http断点续传简单实现（java)

/* WVa#nU^  
**SiteFileFetch.java KbP( ;  
*/ qY^@^)b[  
package NetFox; FWu[{X;  
import java.io.*; T|fmO<e*n  
import java.net.*; zJ9[),;7B  
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public class SiteFileFetch extends Thread { d=J$H<  
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SiteInfoBean siteInfoBean = null; //文件信息Bean dd{pF\a  
long[] nStartPos; //开始位置 BXx0Z %e.3  
long[] nEndPos; //结束位置 Q3OGU}F  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 w,/&oe5M+  
long nFileLength; //文件长度 4x;vn8yh  
boolean bFirst = true; //是否第一次取文件 6~#$bp^-  
boolean bStop = false; //停止标志 L UitY  
File tmpFile; //文件下载的临时信息 9PZY](/  
DataOutputStream output; //输出到文件的输出流 M!Hn`_E  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） G,]%dZHe  
public SiteFileFetch(SiteInfoBean bean) throws IOException WBIJ9e2~  
{ p#fd+  
siteInfoBean = bean; Kx[u9MD  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 7=e!k-G  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); HXY,e$c#y  
if(tmpFile.exists ()) [->uDbtzL  
{ }g@5%DI
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bFirst = false; yv&VK ht  
read_nPos(); Uw:gJ
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} SmR"gu
 
else FdZG%N>Z  
{ 9f+S-!  
nStartPos = new long[bean.getNSplitter()]; bm Hl\?  
nEndPos = new long[bean.getNSplitter()]; ;WG6|QgV?-  
} H/Wo~$  
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} =%UX"K`  
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public void run() K;fRDE){  
{ V< ]l=JOd  
//获得文件长度 #^Io9dAh  
//分割文件 IW1+^F9NEw  
//实例FileSplitterFetch rElbzL"&<  
//启动FileSplitterFetch线程 Q8^fgI|  
//等待子线程返回 TGe)%jZ  
try{ e,0y+~  
if(bFirst) JC[G5$E  
{ x9&{@ ?o  
nFileLength = getFileSize(); _r6aLm2n  
if(nFileLength == -1) kq m$a  
{ %%=PpKYtSD  
System.err.println("File Length is not known!"); uk\-"dS  
} R"0fZENTG  
else if(nFileLength == -2) mV58&SZT  
{ acXB vs  
System.err.println("File is not access!"); No1*~EQ  
} MK*WStY  
else |D ?}6z  
{ lN<,<'&^.  
for(int i=0;i<nStartPos.length;i++) VXpbmg!{S  
{ p` '8M  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); n qR8uL>  
} ND3(oes+;K  
for(int i=0;i<nEndPos.length-1;i++) 8,(FJ7OCT,  
{ fCq  
nEndPos = nStartPos[i+1]; in/ITy-  
} 0VOj,)K=  
nEndPos[nEndPos.length-1] = nFileLength; GOx+%`.R\  
} gp/_# QVWC  
} 8LH"j(H  
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//启动子线程 9w%|Nk>=>  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; X9d~r_2&m<  
for(int i=0;i<nStartPos.length;i++) ^JKV~+ Q  
{ f"8!uE*;  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ^3qo%=i  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), &$!'Cw`,  
nStartPos,nEndPos,i); J#pl7q)^w  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); "gR W91 T  
fileSplitterFetch.start(); ~BSE8M+r  
} w=r3QKm#K  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), )kq3q5*_  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); )7H s  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", U!0 Qf7D  
nEndPos = " + nFileLength); g7-=kmr|V  
// fileSplitterFetch[nPos.length-1].start(); %Q0J$eC  
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//等待子线程结束 ##6_kcL:6G  
//int count = 0; R-8/BTls7  
//是否结束while循环 \U1fUrw$*  
boolean breakWhile = false; s /?&H-  
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@  
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while(!bStop) 6"d^4L?  
{ H|uvcvf
 
write_nPos(); ~sI$xX!  
Utility.sleep(500); ]lKQwpX3  
breakWhile = true; 6__#n`  
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for(int i=0;i<nStartPos.length;i++) t:|+U:! >  
{ o9l =Q  
if(!fileSplitterFetch.bDownOver) b`4R`mo  
{ X CjYm  
breakWhile = false; 2(, `9  
break; E%f;Z7G  
} | Q Y_ci  
} 3Mnm2*\  
if(breakWhile) \Lz2"JI  
break; Q}?yj,DD  
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//count++; ed,w-;(n~  
//if(count>4) "iCR68e  
// siteStop(); 0]F'k8yLN  
} 09f:%!^u  
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System.err.println("文件下载结束！"); WhO;4-q)2  
} yAu-BObD  
catch(Exception e){e.printStackTrace ();} /ry#q%?  
}
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//获得文件长度 $GzTDq Y9@  
public long getFileSize() e$k]z HlQ  
{ >bf29tr  
int nFileLength = -1; c !$ 8>  
try{ -X
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URL url = new URL(siteInfoBean.getSSiteURL()); T;eA<,H  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Su<Ggv"  
httpConnection.setRequestProperty("User-Agent","NetFox"); +TzF*N
p  
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int responseCode=httpConnection.getResponseCode(); 0hKF)b  
if(responseCode>=400) p< fKj  
{ _)J;PbK~  
processErrorCode(responseCode); d9zI A6y  
return -2; //-2 represent access is error >uok\sX  
} O7#ECUH  
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String sHeader; 00') Ol&  
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for(int i=1;;i++) C+r<DC3  
{ &^ sgR$m  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); >K{/Jx&  
//Utility.log(in.readLine()); +Xi#y}%  
sHeader=httpConnection.getHeaderFieldKey(i); /t-m/&>  
if(sHeader!=null) +$MNG  
{ `U4R% qhWA  
if(sHeader.equals("Content-Length")) Bi"7FF(z  
{ zN(fZT}K5  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); g)*[W>M  
break; f-9&n4=H  
} dbTPY`  
} ubV|s|J  
else ,x| 4nk_  
break; m6BIQ(l  
} pV:c`1\`  
} d}K"dr:W5  
catch(IOException e){e.printStackTrace ();} 7qB}Hvh  
catch(Exception e){e.printStackTrace ();} }5H3DavW  
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Utility.log(nFileLength); Le9^,B@Pb  
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return nFileLength; r5qp[Ss3F  
} zcGeXX}V?  
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//保存下载信息（文件指针位置） .*u, !1u  
private void write_nPos() nXDU8|"  
{ AZ)H/#b
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try{
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output = new DataOutputStream(new FileOutputStream(tmpFile)); m~%\f8w-x  
output.writeInt(nStartPos.length); p=U*4[9k  
for(int i=0;i<nStartPos.length;i++) ;z;O}<8s  
{ i,R<`K0  
// output.writeLong(nPos); Kk2PWJ7  
output.writeLong(fileSplitterFetch.nStartPos); \ajy%$;$}  
output.writeLong(fileSplitterFetch.nEndPos); L]L-000D(  
} -LL49P6  
output.close(); Cf`s:A5<J  
} ]/!#
:  
catch(IOException e){e.printStackTrace ();} :E/]Bjq$;  
catch(Exception e){e.printStackTrace ();} ^[}^+  
} 3^l@!Qw  
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//读取保存的下载信息（文件指针位置） Z 6^AO=3  
private void read_nPos() =[!&&,c=  
{ !/G2vF"  
try{ TI-8I)  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); 
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int nCount = input.readInt(); 1hj']#vBu  
nStartPos = new long[nCount];  4I7}  
nEndPos = new long[nCount]; >HatbbA  
for(int i=0;i<nStartPos.length;i++) F}P+3IaE  
{ [*U6L<JI  
nStartPos = input.readLong(); n7`R+4/s  
nEndPos = input.readLong(); !es?GJq`  
} * 8n0  
input.close(); 53d8AJ_@X  
} {-IH?!&v  
catch(IOException e){e.printStackTrace ();} 5BCHWX*y  
catch(Exception e){e.printStackTrace ();} 12;"=9e!  
} ^>02,X mk  
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private void processErrorCode(int nErrorCode) GU'/-6-T  
{ LutP&Ebt8  
System.err.println("Error Code : " + nErrorCode); "ewSh<t
 
} Fyy)665x/  
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//停止文件下载 O,"4HZG  
public void siteStop() ( /{Wu:e  
{ hER]%)#r  
bStop = true; p9k'.H^:_  
for(int i=0;i<nStartPos.length;i++) I/D(gY06<  
fileSplitterFetch.splitterStop(); _|`
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} s86Ij>VLf  
} ?4Z`^uy  
//负责部分文件的抓取 uc]]zI6  
**FileSplitterFetch.java !L4Vz7C  
*/ n}(/>?/  
package NetFox; $s-/![ 6  
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import java.io.*; f0+)%gO{  
import java.net.*; &GF@9BXI3  
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public class FileSplitterFetch extends Thread { oUrNz#U  
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String sURL; //File URL {2Jo|z  
long nStartPos; //File Snippet Start Position 555j@  
long nEndPos; //File Snippet End Position NO5\|.,Z  
int nThreadID; //Thread's ID ?5(Cwy ?  
boolean bDownOver = false; //Downing is over z+IBy+  
boolean bStop = false; //Stop identical {%W'Zx  
FileAccessI fileAccessI = null; //File Access interface YCr:nYm<f  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException rw(EI,G  
{ aMdWT4  
this.sURL = sURL; +VxzWNs*JP  
this.nStartPos = nStart; 34S0W]V  
this.nEndPos = nEnd; &Z!O   
nThreadID = id;  [@YeQ{  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Q!7il<S  
} A)"?GK{*  
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public void run() #[$^M:X.  
{ 5Fa.X|R~  
while(nStartPos < nEndPos && !bStop) *9J>3  
{ o9I=zAGjy  
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try{ BZHba8c(  
URL url = new URL(sURL); ,*_=w^;Rr  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 6 axe  
httpConnection.setRequestProperty("User-Agent","NetFox"); yOHVL~F  
String sProperty = "bytes="+nStartPos+"-"; \\w<.\Yh  
httpConnection.setRequestProperty("RANGE",sProperty); X@;; h  
Utility.log(sProperty); oPP`)b$x  
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InputStream input = httpConnection.getInputStream(); M&auA  
//logResponseHead(httpConnection); Z!HQ|')N5  

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byte[] b = new byte[1024]; "m2g"xa\7  
int nRead; ?r P'PUB  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) _{$eOwB  
{ r"HQ>Wn  
nStartPos += fileAccessI.write(b,0,nRead); "u29| OY  
//if(nThreadID == 1) pjG/`  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 'Lm\ r+$F  
} W}^X;f  
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Utility.log("Thread " + nThreadID + " is over!"); g~ub
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bDownOver = true; ~)ut"4  
//nPos = fileAccessI.write (b,0,nRead); '0ks`a4q  
} #Y|t,x;  
catch(Exception e){e.printStackTrace ();} K"fr4xHq  
} +UvT;"  
} /:S&1'=  
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//打印回应的头信息 BOc2<M/\  
public void logResponseHead(HttpURLConnection con) e'nhP  
{ dV/ ^@[  
for(int i=1;;i++) C[X2]zr  
{ M%{,?
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String header=con.getHeaderFieldKey(i); U+[ p>iP  
if(header!=null) Go;fQ yG  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); GN0s`'#"3%  
Utility.log(header+" : "+con.getHeaderField(header)); 3.0t5F<B  
else pUV4oyGV   
break; fX:=_c   
} Pi/V3D)B  
} kH4xP3. i  
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public void splitterStop() @O]v.<8  
{ "+dByaY  
bStop = true; -K%hug  
} 1iLrKA  
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} J?y0RX  
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/* 0(o{V:l%Z|  
**FileAccess.java Z@1vJH6IbA  
*//文件访问(定位，写) ja2BK\"1:  
package NetFox; ",,W1]"%  
import java.io.*; 6B8gMO  
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public class FileAccessI implements Serializable{ qT153dNA&  
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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 k`(Cwp{Oc  
RandomAccessFile oSavedFile; Kry^47"  
long nPos; L9}%tEP  
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public FileAccessI() throws IOException H*KZZTKd  
{ W ])Lc3X  
this("",0); JmBe1"hs  
} ^.gBHZ  
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public FileAccessI(String sName,long nPos) throws IOException `fM]3]x>  
{ E7`Q=4@e  
oSavedFile = new RandomAccessFile(sName,"rw"); KAI/*G\z  
this.nPos = nPos;
@h E7F}  
oSavedFile.seek(nPos); Ge_Gx*R  
} e8,!x9%J  
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public synchronized int write(byte[] b,int nStart,int nLen) JqTR4[`Z\  
{ Dkyw3*LCn%  
int n = -1; ~TfN*0  
try{  8?4/  
oSavedFile.write(b,nStart,nLen); -Cc2|~n  
n = nLen;
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} bAwFC2jO[  
catch(IOException e) }trQ<*D  
{  k:i}xKu  
e.printStackTrace (); E``\Jre@  
} 0J z|BE3Y  
GOU>j"5}2  
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return n; vxZ :l  
} 
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} /r?EY&9G  
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/* @.8FVF  
**SiteInfoBean.java `gE_u  
*/ kP[LS1}*  
package NetFox; _xu_W;nh  
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public class SiteInfoBean { dw YGhhm  

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private String sSiteURL; //Site's URL ;=lQMKx0  
private String sFilePath; //Saved File's Path @!KG;d:l  
private String sFileName; //Saved File's Name <tI_
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private int nSplitter; //Count of Splited Downloading File 2q}lSa7r  
QdK PzjA  
)\m%&EXG{  
public SiteInfoBean() La8D%N  
{//nSplitter的缺省值为5 $*qQ/hi  
//default value of nSplitter is 5 <!a%GI  
this("","","",5); _%@ri]u{ov  
} |y DaFv  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) P;V5f8r?  
{ l|L ]==M  
sSiteURL= sURL; C+vk9:"  
sFilePath = sPath; Xmv^O  
sFileName = sName; @$R^-_m  
this.nSplitter = nSpiltter; \rSofn#c  
p"|0PlW  
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} 6QX2&[qWS  
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public String getSSiteURL() {1L{  
{ u,`cmyZ  
return sSiteURL; q vGP$g  
} =v6qr~  
JLh{>_Rr  

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public void setSSiteURL(String value) V*%Lc9<d  
{ <G /a-
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sSiteURL = value; cIQe^C  
} 3Bbd2[<W  
4;)aGN{e  
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public String getSFilePath() NxrfRhaU3  
{ 3Q2z+`x'  
return sFilePath; TQ69O +  
} .9$ 7 +  
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public void setSFilePath(String value) ueLdjASJ  
{ c^8csQ fG  
sFilePath = value; {O5(O oDa  
} c;doxNd6  
R=<uf:ca  
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public String getSFileName() SGUZ'}  
{ '"]QAj?N  
return sFileName; -m_H]<lWZ  
} 8^5@J)R8  
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dw3H9(-lp  
public void setSFileName(String value) zc&i 4K  
{ u$ a7  
sFileName = value; ';KZ.D  
} !Nx'4N`&l  
I`S?2i2H  
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public int getNSplitter() R:, |xz  
{ =S<E[D{V`  
return nSplitter; )|`w;F>  
} n1)~/ >  
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!w{(}n2Wq  
public void setNSplitter(int nCount) vxl!`$Pi  
{ C~c|};&%  
nSplitter = nCount; O=\`q6l  
} VL/KC-6  
} Xr]<v%,C  
p{w:^l(  
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/* "4WwiI9  
**Utility.java ANlzF&K  
*/ !d{Ijs'T  
package NetFox; VPUm4%?p$  
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public class Utility { N&]_U%#Q  
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public Utility() DNGj81'c  
{ x?n13C  
KpfQ=~'  
"q3W&@  
} @9\L|O'~?  
#s0Wx47~  
//线程睡眠 cOb,Md  
public static void sleep(int nSecond) 6'i
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{ Ae^Idz  
try{ U%l<48@8  
Thread.sleep(nSecond); %Z{ 7*jtE  
} v|GDPq  
catch(Exception e) mecm,xwm  
{ 7cV GB  
e.printStackTrace (); 6 u}c543  
} xL\R-H^c]  
} 1Gh3o}z  
2F|0
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//日志 "cx#6Bo|  
public static void log(String sMsg) epQdj=h  
{ VTs ,Ln!,U  
System.err.println(sMsg); {O (@}  
} 9q>rUoK^  
:{M1]0NH  
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public static void log(int sMsg) 2PG= T/  
{ ]_y0wLq  
System.err.println(sMsg); /..a9x{At>  
} ibv.M=  
} H*vd  
Cbjx{  
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/* WQ)vu&;  
**TestMethod.java &v.Nj9{zi  
*/ Bb@m-+f  
package NetFox; uYAMW{AT  
,n/^;. _1  
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public class TestMethod { kqt.?iJw  
YZQF*fj  
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public TestMethod() X'.*I])  
{ ///xx/weblogic60b2_win.exe *k<{nj@y  
try{ +WB';D  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); (sL!nRw  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); #*x8)6Ct  
SiteFileFetch fileFetch = new SiteFileFetch(bean); jZP~!q  
fileFetch.start(); DY?;Z98P?  
} Q4QF_um  
catch(Exception e){e.printStackTrace ();} YLFM3IaP  
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} :JfT&YYi"  
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public static void main(String[] args) Oj0,Urs7  
{ m1,yf*U  
new TestMethod(); T;Zv^:]0  
} )&wJ_(z  
} *?s"~XVs  
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