http断点续传简单实现（java)

/* XS1>ti|<  
**SiteFileFetch.java H~$a6T"&  
*/ XGO_n{x  
package NetFox; n\P{Mc  
import java.io.*; N:d" {k  
import java.net.*; RQh4RUm  
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public class SiteFileFetch extends Thread { Z-/

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SiteInfoBean siteInfoBean = null; //文件信息Bean IRcZyry  
long[] nStartPos; //开始位置 3N<FG.6  
long[] nEndPos; //结束位置 &1VC0"YJWy  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 >Vg<J~[
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long nFileLength; //文件长度 !J+5l&
  
boolean bFirst = true; //是否第一次取文件 _$F I>  
boolean bStop = false; //停止标志 M/#<=XhA  
File tmpFile; //文件下载的临时信息 [1Vh3~>J6  
DataOutputStream output; //输出到文件的输出流 WO '33Q(  
HZM&QZHx)`  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） hsVWD,w  
public SiteFileFetch(SiteInfoBean bean) throws IOException 3|@Ske1%Y  
{ O-
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siteInfoBean = bean; @=@WRPGM*9  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); %+`$Lb?{  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); hDfsqSK0 /  
if(tmpFile.exists ()) cQN}z Ke  
{ SFh6'v'1N@  
bFirst = false; Gh@QR`xxc  
read_nPos(); c"fnTJXr79  
} P
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else v_oNM5w  
{ #Ok*Or  
nStartPos = new long[bean.getNSplitter()]; CRS/qso[Q'  
nEndPos = new long[bean.getNSplitter()]; n*'|7#;  
} v+Oo
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} 4Kx;F 9!%~  
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#,$d!l @  
public void run() 4egq Y0A  
{ ` NcWy  
//获得文件长度 #:236^xYS  
//分割文件 U?H!:?,C  
//实例FileSplitterFetch
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//启动FileSplitterFetch线程 hPH=.rX  
//等待子线程返回 MT|}[|_  
try{ gwT"o
 
if(bFirst) Q7f\ 5QjT  
{ gP)g_K(e  
nFileLength = getFileSize(); q*-q5FE  
if(nFileLength == -1) }}K44<]u  
{ d
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System.err.println("File Length is not known!"); #uFP eu:  
} rr2|xL?+u  
else if(nFileLength == -2) 3C2L _ K3  
{ RV7l=G9tq  
System.err.println("File is not access!"); 8g&uCv/Uk  
} $\{@wL  
else bf::bV?T  
{ P b2exS(  
for(int i=0;i<nStartPos.length;i++) p]IF=~b  
{ i!jxjP  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); )CEfG  
} ~x`OCii  
for(int i=0;i<nEndPos.length-1;i++) `0Qzu\gRb  
{ <+pwGKtD  
nEndPos = nStartPos[i+1]; l *.#g  
} gHA"O@HgDI  
nEndPos[nEndPos.length-1] = nFileLength; >STWt>s  
} @)|62Dv /  
} E_7N^htv  
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X>=`{JS1  
//启动子线程 _KC()OIeC  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; B&`#`]  
for(int i=0;i<nStartPos.length;i++) yw$er?  
{
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), &+d>xy\^/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ErHbc2  
nStartPos,nEndPos,i); ;ukwKfs  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 9:IVSD&"Rf  
fileSplitterFetch.start(); GnkNoaU  
} jL>IX`,+6  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 8?h-H#h  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ytKh[Uo  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", U"af3c^2
 
nEndPos = " + nFileLength); 9JpPas$]
 
// fileSplitterFetch[nPos.length-1].start(); iLNKC'  
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//等待子线程结束 %sbDH  
//int count = 0; @|idlIey  
//是否结束while循环 "i(k8+iK  
boolean breakWhile = false; ab: yH ')  
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while(!bStop) O4S~JE3o  
{ g%Sl+gWdJ  
write_nPos(); V31<~&O~%  
Utility.sleep(500); kR3g,P{L  
breakWhile = true; VkZrb2]v  
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for(int i=0;i<nStartPos.length;i++) Zchs/C 9{  
{ M6[&od  
if(!fileSplitterFetch.bDownOver) &2d^=fih  
{ nK)U.SZ  
breakWhile = false; `rN,*kcP  
break; I>B-[QEC  
} |^[]Oy=  
} 2I* 7?`  
if(breakWhile) y
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break; O=?WI   
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//count++; wKIQK!B)mF  
//if(count>4) s
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// siteStop(); '%vb&a!.6  
} 5IE2&V  
bx_`S#*N  
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System.err.println("文件下载结束！"); waz)jEk  
} Zui2O-L?V  
catch(Exception e){e.printStackTrace ();} w$MFCJ:p&  
} NTkGLD1e.  
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//获得文件长度 PbvRh~n  
public long getFileSize() iC10|0%{  
{ ~Pq1@N>n  
int nFileLength = -1; FctqE/>}I  
try{ oi^2Pvauh  
URL url = new URL(siteInfoBean.getSSiteURL()); 33z)F  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); wC+_S*M-K  
httpConnection.setRequestProperty("User-Agent","NetFox"); $6kVhE!;  
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int responseCode=httpConnection.getResponseCode();  \09eH[  
if(responseCode>=400) jCa%(2~iQ7  
{ rXPq'k'h#-  
processErrorCode(responseCode); w7@fiH{  
return -2; //-2 represent access is error  G?AZ%Yx  
} ze@NqCF  
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String sHeader; {4SwCN /  
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for(int i=1;;i++) O$%M.C'  
{ $O9Nprf  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); u.ubw(vv  
//Utility.log(in.readLine()); AIgJ,=9K  
sHeader=httpConnection.getHeaderFieldKey(i); #Drs=7w  
if(sHeader!=null) ,5$V;|  
{ :vZ8n6J[  
if(sHeader.equals("Content-Length")) ? FGzw  
{ ~w_4 nE  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); bw\fKZ  
break; &MKG#Y}  
} 1D%3|_id^  
} 5 0uYU[W  
else ?^t"tY  
break; t{Ck"4Cg  
} 2
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} (C>FM8$J  
catch(IOException e){e.printStackTrace ();} ErIAS6HS'  
catch(Exception e){e.printStackTrace ();} U
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Utility.log(nFileLength); PLD6Ug  
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return nFileLength; D;VQoO  
} &/R`\(
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/I&Hq7SW`  
//保存下载信息（文件指针位置） `B'*ln'r5  
private void write_nPos() $8zsqd 4?  
{ G|MjKe4}  
try{ ^K*uP^B=  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ?@8[1$1a  
output.writeInt(nStartPos.length); .@KpN*`KH  
for(int i=0;i<nStartPos.length;i++) S81Z\=eK  
{ 2NHuZ.af  
// output.writeLong(nPos); VtIPw&KHW  
output.writeLong(fileSplitterFetch.nStartPos); erTb9`N4  
output.writeLong(fileSplitterFetch.nEndPos); f'P}]_3(  
} {uH 4j4)2  
output.close(); \9k$pC+l  
} l`=).k
  
catch(IOException e){e.printStackTrace ();} Au3>=x`  
catch(Exception e){e.printStackTrace ();} 9DcUx-   
} 3yg22y&l  
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//读取保存的下载信息（文件指针位置） o8B_;4uB  
private void read_nPos() 7xz~%xC.  
{ banie{ e  
try{ lCT N dW+=  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 2c:H0O 0o  
int nCount = input.readInt(); rw_T&>!  
nStartPos = new long[nCount]; dayp1%d  
nEndPos = new long[nCount]; 6QS[mWU  
for(int i=0;i<nStartPos.length;i++) m| 8%%E}d  
{ $Gt1T[:QUX  
nStartPos = input.readLong(); D>"U0*h
 
nEndPos = input.readLong();
}%LwaRT  
} `~|8eKFq!  
input.close(); pgT XyAP{  
} . +_IpygQ  
catch(IOException e){e.printStackTrace ();} y\0<f `v6  
catch(Exception e){e.printStackTrace ();} w20E]4"  
} `.>5H\w0e  
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private void processErrorCode(int nErrorCode) \bAsn89O  
{ E><!Owxt/  
System.err.println("Error Code : " + nErrorCode); F%QZe*m[  
} p_h)|*W{  
F jdh&9Zc  
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//停止文件下载 &X0/7)*"v  
public void siteStop() nsR^TD;  
{ uV1H iv-  
bStop = true; V# Mw  
for(int i=0;i<nStartPos.length;i++) [P#^nyOh(  
fileSplitterFetch.splitterStop(); Q)N$h07R  
N!" ]e*q  
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} pcw!e_"+  
} mw}obblR  
//负责部分文件的抓取 JHpoW}7QB  
**FileSplitterFetch.java pL`snVz  
*/ 2{naSiaq  
package NetFox;
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import java.io.*; AU1P?lk  
import java.net.*; #6{"cr6l  
[{3WHS.  
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public class FileSplitterFetch extends Thread { $s2
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 v|+}>g  
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String sURL; //File URL K@xp
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long nStartPos; //File Snippet Start Position +kCVi  
long nEndPos; //File Snippet End Position  (2vR8  
int nThreadID; //Thread's ID /_~b~3{u  
boolean bDownOver = false; //Downing is over 6_/oVvd  
boolean bStop = false; //Stop identical #sit8k`GR8  
FileAccessI fileAccessI = null; //File Access interface :&$4&\_F  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException kf~7
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{ _DfI78`(  
this.sURL = sURL; 5vIuH+0  
this.nStartPos = nStart; 1xK'T_[  
this.nEndPos = nEnd; 0@a6r=`el  
nThreadID = id; \phG$4(7+  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ll;#4~iA  
} &8t?OpB =h  
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public void run() =DT
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{ gOw|s1`2,  
while(nStartPos < nEndPos && !bStop) e2w$
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{ #r 1 $=GY  
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try{ &|<~J(L;  
URL url = new URL(sURL); .UbmU^y|  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); vj0`[X   
httpConnection.setRequestProperty("User-Agent","NetFox"); ?!(/;RU1  
String sProperty = "bytes="+nStartPos+"-"; @%J?[PG  
httpConnection.setRequestProperty("RANGE",sProperty); bTC2Ya  
Utility.log(sProperty); )>at]mH  
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InputStream input = httpConnection.getInputStream(); }4xxge?r  
//logResponseHead(httpConnection); THQW8 V  
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byte[] b = new byte[1024]; `9Ngax=
_  
int nRead; mm%w0dOb"  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) G1B~?i2$ ?  
{ G~)jk+Qq  
nStartPos += fileAccessI.write(b,0,nRead); 'ntb.S)  
//if(nThreadID == 1) *sf9(%j  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ] d| -r:4  
} :YjOv  
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Utility.log("Thread " + nThreadID + " is over!"); T,(IdVlJ  
bDownOver = true; Rz`<E97-  
//nPos = fileAccessI.write (b,0,nRead); 3hR7 ./  
} Bt,qG1>$-  
catch(Exception e){e.printStackTrace ();} dv4)fG]W;_  
} Jf`;F :  
} M4M 4*o  
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//打印回应的头信息 R#tz"T@  
public void logResponseHead(HttpURLConnection con) WlP@Tm5g/  
{ jLvI!q   
for(int i=1;;i++) 7|zt'.56[  
{ `]]gD EPG{  
String header=con.getHeaderFieldKey(i); ]Vjn7P`~N  
if(header!=null) #f.@XIt'  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); Cd#*Wp)s  
Utility.log(header+" : "+con.getHeaderField(header)); f&`v-kiAn=  
else )Tng
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break;  9 N=KU  
} [gzU/:  
} Tv3ZNh  
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public void splitterStop() DWJ%r"aN  
{ $qQ6u!  
bStop = true; V2w[0^L  
} {z@vSQ=)=P  
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}  
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} Th
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/* xx;'WL,g  
**FileAccess.java 6z%3l7#7Yi  
*//文件访问(定位，写) ;~~Oc  
package NetFox; {KwLcSn  
import java.io.*; cdU2ph_  
R$,`}@VqZ3  
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public class FileAccessI implements Serializable{ U YUIpe  
.NjdkHYR  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ec1g7w-n  
RandomAccessFile oSavedFile;  4EB$e?  
long nPos; eV9:AN}K=  
K1:F{*  
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=  
public FileAccessI() throws IOException 6El%T]^  
{ =q xcM+OX1  
this("",0); e7#=F6  
} qx0o,oZN!  
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public FileAccessI(String sName,long nPos) throws IOException r@%32h  
{ :Yz.Bfli  
oSavedFile = new RandomAccessFile(sName,"rw"); NBMY1Xgj  
this.nPos = nPos; p6=#LwL'  
oSavedFile.seek(nPos); Arp4$h  
} @D"|Jq=6P  
[9(B;;R@  
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public synchronized int write(byte[] b,int nStart,int nLen) Cc Ni8Wg_  
{ sef!hS06  
int n = -1; 't)j  
try{ fE7WLV2
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oSavedFile.write(b,nStart,nLen); g1zqh,  
n = nLen; Tg:NeAN7(  
} bMSF-lQ  
catch(IOException e) /-|xxy  
{ ;prp6(c  
e.printStackTrace (); `}Q;2 F  
} 5,Q('t#J  
8#Z$}?W  
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return n; STOE=TC>  
} Q^39Wk@  
I
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} f4tia.  
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/* z0Zl'  
**SiteInfoBean.java ,JZ@qmQ,  
*/ 0]HK(,/h  
package NetFox; :sA-$*&x  
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public class SiteInfoBean { xq~=T:>/A  
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5~[Fh2+  
private String sSiteURL; //Site's URL *n[Fl  
private String sFilePath; //Saved File's Path J|DWT+$#Z  
private String sFileName; //Saved File's Name 6kDU}]c:H]  
private int nSplitter; //Count of Splited Downloading File ,~4(td+R7  
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public SiteInfoBean() /?6y2t  
{//nSplitter的缺省值为5 1gm{.*G  
//default value of nSplitter is 5 V&}Z# 9Dx  
this("","","",5); f Fz8m  
} jcG4h/A  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) dF?pEet?2  
{ @%fkW"y:  
sSiteURL= sURL; <'vM+Lk  
sFilePath = sPath; \Fe5<G'v  
sFileName = sName; zO\"$8q*  
this.nSplitter = nSpiltter; X0P$r6 ;  
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} m76]INq  

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public String getSSiteURL() d8r
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{ bQeYFY#^  
return sSiteURL; 0yZw`|Zh[  
} 3
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public void setSSiteURL(String value) SMy&K[hJ[  
{ 4C[gW  
sSiteURL = value; d)AkA\neWo  
} a*D|$<V  
\C6m.%%={R  
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public String getSFilePath() 50Jr(OeU<  
{ ujSzm=_P  
return sFilePath; Bh.'%[',  
} 'qD9kJ`  
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public void setSFilePath(String value) FG(`&S+,  
{ V,"'k<y  
sFilePath = value; GkO6r'MVE  
} L7b{H22  
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public String getSFileName() ZN1p>+oY!  
{ NR [VGZj  
return sFileName; hPH7(f|c{g  
} Nl8Cctrf  
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public void setSFileName(String value) oe<Y,%u"6
 
{  y1saE  
sFileName = value; OH(+]%B78  
} WT)")0)[  
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public int getNSplitter() ) jvkwC  
{ zhe5i;M  
return nSplitter; -I*A `M  
} kr/h^e  
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public void setNSplitter(int nCount) 9..k/cH  
{ Z8@]e}n  
nSplitter = nCount; -$q/7,os  
} |{nI.>  
} LKZI@i)  
}X?*o`sW  
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/* _7<U[63  
**Utility.java :6 fQE#(s&  
*/ ba ?k:b  
package NetFox; vB{b/xmah  
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)-{~7@yqZ  
public class Utility { xRUYJ=|oh  
@rMW_7[y  
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public Utility() #jJcgR<  
{ YMd&+J`  
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} ("6W.i>  
H-W)Tq_?-  
//线程睡眠 m0"\3@kB  
public static void sleep(int nSecond) 6Ts`5$e  
{ "=(;l3-o  
try{ :I('xVNPz  
Thread.sleep(nSecond); /z5lxS@#  
} #V6 -*  
catch(Exception e) m5pVt4  
{ }}_uN-m  
e.printStackTrace (); *PEuaRDN  
} pYG,5+g  
} * 2%e.d3"M  
bAiw]xi  
//日志 Om  
public static void log(String sMsg) m=}X$QF`^  
{ ~'MWtDe:Z8  
System.err.println(sMsg); .B13)$C  
} G#:!wI  
mW-W7-JhO7  
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public static void log(int sMsg) 'qJ-eQ7e  
{ 02[II_< 1  
System.err.println(sMsg); R!,)?j;  
} gxM8IQ  
} "~<~b2Y"5  
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5XI*I(.%/  
/* A.O~'')X  
**TestMethod.java ^mpB\D)q  
*/ @UX@puK`/  
package NetFox; ;vdgF  
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^\  
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public class TestMethod { l`&6W?C  
c5e\ckqm^  
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public TestMethod() ]gksyxn3  
{ ///xx/weblogic60b2_win.exe 6W;kIoB  
try{ 9 Zm<1Fw  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); )uvFta<(  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); rj~ian  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Z!reX6  
fileFetch.start(); vs|6ww  
} _
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catch(Exception e){e.printStackTrace ();} I;-5]/,  
9`xFZMd31A  
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} r5!M;hU1j  
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public static void main(String[] args) q&Wwtqc9  
{ !h>$bm  
new TestMethod(); p,\bez  
} {K4t8T]  
} [E (M(w':  
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