http断点续传简单实现（java)

/* ZxvqLu  
**SiteFileFetch.java !)!<.x  
*/ <KBzZ !n5  
package NetFox; aDDs"DXx  
import java.io.*; In3},x+$  
import java.net.*; ;*~y4'{z  
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{[ E7Cf
  
public class SiteFileFetch extends Thread { ;usv/8  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Oo)MxY
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long[] nStartPos; //开始位置 hny(:Dj  
long[] nEndPos; //结束位置 @i" ^b  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 t;>"V.F<1  
long nFileLength; //文件长度 4E"OD+  
boolean bFirst = true; //是否第一次取文件 yf
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boolean bStop = false; //停止标志 bwr}Ge  
File tmpFile; //文件下载的临时信息 &,4 3&pFU  
DataOutputStream output; //输出到文件的输出流 Qz[4M`M  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） TgDx3U[  
public SiteFileFetch(SiteInfoBean bean) throws IOException /:<.Cn>-  
{ h
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siteInfoBean = bean; RyAss0Sm^  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 31FQ=(K  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Vm3e6Y,K  
if(tmpFile.exists ()) AV t(e6H  
{ WNE
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bFirst = false; \[!k`6#t7  
read_nPos(); "Z\^dR  
} `1
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else xs'vd:l.Pp  
{ !awsQ!e|  
nStartPos = new long[bean.getNSplitter()]; !yfQ^a_
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nEndPos = new long[bean.getNSplitter()]; c)7i%RF'  
} >$%rsc}^  
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} e>GX]tK  
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public void run() Sz"rp9x+  
{ wM2[i
  
//获得文件长度 ~EV7E F  
//分割文件 0/vmj,&B(  
//实例FileSplitterFetch 7,pn0,HI  
//启动FileSplitterFetch线程 P ~sX S  
//等待子线程返回 $@wTc  
try{ o1dECLQa  
if(bFirst) C2Pw;iK_t  
{ J7p'_\  
nFileLength = getFileSize(); pOe"S  
if(nFileLength == -1) t+2!"Jr  
{ ['G@`e*\  
System.err.println("File Length is not known!");  hxedQvW  
} l9zkx'xt.-  
else if(nFileLength == -2) 9:]w|lE:D  
{ App9um3:  
System.err.println("File is not access!"); + Q $Jq  
} ;I#f:UQ  
else |k3^ eeLk  
{ }8zw| (GR,  
for(int i=0;i<nStartPos.length;i++) sfN6ro  
{ V>Zw" #Q  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 7Zf *T  
} C5W} o:jE  
for(int i=0;i<nEndPos.length-1;i++) jMH=lQ+8  
{ {dbPMx  
nEndPos = nStartPos[i+1]; U6B-{l:W  
} i8kyYMPP  
nEndPos[nEndPos.length-1] = nFileLength; ;1wRo`RD  
} nO{m2&r+  
} wcd1.$ n  
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//启动子线程 $O)fHD'  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 5 wT e?  
for(int i=0;i<nStartPos.length;i++)
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{ 2<  "-  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), @u.%z# h"1  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 7a0kat'\  
nStartPos,nEndPos,i); Q#Vg5H4  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); V"r2 t9A  
fileSplitterFetch.start();   OH*  
} zS6oz=  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), HZ+l){u  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Kb/w+J S  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", Pr!H>dH8o  
nEndPos = " + nFileLength); `E4+#_ v  
// fileSplitterFetch[nPos.length-1].start(); qkg`4'rLg  
1 po.Cmx  
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//等待子线程结束 o~(/Twxam  
//int count = 0; \MY`R  
//是否结束while循环 XEB1%. p  
boolean breakWhile = false;
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while(!bStop) :d!qZFln  
{ y>5??q  
write_nPos(); Z<Pf[C  
Utility.sleep(500); qoo+=eh!  
breakWhile = true;
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for(int i=0;i<nStartPos.length;i++) A\1X-Mm  
{ Z#1'STg  
if(!fileSplitterFetch.bDownOver) iz0GL&<  
{ S=N3qBH6  
breakWhile = false; -fB;pS,  
break; wUj#ACqB  
} 'Pm.b}p<  
} CBVL/pxy  
if(breakWhile) #ox&=MY  
break; RdirEH*H  
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//count++; ^qro0]"LD  
//if(count>4) (:spA5  
// siteStop(); G%RL8HU  
} ,8Yc@P_O  
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System.err.println("文件下载结束！"); ^tFbg+.  
} qpCNvhi  
catch(Exception e){e.printStackTrace ();} ]m(C}}  
} CHojF+e  
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'T7=.Hq<4  
//获得文件长度 A.%MrgOOX  
public long getFileSize() ,?k~>,{3  
{ 0<n*8t?A-  
int nFileLength = -1; z87_/(nu  
try{ u51%~  
URL url = new URL(siteInfoBean.getSSiteURL()); qTA,rr#p0  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); /
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httpConnection.setRequestProperty("User-Agent","NetFox"); /p PSo  
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int responseCode=httpConnection.getResponseCode(); .Z0$KQ'iy  
if(responseCode>=400) _Z>I"m  
{ {j!jm5  
processErrorCode(responseCode); "~|;XoMU  
return -2; //-2 represent access is error 1>pFUf|cV  
} 43HZ)3!me  
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String sHeader; b;O@|HK&~  
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for(int i=1;;i++) _^(}6o  
{ ,+Bp>=pvs  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); !SxZN dv  
//Utility.log(in.readLine()); [l7 G9T}/[  
sHeader=httpConnection.getHeaderFieldKey(i); 0?0$6F  
if(sHeader!=null) I/&uiC{l@  
{ f0h^ULd  
if(sHeader.equals("Content-Length")) RaBq@r*(
 
{ t V:oBT*  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); $}TK,/W  
break; it\U+xu  
} `-J$7)d@  
} mx ]a@tu  
else jO9w7u6  
break; 2`ED?F68gH  
} ' thEZ  
} "8%z,lHw  
catch(IOException e){e.printStackTrace ();} @8;0p  
catch(Exception e){e.printStackTrace ();} -UMPt"o  
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Utility.log(nFileLength); uh8+Y%V p  
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return nFileLength; KBO{g:"  
} =ll{M{0Q]!  
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+,H6)'#Z  
//保存下载信息（文件指针位置） OfAh?^R  
private void write_nPos() wBbJ \  
{ rF*L@HI  
try{ KVC$o+<'`%  
output = new DataOutputStream(new FileOutputStream(tmpFile)); |rhCQ"H  
output.writeInt(nStartPos.length); )=:gO`"D  
for(int i=0;i<nStartPos.length;i++) @ a$HJ:  
{ TSp;VrOP  
// output.writeLong(nPos); ]\8
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output.writeLong(fileSplitterFetch.nStartPos); -2\%?A6L  
output.writeLong(fileSplitterFetch.nEndPos); j0]|$p  
} `O'@T
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output.close(); fho$:S  
} [tP6FdS/M=  
catch(IOException e){e.printStackTrace ();} \`MX\OR  
catch(Exception e){e.printStackTrace ();} f5droys9  
} Og8'K=O#  
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G
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//读取保存的下载信息（文件指针位置） =64%eF  
private void read_nPos() tI&E@  
{ bB#6Xx  
try{ Bp.z6x4  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); QSNLo_z  
int nCount = input.readInt(); F:P&hK  
nStartPos = new long[nCount]; ndY1j5  
nEndPos = new long[nCount]; *a2
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for(int i=0;i<nStartPos.length;i++) 82q_"y>6  
{ F[65)"^  
nStartPos = input.readLong(); }$zJdf,\  
nEndPos = input.readLong(); "V>7u{T  
} a BHV  
input.close(); j+E[[  
} LM~,`#3Ru  
catch(IOException e){e.printStackTrace ();} pH'1be{K  
catch(Exception e){e.printStackTrace ();} yVP 1=pz_[  
} -H;%1y$A-  
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private void processErrorCode(int nErrorCode) :M%s:,]R  
{ hny):59f  
System.err.println("Error Code : " + nErrorCode); 'B$bGQ  
} vcsMU|GGh  
*YhX6J1  
8r 4 L4  
//停止文件下载 %L^S;v3  
public void siteStop() "* Qwaq_  
{ KT5"/fv  
bStop = true; ?_NhR  
for(int i=0;i<nStartPos.length;i++) OcB
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fileSplitterFetch.splitterStop(); r$7D;>*O{  
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} o#IQz_  
} SLiQHWw*J  
//负责部分文件的抓取 *Y2d!9F}Sa  
**FileSplitterFetch.java :e&P's=
 
*/ u}[Z=V  
package NetFox; zg3q\~  
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import java.io.*; D-zqu~f`  
import java.net.*; otsINAizgS  
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public class FileSplitterFetch extends Thread { b;[u=9ez  
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String sURL; //File URL aXSTA,%  
long nStartPos; //File Snippet Start Position wN])"bmB  
long nEndPos; //File Snippet End Position Z~.3)6,z  
int nThreadID; //Thread's ID S"Q$ Ol"  
boolean bDownOver = false; //Downing is over y?|JBf  
boolean bStop = false; //Stop identical @'K+   
FileAccessI fileAccessI = null; //File Access interface e:BKdZGW  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException );$L#XpB  
{ U[S#axak  
this.sURL = sURL; 7@.UkBOx  
this.nStartPos = nStart; <3!jra,h  
this.nEndPos = nEnd; )32BM+f"77  
nThreadID = id; %rz.>4i)(  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 JvHGu&Nr!  
} y`~[R7E  
@Y#{[@Hp%  
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public void run() $=j}JX}z  
{ kCRP?sj  
while(nStartPos < nEndPos && !bStop) |
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{ !J}Bv  
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try{ (i,TxjS'od  
URL url = new URL(sURL); Jmln*,Ol7  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); h5bQ  
httpConnection.setRequestProperty("User-Agent","NetFox"); /^E2BRI  
String sProperty = "bytes="+nStartPos+"-"; HDyus5g  
httpConnection.setRequestProperty("RANGE",sProperty); K4vl#*qn  
Utility.log(sProperty); O;qerE?i`  
}5RCks;)*  
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InputStream input = httpConnection.getInputStream(); o3hsPzOQx  
//logResponseHead(httpConnection); B6gSt3w.  
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byte[] b = new byte[1024]; ,qgph^C  
int nRead; 89>U Koc?  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) RNyw`>  
{ N1RZ  
nStartPos += fileAccessI.write(b,0,nRead); +_8*;k@F'  
//if(nThreadID == 1) r@3VN~  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); =<.8  
} D]9I-
|  

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Utility.log("Thread " + nThreadID + " is over!"); "8U
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bDownOver = true; Cwxy~.mI  
//nPos = fileAccessI.write (b,0,nRead); Fz_SID  
} fPs'A  
catch(Exception e){e.printStackTrace ();} "lo:"y(u  
} h Znq\p~  
} Uk u~"OGC  
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r/E;tm[\  
//打印回应的头信息 s@sr.'yU  
public void logResponseHead(HttpURLConnection con) blcd]7nK  
{ ]7C=.'Y  
for(int i=1;;i++) ).TQYrs  
{ ~+{OSx<S  
String header=con.getHeaderFieldKey(i); (u81
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if(header!=null) Tp.0@aC  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); r00 fvZyK  
Utility.log(header+" : "+con.getHeaderField(header)); S x';Cj-  
else "-Lbz)k  
break; W9~vBU  
} Y"&&=M#  
} C>q,c3s5  
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**V^8'W<  
public void splitterStop() ">}l8MA  
{ y K~;LV  
bStop = true; a%"My;8  
} GJ=<~S"  
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} 8[SiIuIV  
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/* `}ak;^Me  
**FileAccess.java $srb!&~_>  
*//文件访问(定位，写) LB_ylfg  
package NetFox; }qlU  
import java.io.*; 3jIi$X06  
=dD<[Iz6  
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public class FileAccessI implements Serializable{  h&\%~LO.  
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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 [Y_6PR  
RandomAccessFile oSavedFile; 7@u0;5p|  
long nPos; T8
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public FileAccessI() throws IOException XJ~_FiB  
{ `y; s1nL  
this("",0);  H  
} ~d :Z|8  
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public FileAccessI(String sName,long nPos) throws IOException je1f\N45  
{ <JE-#i  
oSavedFile = new RandomAccessFile(sName,"rw"); {dV#"+  
this.nPos = nPos; jW5n^Y)  
oSavedFile.seek(nPos); "$KU+?  
} 8;YeEW5  
)&}\2NK6L  
{yQeLION  
public synchronized int write(byte[] b,int nStart,int nLen) 0S <;T+WA  
{ /T`L;YE  
int n = -1; "Zd4e2>{M\  
try{ B#'TF?HUEn  
oSavedFile.write(b,nStart,nLen); TQDb\d8,f  
n = nLen; [H-,zY  
} 1\:puC\)  
catch(IOException e) R{.5Z/Vp6E  
{ Fx2z lM&  
e.printStackTrace (); e0%?;w-TL  
} _Z'j%/-4@D  
})O^xF~  
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return n; <Y9vc:S  
} w4U]lg<}E  
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} A2VN%dB  
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/* =D.M}xqo  
**SiteInfoBean.java t6&6kl  
*/ y*A#}b*0  
package NetFox; 6]^; s1!  
BX&bhWYGFX  
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public class SiteInfoBean { yCZV:R;  
*(@(9]B~  
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private String sSiteURL; //Site's URL `2\vDy1,j  
private String sFilePath; //Saved File's Path kxt@t#  
private String sFileName; //Saved File's Name 9,=3D2x&  
private int nSplitter; //Count of Splited Downloading File Y<M,/Y_ !  
qy=4zOOD#  
]5W0zNb*  
public SiteInfoBean() WUx}+3eWv  
{//nSplitter的缺省值为5 rH7|r\]r  
//default value of nSplitter is 5 ~Emeo&X  
this("","","",5); 8qL*Nf  
} dABmK;  

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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) @0A7d $J(  
{ @mBZu!,  
sSiteURL= sURL; N*w/\|  
sFilePath = sPath; kFmd):U!R  
sFileName = sName; %7 h_D  
this.nSplitter = nSpiltter; 4VINu9\V  
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} !K^.r_0H.  
v 0mc1g+9  
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public String getSSiteURL() _2+}_ >d  
{ |r5 np  
return sSiteURL; $A\fm`  
} XL>v$7`#  
x'_I{$C&  
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public void setSSiteURL(String value) |SC^H56+  
{ $}&Y$w>S  
sSiteURL = value; 2='gC|&s6  
} ;n_|t/=  
 {h/[!I`  
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public String getSFilePath() LcS\#p#s]  
{ fH?e9E4l  
return sFilePath; DdDO.@-Z  
} ve[` 0  
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public void setSFilePath(String value) =#]^H c  
{ <EFA^,3t%  
sFilePath = value; _MQ)  
} Zyxr#:Qm  
o-\ K]  
. (G9mZFV  
public String getSFileName() Rhh5r0 \5  
{ ||3%REliC  
return sFileName; !'uL  
} V(Ll]g/T_;  
PjZsMHW%  
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public void setSFileName(String value) 7YT%.ID  
{ ]w z`j1  
sFileName = value; h`n,:Y^++P  
} >+y[HTf-  
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public int getNSplitter() *TQXE:vZ[  
{ umZy=KHj  
return nSplitter; ZGgKCCt  
} Rd~-.&
 
9/3gF)I}  

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public void setNSplitter(int nCount) &}:'YK*X  
{ u;p.:{'  
nSplitter = nCount; o))z8n?b  
} m  "'  
} /H.w0fu&.S  
94 58.!3  
!h3$C\  
/* d-Vttxa6  
**Utility.java AsJN~<0h  
*/ I3`WY-uv  
package NetFox; 5%,5Xe4p  
E~vM$$O$  
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public class Utility { wSoIU,I  
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public Utility() 5(RFkZn4[  
{ jMv qKJ(<  
-|;{/ s5  
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} {a aI<u  
<QbD ;(%  
//线程睡眠 Kn-
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public static void sleep(int nSecond) "ee:Z_Sz  
{ ybLl[K(D=  
try{ 2F*spu  
Thread.sleep(nSecond); 278:5yC  
} kN(*.Q|VZ  
catch(Exception e) 4/UY*Us&  
{ Wno{&I63  
e.printStackTrace (); (;DnL|"'8  
} lId}sf  
} (jb9Uk_t  
D5lzrpg_e  
//日志 dqF]kP,VG  
public static void log(String sMsg) t;005]'Mp  
{ )e&U'Fx  
System.err.println(sMsg); n;&08M5an}  
} EB R,j_  
]}7FTMGbY  
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public static void log(int sMsg) N{oi }i6  
{ ~[n]la  
System.err.println(sMsg); ; kP
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}
SOE5`  
} 5cj]Y)I-~  
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}AfX
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/* qw^kA?  
**TestMethod.java cGF_|1`  
*/ wEd+Ds]$  
package NetFox; sG-$d\ 1d  
Ws;S=|9,7~  
='r86vq  
public class TestMethod { Ff6l"A5  
+/xmxh$ $  
l~ 3H
"  
public TestMethod() )~W 35  
{ ///xx/weblogic60b2_win.exe SURbH;[  
try{ }%e"A4v  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {jz?LM  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ]b5E

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SiteFileFetch fileFetch = new SiteFileFetch(bean); eCejO59F9  
fileFetch.start(); Cj{+DXT  
} p;8I@~dh  
catch(Exception e){e.printStackTrace ();} d^uE4F}  
z =mDd  
{Hc [H-  
} \Af25Mcf:  
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>ZRCM  
public static void main(String[] args) iczJXA+  
{ LPuc&8lGWf  
new TestMethod(); tE|W8=be/  
} jnF-kia  
} !97U2L4  
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