http断点续传简单实现（java)

/* _Hj,;Z  
**SiteFileFetch.java !qve1H4d2  
*/ [6N39G$  
package NetFox; VO?NrKyeW  
import java.io.*; :?W:'% (`[  
import java.net.*; 8[IifF1M=&  
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)Q?[_<1Y+  
public class SiteFileFetch extends Thread { lI<8)42yq  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Vk T3_f  
long[] nStartPos; //开始位置 ZA@"uqa6b  
long[] nEndPos; //结束位置 '2oBi6|X  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 vLS6Gb't  
long nFileLength; //文件长度 dBn.DU*B  
boolean bFirst = true; //是否第一次取文件 `d#_66TLr  
boolean bStop = false; //停止标志 +=$G6uR$  
File tmpFile; //文件下载的临时信息 j'n= Xh  
DataOutputStream output; //输出到文件的输出流 n8,/olqwW  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） [}3Y1t{G  
public SiteFileFetch(SiteInfoBean bean) throws IOException j pV  
{ 1!#ZEI C  
siteInfoBean = bean; \zyGJyy.  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); xbA2R4|  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 3|3lUU\I  
if(tmpFile.exists ()) &t4(86Bmq  
{ Vd~k4  
bFirst = false; +N:%`9}2V  
read_nPos(); 0[Aa2H*  
} h 42?^mV4?  
else Y [S^&pF  
{ FFGTIT# {"  
nStartPos = new long[bean.getNSplitter()]; (^\i(cfu6Q  
nEndPos = new long[bean.getNSplitter()]; ,_O[;L  
} +[+Jd)Z  
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} a}\JA`5;)Z  
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public void run() KQ3 On(d  
{ wS4wED&a  
//获得文件长度 I*"]!z1  
//分割文件 ;'}xD5]  
//实例FileSplitterFetch B;Vl+}R  
//启动FileSplitterFetch线程 Jsl,r+'H  
//等待子线程返回 R)z|("%ec  
try{ v>R.ou(  
if(bFirst) =c'LG   
{ [XK"$C]jHJ  
nFileLength = getFileSize(); &5<lQ1  
if(nFileLength == -1) EbH
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{ 2$=HDwv  
System.err.println("File Length is not known!"); HDOaN  
} o
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else if(nFileLength == -2) k=[Ro  
{ nceF4Ty  
System.err.println("File is not access!"); i`;
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} 1;V5b+b  
else l?~h_8&fT  
{ 6G],t)<A'-  
for(int i=0;i<nStartPos.length;i++) :nt%z0_  
{ RZjR d   
nStartPos = (long)(i*(nFileLength/nStartPos.length)); sMK/l @7  
} Ql 1# l:Q  
for(int i=0;i<nEndPos.length-1;i++) Mv3Ch'X[  
{ r{
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nEndPos = nStartPos[i+1]; <[bDNe["?  
} Khl7Ez  
nEndPos[nEndPos.length-1] = nFileLength; XA68H!I  
} YX(%jcj*  
} W%o){+,  
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V<7Gd8rDMM  
//启动子线程 8}"j#tDc  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 4w,}1uNEf  
for(int i=0;i<nStartPos.length;i++) 5I14"Qf  
{ !p$V7pFu6  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Yu=^`I  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),  jQhf)B  
nStartPos,nEndPos,i); 03PVbDq-  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); =Ao;[j)*!  
fileSplitterFetch.start(); I~I%z'"RQd  
} qCMcN<:>  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), dGg+[?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); yY+2;`CH  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 6-~  
nEndPos = " + nFileLength); "?!IPX2\S  
// fileSplitterFetch[nPos.length-1].start(); foeVjL:T  
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//等待子线程结束 [Zf<r1m  
//int count = 0; cD\Qt9EI  
//是否结束while循环 V-31x)  
boolean breakWhile = false; ,\M'jV"SK  
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while(!bStop) m`|Z1CT  
{ Am0$UeSZ  
write_nPos(); T]xGE   
Utility.sleep(500); 6!$S1z#wM  
breakWhile = true; bu.36\78  
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for(int i=0;i<nStartPos.length;i++) d dPJx<  
{ ra3WLK  
if(!fileSplitterFetch.bDownOver) BC+HP9<]  
{ ;u%hwlo  
breakWhile = false; )q,}jeM8  
break; :/3`+&T^/  
} v#6.VUAw  
} M3''xrpC  
if(breakWhile) |lv4X}H  
break; >@X=E3  
1;h>^NOq  
l@Ki`if  
//count++; YW5E |z  
//if(count>4) /X?Nv^Hy  
// siteStop(); Wi[Y@  
} ru&RL HFV  
!"kvXxp^  
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System.err.println("文件下载结束！"); lbPxZ'YO#  
} TcC=_je460  
catch(Exception e){e.printStackTrace ();} @ZVc!5J_,  
} 17GyE=Uu  
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//获得文件长度 kahv1s-  
public long getFileSize() ?z6C8T~+  
{ L=$P  
int nFileLength = -1; fkYQ3d,`  
try{ OV[-m;h|  
URL url = new URL(siteInfoBean.getSSiteURL()); |!|`Je3 K  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 0K!9MDT}*  
httpConnection.setRequestProperty("User-Agent","NetFox"); yP-Dj ,  
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int responseCode=httpConnection.getResponseCode(); B[$e;h*Aw[  
if(responseCode>=400) g (~&  
{ D"hiEz  
processErrorCode(responseCode); yF:fxdpw  
return -2; //-2 represent access is error aZ'p:9e  
} ,R)[$n  
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String sHeader; Eg9502Bl~8  
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for(int i=1;;i++) s(dox; d  
{ G$Dg*<  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); kSDV#8uZ  
//Utility.log(in.readLine()); Z` Aiw."|  
sHeader=httpConnection.getHeaderFieldKey(i); czp5M
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if(sHeader!=null) QhZ%<zN  
{ Ua:EI!`  
if(sHeader.equals("Content-Length")) t!~mbx+  
{  LKm5U6  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); TQ BL!w  
break; Pa.!:N-  
} ^'h~#7s  
} -{<%Wt9  
else B)(A#&nrb  
break; #qPk,a  
} C?|
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} 1/gh\9h  
catch(IOException e){e.printStackTrace ();} 3drgB;:g`  
catch(Exception e){e.printStackTrace ();} Y5;:jYk#<_  
+V) (,f1  
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Utility.log(nFileLength); y0Tb/&xN  
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return nFileLength; JmBYD[h,  
} *)w 8fq  
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//保存下载信息（文件指针位置） j_{gk"2:d`  
private void write_nPos() u]}Xq{ZN
 
{ W=DQ6.  
try{ MDlCU  
output = new DataOutputStream(new FileOutputStream(tmpFile)); 4, :D4WYWD  
output.writeInt(nStartPos.length); 7fVVU+y  
for(int i=0;i<nStartPos.length;i++) w"D"9G  
{ X:dj5v  
// output.writeLong(nPos); Y8P  
output.writeLong(fileSplitterFetch.nStartPos); [)a,rrhj  
output.writeLong(fileSplitterFetch.nEndPos); GY!&H"%  
} 9uq| VU5  
output.close(); A_g'9  
} -uh/W=Q1R  
catch(IOException e){e.printStackTrace ();} mF_/Rhu  
catch(Exception e){e.printStackTrace ();} $q+7,,"  
} -H]svOX  
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:!|xg!|y  
//读取保存的下载信息（文件指针位置） 6"wY;E  
private void read_nPos() 0}ZuF.  
{ 41:Z8YL(  
try{ vEb~QX0~  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); Ghj6&K%b0  
int nCount = input.readInt(); qaUHcdH  
nStartPos = new long[nCount]; \UiuJ+  
nEndPos = new long[nCount]; bi_R.sfK&  
for(int i=0;i<nStartPos.length;i++) hP|5q&wX  
{ /E*P0y~KTW  
nStartPos = input.readLong(); B}3s=+L@8  
nEndPos = input.readLong(); WgY3g1C  
} R&-bA3w$  
input.close(); { u;ntDr  
} CfVz'  
catch(IOException e){e.printStackTrace ();} 0/%zXp&m  
catch(Exception e){e.printStackTrace ();} Z8:iaP)  
} R; IB o  
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8>w/Es5  
private void processErrorCode(int nErrorCode) aB$Y5  
{ $k!t&G  
System.err.println("Error Code : " + nErrorCode); Y!SD^Ie7!  
} oc15!M3$  
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//停止文件下载 tV<Au  
public void siteStop() F'Wef11Yz  
{ NSxDCTw  
bStop = true; 63at lq  
for(int i=0;i<nStartPos.length;i++) L-MpdC  
fileSplitterFetch.splitterStop(); fc M~4yP?  
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} jx-W$@  
} WjA)0HL(  
//负责部分文件的抓取 R=E )j^<F  
**FileSplitterFetch.java OnD+/I  
*/ DB?[h
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package NetFox; uD+;5S]us  
}U8H4B~UtY  
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import java.io.*; u|Db%)
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import java.net.*; aE:fMDS|x  
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public class FileSplitterFetch extends Thread { af>
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String sURL; //File URL hmks\eb~  
long nStartPos; //File Snippet Start Position BB~Qs  
long nEndPos; //File Snippet End Position {lqnn n3  
int nThreadID; //Thread's ID 0C3CqGP  
boolean bDownOver = false; //Downing is over &ts!D!Hj  
boolean bStop = false; //Stop identical TG'A'wXxy  
FileAccessI fileAccessI = null; //File Access interface l'$AmuGj  
>YLwWU<X  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException B:Msn)C~  
{ >\MV/!W  
this.sURL = sURL; uTOL  
this.nStartPos = nStart; $S6AqUk$  
this.nEndPos = nEnd; 3dC8MKPq0  
nThreadID = id; _4.fT  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 84|Hn|4t  
} xUj[d(q  
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public void run() U JY`P4(  
{ *p+%&z_<  
while(nStartPos < nEndPos && !bStop) /J1O{L  
{ Av7bp[OD  
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try{ evZ{~v&/  
URL url = new URL(sURL); ~^:/t<N  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); lshO'I+)*  
httpConnection.setRequestProperty("User-Agent","NetFox"); |f.=Y~aY  
String sProperty = "bytes="+nStartPos+"-"; X8F _Mb*  
httpConnection.setRequestProperty("RANGE",sProperty); 6?z&G6  
Utility.log(sProperty); 6]7iiQz"H  
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InputStream input = httpConnection.getInputStream(); J?u",a]|H"  
//logResponseHead(httpConnection); wvsTP32]  
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byte[] b = new byte[1024]; 1z0&+C3z  
int nRead; J3g>#N]='(  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ,)u}8ty3j  
{ RCnN+b:c  
nStartPos += fileAccessI.write(b,0,nRead); (\>_{"*=  
//if(nThreadID == 1) " #_NA`$i  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); @D Qg1|m  
} M"ZP s   
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Utility.log("Thread " + nThreadID + " is over!"); _ i.CvYe  
bDownOver = true; _hK7hvM>  
//nPos = fileAccessI.write (b,0,nRead); :/K 'P`JaL  
} ) ^!oM  
catch(Exception e){e.printStackTrace ();} ~`u?|+*BO  
} CSR6  
} )d_)CuUBe  
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//打印回应的头信息 3@\vU~=P:  
public void logResponseHead(HttpURLConnection con) Yk6fr~b  
{ t? yMuK  
for(int i=1;;i++) o#4Wn'E  
{ b8feo'4Z   
String header=con.getHeaderFieldKey(i); cg}46)^<QH  
if(header!=null) 9Or3X
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); 'w^1re=R  
Utility.log(header+" : "+con.getHeaderField(header)); J<V}g v  
else #<M
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break; :DR G=-M  
} )Tpc8Hr  
} '[{M"S  

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public void splitterStop() sO~N2  
{ hSQP '6  
bStop = true; |Gzd|$%Oq  
} ph<Z/wlz  
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p}}}~ l
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} L/c$p`-  
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"/O0j/lm  
/* OHR9u  
**FileAccess.java ]j}zN2[A  
*//文件访问(定位，写) lva]jh2  
package NetFox; #Z"N\49  
import java.io.*; v'TkKwl  
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public class FileAccessI implements Serializable{ n,9 *!1y  
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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 3`5?Zgp  
RandomAccessFile oSavedFile; /thCu%%9A  
long nPos; }V ;PaX  
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public FileAccessI() throws IOException
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{ KVSy^-."  
this("",0); s<sqO,!  
} eOZA2  
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public FileAccessI(String sName,long nPos) throws IOException 9 /t}S6b{  
{ 66[yL(*+  
oSavedFile = new RandomAccessFile(sName,"rw"); H \.EKZ  
this.nPos = nPos; 0;!aO.l]K  
oSavedFile.seek(nPos); tZk@ RX  
} (=)+as"u9*  
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public synchronized int write(byte[] b,int nStart,int nLen) IgLP=mqcWK  
{ gA`/t e  
int n = -1; ?F(t`0=  
try{ MP w@O0QS  
oSavedFile.write(b,nStart,nLen); >Cb% `pe  
n = nLen; $_S^Aw?  
} 4Qz  
catch(IOException e) +S<2d.&~  
{ lh(A=hn"n  
e.printStackTrace (); 5u~Ik c~  
} kFw3'OZ,  
{1#5\t>9yD  
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return n; ^X)U^Qd  
} x*}(l%[  
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} 6
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P7 (&*=V  
/* zblh_6  
**SiteInfoBean.java \7$m[h{l  
*/ w^A8ZT0^7  
package NetFox; |jEKUTv,G  
P2 !~}{-  
F2z^7n.S  
public class SiteInfoBean { Mff_j0D  
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private String sSiteURL; //Site's URL P-7!\[];te  
private String sFilePath; //Saved File's Path wAF>C[<\  
private String sFileName; //Saved File's Name 96}/;e]@  
private int nSplitter; //Count of Splited Downloading File `w[0q?}"`  
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public SiteInfoBean() rv9qF |2r{  
{//nSplitter的缺省值为5 sOzjViv  
//default value of nSplitter is 5 '+f!(teLz  
this("","","",5); e4khReF;  
} rZKv:x}{6  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) iBV*G
W  
{ qAivsYN*  
sSiteURL= sURL; .NQoqXR  
sFilePath = sPath; J4!Z,-  
sFileName = sName; &EE6<-B-  
this.nSplitter = nSpiltter; unSF;S<  
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5NJ@mm{0  
} E36<Wog  
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public String getSSiteURL() ZH0 ~:  
{ ?mG ?N(t/h  
return sSiteURL; PM[6U#  
} k8Qv>z  
va~:oA  
_~HGMC)  
public void setSSiteURL(String value) `zZ=#p/  
{ e%wbUr]c2  
sSiteURL = value; [EB2o.EsO  
} B?#@<2*=L
 
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public String getSFilePath() )Qw|)='-  
{ ln3x1^!  
return sFilePath; (0Hhn2JA  
} _L%/NXu,  
~ Z%>N  
A`#5pGR  
public void setSFilePath(String value) V0wK.^]+}/  
{ }9 qsPn  
sFilePath = value; XO"!)qF  
} #uuwzE*M_  
}gag?yQ.^  
Y($"i<rN  
public String getSFileName() /e4hB  
{ Qy0bp;V/  
return sFileName; !%T@DT=l&  
} &b"PjtU.X  
/5U?4l(6[f  
/3FC@?l w4  
public void setSFileName(String value) 5IVASqYp  
{ r[EN`AxDb  
sFileName = value; <0JW[m  
} <9\_b6  
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hh:0m\@<  
public int getNSplitter() Gx'mVC"{  
{ 2=["jP!B  
return nSplitter; KhXW
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} X+P3a/T  
;2#7"a^  
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public void setNSplitter(int nCount) axXAy5  
{ :S~XE  
nSplitter = nCount; @HIC i]  
} j><.tA~i  
} li/IKS)e$  
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/x0zZ+}V  
/* M~ynJ@q  
**Utility.java An/)|B4  
*/ ZLE4XB]  
package NetFox; s49AF  
w y:USS?  
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public class Utility { f{*G%  
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public Utility() 9.vHnMcq  
{ @105 @9F  
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} ZuBVq  
pZjyzH{~  
//线程睡眠 ,((5|MbM/  
public static void sleep(int nSecond) SJy:5e?zk  
{ D?X97jNm  
try{ ?B@iBOcu[  
Thread.sleep(nSecond); =]Qu"nRB  
} @-!w,$F)%d  
catch(Exception e) 2)4{  
{ q SCt=eQ  
e.printStackTrace (); JK[7&C-O  
} t?YGGu^  
} olK%TM[Y  
.hETqE`E  
//日志 3<'SnP3mY  
public static void log(String sMsg) KY2xKco  
{  '=%vf  
System.err.println(sMsg); c @2s!bs  
} l$zo3[  

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LL kAA?P  
public static void log(int sMsg) 
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{ "xnek8F  
System.err.println(sMsg); a&PoUwG  
} (Ozb+W?  
} L7a+ #mGE  
H'
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T'fE4}rY  
/* P9X/yZ42  
**TestMethod.java ^[^uDE <  
*/ =0x[Sa$&,  
package NetFox; )0qXZgs  
VPtA %1  
xJc'tT6@  
public class TestMethod { Yx XDRb\kW  
78}iNGf  
7<-D_$SrU  
public TestMethod() b$.N8W%  
{ ///xx/weblogic60b2_win.exe RFQa9Rxk  
try{ HYW+,ts'  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 1Voo($q.  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 4y%N(^  
SiteFileFetch fileFetch = new SiteFileFetch(bean); d-xKm2sH  
fileFetch.start(); {9'"!fH  
} `|v0@-'$  
catch(Exception e){e.printStackTrace ();} _y5b>+  
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{_ewc/~  
} Q$Vxm+  
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public static void main(String[] args) `~pB1sS{  
{ 1*;?uC\  
new TestMethod(); ^N0hc!$  
} WpSdukXY{  
} ZaXK=%
z  
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