http断点续传简单实现（java)

/* v/x*]c!"`  
**SiteFileFetch.java @| P3  
*/ n-W?Z'H{r  
package NetFox; @T_O6TcY  
import java.io.*; -C=]n<ak  
import java.net.*; K: 4P;ApI  
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public class SiteFileFetch extends Thread { _En]@xK3&  
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SiteInfoBean siteInfoBean = null; //文件信息Bean V.U|OQouT  
long[] nStartPos; //开始位置 rrYp'L  
long[] nEndPos; //结束位置 Ty.drM  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 }\U0[x#q  
long nFileLength; //文件长度 5qeT4| Ol  
boolean bFirst = true; //是否第一次取文件 ;*_I,|A:Xr  
boolean bStop = false; //停止标志 }0vtc[!  
File tmpFile; //文件下载的临时信息 wqf&i^_  
DataOutputStream output; //输出到文件的输出流 nwhm[AaNs  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） y. Tct.  
public SiteFileFetch(SiteInfoBean bean) throws IOException > e;]mU`,  
{ UUD\bWfn  
siteInfoBean = bean; JTjzT2`A.  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ]gEu.Nth`  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ipfm'aQ  
if(tmpFile.exists ()) T4l-sJ'|  
{ k-io$  
bFirst = false; $,g 3*A  
read_nPos(); BSjbnnW}"  
} 8Er[M  
else 7G?Ia%u  
{ F>TYVxQ  
nStartPos = new long[bean.getNSplitter()]; $+iu\MuX  
nEndPos = new long[bean.getNSplitter()]; zz[g{[SN  
} ?!R
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} %}\ vW  
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public void run() t7sUtmq  
{ DS.39NY  
//获得文件长度 :~-)Sm+^  
//分割文件 VyRW'  
//实例FileSplitterFetch r*c82}tc  
//启动FileSplitterFetch线程 )`e^F9L  
//等待子线程返回 -,
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try{ _!|=AIX  
if(bFirst) ?&{S~[;l  
{ [8xeQKp4  
nFileLength = getFileSize(); PXOq#  
if(nFileLength == -1) ?G2qlna  
{ |zK!+fu  
System.err.println("File Length is not known!"); Hf!9`R[  
} b,=,px  
else if(nFileLength == -2) iXt4|0  
{ xU#]w6  
System.err.println("File is not access!"); ;b{pzIe=F  
} k];L!Fj1  
else e?_c[`sg  
{ 5
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for(int i=0;i<nStartPos.length;i++) h4J{jh.  
{ FZM ]o  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); "cIGNTLFA  
} ?3.(Vqwog  
for(int i=0;i<nEndPos.length-1;i++) ^A:!ni@3  
{ [_B+DD=}  
nEndPos = nStartPos[i+1]; eUzU]6h  
} &C CHxjsKR  
nEndPos[nEndPos.length-1] = nFileLength; 41P4?"O  
} i=
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} WHZe)|n  
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//启动子线程 K7)j  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ,Zf :R  
for(int i=0;i<nStartPos.length;i++) Y*]l|)a6_]  
{ =U)n`#6_j2  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), >u'/$k  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), >#Grf)@"6  
nStartPos,nEndPos,i); azz#@f1  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 
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fileSplitterFetch.start(); |JirBz  
} DQL06`pX/  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), KIXwx98  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Dx p>  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", }rFsU\]:q  
nEndPos = " + nFileLength); 
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// fileSplitterFetch[nPos.length-1].start(); ?,A}E|jZ  
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//等待子线程结束 03i?"MvNo  
//int count = 0; 6Cop#kW#  
//是否结束while循环 n"K {uj))  
boolean breakWhile = false; 8=ukS_?Vy  
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while(!bStop) O2V6UX@&<w  
{ I@y2HxM  
write_nPos(); R#[QoyJ  
Utility.sleep(500); ?15POY ?Z  
breakWhile = true; "jkw8UVz  
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for(int i=0;i<nStartPos.length;i++) . }-@;:yh  
{ M]%!n3Fb  
if(!fileSplitterFetch.bDownOver) PVQ#>_~5  
{ |j.KFu845  
breakWhile = false; e+d6R[`M  
break; 2@=cqD7x  
} <;TP@-a  
} ;XKo44%  
if(breakWhile) @w.b |
  
break; ;T"m[D  
!ch[I#&J-  
)%H5iSNG$P  
//count++; B5?c'[V9  
//if(count>4) gMoyy  
// siteStop(); 'Wx\"]:  
} j?Jd@(*y$  
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System.err.println("文件下载结束！"); 9;xL!cy  
} .:|#9%5  
catch(Exception e){e.printStackTrace ();} 0NuL9  
} ~L4*b*W  
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//获得文件长度 e&FX7dsyy  
public long getFileSize() t
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{ $2 +$,:  
int nFileLength = -1; &t9XK8S  
try{ /ut~jf`  
URL url = new URL(siteInfoBean.getSSiteURL()); bH)8UQR%  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 5{!a+  
httpConnection.setRequestProperty("User-Agent","NetFox"); /pSUn"3  
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int responseCode=httpConnection.getResponseCode(); CHdet(_=v  
if(responseCode>=400) r['=a/.C  
{ x1&b@u  
processErrorCode(responseCode); {W:)oh>  
return -2; //-2 represent access is error dl3LDB  
} ^8f|clw"  
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; ei<Q =[  
String sHeader; !lt\2Ae  
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for(int i=1;;i++) yEw"8u'  
{ X'3`Q S:!  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); J*6n6  
//Utility.log(in.readLine()); 2gC&R1H  
sHeader=httpConnection.getHeaderFieldKey(i); R>YMGUH~w  
if(sHeader!=null) f@xfb ie!  
{ k1LtqV  
if(sHeader.equals("Content-Length")) Y/eN)  
{ )2<B$p  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ]%Q]C 8[C  
break; 71n uTE%!  
} w7*b}D@65\  
} BF1O|Q|d6  
else ,$zSJzS  
break; #G4~]Qml  
} Fh!!T%5>C  
} \aJ-q?=   
catch(IOException e){e.printStackTrace ();} bTy'5"  
catch(Exception e){e.printStackTrace ();} uYFcq  
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Utility.log(nFileLength); ;]#4p8lh+  
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return nFileLength; z7us*8X{  
} nm:let7GB  
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//保存下载信息（文件指针位置） >I66R;  
private void write_nPos() pg& ]F  
{ wor'=byh\  
try{ *l'$pJ X  
output = new DataOutputStream(new FileOutputStream(tmpFile)); /cg]wG!n8  
output.writeInt(nStartPos.length); $et :  
for(int i=0;i<nStartPos.length;i++) @,>=X:7  
{ ~|B!.+  
// output.writeLong(nPos); xfF&$K"  
output.writeLong(fileSplitterFetch.nStartPos); X%R^)zKV  
output.writeLong(fileSplitterFetch.nEndPos); NE>JtTF<  
} C[<\ufclD  
output.close(); ??e#E[bI  
} Mpl,}Q!c  
catch(IOException e){e.printStackTrace ();} ]JCB^)tM  
catch(Exception e){e.printStackTrace ();} c7TWAG_+  
}
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//读取保存的下载信息（文件指针位置） XL&
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private void read_nPos() a ~iEps  
{ 'N5r2JL[w  
try{ t=pkYq5t8  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); '/qe#S  
int nCount = input.readInt(); d(B;vL@R2V  
nStartPos = new long[nCount]; \z2hXT@D  
nEndPos = new long[nCount]; ~JmxW;|_x)  
for(int i=0;i<nStartPos.length;i++) \g6 #MNW  
{ o)'=D(  
nStartPos = input.readLong(); }${ZI  
nEndPos = input.readLong(); ALt";8Oa  
} ~\s &]L  
input.close(); .2S
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} fjZveH0  
catch(IOException e){e.printStackTrace ();} zvs 2j"lb  
catch(Exception e){e.printStackTrace ();} wb Tg  
} N+@@EOmH  
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private void processErrorCode(int nErrorCode) yar IR|  
{ _2n/vF;I+_  
System.err.println("Error Code : " + nErrorCode); cZK?kz_Y  
} n,'AFb4AF  
}m lbN0v  
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//停止文件下载 >_%g8T'  
public void siteStop() P9cI{RI  
{ *CD=cmdD*  
bStop = true; h|>n3-k|p  
for(int i=0;i<nStartPos.length;i++) 0c;"bA0>Sx  
fileSplitterFetch.splitterStop(); o!dkS/u-m  
= Ow&UI  
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} ]8cX#N,M  
} +CHO0n  
//负责部分文件的抓取 c94PWPU  
**FileSplitterFetch.java cFNtY~(b  
*/ NU\t3JaR  
package NetFox; J-{E`ibGN  
@
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import java.io.*; /(L1!BPP9m  
import java.net.*; rW>'2m6HU  
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public class FileSplitterFetch extends Thread { v__Go kj-  
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String sURL; //File URL lVBy&f  
long nStartPos; //File Snippet Start Position r ($t.iS  
long nEndPos; //File Snippet End Position J#;m)5[ a%  
int nThreadID; //Thread's ID <6@NgSFz'  
boolean bDownOver = false; //Downing is over Oua/NF)  
boolean bStop = false; //Stop identical jM@I"JZb  
FileAccessI fileAccessI = null; //File Access interface MZF ;k$R  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Z]+Xh  
{ 8l,hP.  
this.sURL = sURL; [GT1,(}. Z  
this.nStartPos = nStart; BTQC1;;N  
this.nEndPos = nEnd; zi 14]FWo  
nThreadID = id; uUB%I 8  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 8[p6C Jl)  
} !8M'ms>s=  
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,>%r|YSJ)  
public void run() *iN]#)3>  
{ t/BiZo|zl  
while(nStartPos < nEndPos && !bStop) I:7,CV  
{ -~aEqj#?  
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try{ `d;izQ1_=  
URL url = new URL(sURL); ,Yt&PE  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); *Bz&  
httpConnection.setRequestProperty("User-Agent","NetFox"); IY6S\Gn  
String sProperty = "bytes="+nStartPos+"-"; P9!]<so  
httpConnection.setRequestProperty("RANGE",sProperty); }Q(I&uz  
Utility.log(sProperty); 4f~ZY]|nM  
LBi>D`]  
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InputStream input = httpConnection.getInputStream(); ^0~1/ PhOw  
//logResponseHead(httpConnection); tzN;;h4C  
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byte[] b = new byte[1024]; iR=aYT~  
int nRead; s*WfRY*=V  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) /T(~T  
{ k&;L(D  
nStartPos += fileAccessI.write(b,0,nRead); xfSvvCy  
//if(nThreadID == 1) } ~bOP^'  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ar}759  
} ?P]md9$(+e  
n
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Utility.log("Thread " + nThreadID + " is over!"); q|2C>{8  
bDownOver = true; ,DZLEsFM  
//nPos = fileAccessI.write (b,0,nRead); *(IO<KAg8  
} VlNzm  
catch(Exception e){e.printStackTrace ();} Sw)ftC~d  
} 03;(v%  
} /LzNr0>2  
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//打印回应的头信息 s3^SjZb  
public void logResponseHead(HttpURLConnection con) )Ggx  
{ (*gpa:Sc  
for(int i=1;;i++) &6EfybAt^_  
{ Br??Gdd  
String header=con.getHeaderFieldKey(i); SQk!o{  
if(header!=null) !*-cf$  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ~h.B\Sc]Q  
Utility.log(header+" : "+con.getHeaderField(header)); bhYaG i0  
else 2kve?/  
break; \59hW%Di  
} u] b6>  
} ;_ton?bF  
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public void splitterStop() HOG7||&y  
{ O}V2>W$  
bStop = true; \O~P !`  
} Q4*cL5j  
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5. i;IOx  
} bcNYoZ8`  
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/* VGIc|Q=F  
**FileAccess.java v0sX'>f  
*//文件访问(定位，写) Y$^QH.h  
package NetFox; Y8T.RS0  
import java.io.*; 'l;|t"R12  
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public class FileAccessI implements Serializable{ #96a7K  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 N1rrKyL!$  
RandomAccessFile oSavedFile; Iq*7F5B  
long nPos; vvCGzOv  
8:MYeE5  
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public FileAccessI() throws IOException s~CA @  
{ kQ+5pFo3  
this("",0); A6VkVJZx  
} IkkrnG8  
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public FileAccessI(String sName,long nPos) throws IOException _19k@a  
{ \c)XN<HH  
oSavedFile = new RandomAccessFile(sName,"rw"); H;8(y4;  
this.nPos = nPos; EifY
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oSavedFile.seek(nPos); $HRpG  
} i~4Kek6,I  
@gd-lcMYW  

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public synchronized int write(byte[] b,int nStart,int nLen) h!MT5B)r.  
{ Tn|reXc0e  
int n = -1; |zf||ju  
try{ Z6I!4K  
oSavedFile.write(b,nStart,nLen); .*,ZcO  
n = nLen; -{?Rq'H  
} _v\QuI6  
catch(IOException e) ()iJvf>
@  
{ I('l)^m%  
e.printStackTrace (); ]TQjk{X<  
} pw,.*N3P  
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return n; _+U`afV  
}
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} xucV$[
f  

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/* S"dQ@r9  
**SiteInfoBean.java $8s&=OW  
*/ 3jQ |C=  
package NetFox; I^o^@C  
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public class SiteInfoBean { T@L
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private String sSiteURL; //Site's URL ]2<g"zo0  
private String sFilePath; //Saved File's Path ~=71){4A  
private String sFileName; //Saved File's Name fRbVc  
private int nSplitter; //Count of Splited Downloading File o,d:{tt  
90q*V%cS  
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public SiteInfoBean() *Q)
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{//nSplitter的缺省值为5 \(u P{,ML  
//default value of nSplitter is 5 TnC'<zm9!  
this("","","",5); x@/!H<y  
} S+He  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ^t| %!r G  
{ $h2h&6mH  
sSiteURL= sURL; !({[^[!  
sFilePath = sPath; WA<~M)rb  
sFileName = sName; aW"BN 5eM>  
this.nSplitter = nSpiltter; F/&&VSv>LO  
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} \d6A<(!=v  
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public String getSSiteURL() D=
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{ (|WqOwmoUt  
return sSiteURL; 8.vD]hO  
} myPo&"_ x  
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public void setSSiteURL(String value) v"^G9u  
{ [[Z*n/tr  
sSiteURL = value; Z*k}I{0,-  
} J~~WV<6  
>BiJ/[9  
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public String getSFilePath() H#f FU  
{ \E n^Vf  
return sFilePath; RxAZ<8T_  
} $:>K-4X\}  
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public void setSFilePath(String value) &n['#7 <(!  
{ WXJ%bH
  
sFilePath = value; se_1wCYz  
} 7r:!H
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public String getSFileName() >2%!=q3)  
{ R@
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return sFileName; %/4ChKf!VR  
} SoCa_9*X  
;XANIT

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public void setSFileName(String value) DRal{?CH  
{ gVb;sk^  
sFileName = value; 9OX&;O+5  
} O}2;>eH  
}LOAT$]XI  
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public int getNSplitter() ,XR1N$LN8_  
{ 3~Ah8
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return nSplitter; [V =O$X_  
} K1jE_]@Z  
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public void setNSplitter(int nCount)
}DoNp[`  
{ L_Z>*s&  
nSplitter = nCount; q5Z]Z.%3O  
} ]5wc8Kh"  
} )A,MTi  
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/* l1nrJm8  
**Utility.java  2>p>AvcK  
*/ JT!-Q!O}O  
package NetFox; SIVzc Hm  
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public class Utility { Ubv<3syR'  
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public Utility() !2=<MO  
{ z`XX[9$qm  
n' &:c}zKO  
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} YB*I'm3q  
zW8rC!
  
//线程睡眠 O,u$L  
public static void sleep(int nSecond) l%L..WCT]  
{ JZB7?@h%  
try{ M$ CnaH  
Thread.sleep(nSecond); F@UbUm2o  
} jhg0H2C8  
catch(Exception e) wX[g\,?}'  
{ 'b~,/lZd  
e.printStackTrace (); DJR_"8  
} |U)M.\h  
} >We4F2?  
D5^wT>3>  
//日志 q-}qrg  
public static void log(String sMsg) 4J{6Wt";  
{ R `  
System.err.println(sMsg); c<Fr^8  
} /?VwoSgV^  
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vq=nG]cE)  
public static void log(int sMsg) d0YDNP%,_  
{ muc6
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System.err.println(sMsg); 54r/s#|-3  
} m7!Mstu  
} n3y`='D  
6fY-DqF!  
@Jr:+|v3B  
/* ^Y,nv,gYn  
**TestMethod.java W"$sN8K>)  
*/ ozB2L\D7  
package NetFox; 9vZ:oO  
=#0f4z  
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public class TestMethod { ~>SqJ&-moo  
Q #IlUo  
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public TestMethod() fRh}n ^X  
{ ///xx/weblogic60b2_win.exe ZD~ra7  
try{ {
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SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); :8=7)cW  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); gjFpM.D-.  
SiteFileFetch fileFetch = new SiteFileFetch(bean); (X zy~l<  
fileFetch.start(); <x-7MU&  
} ]-g9dV_[>j  
catch(Exception e){e.printStackTrace ();} /xq^]0xy  
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} h>k[  
< #FxI  
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public static void main(String[] args) u'`eCrKT*  
{ ;|U !
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new TestMethod(); lV".-:u_  
} q]Vxf!0*>
 
} J~}sQ{ 0  
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