  
} gA8u E  
*h8XbBZH  
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public void setSSiteURL(String value) lu(Omds+  
{ +/^q"/f F  
sSiteURL = value; d=Ihl30m  
} PzG:M7  
@!tmUme1c  
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public String getSFilePath() 2FtEt+A+'  
{ +\@\,{Ujy  
return sFilePath; :=KGQ3V~eK  
} "PM:&v  
[+2^n7R  
]5MRp7  
public void setSFilePath(String value) fN/KXdAy&  
{ O4+w2'.,  
sFilePath = value; Ki6BPi^  
}  6}ewBAq%  
k$m
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[&59n,R`  
public String getSFileName()  )"Yah  
{ iw6M3g#  
return sFileName; +c2>j8e6  
} 5_T>HHR6  
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public void setSFileName(String value) S 2` ;7  
{ 7 @Qlp$[F  
sFileName = value; Nr7.BDA  
} l`G:@}P>G  
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public int getNSplitter() YXOD fd%L  
{ B#lj8I^|  
return nSplitter; DD3yl\#,  
} Fgq*
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public void setNSplitter(int nCount) }|,\?7,  
{ KPK!'4,cu  
nSplitter = nCount; %=>x
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} U-:Z^+Y  
} YS6az0ie  
MA QY/s~F  
2]KPW*V  
/* :D7!6}%  
**Utility.java DO*C]   
*/ 0([jD25J!  
package NetFox; 9Ei#t FMc  
nmAXU!t'  
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public class Utility { M0\[hps~X  
BuO J0$  
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public Utility() 9%veU
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{ N>iCb:_ T;  
D($UbT-v  
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} PhdL@Mr  
4&WzGnK  
//线程睡眠 _Xe< JJvq  
public static void sleep(int nSecond) ^W*)3;5  
{ %Q01EjRes  
try{ )W3l{T(  
Thread.sleep(nSecond); a];i4lt(c  
} vUExS Z^  
catch(Exception e) O\{_)L  
{ zL}DLfy>R  
e.printStackTrace (); uU"s50m  
} V,,iKr@TG  
}
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~UFsiVpL  
//日志 kKO]q#9sO  
public static void log(String sMsg) 09i[2n;O  
{ 7guxkN#  
System.err.println(sMsg); Unk+@$E&  
} &?pAt30K:  
bm|8Jbsb&  
|]^! 4[!U  
public static void log(int sMsg) x$4'a~E  
{ XAkl,Y  
System.err.println(sMsg); 3mpjSL  
} _3JTHf<+  
} CKx}.<_  
6d6SP)|j  
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/* )]Rr:i9n  
**TestMethod.java *GnO&&m'B  
*/ >@W#@W*I@  
package NetFox; KLB?GN?Pb  
ax}Xsk_  
]P5u:~U  
public class TestMethod {

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public TestMethod() bBL"F!.  
{ ///xx/weblogic60b2_win.exe }3e+D  
try{ \6L=^q=  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); P40eK0e6  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); S d -+a  
SiteFileFetch fileFetch = new SiteFileFetch(bean); *8+YR  
fileFetch.start(); ru L
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} }
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catch(Exception e){e.printStackTrace ();} b?,y%D)'  
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} =$J2  
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P@ u%{  
public static void main(String[] args) NmXTk+,L#  
{ qlP=Y .H  
new TestMethod(); s:{%1/  
} *a4eL [  
} ;E_{Zji_e  
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