http断点续传简单实现（java)

/* M .mf
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**SiteFileFetch.java #@Jq~$N|  
*/ Ad_hKO  
package NetFox; M8(t'jN  
import java.io.*; 4H
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import java.net.*; 37o;;
 
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public class SiteFileFetch extends Thread { l]8uk^E  
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SiteInfoBean siteInfoBean = null; //文件信息Bean *$g-:ILRuZ  
long[] nStartPos; //开始位置 uVrd i?3  
long[] nEndPos; //结束位置  }.6[qk  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 wFZP,fQ9l  
long nFileLength; //文件长度 &tj!*k'  
boolean bFirst = true; //是否第一次取文件 4.t-i5
  
boolean bStop = false; //停止标志
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File tmpFile; //文件下载的临时信息 Ysv" 6b}  
DataOutputStream output; //输出到文件的输出流 ew4U)2J+  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） >z@0.pN]7  
public SiteFileFetch(SiteInfoBean bean) throws IOException jse&DQ  
{ S)@j6(HC4  
siteInfoBean = bean; sQZhXaMa $  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 5r^
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tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Cw&KVw*  
if(tmpFile.exists ()) H qx-;F~0  
{ xJ.M;SF4  
bFirst = false; utV_W&  
read_nPos(); IH+|}z4N?>  
} + {'.7#  
else x[e<} 8'$(  
{ nqUV  
nStartPos = new long[bean.getNSplitter()]; Zj'9rXhrM1  
nEndPos = new long[bean.getNSplitter()]; m)v&v6  
} 'm$L Ij?@  
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} 5v*\Zr5ha  
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public void run() b&U62iq  
{ 2D5StCF$O  
//获得文件长度 #Gi$DMW  
//分割文件 [Y`W  
//实例FileSplitterFetch ,I;>aE<#  
//启动FileSplitterFetch线程 x]j W<A  
//等待子线程返回 xyXa .  
try{ 3Jn;}  
if(bFirst) ]6j{@z?{  
{ C;yZ  
nFileLength = getFileSize(); #GFr`o0$^  
if(nFileLength == -1) wC'Szni  
{ -mh3DhJ,  
System.err.println("File Length is not known!"); *{5fq_  
} (/$^uWj  
else if(nFileLength == -2) RxQ*  
{ ~&uHbTq  
System.err.println("File is not access!"); Dw"\/p:-3  
} 7zj{wp!  
else nO-#Q=H,  
{ h{qgEIk&  
for(int i=0;i<nStartPos.length;i++)  rPm x  
{ yB!dp;gM{  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); x4O~q0>:Le  
} +kD R.E:  
for(int i=0;i<nEndPos.length-1;i++) /x *3}oI  
{ 3XNCAb2  
nEndPos = nStartPos[i+1]; DHRlWQox  
} * v#o  
nEndPos[nEndPos.length-1] = nFileLength; rvM{M/4  
} nJ;.Td  
} .6J$,.Ig  
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# f\rt   
//启动子线程 FP>2C9:d
 
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 7xR\kL.,  
for(int i=0;i<nStartPos.length;i++) G#$-1"!`  
{ _yT Ed"$  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), !<F

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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), fV~[;e;U.  
nStartPos,nEndPos,i);
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Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ! dgNtI@  
fileSplitterFetch.start(); 1Z&(6cDY8M  
} W*Y/l~x}  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), $:^td/p J  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Ho]su?  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ;AG()NjOO:  
nEndPos = " + nFileLength); 19] E 5'AI  
// fileSplitterFetch[nPos.length-1].start(); ee=D1qNu;  
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Uw:"n]G]D?  
//等待子线程结束  0+8e,  
//int count = 0; |vC~HJpuv'  
//是否结束while循环 E" vS $  
boolean breakWhile = false; 2KZneS`  
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while(!bStop) K)P%;X  
{ Tj- s4x  
write_nPos(); O".=r}  
Utility.sleep(500); QsW/X0YBv  
breakWhile = true; Fj!U|l\_9  
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for(int i=0;i<nStartPos.length;i++) R|Q?KCI&  
{ 8?C5L8)  
if(!fileSplitterFetch.bDownOver) (-co.  
{ #LNED)Vg  
breakWhile = false; _VXN#
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break; }GIt!PG  
} *K;~!P  
} `0R./|bv\I  
if(breakWhile) o !7va"  
break; d"Y{UE  
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//count++; @j/&m]6%-D  
//if(count>4) f *)Z)6E  
// siteStop(); Q59W#e)  
} W_ZJ0GuE(  
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System.err.println("文件下载结束！"); W{aY}
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} A%-6`>  
catch(Exception e){e.printStackTrace ();} Qwc"[N4H  
} ?h2}#wg  
8;X-)&R  
y
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//获得文件长度 WEpoBP CL  
public long getFileSize() bPMhfK2 %  
{ [00m/fT6  
int nFileLength = -1; ,+ ~W4<f  
try{ I}Q2Vu<  
URL url = new URL(siteInfoBean.getSSiteURL()); J=yT
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HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 3uMy]HUQ  
httpConnection.setRequestProperty("User-Agent","NetFox"); DTs;{c  
}
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int responseCode=httpConnection.getResponseCode(); [Nq*BrzF  
if(responseCode>=400) 2?i7
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{ L0]_X#s>#  
processErrorCode(responseCode); 1 {)Q[#l  
return -2; //-2 represent access is error %>s|j'{  
} azU"G(6y?+  
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String sHeader; |7Kbpj  
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for(int i=1;;i++) C*lJrFpB  
{ 9>$p  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); -Qe Z#w|  
//Utility.log(in.readLine()); A\;U3Zu  
sHeader=httpConnection.getHeaderFieldKey(i); ET >](l9  
if(sHeader!=null) hzC>~Ub5  
{ r_.S>]  
if(sHeader.equals("Content-Length")) *$*ce|V5  
{ Vz[C=_m  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); a: K[ y  
break; @|)Z"m7  
} 8r!zBKq2~  
} nF/OPd  
else ~_a-E  
break; $]8Q(/mbK  
} F<w/PMb  
} RT5T1K08I  
catch(IOException e){e.printStackTrace ();} MY/}-*|  
catch(Exception e){e.printStackTrace ();}  LIdF 0  
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Utility.log(nFileLength); :i7;w%
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return nFileLength; *owU)  
} |D
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&-
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//保存下载信息（文件指针位置） u-C)v*#L  
private void write_nPos() i@CxI<1'  
{ L.WljNo  
try{ 39jG8zr=Z[  
output = new DataOutputStream(new FileOutputStream(tmpFile)); TB^$1C  
output.writeInt(nStartPos.length); w*MpX U<  
for(int i=0;i<nStartPos.length;i++) wdZ/Xp9]  
{ t0I{q0  
// output.writeLong(nPos); =rK+eG#,  
output.writeLong(fileSplitterFetch.nStartPos); >OK^D+v"j  
output.writeLong(fileSplitterFetch.nEndPos); 8.~kK<)!  
} yOKI*.}  
output.close(); abEmRJTmW  
} -!9G0h&i|  
catch(IOException e){e.printStackTrace ();}  Mc}^LDX  
catch(Exception e){e.printStackTrace ();} bJ;'`sw1  
} =I~mKn  
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//读取保存的下载信息（文件指针位置） YAmb`CP  
private void read_nPos() >"<Wjr8W!$  
{ 3yXY.>'  
try{ EZ`{
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DataInputStream input = new DataInputStream(new FileInputStream(tmpFile));  RX5dO%  
int nCount = input.readInt(); CWS4lx  
nStartPos = new long[nCount]; b_):MQ1
{  
nEndPos = new long[nCount]; 4'Zp-k?5`  
for(int i=0;i<nStartPos.length;i++) d`6 'Z  
{ V470C@  
nStartPos = input.readLong(); +t;7tQDVB  
nEndPos = input.readLong(); Xs?o{]Fe  
} "wHFN>5B  
input.close(); ~3 bPIg7D  
} E+JqWR5  
catch(IOException e){e.printStackTrace ();} :/Qq@]O>  
catch(Exception e){e.printStackTrace ();} ?pZOeqqu$  
} kSh( u  
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private void processErrorCode(int nErrorCode) b%5f&N  
{ OBAi2Vw  
System.err.println("Error Code : " + nErrorCode); &8 x-o,  
} B93+BwN>95  
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//停止文件下载 O1mKe%'|  
public void siteStop() ,4oo=&  
{ bY0|N[g  
bStop = true; o0vUj  
for(int i=0;i<nStartPos.length;i++) _ORvo{[:  
fileSplitterFetch.splitterStop(); ;d9QAN&0}  
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#Vha7  
} #YOA`m,'  
} E\,
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//负责部分文件的抓取 1y4  
**FileSplitterFetch.java ^`>/.gL  
*/ $p?aVO  
package NetFox; {!dVDf_  
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import java.io.*; h2""9aP!  
import java.net.*; 5[u]E~Fl}  
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public class FileSplitterFetch extends Thread { hfy_3}_  
b%/ 1$>_  
{jX2}  
String sURL; //File URL Per1
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long nStartPos; //File Snippet Start Position >J>[& zS  
long nEndPos; //File Snippet End Position %-0t?/>  
int nThreadID; //Thread's ID ;BIY^6,7e  
boolean bDownOver = false; //Downing is over .h4 \Y A  
boolean bStop = false; //Stop identical w:Kl6"c  
FileAccessI fileAccessI = null; //File Access interface q#=(e:aCb  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException s}% M4  
{ P}7'm M  
this.sURL = sURL; fx>4  
this.nStartPos = nStart; p"ZG%Ow5Q]  
this.nEndPos = nEnd; w=J3=T@TD  
nThreadID = id; :A'y+MnK<  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ';=O 0)u  
} '(L7;+E  
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public void run() KNIn:K^/  
{ 5,6"&vU,  
while(nStartPos < nEndPos && !bStop) [ ~&/s:Vvo  
{ ah+iZ}E%  
5S--'=fu+  
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try{ xx%j.zDI]  
URL url = new URL(sURL); r #cGop]  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); _8_R 1s  
httpConnection.setRequestProperty("User-Agent","NetFox"); psMvq@>  
String sProperty = "bytes="+nStartPos+"-"; *6DB0X_-}  
httpConnection.setRequestProperty("RANGE",sProperty); g~A`N=r;h  
Utility.log(sProperty); -:y,N 9^  
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InputStream input = httpConnection.getInputStream(); T <ET )
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//logResponseHead(httpConnection); &AbNWtCV+G  
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byte[] b = new byte[1024]; oHn Ky[1  
int nRead; =.]4;z  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) SmSH2m-  
{ U/l&tmIVY  
nStartPos += fileAccessI.write(b,0,nRead); 'Xq|Kf (  
//if(nThreadID == 1) X=fYWj[H,  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); EE'io5\et  
} +Kbjzh3<wG  
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Utility.log("Thread " + nThreadID + " is over!"); y''z5['  
bDownOver = true; X
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//nPos = fileAccessI.write (b,0,nRead); &H/'rd0M  
} S8j{V5R'  
catch(Exception e){e.printStackTrace ();} GM f `A,>  
} M{T-iW"  
} 4-H+vNG{%  
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//打印回应的头信息 ieCEo|b  
public void logResponseHead(HttpURLConnection con) 70tH:Z)"  
{ WX|`1b  
for(int i=1;;i++) ~^fZx5  
{ l$pm_%@2]  
String header=con.getHeaderFieldKey(i); G[I"8iS,  
if(header!=null) zFff`]^`  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 8_B4?` k  
Utility.log(header+" : "+con.getHeaderField(header)); tm RXgTS  
else EGU 0)<  
break; X296tA>C`  
} 9BBmw(M}  
} kr
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public void splitterStop() ;d"F%M y  
{ Y}|X|!0x  
bStop = true; " h~Zu  
} CiLg]va
 
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} /,&<6c-Q@W  
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/* KD7dye  
**FileAccess.java Tg)|or/%  
*//文件访问(定位，写) O6a<`]F  
package NetFox; wX5tp1 ?1J  
import java.io.*; ipgC RHE  
j8{i#;s!"  
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public class FileAccessI implements Serializable{ GmEJhr.3`=  
cyv`B3}  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 {e9@-  
RandomAccessFile oSavedFile; JZ*/,|1}EC  
long nPos; ju8q?Nyhs  
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public FileAccessI() throws IOException 0c'<3@39k|  
{ KNpl:g3{<Q  
this("",0); +LZLy9iKt  
} 1AfnzGvA  
}mq6]ZrK  
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public FileAccessI(String sName,long nPos) throws IOException xU>WEm2  
{ (X1e5j>Ru  
oSavedFile = new RandomAccessFile(sName,"rw"); 37 ,  
this.nPos = nPos; Ou!2[oe@M  
oSavedFile.seek(nPos); X0H!/SlS  
} {V$|3m>:*  
xPk8$1meZM  
O%zU-_|*  
public synchronized int write(byte[] b,int nStart,int nLen) Cc' 37~6~P  
{ +wvWwie  
int n = -1; m=A(NKZ  
try{ ~tUl}  
oSavedFile.write(b,nStart,nLen); %.Fi4}+O  
n = nLen; q?oP?
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} wQH<gJE/:  
catch(IOException e) (*nT(Adk  
{ [.'|_l  
e.printStackTrace (); <+Dn8  
} 3<Zq ]jk?n  
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return n; EQyC1j  
} LX
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} eJVjuG  
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/* V>)OpvoT#  
**SiteInfoBean.java t?ZI".>  
*/ +xSHL|:b  
package NetFox; ^aMg/.
j  
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4 \K7xM!  
public class SiteInfoBean { S)k*?dQ##R  
*1 ]uH e  
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private String sSiteURL; //Site's URL " 4K(jXq|  
private String sFilePath; //Saved File's Path 5k3n\sqZA  
private String sFileName; //Saved File's Name <fjX[l<Uz  
private int nSplitter; //Count of Splited Downloading File {3p4:*}  
Av$^  
7 60Y$/Wz  
public SiteInfoBean() ?m=N]!n  
{//nSplitter的缺省值为5 #*uL)2nR  
//default value of nSplitter is 5 +p_CN*10H  
this("","","",5); UcDS9f_87  
} P[#e/qnXu|  
TJpD{p}  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 6BHXp# #z  
{ Ovt.!8  
sSiteURL= sURL; M~#gRAUJ  
sFilePath = sPath; %@ODs6 R0  
sFileName = sName; mpEK (p  
this.nSplitter = nSpiltter; nFg~< $d  
!/*\}\'4  
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} >~sI8czR*  
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public String getSSiteURL() GR.^glG?6  
{ kr5">"7  
return sSiteURL; }b"yU#`Q\  
} Y3cMC)  
7qLpZ/  
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public void setSSiteURL(String value) %2/EaaR  
{ ksqQM
 
sSiteURL = value; `$<.pOm  
} HTcb_a  
2K6qY)/_  
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public String getSFilePath() <X^
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{ eIEeb,#i  
return sFilePath; q&-`,8#  
} |`,2ri*5A  
|=ba9&q  
ufZDF=$
7  
public void setSFilePath(String value) =/+-<px  
{ j'<<4.(  
sFilePath = value; gHEu/8E  
} x0D*U?A  
sPQQ"|wU  
)0W{]2  
public String getSFileName() xJvmhN/c  
{ L>NL:68yN  
return sFileName; |A9F\A->4  
} x8\?}UnB  
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public void setSFileName(String value) D~iz+{Q4  
{ -1_)LO&H  
sFileName = value; $q{!5-e  
} _QE qk@ql  
x7w4[QYw  
xY8$I6  
public int getNSplitter() Jbg/0|1  
{ J26VnK  
return nSplitter; A_ZY=jP   
} a=1@*ID  
)5JFfp)#  
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public void setNSplitter(int nCount) G]tn i  
{ Xp% v.M  
nSplitter = nCount; tBWrL{xLe  
} rmm0/+jY  
} NiK4d{E&  
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/* ~2N"#b&J  
**Utility.java _
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*/ qLG&WB  
package NetFox; A#<?4&  
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public class Utility { 'n]w"]|  
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@)M9IOR  
public Utility() D|p9qe5%  
{ 9};8?mucr  
,WYPU  
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} ~P,lz!he_  
,HV(l+k {|  
//线程睡眠 0<@KG8@hI;  
public static void sleep(int nSecond) IdYt\^@>  
{ RJ&RTo  
try{ xn(kKB.  
Thread.sleep(nSecond); At>DjKx]O  
}
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catch(Exception e) xml7Uarc  
{ pRpBhm;iJ  
e.printStackTrace (); m,w A:o$'  
} hEH?[>9  
} rfg'G&A(  
 `25yE/  
//日志 69Ne
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public static void log(String sMsg) w3_>VIZJl  
{ pa3{8x{9m  
System.err.println(sMsg); OLGE!&!>  
} 7U"g3a)=  
2- h{N  
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public static void log(int sMsg) AKfDXy  
{ ((;!<5-`s  
System.err.println(sMsg); Eyqa?$R  
} @n /nH?L  
} 'sKk"bi;0  
$( kF#  
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/* #q$HQ&k  
**TestMethod.java ()?(I?I
I  
*/ n;_sG>N  
package NetFox; v{N`.~,^  
u4?L 67x  
_<V)-Y  
public class TestMethod { F~W6Bp^W  
ueWEc^_>  
3(N$nsi  
public TestMethod() .!3|&V'<  
{ ///xx/weblogic60b2_win.exe P3=G1=47U  
try{ RSRS wkC  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ksUcx4;a@F  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); bsli0FJSh'  
SiteFileFetch fileFetch = new SiteFileFetch(bean); V)k4:H  
fileFetch.start(); o5PO=AN  
} 9Q.Yl&A  
catch(Exception e){e.printStackTrace ();} vn8aFA  
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} 3;9^  
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public static void main(String[] args) f'RX6$}\1X  
{ eM6<%?b  
new TestMethod(); Dml;#'IF3  
} v;{#Q&(  
} _;
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