http断点续传简单实现（java)

/* }1rm  
**SiteFileFetch.java Tyck/ EO  
*/ fDP$ sW  
package NetFox; )RcL/n  
import java.io.*; B-r0"MX&  
import java.net.*; N\bocMc,X  
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public class SiteFileFetch extends Thread { 'PP#^aI,  
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SiteInfoBean siteInfoBean = null; //文件信息Bean FJd]D[h  
long[] nStartPos; //开始位置 T'~!9Q  
long[] nEndPos; //结束位置 !Ta>U^7  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 BXyo  
long nFileLength; //文件长度 iya"ky~H  
boolean bFirst = true; //是否第一次取文件 m1*O0Tg]"  
boolean bStop = false; //停止标志 l(Q?rwI8Y  
File tmpFile; //文件下载的临时信息 CJ++?hB]X  
DataOutputStream output; //输出到文件的输出流 Cn[0(s6  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） t N2Md}@e  
public SiteFileFetch(SiteInfoBean bean) throws IOException nb>7UN.9  
{ 1w&!H]%{  
siteInfoBean = bean; fS`$'BQ  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +U3m#Y)k  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); RZCq{|L  
if(tmpFile.exists ()) H8On<C=  
{ x_dy~(*  
bFirst = false; 9cj9SB4  
read_nPos(); &sd}ulEg`  
} =*LS%WI  
else DX|# gUAm  
{ \0gM o&  
nStartPos = new long[bean.getNSplitter()]; vZBc!AW  
nEndPos = new long[bean.getNSplitter()]; 2TA*m{\Hr  
} L{`JRu  
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} ,11H.E Z  
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public void run() Xqm:
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{ ~((w?Yy"v  
//获得文件长度 9uQ 4u/F  
//分割文件 $ <#KA3o\  
//实例FileSplitterFetch X7g1:L1Ys  
//启动FileSplitterFetch线程 >:|q&|x-  
//等待子线程返回 ]]wA[c~G  
try{ : 7`[$<~E  
if(bFirst) +@/"%9w
 
{ n .RhxgC<  
nFileLength = getFileSize(); #
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if(nFileLength == -1) ksN+?E4w  
{ \<)9?M
:  
System.err.println("File Length is not known!"); ])!o5`ltZ  
} 2j[&=R/.  
else if(nFileLength == -2) [YcG(^^  
{ 7fba-7-P  
System.err.println("File is not access!"); }-sdov<<  
} :65~[$2  
else >M/V oV  
{ F;<xnC{[  
for(int i=0;i<nStartPos.length;i++) ML>[^F  
{ fk x \=  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ^cz(}N 6&  
} |YY_^C`"-  
for(int i=0;i<nEndPos.length-1;i++) 9AJ7h9L  
{ p ObX42  
nEndPos = nStartPos[i+1]; k-{<=>uM  
} [+DW >Et  
nEndPos[nEndPos.length-1] = nFileLength; {>)#H
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} A"rf
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}  _ "VkGG  
+P`*kj-P\  
^kB8F"X  
//启动子线程 VQS~\:1  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ]n~ilS.rkl  
for(int i=0;i<nStartPos.length;i++) ,~]tg77  
{ *5^Q7``  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), aN8|J?JH  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), S_IUV)  
nStartPos,nEndPos,i); l.NEkAYPmH  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ?3.b{Cq{-  
fileSplitterFetch.start(); j4uvS!  
} y3o25}"  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), -RvQB  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); "$N+"3I  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 5Ezw ~hn  
nEndPos = " + nFileLength); 5jgR4a*_v  
// fileSplitterFetch[nPos.length-1].start(); ''\O
v  
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//等待子线程结束 L'0B$6  
//int count = 0; [J4gH^Z_  
//是否结束while循环 O%5 r[  
boolean breakWhile = false; h_+dT  

B=^)Ub5'  
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while(!bStop) 7KAO+\)H^Y  
{ :lPb.UCY  
write_nPos(); #x 177I\  
Utility.sleep(500); -v]Sr33L  
breakWhile = true; G <i@ 5\#  
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*  
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for(int i=0;i<nStartPos.length;i++) lE&&_INHQ  
{ "2)H'<  
if(!fileSplitterFetch.bDownOver) @oV9)  
{ }}\vV}s  
breakWhile = false; mUdOX7$c>  
break; lFV N07hG  
} 0Tx{3#  
} y)W@{@{kl  
if(breakWhile) 34%RZG_o'  
break; l0PZ`m+;j  
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//count++; @,cowar*  
//if(count>4) N D(/uyI  
// siteStop(); ,+meT`'vn  
} 3L_\`Ia9  
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System.err.println("文件下载结束！"); ,!Z
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} a1+#3X.  
catch(Exception e){e.printStackTrace ();} C/vIEYG4  
}
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//获得文件长度 !Wy6/F@Z  
public long getFileSize() vY${;#~|  
{ naYrpK,.  
int nFileLength = -1; c#Sa]n  
try{ C)@y5. G;  
URL url = new URL(siteInfoBean.getSSiteURL()); XWS%zL
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); [y'f|XN  
httpConnection.setRequestProperty("User-Agent","NetFox"); mKL<<L[  
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:Q $K<)[  
int responseCode=httpConnection.getResponseCode(); zr+zhpp  
if(responseCode>=400) q)S^P>  
{ ZUVA EH%  
processErrorCode(responseCode); vY }A  
return -2; //-2 represent access is error K9$>Yxe|  
} E:JJ3X|  
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hyCh9YOu)  
String sHeader; XQ9O$ ~q  
5!DBmAB  
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for(int i=1;;i++) uxtWybv  
{ \O*-#}~\  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Rzbj  
//Utility.log(in.readLine()); z3&]%Q&  
sHeader=httpConnection.getHeaderFieldKey(i); M dZ&A}S  
if(sHeader!=null) 5R
@  
{ Bg5Wba%NK  
if(sHeader.equals("Content-Length")) iOR_[y,  
{ ^W'fA{sr  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); cC=[Saatsf  
break; k7?N ?7w  
} <tF9V Jq  
} *)ardZV${  
else Qy^1*j<@&  
break; 4]G?G]lS>  
} e,F1Xi#d  
} 5R'TcWf#W  
catch(IOException e){e.printStackTrace ();} ohFJZ'  
catch(Exception e){e.printStackTrace ();} _LMM,!f  
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Utility.log(nFileLength); 9o;^[Ql-  
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return nFileLength; WM| dKF  
} bvv|;6  
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//保存下载信息（文件指针位置） mQCeo}7N5  
private void write_nPos() CN#+U,NZV  
{ NLUT#!Gr  
try{ Xf02"PXC  
output = new DataOutputStream(new FileOutputStream(tmpFile)); +W:=e,=  
output.writeInt(nStartPos.length); ap&?r`Tu  
for(int i=0;i<nStartPos.length;i++) mz@T  
{ eoai(&o0$  
// output.writeLong(nPos); :n0vQ5a  
output.writeLong(fileSplitterFetch.nStartPos); p[hZ@f(z  
output.writeLong(fileSplitterFetch.nEndPos); HG+%HUO$  
} AvdXEY(-  
output.close(); b4E:Wn9x  
} u=/{cOJI6  
catch(IOException e){e.printStackTrace ();} z.GMqW%B  
catch(Exception e){e.printStackTrace ();} N['qgO/  
} ^aH\7J@Y  
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//读取保存的下载信息（文件指针位置） Pa{%\dsv  
private void read_nPos() DE%KW:Hug  
{ Min ^>  
try{ -j73Wz  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); }dp=?AFg  
int nCount = input.readInt(); AD1=[I3  
nStartPos = new long[nCount]; ep2k%?CX 1  
nEndPos = new long[nCount]; x$1]M DAGb  
for(int i=0;i<nStartPos.length;i++) wQe_vY  
{ ?YZ- P{rTS  
nStartPos = input.readLong(); @&X|5p"[g  
nEndPos = input.readLong(); &Q>k7L!  
} H-~6Z",1  
input.close(); U@-^C"R  
} a#>Yh;FA  
catch(IOException e){e.printStackTrace ();} tS|(K=$  
catch(Exception e){e.printStackTrace ();} w*oeK  
} cIav&Zko  
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private void processErrorCode(int nErrorCode) :a$\/E=  
{ G*-b}f
 
System.err.println("Error Code : " + nErrorCode); JKGc3j,+#  
} }UWL-TkEjF  
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{vuZ{IJa  
//停止文件下载 ?)u@Rf9>  
public void siteStop() #)C[5?{SNq  
{ [/Rf\T(,jn  
bStop = true; a'2$
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for(int i=0;i<nStartPos.length;i++) _NMm/]mN /  
fileSplitterFetch.splitterStop(); G&4&-<  
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} f}x.jxY?  
} Bs O+NP  
//负责部分文件的抓取 P;Ga4Q.  
**FileSplitterFetch.java dvt9u9Vg=  
*/ T[j#M+p  
package NetFox; Of4^?` ^  
5 N#3a0)  
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import java.io.*; Jo@|"cE=  
import java.net.*; i*#-I3  
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public class FileSplitterFetch extends Thread { joiL{  
4}4Pyjh  
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String sURL; //File URL 0tEYU:Qu  
long nStartPos; //File Snippet Start Position LIZRoG8  
long nEndPos; //File Snippet End Position _nbBIaHN{  
int nThreadID; //Thread's ID ] :BX!<  
boolean bDownOver = false; //Downing is over L5 veX}  
boolean bStop = false; //Stop identical aC%m-m  
FileAccessI fileAccessI = null; //File Access interface ?kB2iU_f+  
vK_?<>  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException rdJ d#S
 
{ }>
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this.sURL = sURL; eC[$B99\  
this.nStartPos = nStart; ?34 e-  
this.nEndPos = nEnd; J|w\@inQ  
nThreadID = id; PDrZY.-
 
fileAccessI = new FileAccessI(sName,nStartPos);//定位 -3;*K4
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} rzh#CnL3  
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public void run() +(C6#R<LI  
{ 11<KpxKpk  
while(nStartPos < nEndPos && !bStop) vfq%H(  
{ 4*e0 hWp  
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try{ i1>-QDYnJ  
URL url = new URL(sURL); ]K/DY Do-  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); yjhf   
httpConnection.setRequestProperty("User-Agent","NetFox"); " e}3:U5n  
String sProperty = "bytes="+nStartPos+"-"; ?)`L$Vr=  
httpConnection.setRequestProperty("RANGE",sProperty); l&?}hq^'Dn  
Utility.log(sProperty); ,:Lb7bFv>  
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InputStream input = httpConnection.getInputStream(); j{Txl\D>  
//logResponseHead(httpConnection); j4;0|zx-i  
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+ j
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byte[] b = new byte[1024]; z&{5;A}Q@  
int nRead; A` AaTP  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) []A%<EI7  
{ sfOHarww  
nStartPos += fileAccessI.write(b,0,nRead); jSwf*u  
//if(nThreadID == 1) T`Mf]s)*  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 
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} [&nh5|f  
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Utility.log("Thread " + nThreadID + " is over!"); $`-4Ax4%  
bDownOver = true; v0YG,)_
 
//nPos = fileAccessI.write (b,0,nRead); 1f8GW  
} 5<ux6,E1{  
catch(Exception e){e.printStackTrace ();} |"9 #bU  
} dVFf.  
} 4y5UkU9|  
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//打印回应的头信息 ?HV`| Cw  
public void logResponseHead(HttpURLConnection con) q7-L53.x  
{ K!]1oy'V  
for(int i=1;;i++) kJ-*fe'S  
{ aN $}?  
String header=con.getHeaderFieldKey(i); (>I`{9x>6  
if(header!=null) qq1-DG  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); _dJ{j   
Utility.log(header+" : "+con.getHeaderField(header)); dGFGr}&s  
else ^+m+zd_  
break; K%Rj8J7|u?  
} y:vxE8$Q  
} P b]3&!a  
yT#{UA^  
4|`Bq}sjZf  
public void splitterStop() o,!T2&}  
{ ,+ #6Y_  
bStop = true; p!<$vE  
} .LuB\o$  
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} d'|,[p  
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/* j* *s^Sg  
**FileAccess.java Eb=#9f%y>&  
*//文件访问(定位，写) Qo1eXM
W  
package NetFox; -Z?Vd!H:  
import java.io.*; j$7Xs"
 
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public class FileAccessI implements Serializable{ vc]cNz:mQ  
7]%Ypv$  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 BkZV!Eg  
RandomAccessFile oSavedFile; ad_`x  
long nPos; "sKa`WN}  
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public FileAccessI() throws IOException [*Z`Kc  
{ N|Sf=q?Ko  
this("",0); ne>g?"Pex{  
} F>X-w+b4r  
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;=< ^0hxer  
public FileAccessI(String sName,long nPos) throws IOException 07/L}b`P  
{ (?*BB3b`  
oSavedFile = new RandomAccessFile(sName,"rw"); er.CDKD%L  
this.nPos = nPos; & ``d  
oSavedFile.seek(nPos); U5]pi+r  
} ]O:N-Y  
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public synchronized int write(byte[] b,int nStart,int nLen) cM_Fp  
{ bhs(Qzx  
int n = -1; O3.C:?;x  
try{ $^tv45  
oSavedFile.write(b,nStart,nLen); f):~8_0b  
n = nLen; ZCg`z
  
} ;_:Ool,  
catch(IOException e) !tHt,eJy  
{ Oc&),ru2l  
e.printStackTrace (); 4{qB X?  
} mga6[E<  
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return n; d3]hyTqbtm  
} k?VQi5M  
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} 7);:ZpDv%L  
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/* = c~I .  
**SiteInfoBean.java OSzjK7:  
*/ /dDzZ%/@  
package NetFox; @gSkROCdC)  
:Au /2  
xiyxrR;  
public class SiteInfoBean { ,kgF2K!  
MF[z-7  
 l>v{  
private String sSiteURL; //Site's URL ?
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private String sFilePath; //Saved File's Path ~k'V*ERNSj  
private String sFileName; //Saved File's Name (RXS~8  
private int nSplitter; //Count of Splited Downloading File Xev54!619  
tLcEl'Eo  
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public SiteInfoBean() 83.E0@$  
{//nSplitter的缺省值为5 <E':[.zC  
//default value of nSplitter is 5 KIL18$3J  
this("","","",5); #Nte^
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} fY2wDD  
1h"_[`L'  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) r9ke,7?  
{ fo\\o4Qyh  
sSiteURL= sURL; 6T^lS^  
sFilePath = sPath; iUr xJh  
sFileName = sName; za,2r^  
this.nSplitter = nSpiltter; Q:S\0cI0  
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zj]b&In6;  
} 2/tb6' =  
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ma}
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public String getSSiteURL() kqB\xlS7k  
{ lSc,AOXp  
return sSiteURL; FU@uH U5fd  
} PO ko]@~!i  
|}qjqtZ  
,0T)Oc|HL/  
public void setSSiteURL(String value) B-Y+F  
{ - s|t^  
sSiteURL = value; X}apxSd"  
} <`JG>H*B6  
i X/tt  
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public String getSFilePath() ida*]+ ~  
{ T|f_~#?eV  
return sFilePath; y<r44a_!  
} w2)/mSnu  
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yQS04Bl]  
public void setSFilePath(String value) a R#Cot  
{ 0=m&^Jpp  
sFilePath = value; A;%kl`~iyz  
} (^S5Sc=  
,#%SK;1<  
jI#z/a!j:  
public String getSFileName() -ddOh<U>  
{ &9h  
return sFileName; Wy)('EM  
} nE<J`Wo$f  
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public void setSFileName(String value) nB}e1 /_y  
{ <"ae4  
sFileName = value; | W?[,|e  
} tnRJ#[Io  
q/J3cXa{K  
/T#
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public int getNSplitter() (6[Wr}SW5  
{ &O{t
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return nSplitter; QZYM9a>  
} L3>4t: 8  
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DzmqR0)  
public void setNSplitter(int nCount) U:Fpj~E_w  
{ I,z"_[^G  
nSplitter = nCount; U*xxrt/On/  
} =KW|#]RB^  
} .n=xbx:=  
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/* L`JY4JM"  
**Utility.java e7wKjt2
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*/ tdb4?^.s  
package NetFox;
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public class Utility { ]:Wb1  
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public Utility() "9.6\Y\*  
{ [y$j9  
{bxhH)a'  
<6gU2@1  
} 1w6.  
^r%i3  
//线程睡眠 )8\Z=uC  
public static void sleep(int nSecond) mr
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{ *E$H;wKs8  
try{ ~V|KT}H  
Thread.sleep(nSecond); 78\\8*  
} pvI&-D #}  
catch(Exception e) >E{#HPpBi  
{ &<m WA]cAL  
e.printStackTrace (); <`^>bv9  
} `<bCq\+`  
} Ynv 9v\n|  
-_:
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//日志 F&-5&'6G+  
public static void log(String sMsg) Di]Iy  
{ E]D4']  
System.err.println(sMsg); V:$[~)k8  
} %Td+J`|U+  
?yda.<"g9Y  
t%ou1&SO  
public static void log(int sMsg) {5?!`<fF  
{ qM+!f2t  
System.err.println(sMsg); ~0:$G?fz  
} Au%Wrk3j  
} PLlx~A  
bt.K<Y0  
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/* %DHP
 
**TestMethod.java GN8`xR{J*  
*/ #0#V$AA>  
package NetFox; xQcMQ{&;  
9.]Cy8  
u:p:*u_^I  
public class TestMethod { ,(5dQ`hA0  
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f  
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public TestMethod() NiU tH  
{ ///xx/weblogic60b2_win.exe f^>lObvd  
try{ xf{C'uF/  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); cPa 0n4  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); >(YPkmH  
SiteFileFetch fileFetch = new SiteFileFetch(bean); *+zy\AhkP  
fileFetch.start(); Qg86XU%l  
} 0n=9TmE  
catch(Exception e){e.printStackTrace ();} (&a3v  
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} zrWq!F*-V\  
~]D\&D9=?  
tS*^}e*  
public static void main(String[] args) EIVQu~,H  
{ 9x 6ca  
new TestMethod(); K
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}  Cq~ah  
} U3d
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