http断点续传简单实现（java)

/* rkG*0#k  
**SiteFileFetch.java &hyr""NkAm  
*/ +Rxf~m(pV  
package NetFox; x_bS-B)%Y:  
import java.io.*; VO#]IXaP  
import java.net.*; K=+w,H#`C  
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public class SiteFileFetch extends Thread { @M:j~  
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SiteInfoBean siteInfoBean = null; //文件信息Bean se2+X>@>  
long[] nStartPos; //开始位置 `3/,-  
long[] nEndPos; //结束位置 )MmMs"Um  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 ^xu`NE8;  
long nFileLength; //文件长度 <yE(p  
boolean bFirst = true; //是否第一次取文件 0[);v
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boolean bStop = false; //停止标志 s|%mGt &L  
File tmpFile; //文件下载的临时信息 qW$IpuK  
DataOutputStream output; //输出到文件的输出流 Y'%sA~g  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） DJ[U^dWRn  
public SiteFileFetch(SiteInfoBean bean) throws IOException }bAd@a9>3  
{ vC&y:XMt,`  
siteInfoBean = bean; >2vl & (  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); !`)
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); :7@"EW  
if(tmpFile.exists ()) OZQhT)nS]  
{ Yf7n0Etd,  
bFirst = false; T"dX)~E;  
read_nPos(); #@3RYx  
} Pm#B'N#*N|  
else X./8 PK?&  
{ bx!Sy0PUJ  
nStartPos = new long[bean.getNSplitter()]; !ck=\3pr  
nEndPos = new long[bean.getNSplitter()]; Y}(v[QGV  
} 8/ZJkI  
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} V.:a6>]  
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public void run() U$ _?T-x  
{ Apa)qRJd  
//获得文件长度 :&#hjeltt  
//分割文件 -r/#20Y  
//实例FileSplitterFetch UVxE~801Y  
//启动FileSplitterFetch线程 Ajs<a(,6  
//等待子线程返回 -TjYQ  
try{ yQM7QLbTk  
if(bFirst) 8y/YX  
{ toX4kmC  
nFileLength = getFileSize(); l/DV ?27  
if(nFileLength == -1) LV4
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{ rm1R^n  
System.err.println("File Length is not known!"); -Z4J?b  
} t A\N$  
else if(nFileLength == -2) k2j:s}RHY  
{ q !EJs:AS  
System.err.println("File is not access!"); t \Fc <  
} nxA]EFS  
else vXq=f:y4  
{ PF1!aAvVb  
for(int i=0;i<nStartPos.length;i++) i ao
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{ aluXh?  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); WFjNS'WI_  
} R^f~aLl  
for(int i=0;i<nEndPos.length-1;i++) nwOr  
{ STVJu![  
nEndPos = nStartPos[i+1]; %0Ulh6g;Dt  
} B.
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nEndPos[nEndPos.length-1] = nFileLength; 43A6B  
} de[c3!#1d  
} 4ME8NEE  
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//启动子线程 >Y1?`  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 7h&$^  
for(int i=0;i<nStartPos.length;i++) 9c=Y+=<  
{ 8}{';k  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), agM.-MK  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), P@PZm  
nStartPos,nEndPos,i); %+Z0$Q  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); (+>+@G~o  
fileSplitterFetch.start();
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} {5#P1jlT  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), .%U~ r2Y(  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); -EF(J  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", $io-<Z#Q  
nEndPos = " + nFileLength); 'R*xg2!i  
// fileSplitterFetch[nPos.length-1].start(); nAoGG0$5  
\&&kUpI  
{YcVeCq+N  
//等待子线程结束 x98LOO  
//int count = 0; ]^3_eHa^d  
//是否结束while循环 OcQ_PE5\  
boolean breakWhile = false; zb?wlfT  
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while(!bStop) SL hki)
|  
{ y$r9Y!?s  
write_nPos(); l(v$+  
Utility.sleep(500); l#\z3"b  
breakWhile = true; KQJn\#>  
{l0;G)-  
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for(int i=0;i<nStartPos.length;i++) 69dFd!G\  
{ +&4PGv53J  
if(!fileSplitterFetch.bDownOver) E,c~.jYc  
{ f8#WT$Ewy  
breakWhile = false; -E2[PW4$  
break; J.$<Lnt>u  
} Av.(i2  
} o!q9pt  
if(breakWhile) it&c ,+8  
break; Wey-nsk  
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//count++; Zv7@  
//if(count>4) 0k:&7(j  
// siteStop(); ~BERs;4  
} \xDu#/^  
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\S=!la_T@m  
System.err.println("文件下载结束！"); 9(ZzwkD'>  
} htX'
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catch(Exception e){e.printStackTrace ();} CBnD)1b\  
} S82NU2L  
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//获得文件长度 >, 234ab=d  
public long getFileSize() )@]-bPnv  
{ x3PeU_9  
int nFileLength = -1; ii2oWU  
try{ R>/M>*C  
URL url = new URL(siteInfoBean.getSSiteURL()); g"(N_sv?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); pcur6:8W!  
httpConnection.setRequestProperty("User-Agent","NetFox"); c*RZbE9k  
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int responseCode=httpConnection.getResponseCode(); Qc[[@=S%  
if(responseCode>=400) Yo| H`m,  
{ mH;Z_ME"  
processErrorCode(responseCode); iBp 71x65  
return -2; //-2 represent access is error P^rSpS9  
} E0xUEAO  
$rFv(Qc^=  
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String sHeader; .7ahz8v  
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for(int i=1;;i++) gW/H#T,  
{ ,=$yvZs4[]  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); _\@i&3hkx  
//Utility.log(in.readLine()); d2.n^Q"?3  
sHeader=httpConnection.getHeaderFieldKey(i); "{z9 L+  
if(sHeader!=null) `3pe\s  
{ Qbl6~>T  
if(sHeader.equals("Content-Length")) W.MJyem  
{ g+ 2SB5 2D  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); RVI],O  
break; :&?#~NFH  
} o&(%:|  
} ni2H~{]z  
else 82O`<Ci  
break; ~gI%   
} w2+RX-6Ie  
} gvoK  
catch(IOException e){e.printStackTrace ();} *9PS2*n  
catch(Exception e){e.printStackTrace ();} hXz"}X n  
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Utility.log(nFileLength); }{K)5k@  
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return nFileLength; a.%]5%O;t  
} wTIf#y1=9  

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//保存下载信息（文件指针位置） OR?8F5o?p  
private void write_nPos() c}QQ8'_  
{ *\S>dhJ4  
try{ {/QpEd>3+  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ?a}eRA7  
output.writeInt(nStartPos.length); xZ;';}&pj  
for(int i=0;i<nStartPos.length;i++) X\1D[n:  
{ UwE^ij  
// output.writeLong(nPos); B2845~\.  
output.writeLong(fileSplitterFetch.nStartPos); |I OTW=>  
output.writeLong(fileSplitterFetch.nEndPos); Rx`0VQ  
} QO#ZQ~  
output.close(); rBr28_i   
} Y Nq<%i!>  
catch(IOException e){e.printStackTrace ();} &v 5yo}s  
catch(Exception e){e.printStackTrace ();} y:2o-SJn  
} q8kt_&Ij  
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//读取保存的下载信息（文件指针位置） R`1$z8$  
private void read_nPos() zR{TW
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{ gvcT_'  
try{ f^$\+H"W  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); \s~W;m  
int nCount = input.readInt(); 3J(STIxg  
nStartPos = new long[nCount]; kY_UY~E  
nEndPos = new long[nCount]; OVj,qL)  
for(int i=0;i<nStartPos.length;i++) 9 z3Iwl  
{ j<l>+., U  
nStartPos = input.readLong(); E>4 \9  
nEndPos = input.readLong(); )$th${pd#v  
} Uj!L:u2b  
input.close(); 4 Qw;r  
} %+pXzw`B  
catch(IOException e){e.printStackTrace ();} <78>6u/W%  
catch(Exception e){e.printStackTrace ();} IgFz[)  
} 9R ugkGy  
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private void processErrorCode(int nErrorCode) OmoY] 8N}  
{ Q'A->I<;_s  
System.err.println("Error Code : " + nErrorCode); (1Kh9w:^"  
} n"dT^ g  
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//停止文件下载 v WhtClJ3  
public void siteStop() {?m',sG;&  
{ 5@v!wms  
bStop = true; *S=v1 s/  
for(int i=0;i<nStartPos.length;i++) }'@*Olj  
fileSplitterFetch.splitterStop(); DD~8:\QD  
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} nZ%<2  
}
$}\.)^[}  
//负责部分文件的抓取 l|uN-{w  
**FileSplitterFetch.java oa9T3gQ?  
*/ YEZ"BgUnbp  
package NetFox; +:Y6O'h.  
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import java.io.*; 5,mb]v0k  
import java.net.*; (TY^ kySr  
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public class FileSplitterFetch extends Thread { Z>X-ueV  
?VzST }  

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String sURL; //File URL t;4{l`dk  
long nStartPos; //File Snippet Start Position `[:f;2(@  
long nEndPos; //File Snippet End Position ZAiQofQ:2  
int nThreadID; //Thread's ID ]0O pd9  
boolean bDownOver = false; //Downing is over /Wj9Stj5  
boolean bStop = false; //Stop identical G4=v2_]  
FileAccessI fileAccessI = null; //File Access interface O^IpfS\/  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException W}Z|v M$  
{ s+(8KYTs`  
this.sURL = sURL; S&QZ"4jq  
this.nStartPos = nStart; goxgJOiB  
this.nEndPos = nEnd; U|y+k`  
nThreadID = id; )P,jpE8  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 )D#*Q~  
} .IYE"0)wJ  
'7E?|B0],  
^ 5UIbA(  
public void run() Qb SX'mx<  
{ c5t?S@b  
while(nStartPos < nEndPos && !bStop) #=zh&`  
{ R_Z H+@O  
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try{ fo5!d@Nv  
URL url = new URL(sURL); mk0rAN  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); e<IT2tv>u  
httpConnection.setRequestProperty("User-Agent","NetFox"); jt;,7Ek  
String sProperty = "bytes="+nStartPos+"-"; /O&j1g@  
httpConnection.setRequestProperty("RANGE",sProperty); gN(8T_r  
Utility.log(sProperty); \6sp"KqP  
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InputStream input = httpConnection.getInputStream(); /gPn2e;  
//logResponseHead(httpConnection); 3 D+dM0wM  
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byte[] b = new byte[1024]; N]5-#  
int nRead; !rwv~9I  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 0P!6 .-XU  
{ QRa>W/N  
nStartPos += fileAccessI.write(b,0,nRead); g y&B"`  
//if(nThreadID == 1) 7 bpV=  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); WF:i}+g
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} G-T:7  
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Utility.log("Thread " + nThreadID + " is over!"); B'&%EW]  
bDownOver = true; 'GNT'y_  
//nPos = fileAccessI.write (b,0,nRead); [S*bN!t  
} d7l0;yR&+  
catch(Exception e){e.printStackTrace ();} jMZ{>l.v  
} r0hu?3u1?  
} xy[R9_V  
#,$d!l @  
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//打印回应的头信息 p+A#t~K  
public void logResponseHead(HttpURLConnection con) _ea!psA0  
{ uZg Kex;c  
for(int i=1;;i++) =cg0o_q8  
{ 1'Kn:I  
String header=con.getHeaderFieldKey(i); A<AZs~f  
if(header!=null) Cg-khRgLS  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); friNo^v&  
Utility.log(header+" : "+con.getHeaderField(header)); !7Ta Vx}`(  
else ~u-mEdu3C  
break; R`A@F2  
} Uln[UK  
} HP&+ 8  
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public void splitterStop() .3!=]=  
{ >H?8?a D  
bStop = true; rT5dv3^MW!  
} >*dqFZF  
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@ Al\:  
} nIKh<ws4z  
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/* jsc1B  
**FileAccess.java .J'}qkz~  
*//文件访问(定位，写) X >C*(/a  
package NetFox; fY$M**/,  
import java.io.*; oJ>]=^?k  
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1Y\g{A"  
public class FileAccessI implements Serializable{ kC0F@'D  
)"wWV{k  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 -+-@Yq$  
RandomAccessFile oSavedFile; ^6oz3+  
long nPos; CR&v z3\Q  
-dZ7;n5&_  
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public FileAccessI() throws IOException `/8Dmg  
{ %fo+Y+t  
this("",0); U,~\}$<I  
} !z$.Jcr1  
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public FileAccessI(String sName,long nPos) throws IOException -6(C^X%  
{ vc5g4ud  
oSavedFile = new RandomAccessFile(sName,"rw"); :WJ[a#  
this.nPos = nPos; +r"{$'{^  
oSavedFile.seek(nPos); 6/Q'o5>NL:  
} 6ix8P;;}#  
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8:|F'{<<b  
public synchronized int write(byte[] b,int nStart,int nLen) E~3wdOZv1  
{ VW}xY  
int n = -1; .B+R+2uY3  
try{ 5O%Q*\(  
oSavedFile.write(b,nStart,nLen); NDWpV  
n = nLen; v&;q4b4  
} ,dLh`t<\  
catch(IOException e) %!mJnc%  
{ ]ECzb/  
e.printStackTrace (); yL7D;<!S&  
} u`O
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return n; 4 >at#Zc  
} yF0\$%H>$  
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}
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/* yIC8Rl  
**SiteInfoBean.java @7e h/|Y,  
*/ Ep>3%{V  
package NetFox; s{4|eYR  
# y%Q{  
;!v2kVuS]  
public class SiteInfoBean { R'`q0MoN1  
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private String sSiteURL; //Site's URL ^$}9 Enj+Y  
private String sFilePath; //Saved File's Path 6sJN@dFA  
private String sFileName; //Saved File's Name : 9wW*Ix  
private int nSplitter; //Count of Splited Downloading File 01uMbtM  
]d=SkOq  
k7z;^:  
public SiteInfoBean()
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{//nSplitter的缺省值为5  \09eH[  
//default value of nSplitter is 5 _~ZNX+4  
this("","","",5); /7/d u[P6  
} OXd617  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 61L vT"  
{ MF)Xc\}0p  
sSiteURL= sURL; UE3(L ^  
sFilePath = sPath; #  -e  
sFileName = sName; WvQK$}Ax4N  
this.nSplitter = nSpiltter; *$~H
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} Cp` [0v~0  
Vf9PHHH|   
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public String getSSiteURL() #9M6 q  
{ ^x-vOGlR  
return sSiteURL; uu@Y]0-  
} B8;jRY  
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/n;Ll](ri  
public void setSSiteURL(String value) :34]}`-  
{ rH Et]Xa  
sSiteURL = value; FKRO0%M4}Z  
} _:DnF  
,#:*dl  
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public String getSFilePath() qkVGa%^  
{ PLD6Ug  
return sFilePath; G- wQ weJ9  
} +aR.t@D+"Y  
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public void setSFilePath(String value) (7/
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{ `B'*ln'r5  
sFilePath = value; __o`+^FS  
} ]wFKXZeK  
?@8[1$1a  
|W4 \  
public String getSFileName() hqrI%%  
{ C%_^0#8-0  
return sFileName; Ww-%s9N<  
} #2l6'gWE0  
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public void setSFileName(String value) A`_(L|~  
{ M0VC-\W7f  
sFileName = value; xEdCGwgp#  
} `7_=2C  
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public int getNSplitter() 9DcUx-   
{ 3yg22y&l  
return nSplitter; O92a*)  
} <{!^  
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public void setNSplitter(int nCount) 9QE|
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{ lCT N dW+=  
nSplitter = nCount; 2c:H0O 0o  
} rw_T&>!  
} dayp1%d  
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/* $Gt1T[:QUX  
**Utility.java N5 ITb0Tv  
*/
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package NetFox; `~|8eKFq!  
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. +_IpygQ  
public class Utility { GtI]6t  
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public Utility() ER,,K._?B  
{ +W|MAJtg  
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} k<W n  
$mFsf)1]]?  
//线程睡眠 Jg#L8>p1  
public static void sleep(int nSecond) ^ei[#I  
{ nTrfbK@  
try{ <qZ"W6&&  
Thread.sleep(nSecond); uV1H iv-  
} K^z-G=|N  
catch(Exception e) qT]Bl+h2  
{ iw1((&^)"  
e.printStackTrace (); Yc;cf%c1  
} T{=.mW^ x  
} tMGkm8y-A  
s'%KKC  
//日志 47I5Y5  
public static void log(String sMsg) mtDRF'>P:  
{ G"!YV#"~  
System.err.println(sMsg); x" 2
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} ~/?JRL=  
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public static void log(int sMsg) _i [.5  
{ : sIZ+3  
System.err.println(sMsg); G#V5E)Dx  
} w`XwW#!}@$  
} cyUNJw  
( 8+_~_  
1lRqjnzve&  
/* JtYc'%OF  
**TestMethod.java dIv/.x/V  
*/ 6GzmzhX4  
package NetFox; x)<5f|j  
oH~ZqX.3  
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public class TestMethod { QrDrdA  
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public TestMethod() Bu?"b=B*  
{ ///xx/weblogic60b2_win.exe DJgk"'  
try{ Gjuc"JR7  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); AfvTStwr  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); i gzISYC_  
SiteFileFetch fileFetch = new SiteFileFetch(bean); M52kau  
fileFetch.start(); J{72%S  
} YN4P >d  
catch(Exception e){e.printStackTrace ();} 2cfzLW(  
]7kq@o/7  
#|*;~:fz  
} }8WpX2U  
#r 1 $=GY  
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public static void main(String[] args) :6LOb f\01  
{ cqeId&Cg  
new TestMethod(); G-oCA1UdN  
} b><
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} M"F?'zTkJ  
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