http断点续传简单实现（java)

/* ;d:7\  
**SiteFileFetch.java ~8K~@e$./  
*/ 1>1!oml1E  
package NetFox; S1JB]\  
import java.io.*; .w&Z=
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import java.net.*; #=rI[KI  
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public class SiteFileFetch extends Thread { Zzs pE
}  
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SiteInfoBean siteInfoBean = null; //文件信息Bean mc$dR, H0  
long[] nStartPos; //开始位置 l8Ox]%F  
long[] nEndPos; //结束位置 m`t7-kiZ  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 qabM@+m[  
long nFileLength; //文件长度 k<y$[xV  
boolean bFirst = true; //是否第一次取文件 X$<?:f-  
boolean bStop = false; //停止标志 ~2H)#`\ac8  
File tmpFile; //文件下载的临时信息 P`0aU3pl  
DataOutputStream output; //输出到文件的输出流 @: NrC76  
8G=4{,(A  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） rmhB!Lo  
public SiteFileFetch(SiteInfoBean bean) throws IOException KW)yTE<  
{ f3O3pIA  
siteInfoBean = bean; ~lMsD~$sO  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); %PQC9{hUy$  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); =+u$ZZ0+]o  
if(tmpFile.exists ()) HV>Wf"1  
{ *E>YLkg]  
bFirst = false; ?mMd6U&J  
read_nPos(); )pJzw-m"  
} [@(zGb8  
else WZZD  
{ phTZUmi  
nStartPos = new long[bean.getNSplitter()]; Yq.Omr
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nEndPos = new long[bean.getNSplitter()]; r$+9grm<  
} }=++Lr4*  
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} aJ2-BRn  
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public void run() w>#~_x,`  
{ o] = &  
//获得文件长度 5dhRuc  
//分割文件 b2z~C{l  
//实例FileSplitterFetch "jy'Dpy0m  
//启动FileSplitterFetch线程 {8E hC/=  
//等待子线程返回 fO9e ;  
try{ %Dya-  
if(bFirst) k38Ds_sW6d  
{ ,cS|fG  
nFileLength = getFileSize(); >2_J(vm>  
if(nFileLength == -1) [z?q-$#  
{ H -`7T;t~  
System.err.println("File Length is not known!"); kfn5y#6NZ  
} K2!KMhvQ  
else if(nFileLength == -2) norWNm(n  
{ B4I|"5G2y  
System.err.println("File is not access!"); cU+/I>V  
} zK33.HY  
else Y6V56pOS  
{ ,1od]]>(O  
for(int i=0;i<nStartPos.length;i++) NoV2<m$  
{ XjWoUnz  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); b{9q   
} ze]2-
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for(int i=0;i<nEndPos.length-1;i++) \acjv|]  
{ nx=Zl:Q}  
nEndPos = nStartPos[i+1]; S.BM/M  
} EI]NOG 0  
nEndPos[nEndPos.length-1] = nFileLength; |0dmdrKD  
} $TWt
[  
} {p+7Q
lgK  
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?  
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//启动子线程 <1>\?$)D  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; _yumUk-QW  
for(int i=0;i<nStartPos.length;i++) 0d~>zKho  
{ 36e!je  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), nUD)G<v
 
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), +U% = w8b  
nStartPos,nEndPos,i); $s$z"<  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); r1
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fileSplitterFetch.start(); ._Wm%'uX  
} ]HCu tq  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), r1]shb%J?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ng^`s}?o  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", J[du
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nEndPos = " + nFileLength); !0{":4\  
// fileSplitterFetch[nPos.length-1].start(); :VX?
j3qW  
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//等待子线程结束 I#tn/\n  
//int count = 0; L]I)E`s  
//是否结束while循环 f =B)jYI  
boolean breakWhile = false; FT!|YJz<K  
<:fjWy  
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while(!bStop) UB|f{7~&  
{ HNu/b)-Rb  
write_nPos(); =
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Utility.sleep(500); % V/J6  
breakWhile = true; Y1vl,Yi  
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2&S*> (  
for(int i=0;i<nStartPos.length;i++) OB FG!.)  
{ a=>PGriL  
if(!fileSplitterFetch.bDownOver) *"2TT})  
{ +}@1X&v:  
breakWhile = false; >vF=}1_L  
break; D7T(B=S6  
} -$yNJ5F`  
} %{Ez0XwGCn  
if(breakWhile) ?{ns1nW:  
break; Rs_bM@  
l6IpyIex  
f^\qDvPur  
//count++; W7r1!/ccj  
//if(count>4) M[LjN  
// siteStop(); )>abB?RZ  
} g&I/b/A  
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System.err.println("文件下载结束！"); i'aV=E5  
} Uv?s<  
catch(Exception e){e.printStackTrace ();} x2/L`q"M?=  
} W=fs"
<  
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//获得文件长度 jp?;8rS3  
public long getFileSize() X;25G  
{ |>(d^<nR^v  
int nFileLength = -1; #
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try{ huVw+vAA  
URL url = new URL(siteInfoBean.getSSiteURL()); y8=p;7DY  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); B@XnHh5y  
httpConnection.setRequestProperty("User-Agent","NetFox"); szW_cjS  
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int responseCode=httpConnection.getResponseCode(); g#b[-)Qx  
if(responseCode>=400) ?\[2Po]n  
{ "|<6bA  
processErrorCode(responseCode); t:y} 7un  
return -2; //-2 represent access is error r;m_@*]  
} |L|)r)t  
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tg%s#lLeH  
String sHeader; mRVE@pc2X  
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for(int i=1;;i++) ti6\~SY  
{ "A\.`*6  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); '@OqWdaR  
//Utility.log(in.readLine()); m]LR4V6k|  
sHeader=httpConnection.getHeaderFieldKey(i); rw>X JE  
if(sHeader!=null) H{}0-0o  
{ F-K=Otj  
if(sHeader.equals("Content-Length")) Fl)p^uUtl  
{ M->/vi  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); OT-!n  
break; 15PFnk6E|  
} &.XYI3Ab1  
} 4-lG{I_S:  
else R1.No_`PHq  
break; x\HHu]  
} dMkDNaH,  
} FCO5SX#-g  
catch(IOException e){e.printStackTrace ();} yVds2J'w-  
catch(Exception e){e.printStackTrace ();} ma4Pmk  
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Utility.log(nFileLength); }*vUOQQp*  
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return nFileLength; < H1+qN=]`  
} eK]g FXk  
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//保存下载信息（文件指针位置） NpS*]vSO  
private void write_nPos() w[g(8#*  
{ M9mC\Iz[  
try{ %3v:c|r  
output = new DataOutputStream(new FileOutputStream(tmpFile)); L`"PaIMz  
output.writeInt(nStartPos.length); j1{@?  
for(int i=0;i<nStartPos.length;i++) "YIrqk
 
{ ?_
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// output.writeLong(nPos); _Ju@<V$  
output.writeLong(fileSplitterFetch.nStartPos); dQhh,}  
output.writeLong(fileSplitterFetch.nEndPos); w h4WII  
} f-at@C1L%L  
output.close(); fBgW0o.Bu  
} V*an0@  
catch(IOException e){e.printStackTrace ();} e;LJdd  
catch(Exception e){e.printStackTrace ();} }1EfyR  
} P(z#Wk  
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//读取保存的下载信息（文件指针位置） }lN@J,q  
private void read_nPos() XhF7%KR  
{ ]<3$Sx_{y  
try{ ?NazfK  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); NzRpI5\.  
int nCount = input.readInt(); [/.5{|&GSt  
nStartPos = new long[nCount]; ujF*'*@\  
nEndPos = new long[nCount]; L2v j)(  
for(int i=0;i<nStartPos.length;i++) .gmNE$d  
{ etY/K0  
nStartPos = input.readLong(); V?{[IMRC  
nEndPos = input.readLong(); !E\xn^  
} xRZ9.
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input.close(); f< A@D"m/  
} zP\n<L
5  
catch(IOException e){e.printStackTrace ();} 3U#z {%  
catch(Exception e){e.printStackTrace ();} 8FY.u{93  
} zu6
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private void processErrorCode(int nErrorCode) }F=+*-SYZ  
{ J\iyc,M<M  
System.err.println("Error Code : " + nErrorCode); [qhQj\cK  
}
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//停止文件下载 sS$"6  
public void siteStop() H ]BH  
{ Fv n:V\eb  
bStop = true; %vPs38Fks  
for(int i=0;i<nStartPos.length;i++) )9sRDNr  
fileSplitterFetch.splitterStop(); xA;o3Or  
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} \79KU  
} \I r&&%  
//负责部分文件的抓取 0i}4T:J@`  
**FileSplitterFetch.java K/;FP'.  
*/ x <^vJ1  
package NetFox; {3=\x  
(yk^%  
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import java.io.*; HJl$v#]#+  
import java.net.*; J[9yQ  
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public class FileSplitterFetch extends Thread { \Q.Qos  
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String sURL; //File URL wT?.Mte  
long nStartPos; //File Snippet Start Position FY%v \`@1*  
long nEndPos; //File Snippet End Position 8zew8I~s  
int nThreadID; //Thread's ID TK.a6HJG  
boolean bDownOver = false; //Downing is over =|IB=  
boolean bStop = false; //Stop identical k|W=kt$P  
FileAccessI fileAccessI = null; //File Access interface sY__ak!>  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException %1ofu,%  
{ 5p6Kq=jhb  
this.sURL = sURL; )/FB73!  
this.nStartPos = nStart; b9uo6u4s  
this.nEndPos = nEnd; Hl"rGA>  
nThreadID = id; 7 }`c:u~j  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 D*+uH;ws  
}

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public void run() j`I[M6Qxh  
{ 0;z-I"N  
while(nStartPos < nEndPos && !bStop) t ?8 ?Ok  
{ @xR7>-$0p  
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try{ ~S}>|q$  
URL url = new URL(sURL); 5T,Doxo  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); %zE_Q  
httpConnection.setRequestProperty("User-Agent","NetFox"); XQ.czj  
String sProperty = "bytes="+nStartPos+"-"; .J' 8d"+  
httpConnection.setRequestProperty("RANGE",sProperty); GF5WR e(E  
Utility.log(sProperty); ^.Cfa  
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InputStream input = httpConnection.getInputStream(); {<~0nLyJS  
//logResponseHead(httpConnection); K7}EL|Kx  
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byte[] b = new byte[1024]; 9_'xq.uP  
int nRead; Ggy_ Ct
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) H=]$9ZH!  
{ SeAokz>  
nStartPos += fileAccessI.write(b,0,nRead); 9 O| "Ws>{  
//if(nThreadID == 1) 4s/4z@3a  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); )t={+^Xe  
} quc?]rb  
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RC Fb&,51  
Utility.log("Thread " + nThreadID + " is over!"); }xTTz,Oj$  
bDownOver = true; Z"#ysC  
//nPos = fileAccessI.write (b,0,nRead); \{J gjd  
} M= !Fb  
catch(Exception e){e.printStackTrace ();} |RwpIe8~  
} <4}zl'.  
} \~:Kp Kq  
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Acr\2!))  
//打印回应的头信息 d{&+xl^ll  
public void logResponseHead(HttpURLConnection con) bTZ/$7pp9  
{ {EbR =  
for(int i=1;;i++) gWA)V*}f  
{ #*q`/O5n  
String header=con.getHeaderFieldKey(i); @PuJre4!;L  
if(header!=null) p3I{  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); t/WauY2JUC  
Utility.log(header+" : "+con.getHeaderField(header)); Fh& `v0  
else i`7{q~d=  
break; bW<_K9"  
} Cl[ '6Lk  
} T+NEw8C?/  
:bwdEni1P  
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public void splitterStop() rklr^ e  
{ gbwKT`N*  
bStop = true; EiWy`H;  
} GdEkA  
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} n )YNt  
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/* YQ X+lE  
**FileAccess.java tY !fO>Fn~  
*//文件访问(定位，写) B)/X:[  
package NetFox; rZ 9bz}K  
import java.io.*; }$#e&&)n  
nH}api^0A  
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public class FileAccessI implements Serializable{ fJLlz$H  
iN+Dmq5  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 #rMMOu9r2  
RandomAccessFile oSavedFile; X'.}#R1  
long nPos; mu)?SGpyE  
rJ
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vmJ1-<G4*  
public FileAccessI() throws IOException Bka\0+  
{ *!%y.$
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this("",0); /:>qhRFJA:  
} *ntq;]  
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public FileAccessI(String sName,long nPos) throws IOException dG.s8r*?M  
{ OJ8W'"`L&  
oSavedFile = new RandomAccessFile(sName,"rw"); cKh
{ s  
this.nPos = nPos; !FipKX  
oSavedFile.seek(nPos); VF!?B>  
} .x$+R%5U  
\ 
  
?'CIt5n+\{  
public synchronized int write(byte[] b,int nStart,int nLen) 6hXL`A&},  
{ C>$5<bx  
int n = -1; Z/sB72K1  
try{ i96Pel  
oSavedFile.write(b,nStart,nLen); \ lP c,8)  
n = nLen; =#^%; 66z  
} mj[PKEdkB  
catch(IOException e) .oH0yNFX  
{ c 6}d{B[  
e.printStackTrace (); oaHg6
PT!  
} o;
{  
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return n; )I 4d_]&  
} 'Z+w\0}@  
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} yX$I<L<Suz  
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ul/=1]1?  
/* /S$p_7N  
**SiteInfoBean.java Zn1+} Z@I  
*/ = PcmJG]  
package NetFox; S9<J\`FG  
ED"@!M`1  
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public class SiteInfoBean { yAU[A  
:t?9$ dL  
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private String sSiteURL; //Site's URL /gL(40  
private String sFilePath; //Saved File's Path xM9EO(u  
private String sFileName; //Saved File's Name r7c(/P^$G  
private int nSplitter; //Count of Splited Downloading File j,80EhZ  
VE& ?Zd~  
pB@8b$8(Z  
public SiteInfoBean() K0@2>nR  
{//nSplitter的缺省值为5 ]3 YJEP  
//default value of nSplitter is 5 k.rP}76  
this("","","",5); yX,2`&c  
} RU,f|hB4  
 LS,/EGJ  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) S59!+V  
{ %:h)8e-;  
sSiteURL= sURL; >T%Jlj3ZG  
sFilePath = sPath; *!,+%0  
sFileName = sName; S5
@/;T  
this.nSplitter = nSpiltter; o*:VG\#Z6  
%.r{+m  
/u<lh. hPW  
} }Y(Q7l  
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public String getSSiteURL() _U1~^ucV  
{ 3P6pQm'.f  
return sSiteURL; o$'Fz[U  
} o{4ya jt  
q]0a8[]3  
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public void setSSiteURL(String value) >Gk<[0U  
{ V`TXn[7  
sSiteURL = value; GD}3r:wDs  
} $|C%G6!s?@  
]cc4+}L~  
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public String getSFilePath() q =b.!AZy  
{ N:)`+}  
return sFilePath; UIvTC S  
} P|v;
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/&$'v:VB  
oB-&ma[ZS  
public void setSFilePath(String value) xp7,0'(;  
{ {DI_i +2  
sFilePath = value; +o?.<[>!GR  
} H:`W\CP7_  
rnIv|q6@  
&"._%S58V  
public String getSFileName() H.7gSB1  
{ WnLgpt2G  
return sFileName; X@b$C~+  
} a{L`C"rJ  
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s^^X.z ,  
public void setSFileName(String value) ?f1%)]>   
{ Q0gO1T  
sFileName = value; e=%7tK*  
} ,YSQog  
Fw+JhIVP  
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public int getNSplitter() 9|v  
{ fm;1Iu#  
return nSplitter; 7t\kof  
} enF.}fo]  
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3SpDV'}  
public void setNSplitter(int nCount) $sU?VA'h  
{ ~r]ZD)  
nSplitter = nCount; ^Xt9AM]e  
} st{:]yTRk  
} -v&Q'a  
N ]}Re$5  
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/* YJuaQxs  
**Utility.java vn .wM  
*/ RL~\/#  
package NetFox; cK(}B_D$  
;p BXAl  
VDPqI+z  
public class Utility { <9"s&G@  
c[sC 2  
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public Utility() IqfR`iAix  
{ 4-E9a_  
_L_SNjA_  

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} csRba;Z[  
SQvicZAN)`  
//线程睡眠 5irewh'R  
public static void sleep(int nSecond) QDBptI:  
{ :lgIu .  
try{ IhM-a Y y5  
Thread.sleep(nSecond); ;r49H<z  
} !h?N)9e  
catch(Exception e) s_zZ@azJ  
{ '(+l77G  
e.printStackTrace (); j[iJo 5  
} 9rn!U2  
} 6jCg7Su]  
d^ipf*aLC  
//日志 6@H&S  
public static void log(String sMsg) d>@{!c-  
{ b2U[W#  
System.err.println(sMsg); :eHh }  
} dam.D.o"  
-/#3U{O  
/Klwh1E  
public static void log(int sMsg) YyK9UZjI  
{ `'0opoQRe  
System.err.println(sMsg); fkRb;aIl  
} t,k9:p  
} +=\S"e[F  
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oS_'@u.5  
/* CdWGb[uI  
**TestMethod.java %{zM> le9  
*/ J)'6 z  
package NetFox; 7T4rx53  
.?AtW:<*I  
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public class TestMethod { pC5-,Z;8  
f}Uw%S=w,  
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public TestMethod() g](m& O  
{ ///xx/weblogic60b2_win.exe eRVu/TY  
try{ yv$MQ~]  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); .rxc"fR4_  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Ls|;gewp  
SiteFileFetch fileFetch = new SiteFileFetch(bean); Xk7zXah  
fileFetch.start(); Aqp3amW!  
} zYls>fbp,  
catch(Exception e){e.printStackTrace ();} Rw$ @%o%  
;=C^l  
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} hrS/3c'<Z  
8d Ftp3(  
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public static void main(String[] args) T}u'  
{ $1Xg[>1g5  
new TestMethod(); foL`{fA  
} @B&hR} 4  
} *}
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