http断点续传简单实现（java)

/* p.q:vI$J  
**SiteFileFetch.java ?@9kVB*|  
*/ 9<5SQ  
package NetFox; XG"&\FL{T  
import java.io.*; Q>nq~#3?  
import java.net.*; &0Zn21q  
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public class SiteFileFetch extends Thread { )2}{fFa%  
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SiteInfoBean siteInfoBean = null; //文件信息Bean OpY2Z7_  
long[] nStartPos; //开始位置 Wy%q9x]}  
long[] nEndPos; //结束位置 QP|Ou*Qm)  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 =+q9R`!L]  
long nFileLength; //文件长度 zIWw055W  
boolean bFirst = true; //是否第一次取文件 1
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boolean bStop = false; //停止标志 wJJ4F$"b  
File tmpFile; //文件下载的临时信息 CzxU @  
DataOutputStream output; //输出到文件的输出流 1TfK"\  
hS&,Gm`^  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类）
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public SiteFileFetch(SiteInfoBean bean) throws IOException )((Jnm D  
{ 2%N$Y]  
siteInfoBean = bean; nBL7LocvR  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); ~C< X~$y&  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); WO$PW`k  
if(tmpFile.exists ()) @L^2VVWk^  
{ ^Sx0t  
bFirst = false; < pI2
}  
read_nPos(); _3h(R`VdWO  
} cTmo
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else s;q]:+#7g  
{ xA]CtB*o7  
nStartPos = new long[bean.getNSplitter()]; |@={:gRJ{x  
nEndPos = new long[bean.getNSplitter()]; -UkP{x)S  
} >z6(fM`i  
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} p~I+ZYWF'  
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public void run() s S8Z5k;  
{ km'3[}8o&  
//获得文件长度 A!s\;C  
//分割文件 sM
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//实例FileSplitterFetch #EAP<h  
//启动FileSplitterFetch线程 !v^D}P 3Y  
//等待子线程返回 ~fB: >ceD  
try{ ivC1=+  
if(bFirst) "K`B'/08^  
{ vrdlI^  
nFileLength = getFileSize(); w
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if(nFileLength == -1) |$#u~<r_ w  
{ Ol:&cX3G  
System.err.println("File Length is not known!"); LF <fp&C)h  
} F{
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else if(nFileLength == -2) Ae:(_UJz  
{ oC>e'_6_b  
System.err.println("File is not access!"); y5iLFR3z  
} OwV>`BIwns  
else ex7zg!  
{ |\2zw _o  
for(int i=0;i<nStartPos.length;i++) /ZZo`   
{ >|!F.W  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); E#r6e+e1Q%  
} %TdZ_  
for(int i=0;i<nEndPos.length-1;i++) ed4:r/Dpo  
{ ji<b#YO4  
nEndPos = nStartPos[i+1]; ws Lg6  
} U.hV1  
nEndPos[nEndPos.length-1] = nFileLength; NY\q  
} p!>FPS  
} =2pGbD;*  
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//启动子线程 ;rJR+wpNa  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; EP&iG%(k  
for(int i=0;i<nStartPos.length;i++) KZzOs9 s
 
{ }rsD$  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), x)l}d3   
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), g}0}$WgH:  
nStartPos,nEndPos,i); 1Vt7[L*  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _ 0%sYkUc  
fileSplitterFetch.start(); 5j
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} ii0AhQ  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), q$e2x=?  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); EcrM`E#kaZ  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", V"(S<o  
nEndPos = " + nFileLength); $q]((@i.  
// fileSplitterFetch[nPos.length-1].start(); 9kL'"0c  
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9r@r\-  
//等待子线程结束 :pcKww|V  
//int count = 0; /E$"\m
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//是否结束while循环 jFpXTy[>  
boolean breakWhile = false; -X5rGp++  
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while(!bStop) +[8s9{1{C  
{ lBh|+KN  
write_nPos(); vC[)/w  
Utility.sleep(500); #sdW3m_%  
breakWhile = true; FiJJe  
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for(int i=0;i<nStartPos.length;i++) |Y|{9Osus  
{ kM|ak
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if(!fileSplitterFetch.bDownOver) Bu">)AnN  
{ NmYSk6kWJ  
breakWhile = false; rc1EJ(c  
break; Um]>B`."wK  
} u&?J+  
} ]7
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if(breakWhile) *5]fjh{  
break; 1u75  
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//count++; !L:!X88  
//if(count>4) /lkIbmV  
// siteStop(); HT)b3Ws~M8  
} ]Gm,sp.x  
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System.err.println("文件下载结束！"); }MW*xtGV  
} [tym~ZZ]_m  
catch(Exception e){e.printStackTrace ();} OJ\IdUZ  
} B2:6=8<  
1U.se`
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//获得文件长度 HE(|x1C)j  
public long getFileSize() 'm}K$h(U  
{ ZW}*]rg  
int nFileLength = -1; y_M<\b  
try{ ]24aK_Uu  
URL url = new URL(siteInfoBean.getSSiteURL()); g*F?  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); U(]
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httpConnection.setRequestProperty("User-Agent","NetFox");
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'A .c*<_  
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int responseCode=httpConnection.getResponseCode(); YlwCl4hq  
if(responseCode>=400) |`_qmk[:R  
{ ?Q[uIQ?dV  
processErrorCode(responseCode); ;0O3b  
return -2; //-2 represent access is error q]YPDdR#  
} "8%B (a 5A  

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String sHeader; uS<7X7|!0  
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for(int i=1;;i++) M8a^yoZn  
{ ]N_(M   
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); f1(V~{N,+  
//Utility.log(in.readLine()); c<L^ 1,G2  
sHeader=httpConnection.getHeaderFieldKey(i); {[hH: \  
if(sHeader!=null) *Uie{^p?  
{ <:0649ZB  
if(sHeader.equals("Content-Length")) U:m[* }+<  
{ f
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); (xpj?zlmM  
break; =`[08  
} =Ig'Aw$x  
} ^5j|   
else mv|eEz)r  
break; W!8g.r4u+,  
} akHcN]sa2  
} oGx OJyD  
catch(IOException e){e.printStackTrace ();} _R<e
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catch(Exception e){e.printStackTrace ();} ewg&DBbN"  
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Utility.log(nFileLength); H|k!5W^  
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return nFileLength; ojU:RRr4l$  
} ~Z!!wDHS  
}UJS*mR  
p0~=
 
//保存下载信息（文件指针位置） 9YRoWb{y  
private void write_nPos() w~+5FSdH  
{ T#xCu|
5  
try{ (M5w:qbR  
output = new DataOutputStream(new FileOutputStream(tmpFile)); ,IoPK!5xy  
output.writeInt(nStartPos.length); T{3C3EE?]  
for(int i=0;i<nStartPos.length;i++) 5A/8G}'XZ  
{ EKoAIC*?p  
// output.writeLong(nPos); ps=jGh[  
output.writeLong(fileSplitterFetch.nStartPos); {.pR$]6B"+  
output.writeLong(fileSplitterFetch.nEndPos); pV{MW#e  
} %5V!Fdb  
output.close(); ['ol
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} $Nvt:X_  
catch(IOException e){e.printStackTrace ();} y E-H-r~I  
catch(Exception e){e.printStackTrace ();} 8Kt_irD  
} ^IGutZov  
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//读取保存的下载信息（文件指针位置） /1 lIV_Z  
private void read_nPos() s `fIeP  
{ u,e'5,`N  
try{ P3V=DOG"  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); BV,P;T0"D  
int nCount = input.readInt(); Cv862kP  
nStartPos = new long[nCount]; FVM:%S JjT  
nEndPos = new long[nCount]; M-1 VB5  
for(int i=0;i<nStartPos.length;i++) zM{'GB+en  
{ uH[d%y/  
nStartPos = input.readLong(); 7|LJwXQ-  
nEndPos = input.readLong(); E;$)Oz  
} >y)(M(o  
input.close(); Ug02G  
} e\x=4i  
catch(IOException e){e.printStackTrace ();} <6^MVaD  
catch(Exception e){e.printStackTrace ();} {WUW.(^]G  
} N p9N
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private void processErrorCode(int nErrorCode) ks|[`FH  
{ ktLXL;~X  
System.err.println("Error Code : " + nErrorCode); LW6&^S?4{  
} =S/$h}Vi  
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>yFEUD:  
//停止文件下载 !]1X0wo\  
public void siteStop() b:3n)-V{u  
{ +shT}$cb1  
bStop = true; ;@p2s'(  
for(int i=0;i<nStartPos.length;i++) OrP-+eg  
fileSplitterFetch.splitterStop(); sW!p
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} s\QhCS  
} RK?b/9y  
//负责部分文件的抓取 P\\4 w)C  
**FileSplitterFetch.java cAq>|^f0a  
*/ hNBv|&D#  
package NetFox; <![tn#_  
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import java.io.*; Uf)?sz  
import java.net.*; dA>=#/"  
=!7k/n';  
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public class FileSplitterFetch extends Thread { h<H.8.o  
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String sURL; //File URL "3o{@TdU  
long nStartPos; //File Snippet Start Position 2?YN8 n9n  
long nEndPos; //File Snippet End Position N^7Qn*qt[  
int nThreadID; //Thread's ID &No6k~T0:b  
boolean bDownOver = false; //Downing is over ~$XbYR-  
boolean bStop = false; //Stop identical &.z: i5&o!  
FileAccessI fileAccessI = null; //File Access interface MMCac6;Aea  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException p\I,P2on  
{ %7=B?c|  
this.sURL = sURL; ,73kh  
this.nStartPos = nStart; )\!_`ob  
this.nEndPos = nEnd; wY|&qX,  
nThreadID = id; W^; wr#  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 IJHNb_Cku  
} nIdB,  
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public void run() MGpP'G:
v  
{ Jydz2 zt!  
while(nStartPos < nEndPos && !bStop) )6U&^9=  
{ H.|v^e  
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try{ j`jF{k b  
URL url = new URL(sURL); !4-B xeNY\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 3wZA,Z  
httpConnection.setRequestProperty("User-Agent","NetFox"); HqNM31)  
String sProperty = "bytes="+nStartPos+"-"; N,U<.{T=A  
httpConnection.setRequestProperty("RANGE",sProperty); bM7y}P5`1  
Utility.log(sProperty); oC0K!{R*  
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InputStream input = httpConnection.getInputStream(); $g&,$7}O_  
//logResponseHead(httpConnection); S <~"\<ED  
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byte[] b = new byte[1024]; @+II@[_lT  
int nRead; iu!j#VO  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) x+Vp&  
{ 1SIhW:C  
nStartPos += fileAccessI.write(b,0,nRead); }T=0]u4,  
//if(nThreadID == 1) S9kagiFX\  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 8a{S*  
} BeP]M1\?>  
q#9JJWSs  
>7%Gd-;l  
Utility.log("Thread " + nThreadID + " is over!"); CVfQ  
bDownOver = true; $1<V'b[E  
//nPos = fileAccessI.write (b,0,nRead); +Hx$ABH  
} [1{#a
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catch(Exception e){e.printStackTrace ();} MX!t/&X(n  
} gP=(2EVE  
} mFCDwh]  
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//打印回应的头信息 v+XB$j^H  
public void logResponseHead(HttpURLConnection con) H]e%8w))0  
{ sevaNs  
for(int i=1;;i++) *s4h tt  
{ 57r?`'#*  
String header=con.getHeaderFieldKey(i); bxX[$q  
if(header!=null) &w\E*$  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); H9nVtS
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Utility.log(header+" : "+con.getHeaderField(header)); 9W{`$30  
else LASR*  
break; .)Xyzd  
} g/H:`J
  
} <vS J<WY  
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public void splitterStop() +$Q.N{LV  
{ ,<iJ#$: Sx  
bStop = true; pqmb&"l  
} .b'o}DLa  
ygt7;};!  
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} 9WN4eC$  
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/* 'iy &%?  
**FileAccess.java c_$9z>$  
*//文件访问(定位，写) gG"W~O)yv  
package NetFox; 4wp5ghe  
import java.io.*; vLQ!kB^\W  
:4 9ttJl  
#H9J/k_  
public class FileAccessI implements Serializable{ V%
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{#>>dILPr  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 +#qW 0g  
RandomAccessFile oSavedFile; 8@`"ZzM  
long nPos; Z^t"!oY  

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public FileAccessI() throws IOException &YMz3ugI  
{ 9qyA{ |3  
this("",0); yEYlQ=[#  
} OVr, {[r  
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public FileAccessI(String sName,long nPos) throws IOException IIC1T{D}v  
{ E,"?RbG  
oSavedFile = new RandomAccessFile(sName,"rw"); 3`y9V2&b  
this.nPos = nPos; #H]cb#  
oSavedFile.seek(nPos); 32DT]{-N!  
} CXC,@T  
QcZ*dI7]:
 
l| 1O9I0Gd  
public synchronized int write(byte[] b,int nStart,int nLen) #"tHT<8u  
{ QwaCaYoh  
int n = -1; K9JW&5Q  
try{ r{DR$jD  
oSavedFile.write(b,nStart,nLen); 8m? 9?OV5  
n = nLen; eK_Q>;k5A  
} |e+8Xz1>  
catch(IOException e) S`,(10Y  
{ \ ;.W;!*  
e.printStackTrace (); Af8&PhyrU  
} z#qlu=  
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H>8B$fi)$  
return n; DPENYr  
} t__UqCq~h  
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} _N`:NOM  
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/* . J"g.Q  
**SiteInfoBean.java _g+^jR4  
*/ D ff0$06Nq  
package NetFox; "PA
:  
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.~#<>  
public class SiteInfoBean { ;XFo:?  
IooAXwOF  
YE<_a;yh1  
private String sSiteURL; //Site's URL "9=F/o9  
private String sFilePath; //Saved File's Path jq6BwUN  
private String sFileName; //Saved File's Name ,xA`Fu9^  
private int nSplitter; //Count of Splited Downloading File }UwDHq=  
y%.^| G  
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public SiteInfoBean() 9IFK4>&O6  
{//nSplitter的缺省值为5 sQt]Y&_/@  
//default value of nSplitter is 5 B+:'Ld](  
this("","","",5); ia.95H;  
} x!CCSM;q  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) [a~|{~?8  
{ ]Bo !v*12  
sSiteURL= sURL; |2mm@):  
sFilePath = sPath; jkd'2  
sFileName = sName; #7S[Ch}O  
this.nSplitter = nSpiltter; OhT?W
[4  
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;q:.&dak1  
} TxZ ^zj  
iU^
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public String getSSiteURL() |KR
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{ Obd@#uab  
return sSiteURL; <uXZ*E  
} JTuU}nm+  
"F/%{0d  
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public void setSSiteURL(String value) Y#3<w  
{ 8^26g3  
sSiteURL = value; N%Gb  
} 5[Sa7Mk  
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public String getSFilePath() z:B4  
{ qKX3Npw  
return sFilePath; .W_'6Q+  
} 1-`Il]@?8  
qV^Z@N+,  
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public void setSFilePath(String value) wO6 D\#  
{ jqULg iC  
sFilePath = value; nH*JR  
} L;d(|7BVv  
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public String getSFileName() &rY73qfP'  
{ 'CiV=&3/  
return sFileName; .W[ 9G\  
} r(g:b ^S  
%fY\vd2  
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public void setSFileName(String value) 7`113`1  
{ R-Y07A  
sFileName = value; 8KH|:>s=  
} V/C":!;  
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public int getNSplitter() L1'R6W~%dN  
{ M`6rI  
return nSplitter; 6_`9 4+  
} QDO.
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9F[k;Uw  
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public void setNSplitter(int nCount) bb@@QzR  
{ [I*zZ`  
nSplitter = nCount; A.0eeX{  
} X=QaTV  
} s,&tD WU  
~?l>QP|o  
-\ {.]KL  
/* \]bAXa{ p  
**Utility.java ;[pY>VJ(  
*/ $\:;N]Cs~0  
package NetFox; W!@*3U]2R  
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public class Utility { Rn(6Fk?   
;3~+M:{2  
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public Utility() 7RE'KH_$  
{ IEbk_-h[  
&w4~0J>v!  
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} d~ m,hCTe  
W7R`})F  
//线程睡眠 /j}"4_.8  
public static void sleep(int nSecond) H Pvs~`>V  
{ ak_&\'P  
try{ 0+H4sz%.  
Thread.sleep(nSecond); Z4@%0mFll  
} Dht,!LVb;  
catch(Exception e) o3=2`BvJ  
{ qKL:#ny  
e.printStackTrace (); ;ty08D/  
} ONc-jU^  
} gGdt&9z %  
2|n)ZP2cp  
//日志 /*$B  
public static void log(String sMsg) 1-!q,q  
{ 5Xe1a'n5]  
System.err.println(sMsg); |ORro r}  
} J
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oZ CvEVUk  
,)u7PMs  
public static void log(int sMsg) ZKk*2EK]2z  
{ ysHmi{V~  
System.err.println(sMsg); OVy ZyZ#  
} {y>o6OTITR  
} E:!qncL:  
.66_g@1  
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/* ,p3moD 3  
**TestMethod.java cz{5-;$9Z  
*/ IRq@~vdt)  
package NetFox; f>i" j  
S(&]?!  
il403Ae0  
public class TestMethod { IN{ 1itE  
*{#l0My  
O /S:S  
public TestMethod() czp
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{ ///xx/weblogic60b2_win.exe K1*oYHB  
try{ v \xuq`  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {(00,6M)i  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); h3udS{9'8  
SiteFileFetch fileFetch = new SiteFileFetch(bean); \os iY^  
fileFetch.start(); 5:T)hoF@  
} <E&[sQ|3  
catch(Exception e){e.printStackTrace ();} c;M&;'#x  
94Hs.S)  
"{1SDbwmMo  
} Ho_ 2zx:8b  
mh5ozv$  
+6i~Rx>  
public static void main(String[] args) 7K.in3M(  
{ !+F6Bf  
new TestMethod(); Bkq3-rX\  
} ea\b7a*  
} JiXkW%  
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