http断点续传简单实现（java)

/* H _zo1AW  
**SiteFileFetch.java <+?7H\b  
*/ #ML%ij 1  
package NetFox; ~E2KZm  
import java.io.*; 4\8+9b\9"  
import java.net.*; H[U!%Z  
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public class SiteFileFetch extends Thread { "hH.#5j  
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SiteInfoBean siteInfoBean = null; //文件信息Bean (ROY?5 @c  
long[] nStartPos; //开始位置 q_MG?re  
long[] nEndPos; //结束位置 K;?m';z0  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 )<h*eS{  
long nFileLength; //文件长度 U`,6 * MS  
boolean bFirst = true; //是否第一次取文件 r\'A i6  
boolean bStop = false; //停止标志 1mOh{:1u  
File tmpFile; //文件下载的临时信息 g| I6'K!<  
DataOutputStream output; //输出到文件的输出流 4;yKOQD|
 
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） eD?tLj  
public SiteFileFetch(SiteInfoBean bean) throws IOException ^/I 7|u]  
{ _E@2ZnD2  
siteInfoBean = bean; K*LlW@  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); X86O lP)eX  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); XDOY`N^L  
if(tmpFile.exists ()) Ezc?#<+7  
{ L*xhGoC=  
bFirst = false; `T@i.'X  
read_nPos(); "O3tq=Q  
} S&Zm0Ku  
else fI?>+I5  
{ %Nlt H/I  
nStartPos = new long[bean.getNSplitter()]; GfoLae  
nEndPos = new long[bean.getNSplitter()]; snE8 K}4  
} t5\-v_mG=&  
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} #+Ir>GU  
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public void run() g:g\>@Umo  
{ {f3YsM;]C  
//获得文件长度 BO~0ON0  
//分割文件 S 6@u@C  
//实例FileSplitterFetch _hAcJ{Y  
//启动FileSplitterFetch线程 )B"jF>9)[  
//等待子线程返回 V,lOt4b  
try{ ?pW`cFLDHF  
if(bFirst) ##,a0s^  
{ n4;.W#\  
nFileLength = getFileSize(); W9 GxXPA  
if(nFileLength == -1) I667Gz$j5  
{ $v4.sl:x  
System.err.println("File Length is not known!"); lk/n}bx  
} :3v}kLO7|  
else if(nFileLength == -2) ;#g"(  
{ dI.WK@W'o  
System.err.println("File is not access!"); uw>Ba %5  
} "h{q#~s  
else 7OcWC-<  
{ ]l_\71  
for(int i=0;i<nStartPos.length;i++) |GdUL%1hnC  
{ hci6P>h<ia  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); Qf~vZtJ+J  
} zqimR#u  
for(int i=0;i<nEndPos.length-1;i++) u@Ih GME  
{ dU&a{$ku[  
nEndPos = nStartPos[i+1]; {2O1"|s ,  
} g!g#]9j  
nEndPos[nEndPos.length-1] = nFileLength; ~8'sBT  
} }*M6x;t  
} kvL=> A  
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//启动子线程 ;km`P|
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; %f&/E"M  
for(int i=0;i<nStartPos.length;i++) >8~.wXyoC  
{ 5bRJS70M  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), wT6"U$cV  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), VQc_|z_s  
nStartPos,nEndPos,i); R5N%e%[  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); VACQ+  
fileSplitterFetch.start(); t|w_i-&b,  
} iOd&BB6  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), @x*c1%wg  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); C8J[Up  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", F|'>NL-=  
nEndPos = " + nFileLength); Xpr?Kgz  
// fileSplitterFetch[nPos.length-1].start(); {BP{C=p  
OV1_|##LC  
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//等待子线程结束 LK{*sHi$  
//int count = 0; iN bIp"W  
//是否结束while循环 D#_3^Kiawj  
boolean breakWhile = false; 2~Kg
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while(!bStop) z 9vInf@M  
{ J4k=A7^N  
write_nPos(); dcDyK!zz"  
Utility.sleep(500);
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breakWhile = true; prWk2_D;*  
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for(int i=0;i<nStartPos.length;i++) {0[tNth'h  
{ b:U$x20n$  
if(!fileSplitterFetch.bDownOver) ]3D0R;  
{ MU($|hwiL  
breakWhile = false; EuEZ D+  
break; Z_LFIz*c  
} NpE*fR')  
} NN%*b yK  
if(breakWhile) zG }@0  
break; ^ sOQi6pL  
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//count++; a4mn*,  
//if(count>4) kDEXN  
// siteStop(); ny]?I
  
} Y[ j6u\y  
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System.err.println("文件下载结束！"); +G$4pt|=  
} _mj,u64  
catch(Exception e){e.printStackTrace ();} =T3<gGM  
} 8Q.T g.  
[T|aw1SoN  
)\1QJ$-M&  
//获得文件长度 /,BD#|  
public long getFileSize() ]P9l jwR  
{ AgWa{.`f:  
int nFileLength = -1; s%vis{2  
try{ vt/x ,Y  
URL url = new URL(siteInfoBean.getSSiteURL()); )1Y{Q Y}l  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 6`&a&%,O  
httpConnection.setRequestProperty("User-Agent","NetFox"); eln)BW#  
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int responseCode=httpConnection.getResponseCode(); R#s)r  
if(responseCode>=400) =
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{ ]>W6 bTK  
processErrorCode(responseCode); T"(&b~m2b4  
return -2; //-2 represent access is error kS%Ydy#:'  
} 0XOp3  
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String sHeader; J9..P&c\  
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for(int i=1;;i++) #{6{TFx\  
{ LHyB3V  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); S~<$Hy*kh  
//Utility.log(in.readLine()); zZ:>do\2  
sHeader=httpConnection.getHeaderFieldKey(i); *-#&K\  
if(sHeader!=null) @Y?#Sl*  
{ -fM1nH&  
if(sHeader.equals("Content-Length")) *o]L|Vu  
{ xn?a. 3b'  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); biLs+\C  
break; vXev$x=w-  
} mJ<=n?{Z  
} O5!7'RZ  
else |e=,oV"  
break; pXtl 6K%  
} <c*FCblv  
} x" 7H5<  
catch(IOException e){e.printStackTrace ();} tCw<Ip  
catch(Exception e){e.printStackTrace ();} y3vdUauOn  
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Utility.log(nFileLength); I"xo*}  
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return nFileLength; !'Ak&j1:`  
} n#mA/H;wV  
;[(oaK@+n  
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//保存下载信息（文件指针位置） t1]K<>g  
private void write_nPos() k3~}7]O)  
{ '_<{p3M  
try{ K:J3Z5"  
output = new DataOutputStream(new FileOutputStream(tmpFile)); n*o-Lo+Fe.  
output.writeInt(nStartPos.length); #+JG(^%B  
for(int i=0;i<nStartPos.length;i++) <<UB ^v m  
{ 7 G)ZN{'  
// output.writeLong(nPos); j 'FVz&  
output.writeLong(fileSplitterFetch.nStartPos); {M3qLf~z#C  
output.writeLong(fileSplitterFetch.nEndPos);
/Jta^Bj  
} O3;u G.:1  
output.close(); hC:n5]K  
} +2(I1  
catch(IOException e){e.printStackTrace ();} Mc@
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catch(Exception e){e.printStackTrace ();} ~Cbc<[}  
} Y21g{$~Q{  
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//读取保存的下载信息（文件指针位置） N%kt3vmQ_  
private void read_nPos() C,wL0Yj[  
{ #||}R[~P"  
try{ Y1L[;)Hn  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); !1rlN8w(qr  
int nCount = input.readInt(); m&xW6!x  
nStartPos = new long[nCount]; YD<:,|H  
nEndPos = new long[nCount]; i1UiNJh86  
for(int i=0;i<nStartPos.length;i++) -#7'r<I9@  
{ 09|K>UC)v  
nStartPos = input.readLong(); j_/>A=OD  
nEndPos = input.readLong(); 
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} RW|`nL  
input.close(); ;m0~L=w  
} t

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catch(IOException e){e.printStackTrace ();} tankR9(o  
catch(Exception e){e.printStackTrace ();} S3F;(PDzy  
} ?OId\'q  
#[,IsEpDO1  
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private void processErrorCode(int nErrorCode) :=}BN  
{ &[_g6OL  
System.err.println("Error Code : " + nErrorCode); P !AEf#1  
} d.3E[AJa(  
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"76]u)  
//停止文件下载 2X.r%&!1M  
public void siteStop() 1G"z<v B  
{ g~ZvA(`  
bStop = true; Q8C_9r/:N>  
for(int i=0;i<nStartPos.length;i++) \O}E7-  
fileSplitterFetch.splitterStop(); nv GF2(;l  
J cPtwa;q@  

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} [6pD  
} ={_C&57N1  
//负责部分文件的抓取 1Y/s%L  
**FileSplitterFetch.java ?@BTGUK"C  
*/ dpJ_r>NI  
package NetFox; 0f~C#/[t7  
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import java.io.*; 
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import java.net.*; "*($cQ$v  
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public class FileSplitterFetch extends Thread { 
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String sURL; //File URL 6tB+JF  
long nStartPos; //File Snippet Start Position R,gR;Aarw  
long nEndPos; //File Snippet End Position t|a2;aq_  
int nThreadID; //Thread's ID 3cFf#a#  
boolean bDownOver = false; //Downing is over !5.8]v
 
boolean bStop = false; //Stop identical ,X#2\r<|  
FileAccessI fileAccessI = null; //File Access interface {K <iih  
w0ht  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException t=|evOz]  
{ y6LWx:  
this.sURL = sURL; 5XO;
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this.nStartPos = nStart; M|6A0m#Q  
this.nEndPos = nEnd; qo p^;~  
nThreadID = id; \
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 c0PIc^R(@  
} 0C1pt5K  
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public void run() "*m_> IU  
{ /~}}"zx&  
while(nStartPos < nEndPos && !bStop) *;1,5L  
{ [p{#XwN  
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)#P; x"  
try{ }3o|EXx=  
URL url = new URL(sURL); u\ #"L  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 8JM&(Q%#  
httpConnection.setRequestProperty("User-Agent","NetFox"); 5Y.vJz  
String sProperty = "bytes="+nStartPos+"-"; }'"
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httpConnection.setRequestProperty("RANGE",sProperty); "^4_@ oo  
Utility.log(sProperty); }vZ+A
 
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InputStream input = httpConnection.getInputStream(); '>&^zgr  
//logResponseHead(httpConnection); ?!9)q.bW  
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byte[] b = new byte[1024]; 
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int nRead; }2<r,  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ,a gc  
{ \n{qsf:  
nStartPos += fileAccessI.write(b,0,nRead); ,$+lFv3LE  
//if(nThreadID == 1) 3 DDML,  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); gXYI\.  
} $>GgB`  
&=#[(vl  
q<\
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Utility.log("Thread " + nThreadID + " is over!"); U'8bdsF_  
bDownOver = true; iMIlZ  
//nPos = fileAccessI.write (b,0,nRead); fIj|4a+  
} T^w36}a  
catch(Exception e){e.printStackTrace ();} PE~G=1x3  
} I|>^1kr8w  
} $UgA0]qn  
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//打印回应的头信息 ])L A42|  
public void logResponseHead(HttpURLConnection con) ux_Mr
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{ I2 j}Am  
for(int i=1;;i++) 7]9 a<  
{
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String header=con.getHeaderFieldKey(i); 0}$Hi  
if(header!=null) K@#(*."  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); twP,cyR  
Utility.log(header+" : "+con.getHeaderField(header)); -sw  .  
else hJDi7P  
break; c%&:6QniZ  
} pV20oSJNt  
} I 6<*X  
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I 4,K43|  
public void splitterStop() {.QEc0-  
{ &m|wH4\  
bStop = true; ;\lW5ZX  
} 1j
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} | \'rP_I>  
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/* O+?<h{"  
**FileAccess.java &e;=cAXG  
*//文件访问(定位，写) O)ME"@r@:  
package NetFox; Xb{ [c+.  
import java.io.*; }z\_;\7  
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public class FileAccessI implements Serializable{ y($%;l   
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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 $: ]o]a  
RandomAccessFile oSavedFile; rb1`UG"h$  
long nPos; u86"Y^d#  
=|I>G?g-  
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public FileAccessI() throws IOException @6mBqcE'?  
{ qEpi]=|  
this("",0); qe!fk?T}  
} WHjUR0NZ  
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public FileAccessI(String sName,long nPos) throws IOException Gm(b/qDDe  
{ |!"2fI  
oSavedFile = new RandomAccessFile(sName,"rw"); l2l(_$@3  
this.nPos = nPos; 6(G?MW.  
oSavedFile.seek(nPos); Q($Z%1S  
} 7.Z@Wr?  
:cGt#d6  
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public synchronized int write(byte[] b,int nStart,int nLen) d1U\ft:gV  
{ 4dhvFGlW  
int n = -1; ~ug= {b  
try{ {%IExPJ  
oSavedFile.write(b,nStart,nLen); ]p;FZ4-T  
n = nLen; f|R"uW +  
}  b^p"|L  
catch(IOException e) mExVYp h  
{ (iRide  
e.printStackTrace (); pp
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} R1& [S/  
NMww>80  
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return n; 7DIIx}
A  
} @DZB9DDR  
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6%fKuMpK(  
} C&6IU8l\  
"m^' &L  
^b7GH9<&  
/* qA!]E^0*Ke  
**SiteInfoBean.java VMCLHpSfW  
*/ T}4/0yR2  
package NetFox; CYKr\DA  
ZeEWp3vW  
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public class SiteInfoBean { vmLxkjUm#  
J]q%gcM  
me'd6!O9-  
private String sSiteURL; //Site's URL k<cgO[m  
private String sFilePath; //Saved File's Path 0 s70r  
private String sFileName; //Saved File's Name aM{xdTYaU  
private int nSplitter; //Count of Splited Downloading File 4WE6fJ2X  
r)i>06Hd  
|gsE2vV  
public SiteInfoBean() @fa@s-wb  
{//nSplitter的缺省值为5 $DZHQH  
//default value of nSplitter is 5 |=EZ1<KzD  
this("","","",5); **+e7k  
} NHl|x4Zpw  
QMsHC%l3b  
NuYkz"O]  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 11,!XD*"  
{ ;/0 Q1-  
sSiteURL= sURL; 5l,ZoB
8  
sFilePath = sPath; e5OsIVtjr  
sFileName = sName; Uz7^1.-g4  
this.nSplitter = nSpiltter; )LdyC`S\c  
fd#jY}  
&<+ A((/i  
} nN~~cV  
1-PoZ[p-R  
,&d@O>$E:  
public String getSSiteURL() !sRngXCXk?  
{ sO5?aB&  
return sSiteURL; ncSFj.}w]  
} T2D<UhP  
E( h<$w8s  
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public void setSSiteURL(String value) gh>>Ibf  
{ jA(>sz  
sSiteURL = value; 3&x-}y~sg  
} }'OHE(s
  
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public String getSFilePath() 7t?*  
{ >I<r)w]  
return sFilePath; 'SYo_!  
} U#n#7G6fRp  
@VN&t:/l  
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public void setSFilePath(String value) x'zBK0i  
{ hb/]8mR  
sFilePath = value; Jjl%R[mI  
} g}f9dB,F  
HK)cKzG[s!  
W[[bV  
public String getSFileName() yIb,,!y9{  
{ j,d*?'X  
return sFileName; ]hud4i~  
} h8G5GRD  
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o  

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public void setSFileName(String value) eh*6cQ.0  
{ 4Iq'/r  
sFileName = value; l/
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} @=5qT]%U3J  
h7X_S4p/Mg  
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public int getNSplitter() ^+SkCO  
{ 'O6]0l  
return nSplitter; <e%F^#y_
 
} as+GbstN  
NDO\B,7  
%~NH0oFO  
public void setNSplitter(int nCount) YHV-|UNF  
{ Q{QYBh&  
nSplitter = nCount; xw<OLWW  
} GO! uwo:  
} 8_H=^a>2  
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@^ ik[9^H  
/* xKOq[d/8  
**Utility.java `A/j1UWJ  
*/ r
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3  
package NetFox; /q\_&@  
RE3Z%;'  
=\, qP  
public class Utility { 9^F2$+T[:  
~9Cz6yF  
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public Utility() iF+RnWX\  
{ V+wH?H=  
%ICglF R  
!SHj$Jwa'  
} G&eP5'B4i  
^]p  
//线程睡眠 r!N]$lB  
public static void sleep(int nSecond) 4YU/uQm  
{ [LM^),J?  
try{ d6 _C"r  
Thread.sleep(nSecond); &ogt2<1W  
} *HM?YhR  
catch(Exception e) PHM:W%g:  
{ GgFi9F
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e.printStackTrace (); MN= sIP,zk  
} E^ h=!RW{  
} b1^n KB  
vC/[^  
//日志 -[#n+`M  
public static void log(String sMsg) q$ghLGz  
{ iy
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System.err.println(sMsg); GtI6[ :1t  
} R -e
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|@VF.)_  
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public static void log(int sMsg) J>S3sP  
{ wod/&!)]A  
System.err.println(sMsg); U_z2J(e~  
} >X Qv?5  
} {0jI
Y  
?H;{~n?  
f5dR 5G  
/* /nB'kg[h\  
**TestMethod.java q
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*/ @6xGJ,s  
package NetFox; \MYU<6{u  
@] .VQ<X|0  
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public class TestMethod { 9fVj 8G  
%JoxYy-  
.5hp0L}  
public TestMethod() )@PnTpL*  
{ ///xx/weblogic60b2_win.exe x
l!K;Y2<  
try{ T[Q"}&bB  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); z&'f/w8  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); !;}2F
-  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ]if;A)'  
fileFetch.start(); $iJnxqn  
} [ #]jC[  
catch(Exception e){e.printStackTrace ();} j=3-Qk`"/|  
!]DuZ=  
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} kO3`54  
&6"P7X  
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public static void main(String[] args) T^)plWw  
{ (Pz8iz  
new TestMethod(); G,DOBA  
} I6w/0,azC  
} t"YIq/08  
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