http断点续传简单实现（java)

/* 0SJ(Ln`0K  
**SiteFileFetch.java AH^'E
 
*/ &0OH:P%  
package NetFox; B.#-@  
import java.io.*; >bg{  
import java.net.*; hfs QAa  
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public class SiteFileFetch extends Thread { ^CB@4$!   
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SiteInfoBean siteInfoBean = null; //文件信息Bean x6Q_+!mnk  
long[] nStartPos; //开始位置 \psO$TxF=  
long[] nEndPos; //结束位置 fF.+{-.  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 +B4i,]lCx  
long nFileLength; //文件长度 R[H#av  
boolean bFirst = true; //是否第一次取文件 \M~uNWv|  
boolean bStop = false; //停止标志 B XO,  
File tmpFile; //文件下载的临时信息 9/O\769"'  
DataOutputStream output; //输出到文件的输出流 m [BV{25  
\mw5 ~Rf;  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） >d
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public SiteFileFetch(SiteInfoBean bean) throws IOException Hh%|}*f_,  
{ 'i 8`LPQ  
siteInfoBean = bean; pMkM@OH  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +l<;?yk:;  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); |C7=$DgwY  
if(tmpFile.exists ()) % xBQX  
{ }1NNXxQ  
bFirst = false; ;s5JYR  
read_nPos(); I3YSW  
} 
3 op{h6  
else th+LScOX  
{ ~2QD.(  
nStartPos = new long[bean.getNSplitter()]; hjp,v)#  
nEndPos = new long[bean.getNSplitter()]; -c%'f&P  
} T!>sL=uf  
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} .<6'*XR  
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public void run() cY.5z:7u~v  
{ 3GXmyo:o$  
//获得文件长度 aF.fd2k  
//分割文件 }q:4Zh'l!  
//实例FileSplitterFetch (1%A@4  
//启动FileSplitterFetch线程 H~W
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//等待子线程返回 GsIqUM#R  
try{ JY$;m3h  
if(bFirst) yRt7&,}zL  
{ MkM`)g 5  
nFileLength = getFileSize(); #X0Y8:vj  
if(nFileLength == -1) 1c4:'0  
{ %5j*e  
System.err.println("File Length is not known!"); 2QKt.a  
} z!)@`?  
else if(nFileLength == -2) E+Dcw  
{ 9M@,BXOt  
System.err.println("File is not access!"); @[]#[7  
} {Bb:\N8X  
else 2FE
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{ w+hpi
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for(int i=0;i<nStartPos.length;i++) |^OK@KdL1  
{ Uq.hCb`:  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); B9]bv]  
} ]i8t  
for(int i=0;i<nEndPos.length-1;i++) .v['INK9  
{ o RK:{?Y  
nEndPos = nStartPos[i+1]; [!`5kI  
} )-\qo#0l  
nEndPos[nEndPos.length-1] = nFileLength; -K6y#O@@  
} -6# _t  
} ~g*5."-i  
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]qiX"<s>~C  
//启动子线程 `{Fz  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; igF<].'V  
for(int i=0;i<nStartPos.length;i++) 0*6Q8`I  
{ FPu$Nd&\  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Tj!rAMQk  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), A&X XL~yH  
nStartPos,nEndPos,i); 8*&YQId~  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ,Eo\(j2F.  
fileSplitterFetch.start(); (SByN7[gb  
} J#\oc@  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), W4)bEWO+q  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); yn.[-  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", TpxAp',#7  
nEndPos = " + nFileLength); X5+$:jq&  
// fileSplitterFetch[nPos.length-1].start(); ix
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//等待子线程结束 e /L([  
//int count = 0; HP:[aR!2P  
//是否结束while循环 AL|3_+G  
boolean breakWhile = false; D{JwZL@7k2  
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while(!bStop) =:\5*  
{ SA?1*dw)  
write_nPos(); =D)ADZ\<r  
Utility.sleep(500); T2|os{U  
breakWhile = true; T/jxsIt3  
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for(int i=0;i<nStartPos.length;i++) hbs /S  
{ hd)WdGJp
  
if(!fileSplitterFetch.bDownOver) otQ G6  
{ 9G4os!x)  
breakWhile = false; xp*d:  
break; =)J<R;  
} l/A!ofc#)  
} 6Y9<| .  
if(breakWhile) W?n/>DML  
break; M*aYcIU((  
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)#sN#ZR$  
//count++; j3j^cO[8v  
//if(count>4) {d> 6*b  
// siteStop(); N[N4!k )!$  
} ."`||@|  
7t+H94KG7  
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System.err.println("文件下载结束！"); (*\y  
} A:5P  
catch(Exception e){e.printStackTrace ();} X,D ]S@  
} w{GEWD{&  
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%
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//获得文件长度 ypx`!2Q$  
public long getFileSize() A>\3FeU>UC  
{ >S%}HSPKq  
int nFileLength = -1; NWj4U3x  
try{ !
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URL url = new URL(siteInfoBean.getSSiteURL()); }sp?@C,Z  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); AnpO?+\HF  
httpConnection.setRequestProperty("User-Agent","NetFox"); ,_K:DSiB  
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int responseCode=httpConnection.getResponseCode(); Fzz9BEw(i  
if(responseCode>=400) & d* bQv$  
{
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processErrorCode(responseCode); Y]i:$X]C?X  
return -2; //-2 represent access is error W9{y1,G9  
} m<!CF3g  
#hXuGBZEI  
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String sHeader; }&%&0$%  
#;UoZJ B  
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for(int i=1;;i++) &iT^IkA{  
{ &uI33=  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ER:K^ Za  
//Utility.log(in.readLine()); (U:6vk3Q  
sHeader=httpConnection.getHeaderFieldKey(i); 1;vwreJ  
if(sHeader!=null)
}xY|z"&  
{ rw75(Lp{  
if(sHeader.equals("Content-Length")) |C>\ku*  
{ -o57"r^x  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); (A-Uo   
break; EW/NH&{  
} 'lmjZ{k  
} l!ZzJ&  
else muO;g&  
break; A@reIt  
} ?28)l 4 Ml  
} In*0.   
catch(IOException e){e.printStackTrace ();} {fMo#`9=  
catch(Exception e){e.printStackTrace ();} Z1wfy\9c8  
;XXEvRk  
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Utility.log(nFileLength); WL3J>S_  
Y>K8^GS  
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return nFileLength; !RN9wXS7  
} y tTppmJF  
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//保存下载信息（文件指针位置） 5"D\n B%  
private void write_nPos() Ah
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{ f?"909&  
try{ fLV@~T|  
output = new DataOutputStream(new FileOutputStream(tmpFile)); NC|VZwQtm  
output.writeInt(nStartPos.length); y/+y |.Xg  
for(int i=0;i<nStartPos.length;i++) {wD "|K  
{ P5'VLnE R{  
// output.writeLong(nPos); ?l`|j*  
output.writeLong(fileSplitterFetch.nStartPos); \*c=b
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output.writeLong(fileSplitterFetch.nEndPos); s*vtCdrE.  
} .C1g Dry]  
output.close(); pWKI^S  
} #?~G\Ux0/  
catch(IOException e){e.printStackTrace ();} ,Uy~O(Ft  
catch(Exception e){e.printStackTrace ();} Po.izE!C  
} P+,YWp  
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//读取保存的下载信息（文件指针位置） vQ[ TcV  
private void read_nPos() E%$[*jZ  
{ ictOCF  
try{ xP 3>8Y  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); SnoEi~Da  
int nCount = input.readInt(); ,;yaYF6|/  
nStartPos = new long[nCount]; t<cWMx5ra  
nEndPos = new long[nCount]; &pAmFe  
for(int i=0;i<nStartPos.length;i++) S4{\5ulr7  
{ \G6V-W  
nStartPos = input.readLong(); +Xmza8T9  
nEndPos = input.readLong(); >9[wjB2?}  
} MED_#OS  
input.close(); a(x#6
  
} T=fVD8  
catch(IOException e){e.printStackTrace ();} Vtk}>I@%  
catch(Exception e){e.printStackTrace ();} bWzUWLa  
} ^k!u  
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private void processErrorCode(int nErrorCode) ;$UB@)7%  
{ ,km`-6.2?  
System.err.println("Error Code : " + nErrorCode); oSP^ .BJ$  
} ?q"9ZYX<  
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bbWW|PtWwP  
//停止文件下载 W}
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public void siteStop() 1["IT.,f.  
{ 'he&h4fm  
bStop = true; x!UGLL]_M  
for(int i=0;i<nStartPos.length;i++) ?)4c!3#  
fileSplitterFetch.splitterStop(); Q>\9/DjUp  
/-g%IeF  
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} ts=+k/Z  
} K?V' ?s  
//负责部分文件的抓取 M'$?Jp#]}  
**FileSplitterFetch.java wVUm!Y  
*/ XMpE|M!c  
package NetFox; smX&B,&@  
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import java.io.*; 
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import java.net.*; &-|(q!jm  
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public class FileSplitterFetch extends Thread { AaJz3oncJ  
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String sURL; //File URL 58Z,(4:E  
long nStartPos; //File Snippet Start Position _i0,?U2C  
long nEndPos; //File Snippet End Position s?&UFyYb,  
int nThreadID; //Thread's ID <2PO3w?Z  
boolean bDownOver = false; //Downing is over C6:; T%  
boolean bStop = false; //Stop identical Y^,G} &p  
FileAccessI fileAccessI = null; //File Access interface 0j[%L!hny  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException M\=/i\-  
{ /^Zgv-n  
this.sURL = sURL; 0+_:^z  
this.nStartPos = nStart; yzz(<s:o/  
this.nEndPos = nEnd; )H<F([Jri  
nThreadID = id; y;tX`5(fe  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 A<cnIUW  
} K<"Y4O#]  
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public void run() CSIsi]H  
{ !,;/JxfgVh  
while(nStartPos < nEndPos && !bStop) aP +)  
{ Evq^c5n>{  
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try{ q]z%<`.9*  
URL url = new URL(sURL); Su[f"2oR  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Y_M3-H=0  
httpConnection.setRequestProperty("User-Agent","NetFox"); x5!lnN,#  
String sProperty = "bytes="+nStartPos+"-"; J ?H|"  
httpConnection.setRequestProperty("RANGE",sProperty); zvh&o*\2<d  
Utility.log(sProperty); $lAhKpdlW  
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InputStream input = httpConnection.getInputStream(); bOdyrynh  
//logResponseHead(httpConnection); ,F0bkNBG  
/PtmJ2[  
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byte[] b = new byte[1024]; yyuf  
int nRead; 8,&QY%8pX  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Z~ {[YsG  
{ R>`TV(W`9  
nStartPos += fileAccessI.write(b,0,nRead); r!O4]j_3  
//if(nThreadID == 1) OEj%cB!  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 7a'@NgiGg  
} m*H6\on:  
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Utility.log("Thread " + nThreadID + " is over!"); iCZ1
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bDownOver = true; W8s/"  
//nPos = fileAccessI.write (b,0,nRead); h%(0|  
} (Qz| N  
catch(Exception e){e.printStackTrace ();} 8nHFNOv6  
} 9y5nG  
} ;p2a .P  
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//打印回应的头信息 #kL4Rm;  
public void logResponseHead(HttpURLConnection con) B}2JK9  
{ Km,:7#aV  
for(int i=1;;i++) St~a/Lq6  
{ %%Z|6V74  
String header=con.getHeaderFieldKey(i); >PK\bLEo  
if(header!=null) D*o[a#2_  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 8i?h{G IMV  
Utility.log(header+" : "+con.getHeaderField(header)); h**mAa0fo  
else FQ6{NMz,h  
break; gjhW
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} dFVm18  
} ,daZKxT  
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b>"=kN/  
public void splitterStop() N"#=Q=)x  
{ 5K %  
bStop = true; Fwv(J_'q  
} fW.)!EPO  
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} qECta'b&  
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/* ~V<62"G  
**FileAccess.java G9i?yd4n=B  
*//文件访问(定位，写) (3M7RpsL@  
package NetFox; U `<?~Bz  
import java.io.*; \%011I4  
dGBVkb4]T  
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public class FileAccessI implements Serializable{ +~]LvZtI_  
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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_?&pgy  
RandomAccessFile oSavedFile;
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long nPos; $+.!(Js"K  
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{!rpE7P-  
public FileAccessI() throws IOException orzy&4  
{ o{wXq
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this("",0); X:Z*7P/  
} 6t(I.>-  

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public FileAccessI(String sName,long nPos) throws IOException 7*&$-Hv  
{ #GT4/Ej}W  
oSavedFile = new RandomAccessFile(sName,"rw"); Jv9yy~  
this.nPos = nPos; W6[# q%o  
oSavedFile.seek(nPos); z?i{2Fz6  
} X6g{qzHg_  
B'"RKs]  
5Myp#!|x:  
public synchronized int write(byte[] b,int nStart,int nLen) H]/!J]  
{ zV8^Hxl  
int n = -1; ?h4Rh0rkX  
try{ 49m}~J=*  
oSavedFile.write(b,nStart,nLen); C0@[4a$8f  
n = nLen; B&oP0 jS  
} d;9F2,k$w  
catch(IOException e) E\!<=  
{ R7xEE7p
 
e.printStackTrace (); J|A:C[7 2  
} 4BgrG[l)  
zU$S#4/C  
hB)TH'R{:  
return n; M} {'kK  
} 3\jcq@N  
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} BE]PM nI  
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/* j\S}TaH0e  
**SiteInfoBean.java };=44E'7  
*/ CnA
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package NetFox; AT%@T|  
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public class SiteInfoBean { Htu}M8/4  
{KO+t7'Q  
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private String sSiteURL; //Site's URL v!
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private String sFilePath; //Saved File's Path Q7b$j\;I  
private String sFileName; //Saved File's Name &7CAxU;i3  
private int nSplitter; //Count of Splited Downloading File wUbs9y<  
O$Z<R:vVA  
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public SiteInfoBean() gZD,#D.hR  
{//nSplitter的缺省值为5 dUg| {l  
//default value of nSplitter is 5 GcL:plz  
this("","","",5); xJ(4RaP  
} ;^K4
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Y79{v nlGk  
{ X( H-U q*(  
sSiteURL= sURL; g^dPAjPQ  
sFilePath = sPath; sZ!/uN!6  
sFileName = sName; CI };$4W~  
this.nSplitter = nSpiltter; Jm l4EW7  
(\=iKE4#  
OYsG#  
} v)a$;P%  
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public String getSSiteURL() $Jt+>.44  
{ j5yxdjx9  
return sSiteURL; 9(PQ7}  
} #6%9*Rh  
^l(Kj3gM  
LmKG6>Q1#1  
public void setSSiteURL(String value) !h "6h  
{ rz@;Zn  
sSiteURL = value; pg%'_+$~m  
} 0rtP :Nj$  
ZKv^q%92  
)+nY-DB(  
public String getSFilePath() x*" 0dYH  
{ LS=HX~5C  
return sFilePath; 'L"dM9#>  
} )fo9Qwe  
>,Zf3M  
V>`xTQG  
public void setSFilePath(String value) %0z&k!P  
{ SbLx`]rI  
sFilePath = value; -R[ *S "  
} f
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public String getSFileName() -2dk8]KB]  
{ cG"+n@\  
return sFileName; H ',Nt  
} Fj`6v"h  
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public void setSFileName(String value) Zljj  
{ `nxm<~-\  
sFileName = value; kAEm#oz=g  
} =3Y:DPMB  
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public int getNSplitter() .5',w"R  
{ GJLlMi  
return nSplitter; _IA@X. )?  
} XL/?v" /  
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public void setNSplitter(int nCount) yJ(p-3O5  
{ MmjeFv  
nSplitter = nCount; uHv9D%R  
} Hvn{aLa.  
} nH#|]gVI  
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4&Q.6HkL  
/* O;u&>BMk  
**Utility.java ~"E@do("  
*/ yX}riXe
  
package NetFox; }4!R
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public class Utility { |G+6R-_  
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public Utility() z(AhO  
{ V Q6&7@ c  
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} p*T`fOL  
.kl _F7  
//线程睡眠 ]*8K4n G  
public static void sleep(int nSecond) .Y8z3O  
{ cax]lO  
try{ Ylc[ghx  
Thread.sleep(nSecond); 8\+Q*7~@i  
} Jon<?DQj  
catch(Exception e) e5!LbsJv  
{ H]LH~l  
e.printStackTrace (); i)Hjmf3  
} >Cb[  
} Vf67gux  
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//日志 8._ A[{.f  
public static void log(String sMsg) L#Mul&r3x0  
{ YxEc(a"  
System.err.println(sMsg); K5O#BBX=  
} zFy0SzF  
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public static void log(int sMsg) p#VA-RSUQ|  
{ N|n"JKw)  
System.err.println(sMsg); ,4bqjkX5q  
} 9oly=&lJ  
} <q V<dK&W  
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 a=<l}`*  
/* Le&SN7I  
**TestMethod.java r sf +dC  
*/ <1HbjRw  
package NetFox; nu1s
 
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public class TestMethod { fdIO'L_  
ZGUhje!  
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public TestMethod() gpBpG  
{ ///xx/weblogic60b2_win.exe ^-, aB  
try{ UN7>c0B  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); "r6DZi(^K  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); wI!>IV(5  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ?U~9d"2=  
fileFetch.start(); <P)vx  
} K,7IBv,B[  
catch(Exception e){e.printStackTrace ();} k_p4 f%9  
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} D<=:9  
j'#Y$d1.  
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public static void main(String[] args) /Ulv/Thl  
{ 4ZY0!'be-R  
new TestMethod(); ,qF;#nB-  
} :Ogt{t  
} #&JhA2]q  
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