http断点续传简单实现（java)

/* 7wivu*0  
**SiteFileFetch.java o_.f7|U!  
*/ ; S
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package NetFox; PJ-EQ6W  
import java.io.*; cN#c25S>  
import java.net.*; "~1{|lj|)  
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public class SiteFileFetch extends Thread { Yq6e=?-  
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SiteInfoBean siteInfoBean = null; //文件信息Bean fEdp^oVg  
long[] nStartPos; //开始位置 lUL6L4m  
long[] nEndPos; //结束位置 eucacXiZ  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 kB2]Z}  
long nFileLength; //文件长度 qhdY<[6
 
boolean bFirst = true; //是否第一次取文件 v%ldg833l  
boolean bStop = false; //停止标志 p;y\%i_  
File tmpFile; //文件下载的临时信息 #~_ZG% u  
DataOutputStream output; //输出到文件的输出流 gMGX)Y ,=/  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） UJ/=RBfkJ  
public SiteFileFetch(SiteInfoBean bean) throws IOException wWVLwp4-  
{ $ $=N'Q  
siteInfoBean = bean; YB`;<+sY  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); '`)r<lYN,  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 
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if(tmpFile.exists ()) $QNII+o  
{ (~6D`g`B  
bFirst = false; W~!uSrY  
read_nPos(); lYF~CNvE  
} m@Q%)sc)  
else c%jW'  
{ ezq<
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nStartPos = new long[bean.getNSplitter()]; /8Sr(  
nEndPos = new long[bean.getNSplitter()]; G1=/G  
} ul-A'  

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} + a
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public void run() tL#]G?0d  
{ pV^(8!+  
//获得文件长度 &OMe'P  
//分割文件 e5GJ:2sH  
//实例FileSplitterFetch <o aVI?  
//启动FileSplitterFetch线程 Vx~N`|yY  
//等待子线程返回 #:)yh]MP  
try{ pX/42W  
if(bFirst) 
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{ CJ~gE"  
nFileLength = getFileSize(); URo#0fV4C  
if(nFileLength == -1) Xi:y35q  
{ -4=\uvYh  
System.err.println("File Length is not known!"); Dcep^8'  
} z6Xn9  
else if(nFileLength == -2) ta*6xpz-\Q  
{ M>yt\qbkA  
System.err.println("File is not access!"); <hv {,1p-r  
} ru5T0w";V  
else (2l?~CaK  
{ 7`G FtX}  
for(int i=0;i<nStartPos.length;i++) `{B<|W$=  
{ sN8)p%'Lg  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); >T)#KQ1t  
} o
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for(int i=0;i<nEndPos.length-1;i++) VGVb3@  
{ ImG7E w  
nEndPos = nStartPos[i+1]; jgyXb5GY  
} skeXsls  
nEndPos[nEndPos.length-1] = nFileLength; H!
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} rHMr8,J;  
} c+bOp 05o-  
6a%dq"5 +  
FRR`<do5$,  
//启动子线程 +vSp+X1E  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; \G~<O071  
for(int i=0;i<nStartPos.length;i++) fJdTVs@  
{ ^h5h kIx0  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 'ZXd|WI  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), )_H>d<di
 
nStartPos,nEndPos,i); -Z<V?SFOK  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); q qFN4AO  
fileSplitterFetch.start(); Q$B\)9`v[  
} ? JliKFD%  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), T:G8xI1 P  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); 3yXSv1  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", iuGly~  
nEndPos = " + nFileLength); 8ED}!;ZU  
// fileSplitterFetch[nPos.length-1].start(); Es^=&2''  
Q\qI+F2?  
{*NM~yQ  
//等待子线程结束 Z<4Du  
//int count = 0; +W}dO#  
//是否结束while循环 dSkx*#FEE  
boolean breakWhile = false; 9N*!C{VW  
X[;-SXq  
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while(!bStop) +)06*"I  
{ ./r#\X)dc  
write_nPos(); ~1g)4g~  
Utility.sleep(500); /f Ui2[y  
breakWhile = true; SbX#$; ks~  
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for(int i=0;i<nStartPos.length;i++) :vWixgLg  
{ 6qYK"^+xu  
if(!fileSplitterFetch.bDownOver) QZ?%xN(4  
{ EA=EcUf'  
breakWhile = false; /@xL {  
break; .{t]Mc  
} '1NZSiv+C?  
} ~]S%b3>  
if(breakWhile) dZ;rn!dg>  
break; s^lm 81;  
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//count++; CeD(!1VG  
//if(count>4) v;$cx*?  
// siteStop(); ;>jLRx<KC  
} F*{1, gb  
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System.err.println("文件下载结束！"); L`@)*x)~R  
} 71wtO  
catch(Exception e){e.printStackTrace ();} Zf*DC~E_  
} u7G9 eN  
f)9{D[InM^  
JM>4m)h#  
//获得文件长度 y-R:-K XH=  
public long getFileSize() U!D\Vd  
{ !`qw"i  
int nFileLength = -1; >@
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try{ "IMq +  
URL url = new URL(siteInfoBean.getSSiteURL()); I5H#]U  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ,Z aPY  
httpConnection.setRequestProperty("User-Agent","NetFox"); ki<4G  
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int responseCode=httpConnection.getResponseCode(); <52)  
if(responseCode>=400) -l i71.M  
{ A"pV 7 y  
processErrorCode(responseCode); LPK[^  
return -2; //-2 represent access is error NU |vtD  
} [D= KI&@&O  
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String sHeader; i8 fUzg)  
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for(int i=1;;i++) snti*e4"V  
{ Rf0F`D k  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); }&qr"z4  
//Utility.log(in.readLine());
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sHeader=httpConnection.getHeaderFieldKey(i); nA 5-P}  
if(sHeader!=null) LAcK%  
{ Y>a2w zr  
if(sHeader.equals("Content-Length")) x^u[L$  
{ ,?(IRiq%  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Wt $q{g{C  
break; %o4HCzId<  
} \L4+Dv<z  
} /aX#j`PrH  
else @$] CC1Y  
break; r}~|,O3bc'  
} d_w^u|(K  
} `@#,5S$ E  
catch(IOException e){e.printStackTrace ();} q+)csgN  
catch(Exception e){e.printStackTrace ();} UukHz}(E  
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Utility.log(nFileLength); C$#X6Q!,  
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return nFileLength; O}cg1Q8p  
} y jQpdO  
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//保存下载信息（文件指针位置） n=tg{_9f%  
private void write_nPos() <'l;j"&lp  
{ (14J~MDB  
try{ -Ka0B={Z  
output = new DataOutputStream(new FileOutputStream(tmpFile)); dd|/I1  
output.writeInt(nStartPos.length); T*irCe  
for(int i=0;i<nStartPos.length;i++) &bw ``e&c  
{ }Pf7YuUZZ  
// output.writeLong(nPos); #M5[TN!  
output.writeLong(fileSplitterFetch.nStartPos); Tt*n.HA  
output.writeLong(fileSplitterFetch.nEndPos); (
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} :"e,& %  
output.close(); 3|g]2|~w@h  
} mbCY\vEl  
catch(IOException e){e.printStackTrace ();} +'f38D*  
catch(Exception e){e.printStackTrace ();} '@ C\,E  
} pGhA  
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//读取保存的下载信息（文件指针位置） ^"hsbk&Yu  
private void read_nPos() ^d[s*,i?  
{ p@x1B &Z  
try{ r-SQk>Y}  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); q9mYhT/Im  
int nCount = input.readInt(); }iF"&b0n"  
nStartPos = new long[nCount]; jhmWwT/O8^  
nEndPos = new long[nCount]; *[?DnF+  
for(int i=0;i<nStartPos.length;i++) n^m6m%J)  
{ M.QXwIT  
nStartPos = input.readLong(); _O*"_^6  
nEndPos = input.readLong(); @vc
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} Tl ?]K  
input.close(); 2~BId&]  
} 3cztMi  
catch(IOException e){e.printStackTrace ();} ?]bZ
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catch(Exception e){e.printStackTrace ();} I%q&4L7pj  
} 7 *#pv}Y  
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private void processErrorCode(int nErrorCode) MX.=k>  
{ !Qd4Y=  
System.err.println("Error Code : " + nErrorCode); E*_lT`Hzf  
} V$7SVq  
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)^o7%KX  
//停止文件下载 ctg[C$<q|  
public void siteStop() pdQ6/vh  
{ z9#iU>@  
bStop = true; 8`/nk`;  
for(int i=0;i<nStartPos.length;i++) (!^(74  
fileSplitterFetch.splitterStop(); o]vU(j_Ju  
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} 8>sToNRNe  
} ^KsiTVY  
//负责部分文件的抓取 1Lf:TQB  
**FileSplitterFetch.java Y:0SrB!\  
*/ Jm+hDZrW  
package NetFox; j+c<0,Kj  
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import java.io.*; u}7#3JfLn  
import java.net.*; b%fn1Ag9  
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public class FileSplitterFetch extends Thread { #.(6.Li  
yBPaGZ{f  
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String sURL; //File URL P"<HxT?  
long nStartPos; //File Snippet Start Position bw8~p%l?  
long nEndPos; //File Snippet End Position (Hcd{]M~  
int nThreadID; //Thread's ID &a>fZ^Y=k  
boolean bDownOver = false; //Downing is over T{iv4`'  
boolean bStop = false; //Stop identical EEaf/D/jt  
FileAccessI fileAccessI = null; //File Access interface 2B# ]z  
f@R j;R~Jp  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException XZv(B^  
{ ~7W?W<  
this.sURL = sURL; IQS:tL/  
this.nStartPos = nStart; T>&d/$;]  
this.nEndPos = nEnd; wnL\.%Y^  
nThreadID = id; 0wLu*K5$4E  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 d (Fb_  
} D! 1oYr  
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public void run() -
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{ `o6Hm  
while(nStartPos < nEndPos && !bStop) ag-\(i;K]  
{ /.<T^p@\&  
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try{ 8"4&IX  
URL url = new URL(sURL); lEBt<  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ,OX(z=i_  
httpConnection.setRequestProperty("User-Agent","NetFox"); #cqia0.H  
String sProperty = "bytes="+nStartPos+"-"; gc 14%  
httpConnection.setRequestProperty("RANGE",sProperty); S=>54!{`x  
Utility.log(sProperty); gL(ny/Ob9  
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InputStream input = httpConnection.getInputStream(); 4+od
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//logResponseHead(httpConnection); 1Z?en  
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byte[] b = new byte[1024]; 'b#`8k~>  
int nRead; ysV0Ed  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) k[]B P4  
{ (bxSN@hp2  
nStartPos += fileAccessI.write(b,0,nRead); L\Uf+d:&}G  
//if(nThreadID == 1) !F*7Mif_E  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); O+Fu zCWj  
} gRS}Y8  
){|Bh3XV  
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Utility.log("Thread " + nThreadID + " is over!"); 1M
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bDownOver = true; .v36xXK(  
//nPos = fileAccessI.write (b,0,nRead); >;eWgQ6V  
} aU,Zjm7fp  
catch(Exception e){e.printStackTrace ();} (c ?OcwTH  
} \f6SA{vR|  
} %vvA'WG  
I @TR|  
H3YFbR  
//打印回应的头信息 .eAN`-t;  
public void logResponseHead(HttpURLConnection con) |1zoT|}q  
{ IWvLt  
for(int i=1;;i++) .az+'1  
{ vT V'D&x2  
String header=con.getHeaderFieldKey(i); 3%Z:B8:<y  
if(header!=null) tr6<89e(o  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); r#^/qs(~  
Utility.log(header+" : "+con.getHeaderField(header)); P#(BdKjM  
else ~ztsR;iL  
break; =B g  
} bT<if@h-  
} {ZiJnJX  
*2ZX*w37  
/s"mqBXCG  
public void splitterStop() ;Bk?,g  
{ x2*l5t  
bStop = true; I@a y&NNh  
} .5*h']iFr1  
=*7K_M&  
{<{ O!  
} iB;EV8E  
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/* 'M>QA"*48E  
**FileAccess.java LeDty_  
*//文件访问(定位，写) ezn%*X y,  
package NetFox; MaDdiyeC  
import java.io.*; 68 %= V>V  
8"L#5MO t  
@:u>  
public class FileAccessI implements Serializable{ S)T]>Ash  
{ O+d7,C  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节  #nV F.  
RandomAccessFile oSavedFile; Gf'qPLK0  
long nPos; G+2!+N\P  
u`I&&  
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public FileAccessI() throws IOException kR2kV"-l  
{ DPCB=2E  
this("",0); r(;sX  
} 0Q?XU.v  
d[mmwgSR?I  
v?e@`;- <  
public FileAccessI(String sName,long nPos) throws IOException F?#^wm5TZ  
{ 6-8,qk  
oSavedFile = new RandomAccessFile(sName,"rw"); K.s\xA5`_  
this.nPos = nPos; 0$)uOUVJ  
oSavedFile.seek(nPos); HBHDu;u  
} \$GM4:R D  
mw2/jA7  
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public synchronized int write(byte[] b,int nStart,int nLen) q1!45a  
{ {cmY`to  
int n = -1; <d89eV+  
try{ ~9%L)nC2'  
oSavedFile.write(b,nStart,nLen); _m.u@+g  
n = nLen; DX>Yf}  
} 4D+S\S0bk  
catch(IOException e) L?_'OwaY  
{ z,pKyInw  
e.printStackTrace (); = F*SAz  
} WWf#
in  
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return n; .SZZT0Z  
} E,u/^V9x  
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} D d['e  
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/* .nDB{@#  
**SiteInfoBean.java KrVP#|9%"  
*/ og0su  
package NetFox; \ZNUt$\  
yW3!V-iA  
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public class SiteInfoBean { 'W'['TV  
9
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:wWPEhK  
private String sSiteURL; //Site's URL jQ>~  
private String sFilePath; //Saved File's Path $K& #
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private String sFileName; //Saved File's Name '" MT$MrT  
private int nSplitter; //Count of Splited Downloading File 1ym^G0"s  
&+0WZ#VI  
Tvp~~Dk  
public SiteInfoBean() }6S~"<Ym  
{//nSplitter的缺省值为5 2bIP.M2Fs  
//default value of nSplitter is 5 |E]`rfr  
this("","","",5); 73C7g< Mx  
} Fsdp"X.  
iO$Z?Dyg9  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) c+dmA(JC  
{ Z+p'
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sSiteURL= sURL; {Xr|L  
sFilePath = sPath; "XKcbdr8-  
sFileName = sName; $TU:iv1Fm  
this.nSplitter = nSpiltter; 7-#R[8S  
{HF,F=W  
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} !H)Cua)  
]2zzY::Sd=  
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public String getSSiteURL() oGIh:n7 q+  
{ Nqy)jfyex  
return sSiteURL; le7!:4/8  
} !+R_Z#gB  
,a6Oi=+>/U  
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public void setSSiteURL(String value) 9nGS"E l{  
{ PiL[&_8g  
sSiteURL = value; Hl|EySno  
} -F->l5  
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public String getSFilePath() K>a@A
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{ bM@8[&ta  
return sFilePath; Ca]V%
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} Aq]*$s2\G  
@Z+(J:Grm5  
[D$%LRX  
public void setSFilePath(String value) vx7wW<e%D  
{ "aT"o  
sFilePath = value; tKP zM  
} oS0rP'V^  
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0
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public String getSFileName() ;NoD4*  
{ fkHCfcU  
return sFileName; ov xX.hO  
} x<=<Lx0B;  
Lb=4\ _  
@Jh;YDr`A  
public void setSFileName(String value) ]DJ]L=T7  
{ %^qf0d*  
sFileName = value; m[w 8|[  
} GZx?vSoHh  
h\<;N*Xi  
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public int getNSplitter() -dO9y=?t  
{ .9uw@Eq  
return nSplitter; x2M{=MExE.  
} o0&pSCK  
.E/NlGm[  
cedH#;V!j  
public void setNSplitter(int nCount) ]"X} FU  
{ KQulz  
nSplitter = nCount;  \LP?,<  
} 4*9WxhJ ]0  
} 6 _n~E e  
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a? <Ar#)j  
/* eb*w$|y6"  
**Utility.java n38l!m(.  
*/ 6Gj69Lr  
package NetFox; 0s2@z5bfX  
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public class Utility { =N?K)QD`  
;n2b$MB?nM  
-egu5#d>  
public Utility() VGL!)1
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{ l(A>Rw|  
@FLa i  
];U}'&  
} JQO%-=t  

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//线程睡眠 Xxmvg.Nl  
public static void sleep(int nSecond) OE8H |?%  
{ ^(.utO  
try{ #- z(]Y,y  
Thread.sleep(nSecond); ;e#bl1%#  
} I]jK]]@  
catch(Exception e) S!{Kn ;@  
{ tLc~]G*\`s  
e.printStackTrace (); jHx)q|2\  
} ?S0gazZm
 
} y
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\?K>~{)  
//日志 5Vu@gRk_  
public static void log(String sMsg) a"pejW`m  
{ 15U[F0b  
System.err.println(sMsg); >&DNxw  
} @;P\`[
(*  
3`
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public static void log(int sMsg) H'2Un(#Al  
{ Y:3\z?oV[  
System.err.println(sMsg); FZJyqqA$_  
} ?6>rQ6tBv  
} `mo>~c7  
mj^]e/s%  
n<3*7/-  
/* h_?#.z0ih;  
**TestMethod.java h"849c;C.  
*/ N^U<;O?YDW  
package NetFox; lBcRt)_O7  
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]>'yt #]  
public class TestMethod { 3!<} -sW4  
B_uAa5'  
oHj6
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public TestMethod() U.0bbr  
{ ///xx/weblogic60b2_win.exe \[5mBuk  
try{ +/Vi"  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); m<wEw-1.  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); (g 9G!I   
SiteFileFetch fileFetch = new SiteFileFetch(bean); /&Vgo~.J  
fileFetch.start(); a"|\n_  
} u*C"d1v=  
catch(Exception e){e.printStackTrace ();} C~([aH@-I  
ab-MEN`5  
sXmo.{Ayb  
} y|0I3n]e  
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public static void main(String[] args) %\n&iRwDF  
{ GP._C=]?c  
new TestMethod(); g"&e*fF  
} YkqauyV^  
} @Tl!A1y?  
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