http断点续传简单实现（java)

/* m\/ Tj0e  
**SiteFileFetch.java \D>$aLO*?  
*/ MxzLK%am  
package NetFox; Knhp*V?  
import java.io.*; ?^:h\C^
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import java.net.*; &D%(~|'  
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public class SiteFileFetch extends Thread { :b[` 
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SiteInfoBean siteInfoBean = null; //文件信息Bean pf4 ^Bk}e  
long[] nStartPos; //开始位置 oJKa"H-jL  
long[] nEndPos; //结束位置
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 >=iy2~Fz,  
long nFileLength; //文件长度 4'KOp&#l K  
boolean bFirst = true; //是否第一次取文件 v){ .Z^_C  
boolean bStop = false; //停止标志 jkiTj~WE-  
File tmpFile; //文件下载的临时信息 RFh"&0[  
DataOutputStream output; //输出到文件的输出流 rQTr8DYH  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） \,!QJp4  
public SiteFileFetch(SiteInfoBean bean) throws IOException \.XLcz  
{ 2cu#lMq  
siteInfoBean = bean; 8 i&_Jgmr  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +l^LlqA  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); >r &;3:"  
if(tmpFile.exists ())
9;yn}\N `  
{ 6io, uh!  
bFirst = false; UZ8?[  
read_nPos(); nS()u}c;r  
} U $Qv>7  
else zF4
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{ ,fEO> i  
nStartPos = new long[bean.getNSplitter()]; Z -%(~  
nEndPos = new long[bean.getNSplitter()]; wOB azWa
 
} LtT\z<bAI  
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} 2/,0iwj-  
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public void run() {f9{8-W<u  
{ 0oy-os  
//获得文件长度 j
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//分割文件 ]0D}T'wM  
//实例FileSplitterFetch [6jbg
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//启动FileSplitterFetch线程 ThW,Y" l  
//等待子线程返回 @1zQce
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try{ K}[>T(0E  
if(bFirst) cYNJhGY  
{ ,? E&V_5  
nFileLength = getFileSize(); 9>/wUQs!]  
if(nFileLength == -1) HG/p$L*  
{ =TR,~8Z|  
System.err.println("File Length is not known!"); Gf8s?l  
} G ;?qWB,  
else if(nFileLength == -2)  Lw1T 4n  
{ l0*
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System.err.println("File is not access!"); 3CTX -#)vS  
} 4eVI},  
else (3\Xy   
{ r!}al5~&  
for(int i=0;i<nStartPos.length;i++) Dc~,D1xWj  
{ H* !EP  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); %/kyT%1  
} ]IJRnVp%  
for(int i=0;i<nEndPos.length-1;i++) ^"8G`B$r  
{ 9Qj2
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nEndPos = nStartPos[i+1]; {#IPf0O  
} {|9}+ @5Q1  
nEndPos[nEndPos.length-1] = nFileLength; 4t4olkK3Oa  
} QD{:vG g  
} `h;k2Se5  
9^P2I)aD  
!BU)K'mj  
//启动子线程 Kex[ >L10G  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 0ZAj=u@O  
for(int i=0;i<nStartPos.length;i++) l2b{u GE  
{ 0f ER*.F  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), F{k+7Ftc  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 1|,Pq9  
nStartPos,nEndPos,i); gG54:  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); N132sN2  
fileSplitterFetch.start(); fYebB7Pv  
} WUAJjds  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), fbZibcQ%k  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); OH<?DcfeL  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", T0j2a&Pv  
nEndPos = " + nFileLength); 3L-^<'~-k;  
// fileSplitterFetch[nPos.length-1].start(); jW*1E*"  
:

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~Pk0u{,4XQ  
//等待子线程结束 %R_{1GrL'c  
//int count = 0; m$>iS@R
 
//是否结束while循环 =fc:6JR  
boolean breakWhile = false; ,KW;2t*IQ@  
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while(!bStop) /I&wj^  
{ #nyv+x;  
write_nPos(); j{#Wn !,  
Utility.sleep(500); 'p)Q68;&  
breakWhile = true; =4C}{IL  
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for(int i=0;i<nStartPos.length;i++) ;mm!0]V  
{ &!7+Yb(1  
if(!fileSplitterFetch.bDownOver) ic6L9>[  
{ Y5A~E#zw  
breakWhile = false; h~HB0^|  
break;  ~QG?k  
} fF?6j  
} >AD=31lq  
if(breakWhile) #?}6t~  
break; 1`r| op},  

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//count++; c $;\i  
//if(count>4) upn8n vy4(  
// siteStop(); 8?TKN~ja  
} lpQP"%q  
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System.err.println("文件下载结束！"); <2Y0{ 8)  
} 6=|
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catch(Exception e){e.printStackTrace ();} t\U$8l_;  
} 2iXoj&3e  
#Olg(:\  
<SXZx9A!  
//获得文件长度 ?z`MPdO  
public long getFileSize() vM0_>1nN  
{ ,^T]UHRO  
int nFileLength = -1; %j]STD.E  
try{ ,j980/  
URL url = new URL(siteInfoBean.getSSiteURL()); )@QJ  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); "mj^+u-  
httpConnection.setRequestProperty("User-Agent","NetFox"); m$UvFP1>u1  
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int responseCode=httpConnection.getResponseCode(); i1*C{Lf;%)  
if(responseCode>=400) vx0UoKX  
{ ]Bu DaxWN  
processErrorCode(responseCode); %&] 1Fh
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return -2; //-2 represent access is error p]LnE`v  
} 7s>a2  
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String sHeader; 4^Qi2[w  
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for(int i=1;;i++) ~@c-*  
{ g,
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//DataInputStream in = new DataInputStream(httpConnection.getInputStream ());  0%Q9}l#7  
//Utility.log(in.readLine()); hYt7kq!"  
sHeader=httpConnection.getHeaderFieldKey(i); >S&U.  
if(sHeader!=null) 4\Di,PPu  
{ ?9?4p@  
if(sHeader.equals("Content-Length")) e9@(/+
 
{ ]S/G\z  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); tW6#e(^l6  
break; }OKL z.5  
} XCPb9<L  
} ]mkJw3  
else `"<2)yq?  
break; p]f&mBO*  
} $4j^1U`~)K  
} )h"Fla  
catch(IOException e){e.printStackTrace ();} +^Jwo)R'b  
catch(Exception e){e.printStackTrace ();} Xz1c6mX|o  
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Utility.log(nFileLength); D$pj#  
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return nFileLength; 'C]jwxy  
} H`|0-`q  
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//保存下载信息（文件指针位置） V9jFjc?  
private void write_nPos() : ^(nj7D  
{ *FPg
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try{ Z`xyb>$  
output = new DataOutputStream(new FileOutputStream(tmpFile)); gduxA/aT  
output.writeInt(nStartPos.length); Q_lu`F|  
for(int i=0;i<nStartPos.length;i++) EVz9WY  
{ p$OD*f_b  
// output.writeLong(nPos); 9eSRCLhgD  
output.writeLong(fileSplitterFetch.nStartPos); /RF%1!M K  
output.writeLong(fileSplitterFetch.nEndPos); rgR?wXW]jE  
} elKx]%k*)  
output.close(); g~R/3cm4  
} Uz>Yn&{y6  
catch(IOException e){e.printStackTrace ();} 2]Fu 1  
catch(Exception e){e.printStackTrace ();} 6Kht:WE  
} hmzair3X  
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//读取保存的下载信息（文件指针位置） j;0ih_Z@4W  
private void read_nPos() iPFL"v<#J  
{ !$E~\uT  
try{ wO.B~`y  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); mVrKz  
int nCount = input.readInt(); \9jpCNdJ  
nStartPos = new long[nCount]; 32KR--mn%  
nEndPos = new long[nCount]; 9S"N4c>  
for(int i=0;i<nStartPos.length;i++) .HDebi  
{ "o==4?*L  
nStartPos = input.readLong(); d<Dn9,G  
nEndPos = input.readLong(); Lw*1 .~  
} {{zua-F  
input.close(); BD4"pcr  
} /$*; >4=>f  
catch(IOException e){e.printStackTrace ();} 0~i qG  
catch(Exception e){e.printStackTrace ();} TQ~&Y)".  
} W9jNUZVXE#  
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private void processErrorCode(int nErrorCode) Nh :JU?h  
{ JJNmpUJ  
System.err.println("Error Code : " + nErrorCode); 5=.7\#D  
} ahoh9iJ  
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//停止文件下载 "o<D;lO  
public void siteStop() _DrnL}9I7  
{ y3AL)  
bStop = true; :+1bg&wQ  
for(int i=0;i<nStartPos.length;i++) JOgmF_(>Z  
fileSplitterFetch.splitterStop(); f-s~Q4  
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{"}+V`O{  
} s#`cX0L)  
} ;$[VX/A`f  
//负责部分文件的抓取 QS%,7'EG  
**FileSplitterFetch.java wK ][qZ ]  
*/ =%)})  
package NetFox; @|]iSD&T #  
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import java.io.*; ~q5-9{ma  
import java.net.*; 2}|vWKej{  
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public class FileSplitterFetch extends Thread { X`tOO  
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String sURL; //File URL M+\rX1T  
long nStartPos; //File Snippet Start Position >pa\n9=Q^  
long nEndPos; //File Snippet End Position =Y:5,.U  
int nThreadID; //Thread's ID zH'!fhcy  
boolean bDownOver = false; //Downing is over .0KOnLdK  
boolean bStop = false; //Stop identical I(y`)$}  
FileAccessI fileAccessI = null; //File Access interface 0A@-9w=u  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 0rGj|@+;  
{ yCZ2^P!a
 
this.sURL = sURL; ]~ >@%v&  
this.nStartPos = nStart; l`oT:  
this.nEndPos = nEnd; QM7[O]@  
nThreadID = id; A>[hC{  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 H2s*s[T -  
} $kM'  
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public void run() J~fuW?a]r  
{ 5=Zp%[#  
while(nStartPos < nEndPos && !bStop) L>i<dD{  
{ -.^=Z!=M  
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try{ '=-s1c@^  
URL url = new URL(sURL); ;cnnqT6  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ,q/tyGj  
httpConnection.setRequestProperty("User-Agent","NetFox"); \;'_|bu3.  
String sProperty = "bytes="+nStartPos+"-"; ;}$Z 80  
httpConnection.setRequestProperty("RANGE",sProperty); VoWA
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Utility.log(sProperty); m]Hb+Y=;h  
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InputStream input = httpConnection.getInputStream(); ZKZl>dDuh  
//logResponseHead(httpConnection); |2[S/8g!  
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byte[] b = new byte[1024]; nmTm(?yE  
int nRead; zK[ 7:<  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 5/zf x  
{ Cca~Cq[%*(  
nStartPos += fileAccessI.write(b,0,nRead); ;*n_N!v  
//if(nThreadID == 1) pE~9o 9  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); [BJ$|[11  
} rDK;6H:u{  
Qo]vpp^[#  
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Utility.log("Thread " + nThreadID + " is over!"); z+y;y&P  
bDownOver = true; BLWA!-  
//nPos = fileAccessI.write (b,0,nRead); |Gf1^8:C9  
} s@.`"TF.7  
catch(Exception e){e.printStackTrace ();} UZ[/aq  
} "u .)X3  
} yBJ/>SAcG  
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//打印回应的头信息 :<'i-Ur8  
public void logResponseHead(HttpURLConnection con) A73V6"  
{ GMVC&^  
for(int i=1;;i++) h[Ndtq>3{  
{ 2V#c[%vI  
String header=con.getHeaderFieldKey(i); d08`42Z69  
if(header!=null) Tb5$  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); r\4*\  
Utility.log(header+" : "+con.getHeaderField(header)); OL,/-;z6  
else !C9ps]6
 
break; hr)+Pk  
} @&!=m]D*  
} U)O?| VN^o  
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public void splitterStop() 6\NX
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{ JL}hOBqfI  
bStop = true; {mCKTyN+  
} +#de8/x  
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} vkDZv@  
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/* jsZiARTZRl  
**FileAccess.java /Bg6z m  
*//文件访问(定位，写) l(3'Re  
package NetFox; se^NQ=  
import java.io.*; 2)HxW
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public class FileAccessI implements Serializable{ ~#HH;q_7m  
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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 X+?Il)Bv  
RandomAccessFile oSavedFile; knNhN=hG+  
long nPos; T:w2  
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public FileAccessI() throws IOException
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{ Mhu53DT  
this("",0); P%<aGb4  
} m<X#W W)N  
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public FileAccessI(String sName,long nPos) throws IOException l`~a}y"n  
{ Z>>gXh<e[  
oSavedFile = new RandomAccessFile(sName,"rw"); 8|S1|t,  
this.nPos = nPos; !4qp
s$p{  
oSavedFile.seek(nPos);
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} :>AW@SoTp  
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public synchronized int write(byte[] b,int nStart,int nLen) h;4y=UU  
{ P!)7\.7  
int n = -1; R"9oMaY  
try{ 'NG^HLD/  
oSavedFile.write(b,nStart,nLen); (7rz:  
n = nLen; `[C v-  
} Q*mMF@-:  
catch(IOException e) A|`Joxr  
{ ~_f |".T  
e.printStackTrace (); +7lRP)1R  
} Xj})?{FP  
x 1%J1?Fp  
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return n; &dwI8@&  
} ~q'w),bE"Q  
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} ?C#F?N0  
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]$?zT`>(F  
/* (TbB?X}  
**SiteInfoBean.java ||
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*/ A^= Hu,"
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package NetFox; U:pLnNp`  
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public class SiteInfoBean { O_s9  
b Q9"GO<X  
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private String sSiteURL; //Site's URL [X$|dOm'N  
private String sFilePath; //Saved File's Path 1=/MT#d^?  
private String sFileName; //Saved File's Name 5w,YBUp  
private int nSplitter; //Count of Splited Downloading File vBCZ/F[  
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public SiteInfoBean() :(S/$^U  
{//nSplitter的缺省值为5 RB$ 8^#  
//default value of nSplitter is 5 L[QI 5N  
this("","","",5); "PDSqYA  
} +n8I(l=  
9rf|r 3  
)@lo ';\  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ]' "^M  
{ 8^~ZNU-~v  
sSiteURL= sURL; kw-
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sFilePath = sPath; ]~g|SqPA@  
sFileName = sName; F|n$0vQ*  
this.nSplitter = nSpiltter; 9bzYADLI  
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O+8ApicjTc  
} P7BJ?x  
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public String getSSiteURL() &:cTo(C'  
{ d)17r\*>I  
return sSiteURL; 5f^`4pT  
} >{LJ#Dc6  
m|?" k38  
5@%=LPV  
public void setSSiteURL(String value) 4~pO>6P   
{ ?GMeA}j  
sSiteURL = value; $Zu4tuXA  
} 7PQj7&m  
g)r,q&*  
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public String getSFilePath() onJ[&f  
{ M'!!EQo  
return sFilePath; hcp'+:  
} sVm'9k  
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public void setSFilePath(String value) loqS?bC]  
{ -WHwz m  
sFilePath = value; \<MTY:  
} a\.OL}"   
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public String getSFileName() "6Hjji@A  
{ m%$E[cUW!  
return sFileName; .n|3A3:  
} [F>n!`8  
:+Je989\[C  
.D2ub/er  
public void setSFileName(String value) Z5^,!6  
{  V\7u  
sFileName = value; bM3'm$34  
} 2Nt]Nj`  
*}WqYqOow  
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public int getNSplitter() K?9H.#(  
{ $m%/veD k  
return nSplitter; AdN=y8T  
} B8#f^}8  
7_'k`J@_  
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public void setNSplitter(int nCount) @S
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{ GPhwq n{  
nSplitter = nCount; fS$Yl~-m?  
} $;`
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} U-^S<H  
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/* Y<$"]@w  
**Utility.java zZ"')+7q&%  
*/ wCEfR!i  
package NetFox; N@`9 ~JS  
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public class Utility { x?k |i
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public Utility() nOoh2jUM  
{ E=U^T/  
V@s/]|rf,  
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} !Q/O[6  
PL B=%[  
//线程睡眠 ++RmaZ  
public static void sleep(int nSecond) sVl:EVv  
{ 'A@Oia1;{  
try{ C g,w6<7  
Thread.sleep(nSecond); o>k-~v7  
}  u^eC  
catch(Exception e) _"e( ^yiK  
{ E^>7jf09,  
e.printStackTrace (); r3lr`s`  
} #S74C*'8  
} 2OOj8JS  
eMMiSO!3  
//日志 VQJ5$4a&  
public static void log(String sMsg) mp$II?hZ*  
{ Rn^N+3o'M  
System.err.println(sMsg); MhB=+S[@  
} t$ ~:C  
;."{0gq  
f2K3*}P  
public static void log(int sMsg) $fpDABf  
{ "Q!{8 9Y  
System.err.println(sMsg); +?eAaC7s  
} j W]c9u  
} 9Yne=R/]  
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/* W${sD|d-  
**TestMethod.java wx7>0[zE  
*/ <5L`d}  
package NetFox; @)B5^[4(;  
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0 #; s{7k  
public class TestMethod { d~s-;T  
\evgDZf  
uPD_s[  
public TestMethod() \nt'I;f  
{ ///xx/weblogic60b2_win.exe -PuVI5L<  
try{ Ho{?m^  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); lt2&uYgp  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ^g"6p#S=n  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ?O]gFn  
fileFetch.start(); NY w(hAPv  
} 78A4n C  
catch(Exception e){e.printStackTrace ();} $w}aX0dK&  
%ieAY-<"  
m`6`a|Twp$  
} 5w%9b  
V^H47O;VC  
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public static void main(String[] args) 3Jit2W4  
{ Xq$0% WjG  
new TestMethod(); c=mFYsSv  
} 4h@of'  
} g5]DA.&(  
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