http断点续传简单实现（java)

/* ;s\;78`0  
**SiteFileFetch.java !H|82:`t+  
*/ Ryba[Fz4Di  
package NetFox; 3E!<p  
import java.io.*; "R2t&X[9  
import java.net.*; DxKfWb5 R  
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public class SiteFileFetch extends Thread { C7 ]DJn  
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 Ep\  
SiteInfoBean siteInfoBean = null; //文件信息Bean fHe0
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long[] nStartPos; //开始位置 FL#g9U>  
long[] nEndPos; //结束位置 Uy59zB2|=  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 r3H}*Wpf  
long nFileLength; //文件长度 ^/C$L8#  
boolean bFirst = true; //是否第一次取文件 k'ZUBTRq!  
boolean bStop = false; //停止标志 Go\} A:|s  
File tmpFile; //文件下载的临时信息 Z#F,y)YiO  
DataOutputStream output; //输出到文件的输出流 $TA6S+  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） jxnQG A  
public SiteFileFetch(SiteInfoBean bean) throws IOException RHx+HBZ  
{ ~i }+P71  
siteInfoBean = bean; }xf='lE  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ?#*
  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); v=*Bb3dt  
if(tmpFile.exists ()) 5&<d2EG6l'  
{ 3cCK"kr  
bFirst = false; @UpC{M--Wr  
read_nPos(); h-La'}>?  
} B]|6`UfB  
else vNz;#Je  
{ ,zN3? /7  
nStartPos = new long[bean.getNSplitter()]; OJ35En  
nEndPos = new long[bean.getNSplitter()]; d2A wvP  
} I>H;o{X#  
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} P^8^1-b  
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public void run() .lvI8Jf~X  
{ b$v[@"1  
//获得文件长度 ntj`+7mw  
//分割文件 =|E 09  
//实例FileSplitterFetch \m=-8KpU  
//启动FileSplitterFetch线程 A \MfF  
//等待子线程返回 8 )mjy!,  
try{ -7I
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if(bFirst) #ox9&  
{ q}<.x8\  
nFileLength = getFileSize(); 1iNsX\M  
if(nFileLength == -1) oNuPP5d[]  
{ \6SMn6a4  
System.err.println("File Length is not known!"); 6.U"_%  
} X(GmiH /E  
else if(nFileLength == -2) C#Hcv*D  
{ ~5r=FF6
  
System.err.println("File is not access!"); I(OAEIz  
} <H5n>3#pH  
else aFRTNu/r  
{ 9Qzjqq:"Li  
for(int i=0;i<nStartPos.length;i++) y Y>-MoF/t  
{ 1 [Sv  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); v)@,:u)  
}
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for(int i=0;i<nEndPos.length-1;i++) 5c:'>  
{ IjG5X[@  
nEndPos = nStartPos[i+1];
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} _m
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nEndPos[nEndPos.length-1] = nFileLength; b:P\=k]8#  
}  2Vp>"  
} X,RT<GNNb  
(
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//启动子线程 R9tckRG#  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; O9t=lrYV!  
for(int i=0;i<nStartPos.length;i++) N@Xg5huO  
{ 7fTxGm  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 1@A7h$1P  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), cVQatm  
nStartPos,nEndPos,i); xi680'  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ^Sy^+=wK3  
fileSplitterFetch.start(); 29"mE;j  
} EHpu*P~W  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), YXF#c)#  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 44|deE3Z  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 2?GXkPF2;A  
nEndPos = " + nFileLength); bnijM/73  
// fileSplitterFetch[nPos.length-1].start(); wL'oImE  
94Xjz(  
9v~1We;{$  
//等待子线程结束 Bj@x$v#/^  
//int count = 0; Bu7A{DRf  
//是否结束while循环 %6AYCN?Ih  
boolean breakWhile = false; >9-Dd)<  
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*!f|=of  
while(!bStop) 9c#lLKrzG  
{ 6#<Ir @z  
write_nPos(); c}\ 'x5:o  
Utility.sleep(500); U?8i'5)  
breakWhile = true; Dba+z-3Nzy  
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for(int i=0;i<nStartPos.length;i++) xM&EL>m>L  
{ 1'NhjL  
if(!fileSplitterFetch.bDownOver) y:Z$LmPc<  
{ z{%oJ_  
breakWhile = false; y k?SD1hj  
break; j7f5|^/x3  
} Ll,I-BQ9  
} aT&t_^[]   
if(breakWhile) GF&_~48GD  
break; XmP;L(wa  
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F y b[{"  
//count++; xXORIlD  
//if(count>4) ZQ|5W6c  
// siteStop(); <BSSa`N`  
} {`a(Tl8V  
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System.err.println("文件下载结束！"); Fav?,Q,n  
} {Jrf/p9w  
catch(Exception e){e.printStackTrace ();} ^Sw2xT$p{j  
} \H^;'agA  
)&>L !,z  
 q$F)!&  
//获得文件长度 =tq1
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public long getFileSize() ThtMRB)9  
{ 6_WmCtvF  
int nFileLength = -1; mxgqS
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try{ jDkm:X}:  
URL url = new URL(siteInfoBean.getSSiteURL()); -!l^]MU  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); L${m/@9  
httpConnection.setRequestProperty("User-Agent","NetFox"); >zQNHSi  
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Y.7}  
int responseCode=httpConnection.getResponseCode(); MZ WmlJ   
if(responseCode>=400) Y,'%7u  
{ E${J  
processErrorCode(responseCode); n!ZMTcK8  
return -2; //-2 represent access is error
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} ^
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R }1W  
String sHeader; 0*/kGvw`i  
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for(int i=1;;i++) s'TY[  
{ 7#ofNH J  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); "mR*7o$|  
//Utility.log(in.readLine()); 6(Vhtr2(*  
sHeader=httpConnection.getHeaderFieldKey(i); J smB^  
if(sHeader!=null) =5?.'XMk  
{ `%Q&</X  
if(sHeader.equals("Content-Length")) 6AAswz'$P  
{ F_ 81l<  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); U9 bWU
'  
break; /[%w*v*'  
} okstY4f'  
} p-xd k|'[  
else D^|9/qm$  
break; K3L"^a  
} yPoSJzC=[  
} gGEIK0\{  
catch(IOException e){e.printStackTrace ();} eeW`JG-E  
catch(Exception e){e.printStackTrace ();} uaaf9SL?  
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Utility.log(nFileLength); _lX8K:C(  
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return nFileLength; b1xpz1  
} b!^@PIX  
|NJ}F@t/5  
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//保存下载信息（文件指针位置） P#MK  
private void write_nPos() &<Zdyf?[Ou  
{ QD$Gw-U-l=  
try{ FAw1o  
output = new DataOutputStream(new FileOutputStream(tmpFile)); <: :VCA%  
output.writeInt(nStartPos.length); $Asr`Q1i   
for(int i=0;i<nStartPos.length;i++) g5Hr7Km  
{ *C7F2o  
// output.writeLong(nPos); R
5(F)abi  
output.writeLong(fileSplitterFetch.nStartPos); '#q4Bc1  
output.writeLong(fileSplitterFetch.nEndPos); bY)#v?  
} JRY_nX  
output.close(); Zj!Abji=O  
} FshC )[w,  
catch(IOException e){e.printStackTrace ();} 2 x32U MD  
catch(Exception e){e.printStackTrace ();} _~&9*D$ {>  
} DZk1Z
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@PX\{6&  

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//读取保存的下载信息（文件指针位置） Vm,,u
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private void read_nPos() I3(d<+M  
{ !),t"Ae?>  
try{ oL-2qtv  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); RgZOt[!.  
int nCount = input.readInt(); Hhl-E:"H`  
nStartPos = new long[nCount]; /8c&Axuv  
nEndPos = new long[nCount]; -{{[cTI  
for(int i=0;i<nStartPos.length;i++) R/~,i;d>  
{ 0%#\w*X8  
nStartPos = input.readLong(); G\kpUdj}  
nEndPos = input.readLong(); 4MLH+/e  
} TH:W#Ot  
input.close(); 59lj7  
} sJU`u'w  
catch(IOException e){e.printStackTrace ();} vy9dAl  
catch(Exception e){e.printStackTrace ();} ]iVLHVqz  
} /iG7MC\`  
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private void processErrorCode(int nErrorCode) J# EP%  
{ :c=.D;,  
System.err.println("Error Code : " + nErrorCode); cbYK5fj"T  
} -[heV|$;  
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 #^0(  
//停止文件下载 g)1X&>  
public void siteStop() !OAvD#  
{ %u!b& 5]e  
bStop = true; !MV@) (.  
for(int i=0;i<nStartPos.length;i++) W5 ec  
fileSplitterFetch.splitterStop(); #|f~s  
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*x(Jq?5O7X  
} >2lwWXA  
} pj8azFZ  
//负责部分文件的抓取 g7n"  
**FileSplitterFetch.java ?fK1  
*/ E!mmLVa9  
package NetFox; qZ+H5AG2  
!
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import java.io.*; Gu;OVLR|  
import java.net.*; ;;#`#v  
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public class FileSplitterFetch extends Thread { tC)6  
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String sURL; //File URL *y]+dK&-  
long nStartPos; //File Snippet Start Position 5-vo0:hk  
long nEndPos; //File Snippet End Position (kw5>c7  
int nThreadID; //Thread's ID #g9ZX16}  
boolean bDownOver = false; //Downing is over |He=LQ}0  
boolean bStop = false; //Stop identical @Rq}nq=k  
FileAccessI fileAccessI = null; //File Access interface ]?K. S6  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Jp~zX lu  
{ X.V[0$.;  
this.sURL = sURL; L:R<e#kgS  
this.nStartPos = nStart; .%}+R|g  
this.nEndPos = nEnd; ]Kh2;>= Xj  
nThreadID = id; 8Vn4.R[vE  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 /,tAoa~FA  
} (S/F)?  
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public void run() A)NkT`<)  
{ 2`bdrRD0  
while(nStartPos < nEndPos && !bStop) (K<9hL+X  
{ l"pN90B4  
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try{ ;['a  
URL url = new URL(sURL); MesRa(  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); o\=n4;S  
httpConnection.setRequestProperty("User-Agent","NetFox"); HdX2
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String sProperty = "bytes="+nStartPos+"-"; bGmx7qt#  
httpConnection.setRequestProperty("RANGE",sProperty); zm#nV Y`  
Utility.log(sProperty);

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InputStream input = httpConnection.getInputStream(); A9:NKY{z  
//logResponseHead(httpConnection); uGVy6,  
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byte[] b = new byte[1024]; I;MD>%[W,  
int nRead; h<l1U'Bn7  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) %,q.),F  
{ anN#5jt  
nStartPos += fileAccessI.write(b,0,nRead); <48<86TP  
//if(nThreadID == 1) \}"m'(\c  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 5M_Wj*a}7  
} 6lFfS!ZFA  
rf K8q'@  
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Utility.log("Thread " + nThreadID + " is over!"); nsuX*C7  
bDownOver = true; n1v5Q2xw  
//nPos = fileAccessI.write (b,0,nRead); g@
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} ,xsH|xW  
catch(Exception e){e.printStackTrace ();} nE W31 8  
} sRhKlUJG  
} *_-'/i  
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//打印回应的头信息 [iS$JG-  
public void logResponseHead(HttpURLConnection con) iCQ>@P]nE  
{ 8|g<X1H{M  
for(int i=1;;i++) 8y2+&#$  
{ dK9Zg,DZL  
String header=con.getHeaderFieldKey(i); kLP0{A  
if(header!=null) UQ
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); Xrqx\X  
Utility.log(header+" : "+con.getHeaderField(header)); zu\`1W^  
else 6,b"  
break; j<yiNHC  
} P 7D!6q  
} )%Iv[TB[  
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public void splitterStop() Dm0a.J v  
{ 1NLg _UBOK  
bStop = true; `ldz`yu6++  
} Me3dpF  
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} /n,a?Ft^N)  

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/* bn9;7`>.  
**FileAccess.java zw@'vncc  
*//文件访问(定位，写) o^p  
package NetFox; M[]A2'fS  
import java.io.*; L:&k(YOBA  
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public class FileAccessI implements Serializable{ (R}ii}
&  
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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 Vm1-C<V9  
RandomAccessFile oSavedFile; ps|)cW3`  
long nPos; VR?^HA9  
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public FileAccessI() throws IOException R W/z1  
{ va)%et0!  
this("",0); L@Nu/(pB=  
} >]D4Q<TY  
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public FileAccessI(String sName,long nPos) throws IOException  a*dQ _  
{ NZLAk~R;0  
oSavedFile = new RandomAccessFile(sName,"rw"); *?p|F&J  
this.nPos = nPos; &"Ux6mF-"  
oSavedFile.seek(nPos); {Tp2H_EG  
} Rd*[%)  
W&Y"K)`  
{tP%epQ  
public synchronized int write(byte[] b,int nStart,int nLen) B2=\2<  
{ o2H1N~e#c  
int n = -1; G@ \Pi#1  
try{ 'I}:!Z  
oSavedFile.write(b,nStart,nLen); J4$! 68  
n = nLen; .^(/n9|o-  
} +C]&2zc.  
catch(IOException e) j{++6<tr  
{ ?X$,fQ#F|  
e.printStackTrace (); y2L#:[8  
} }ut]\]b  
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return n; D=f7NVc>Q  
} : esg(  
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} bzpFbfb  
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/* p/6zEZ*  
**SiteInfoBean.java p zw8T  
*/ c
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package NetFox; k`KGB  
<!d"E@%v@  
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public class SiteInfoBean { j V3)2C}  
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private String sSiteURL; //Site's URL kh$_!BT  
private String sFilePath; //Saved File's Path g\fhp{gWB  
private String sFileName; //Saved File's Name ;!>Wz9  
private int nSplitter; //Count of Splited Downloading File Xf'=+f2p  
a dfR
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public SiteInfoBean() sUkm|K`#  
{//nSplitter的缺省值为5 6rti '  
//default value of nSplitter is 5 )K
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this("","","",5); %V!iQzL1  
} d[gl]tj9  
3L>IX8_   
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) NR%Y+8^M  
{ ,Z9>h[JF  
sSiteURL= sURL; iOw3MfO  
sFilePath = sPath; gbBy/_b  
sFileName = sName; W[bmzvJ_X  
this.nSplitter = nSpiltter; !\ND(  
V)M1YZV{  
5X.ebd;PT  
} +]xFoH  
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public String getSSiteURL() 5i6
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{ >B -q@D  
return sSiteURL; AIl4]F5I  
} \5 pu|2u  
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public void setSSiteURL(String value) qZk'tRv  
{ _mE^rT  
sSiteURL = value; P@}Pk  
} 0*%&>  
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public String getSFilePath() n^(A=G  
{ 9v)%dO.  
return sFilePath; bKVj[r8D~  
} %y[1H5)3<  
A?!I/|E^;  
WKM)*@#,  
public void setSFilePath(String value)
"@3@/I  
{ &-yGVx  
sFilePath = value; \YJy#2K  
} 'm=*u SJK  
/TQ}} YVw  
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public String getSFileName() 5ABhj*7  
{ fIC9WbiH-  
return sFileName; P'Q$d+F,  
} m*0,s  
L6P1L)
 
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public void setSFileName(String value) 8y';\(;  
{ v`[Eb27W.  
sFileName = value; 's x\P[a  
} qOV[TP,  
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public int getNSplitter()  4-Z()F  
{ HjNxqaljt  
return nSplitter; Btt]R
 
} Yepe=s+9  
?kw&=T!  
al9.}  
public void setNSplitter(int nCount) \(UKdv  
{ L#[]I,  
nSplitter = nCount; Z{NC
9  
} VObrlOkp  
} j5$BK[p.  
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/* 9Mm!%Hu  
**Utility.java yR~-k?7b  
*/ iX{G]< n  
package NetFox; 1t[j"CG(o  
pY8q=Kl  
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public class Utility { `em9T oJV  
FE7)E.U  
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public Utility() hv$yV%.`  
{ m#H3:-h,  
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} AF,BwLN  
^cvl:HOog  
//线程睡眠 Br>Fpe$q4  
public static void sleep(int nSecond) u~zs* qp  
{ lb'Cl3H  
try{ F9q8SA#"  
Thread.sleep(nSecond); 7\ SUr9[  
} BZK`O/  
catch(Exception e) 4pz|1Hw7  
{ -_VG;$,jE  
e.printStackTrace (); }f>H\iJe  
} + bhym+  
} vdoZ&Tu  
)wXuwdc[  
//日志 CR<`ZNuWz  
public static void log(String sMsg) v{x{=
M]  
{ -]G(ms;}/Y  
System.err.println(sMsg); HHk)ZfWRo  
} Y]aW)u  

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}*U[>Z-eO  
public static void log(int sMsg) 2Nc>6  
{ -5G)?J/*  
System.err.println(sMsg); :B*}^g  
} uUR~&8ERX  
} M<?Q4a'Q  
%%%fL;-y  
uv{P,]lK  
/* Jc4L5*Xn/  
**TestMethod.java cX!Pz.C  
*/ or ;f&![w  
package NetFox; l?E a#  
|w}w.%  
a5'#j35  
public class TestMethod { jZfx Jm  
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iGXI6`F"  
public TestMethod() `xS{0P{uj  
{ ///xx/weblogic60b2_win.exe t-%Q`V=[  
try{ $9 p!Y}  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ^S)TO
}e  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); [(LV
  
SiteFileFetch fileFetch = new SiteFileFetch(bean); p 5u_1U0  
fileFetch.start(); )QKf7 [:  
} {C*\O)Gep  
catch(Exception e){e.printStackTrace ();} u9-nt}hGYM  
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}`_@'4:t  
} -PB[-CX  
v"u^M-_  
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public static void main(String[] args) ~o3Hdd_#}N  
{ C}g9'jY  
new TestMethod(); |V[9}E:
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} [K~]&  
} 3-s}6<0v1  
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